2008 Physics Recalls

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How many electrons are in Pb A=207 Z= 82 : 

How many electrons are in Pb A=207 Z= 82 A) 82 125 289 D) 207

How many electrons are in Pb A=207 Z= 82 : 

How many electrons are in Pb A=207 Z= 82 A) 82 125 289 D) 207

What determines chemical properties of an atom? : 

What determines chemical properties of an atom? A) Proton B) Neutron C) Orbital electrons D) Isotopes

What determines chemical properties of an atom? : 

What determines chemical properties of an atom? A) Proton B) Neutron C) Orbital electrons D) Isotopes

3) What is the estimated ESE in Gy for 5 minutes of Flouroscopy? : 

3) What is the estimated ESE in Gy for 5 minutes of Flouroscopy? .01mGy-.05mGy .1mGy-.5mGy 1mGy-5mGy 10mGy-50mGy 100mGy-500mGy 40-50mGy

3) What is the estimated ESE in Gy for 5 minutes of Flouroscopy? : 

3) What is the estimated ESE in Gy for 5 minutes of Flouroscopy? .01mGy-.05mGy .1mGy-.5mGy 1mGy-5mGy 10mGy-50mGy 100mGy-500mGy Typical ESE is about 5 R/Min 5R=5cGy=50mGy 50mGy x 5min = 250mGy 40-50mGy

The fraction of a given spatial frequency in the object that is actually transferred to the image is defined by which of the following? : 

The fraction of a given spatial frequency in the object that is actually transferred to the image is defined by which of the following? Modulation Transfer Function “The MTF illustrates the function (or percentage) of an object’s contrast that is recorded by the imaging system, as a function of size (i.e., spatial frequency) of the object” (Bushberg p. 271) -Spatial frequency on x axis, and image contrast on y axis

Copper filtration is used in a fluoro case, which of the following is true? : 

Copper filtration is used in a fluoro case, which of the following is true? decrease mA to avoid overheating higher average kEv There is a decrease in the intensity of the low energy photons decreased average energy of the xray beam decreased dose secondary to beam hardening

Copper filtration is used in a fluoro case, which of the following is true? : 

Copper filtration is used in a fluoro case, which of the following is true? decrease mA to avoid overheating higher average kEv There is a decrease in the intensity of the low energy photons decreased average energy of the xray beam decreased dose secondary to beam hardening “because the low-energy x-rays are absorbed by the filters instead of the patient, the radiation dose is reduced” –Bush p.114

Copper is used for x-ray filtration because…? : 

Copper is used for x-ray filtration because…? A) Decreases the low energy x-rays that contribute to dose B) Produces characteristic radiation that is ideal for x-ray imaging C) Decreases the average keV D) It improves image contrast

Copper is used for x-ray filtration because…? : 

Copper is used for x-ray filtration because…? A) Decreases the low energy x-rays that contribute to dose B) Produces characteristic radiation that is ideal for x-ray imaging C) Decreases the average keV D) It improves image contrast

Radiologist in flouro changes from a 15 Cm “Mag” View To 30 Cm “Normal” View But Keep Collimator At 15 Cm FOV. : 

Radiologist in flouro changes from a 15 Cm “Mag” View To 30 Cm “Normal” View But Keep Collimator At 15 Cm FOV. (Decreased Spatial Resolution was not given as a choice) B) Increase Dose C) Increase Noise D) Increase FOV E) decrease scatter F) decrease dose G) increased resolution

Radiologist in flouro changes from a 15 Cm “Mag” View To 30 Cm “Normal” View But Keep Collimator At 15 Cm FOV. : 

Radiologist in flouro changes from a 15 Cm “Mag” View To 30 Cm “Normal” View But Keep Collimator At 15 Cm FOV. (Decreased Spatial Resolution was not given as a choice) B) Increase Dose C) Increase Noise D) Increase FOV E) decrease scatter F) decrease dose G) increased resolution

Collimation remains unchanged at 15 cm. However, image intensifier is changed from “magnification” mode of 15 cm to “normal” mode of 30 cm… : 

Collimation remains unchanged at 15 cm. However, image intensifier is changed from “magnification” mode of 15 cm to “normal” mode of 30 cm… A) Improved resolution B) Decreased noise C) Decreased dose D) Increased scatter

Collimation remains unchanged at 15 cm. However, image intensifier is changed from “magnification” mode of 15 cm to “normal” mode of 30 cm… : 

Collimation remains unchanged at 15 cm. However, image intensifier is changed from “magnification” mode of 15 cm to “normal” mode of 30 cm… A) Improved resolution B) Decreased noise C) Decreased dose “Going from 12-inch to 7-inch mode will increase the exposure rate by a factor of (12/7)2 …so the fluoroscopist should use the largest (FOV) [the least magnification] possible” Bush p. 237 “Increase noise, decrease dose” (Duke recall) D) Increased scatter

If you want to decrease the noise by a factor of 4 then you must increase the number of x-rays incident on the detector by? Other people remembered increasing the mAs by a factor of? : 

If you want to decrease the noise by a factor of 4 then you must increase the number of x-rays incident on the detector by? Other people remembered increasing the mAs by a factor of? A) 2 B) 4 C) 16 D) 32

If you want to decrease the noise by a factor of 4 then you must increase the number of x-rays incident on the detector by? : 

If you want to decrease the noise by a factor of 4 then you must increase the number of x-rays incident on the detector by? A) 2 B) 4 C) 16 Noise (Quantum mottle) = “factor of”/(radiation dose or # xrays)0.5 Ex: to reduce the noise (Quantum mottle) by half, you must increase radiation to form the image by four = 0.5=“factor of”/(x) 0.5 or x=“factor of”22 = “factor of” 4 So for our problem, to decrease noise by “factor of” 4: N x .25= “factor of”/(x) 0.5 factor of 42 = N = factor of 16 Nickolof p112 D) 32

Advantage/Benefit Of CR Over Screen/Film Radiography? : 

Advantage/Benefit Of CR Over Screen/Film Radiography? A) Ability to adjust displayed contrast B) Increased Resolution C) Less Dose

Advantage/Benefit Of CR Over Screen/Film Radiography? : 

Advantage/Benefit Of CR Over Screen/Film Radiography? A) Ability to adjust displayed contrast (increased dynamic range) B) Increased Resolution C) Less Dose

9) Lateral decentering of a focused grid will cause… : 

9) Lateral decentering of a focused grid will cause… A) Grid cutoff with increased grid ratio B) Loss of primary photons with increased grid ratio C) Decrease in scattered photons

9) Lateral decentering of a focused grid will cause… : 

9) Lateral decentering of a focused grid will cause… A) Grid cutoff with increased grid ratio Alt: “More of the primary beam is deflected with increasing grid ratio” B) Loss of primary photons with increased grid ratio (this is true regardless, so likely a misremembered answer) C) Decrease in scattered photons

10) A 20 cm AP diameter thick pregnant women gets a KUB. What percent of entrance exposure is in the middle of the patient/center of the abd? : 

10) A 20 cm AP diameter thick pregnant women gets a KUB. What percent of entrance exposure is in the middle of the patient/center of the abd? 0.01% 2% 10% 50% 25%

10) A 20 cm AP diameter thick pregnant women gets a KUB. What percent of entrance exposure is in the middle of the patient/center of the abd? : 

10) A 20 cm AP diameter thick pregnant women gets a KUB. What percent of entrance exposure is in the middle of the patient/center of the abd? 0.01% 2% 10% 50% 25%

If a patient’s abdomen is 20 cm thick, what is the dose at the midline if the entrance dose (fluoro) is 100? : 

If a patient’s abdomen is 20 cm thick, what is the dose at the midline if the entrance dose (fluoro) is 100? A) 100 B) 50 C) 10 D) 2 E) 1

If a patient’s abdomen is 20 cm thick, what is the dose at the midline if the entrance dose (fluoro) is 100? : 

If a patient’s abdomen is 20 cm thick, what is the dose at the midline if the entrance dose (fluoro) is 100? A) 100 B) 50 C) 10 D) 2 E) 1

What is the attenuation of the fluoro beam in the center of the body? : 

What is the attenuation of the fluoro beam in the center of the body? 1% 10% 50% 99%

What is the attenuation of the fluoro beam in the center of the body? : 

What is the attenuation of the fluoro beam in the center of the body? 1% 10% 50% 99%

Which gives the least amount of radiation dose/ESE? : 

Which gives the least amount of radiation dose/ESE?

Which gives the least amount of radiation dose/ESE? : 

Which gives the least amount of radiation dose/ESE?

12) If the CR cassette is accidentally opened in room light, what is the primary concern? : 

12) If the CR cassette is accidentally opened in room light, what is the primary concern? A) Dust particles B) Damaged phosphor C) Sensitization of phosphor D) Blackened image

12) If the CR cassette is accidentally opened in room light, what is the primary concern? : 

12) If the CR cassette is accidentally opened in room light, what is the primary concern? A) Dust particles B) Damaged phosphor C) Sensitization of phosphor D) Blackened image

If a phosphor cassette is opened in a lighted room before an xray exposure is obtained, what is the problem with the next exposure? : 

If a phosphor cassette is opened in a lighted room before an xray exposure is obtained, what is the problem with the next exposure? A) Will have artifacts from dust B) Be too black C) Be too light

If a phosphor cassette is opened in a lighted room before an xray exposure is obtained, what is the problem with the next exposure? : 

If a phosphor cassette is opened in a lighted room before an xray exposure is obtained, what is the problem with the next exposure? A) Will have artifacts from dust B) Be too black C) Be too light

13 A patient attenuates 98% of the primary radiation beam. The cassette absorbs 50% of the radiation incident on it. Neglecting the inverse square rule, how much of the primary radiation reaches the film : 

13 A patient attenuates 98% of the primary radiation beam. The cassette absorbs 50% of the radiation incident on it. Neglecting the inverse square rule, how much of the primary radiation reaches the film A. 0.1% B. 1% C. 2% D. 5%

13 A patient attenuates 98% of the primary radiation beam. The cassette absorbs 50% of the radiation incident on it. Neglecting the inverse square rule, how much of the primary radiation reaches the film : 

13 A patient attenuates 98% of the primary radiation beam. The cassette absorbs 50% of the radiation incident on it. Neglecting the inverse square rule, how much of the primary radiation reaches the film A. 0.1% B. 1% C. 2% D. 5%

14 Calculate the total MTF from a screen film system with individual MTF of: Glass 1.0, Screen 0.8, Film 0.5, and cassette 0.7. : 

14 Calculate the total MTF from a screen film system with individual MTF of: Glass 1.0, Screen 0.8, Film 0.5, and cassette 0.7. 0.01 1.0 0.26 0.28 0. 4

14 Calculate the total MTF from a screen film system with individual MTF of: Glass 1.0, Screen 0.8, Film 0.5, and cassette 0.7. : 

14 Calculate the total MTF from a screen film system with individual MTF of: Glass 1.0, Screen 0.8, Film 0.5, and cassette 0.7. 0.01 1.0 0.26 0.28 “The overall MTF for the composite system is the product of the individual components” –Nickolof p112 MTFSYSTEM = MTF1 x MTF2 x MTF3 x … = 0.8 x 0.5 x 0.7 x 1.0 = 0.28 0. 4

15 Which one of the configurations will have the highest focal spot blur? : 

15 Which one of the configurations will have the highest focal spot blur?

15 Which one of the configurations will have the highest focal spot blur? : 

15 Which one of the configurations will have the highest focal spot blur? “Focal spot blur increases as an object moves farther from the film and as focal spot size increases” Huda 71 ”Focal spot blur increases w/mag and focal spot size…in magnification rads, it is important to have very small focal spot sizes” Huda 72 “Object furthest from film…likely related to SID/SOD” Duke recall Focal spot blur is = (Magnification-1) x F (F = focal spot ) Magnification = SID/SOD

Using the graph what KvP would you use? : 

Using the graph what KvP would you use? 60 70 80 90 100 40 a b 0 60 80 90 100 44. Shown: X-ray spectrum with maximum x-ray energy at 90 keV. For a tungsten anode, what is the applied voltage to give this spectrum? 65 kVp 70 kVp 90 kVp 100 kVp 120 kVp

Using the graph what KvP would you use? : 

Using the graph what KvP would you use? 60 70 80 90 100 40 a b 0 60 80 90 100

Which of the following fluoroscopy set-ups will result in the highest patient entrance skin exposure? : 

Which of the following fluoroscopy set-ups will result in the highest patient entrance skin exposure?

Which of the following fluoroscopy set-ups will result in the highest patient entrance skin exposure? : 

Which of the following fluoroscopy set-ups will result in the highest patient entrance skin exposure?

Focal spot blur (or resolution) is 0.25 mm. How many line pairs per mm do you have? : 

Focal spot blur (or resolution) is 0.25 mm. How many line pairs per mm do you have? A 1 lp/mm B 2 lp/mm C 2.5 lp/mm D 4 lp/mm E 6 lp/mm

A system’s geometric blur is approximately 0.25 mm. To which spatial resolution value does this correspond? : 

A system’s geometric blur is approximately 0.25 mm. To which spatial resolution value does this correspond? A 1 lp/mm B 2 lp/mm F in lp/mm = 1/(2 x D) where D is 0.25 in this case (or potentially FOV/matrix) X = 1/ 2 x .25 = 2 “if you know the size of an object D, you can convert it to spatial frequency (F=1/2 D ) – and if you know the spatial frequency, F, you can convert it to object size (D =1/2F)” -bushberg p270 C 2.5 lp/mm D 4 lp/mm E 6 lp/mm

Slide 46: 

Huda 70: -Spatial resolution is the ability of an imaging system to resolve to adjacent high-contrast objects as discrete entities. -Also known as high-contrast resolution, blur, and modulation transfer function (MTF) -Focal spot size, screen thickness, and patient motion are the most important factors -Most often expressed in lp/mm, a measure of spatial frequencies -High-contrast resolution is estimated using a parallel bar phantom: *One lp/mm has 0.5 mm lead bars separated by 0.5 mm of radiolucent material *Two lp/mm has 0.25 mm lead bars separated by 0.25 mm, and so on

19 Magnification radiography is limited by what? (What limits geometric unsharpness per duke?) : 

19 Magnification radiography is limited by what? (What limits geometric unsharpness per duke?) A Focal spot size

19 Magnification radiography is limited by what? : 

19 Magnification radiography is limited by what? A Focal spot size

20 The number of DSA images that you can acquire is limited by : 

20 The number of DSA images that you can acquire is limited by A Heating of the anode B Rotation speed of the anode

20 The number of DSA images that you can acquire is limited by : 

20 The number of DSA images that you can acquire is limited by A Heating of the anode?? Not 100% sure about this one since “during flouroscopy, the heating is counterbalanced by cooling as flouro uses lower mA… usually, xray tube never overheats during flouroscopy” B Rotation speed of the anode

21 After performing a radiograph using a system with AEC, the area of interest is underexposed (too light). What causes too light an area of interest? : 

21 After performing a radiograph using a system with AEC, the area of interest is underexposed (too light). What causes too light an area of interest? A) Too low mA B) AEC setting was incorrect C) Too high filtration

21 After performing a radiograph using a system with AEC, the area of interest is underexposed (too light). What causes too light an area of interest? : 

21 After performing a radiograph using a system with AEC, the area of interest is underexposed (too light). What causes too light an area of interest? A) Too low mA B) AEC setting was incorrect C) Too high filtration

22 When you use tighter collimation, what happens? : 

22 When you use tighter collimation, what happens? A Decreased scatter

22 When you use tighter collimation, what happens? : 

22 When you use tighter collimation, what happens? A Decreased scatter

23 In screen film radiology, noise predominates from : 

23 In screen film radiology, noise predominates from A Photons entering the patient B Photons exiting the patient C Photons incident on the screen D Photons absorbed by the screen E Light produced by the screen after photon absorption

23 In screen film radiology, noise predominates from : 

23 In screen film radiology, noise predominates from A Photons entering the patient B Photons exiting the patient C Photons incident on the screen D Photons absorbed by the screen “Noise is determined by how many x-ray photons are absorbed by the screen to produce the image” -Huda p74 E Light produced by the screen after photon absorption The random variations of photons incident on a radiation detector is known as quantum mottle Huda 73

24 When you increase the II detector diameter from 15 to 30 cm : 

24 When you increase the II detector diameter from 15 to 30 cm A. The monitor brightness is increased B. Patient dose is decreased C. Noise is decreased

24 When you increase the II detector diameter from 15 to 30 cm : 

24 When you increase the II detector diameter from 15 to 30 cm A. The monitor brighness is increased The minifcation gain is increased BG = MG x Flux = (Di/Do)^2 x Flux B. Patient dose is decreased Yes and no – because the ABC would turn down the mAs to keep the brightness constant but you are covering a larger portion of the patient C. Noise is decreased No, noise is increased because the mAs/kVp are decreased with icnreased minification gain + flux gain

Which of the following imaging modalities makes use of this phantom? : 

Which of the following imaging modalities makes use of this phantom? A Nuclear medicine B CT C Standard radiography D US E Mammography

Which of the following imaging modalities makes use of this phantom? : 

Which of the following imaging modalities makes use of this phantom? A Nuclear medicine B CT C Standard radiography D US E Mammography

Photostimulable phosphors are used in : 

Photostimulable phosphors are used in A) Angiography B) Computed radiography D) Computed Tomography C) Nuclear Medicine

Photostimulable phosphors are used in : 

Photostimulable phosphors are used in A) Angiography B) Computed radiography D) Computed Tomography C) Nuclear Medicine

27 How do you increase the visibility of a large low contrast object?Or For a low contrast 4cm diameter hepatoma on a noncontrast enhanced CT scan, visibility will be increased by : 

27 How do you increase the visibility of a large low contrast object?Or For a low contrast 4cm diameter hepatoma on a noncontrast enhanced CT scan, visibility will be increased by A. Increasing slice thickness B. Increasing cutoff frequency of ramp filter C. Decreasing mAs D. Decreasing scan time

27 How do you increase the visibility of a large low contrast object?Or For a low contrast 4cm diameter hepatoma on a noncontrast enhanced CT scan, visibility will be increased by : 

27 How do you increase the visibility of a large low contrast object?Or For a low contrast 4cm diameter hepatoma on a noncontrast enhanced CT scan, visibility will be increased by A. Increasing slice thickness(increase mA would also be correct) B. Increasing cutoff frequency of ramp filter C. Decreasing mAs D. Decreasing scan time

What is the cause of the artifact on the above mammogram : 

What is the cause of the artifact on the above mammogram Processor-related plus-density Wet roller or surface drying marks improper developer fixation Static electricity

What is the cause of the artifact on the above mammogram : 

What is the cause of the artifact on the above mammogram Processor-related plus-density Wet roller or surface drying marks improper developer fixation Static electricity

29 Which of the following MQSA tests must be performed most often? : 

29 Which of the following MQSA tests must be performed most often? A. Sensitometry B. Repeat Analysis C. Film-screen contact D. Darkroom fog.

29 Which of the following MQSA tests must be performed most often? : 

29 Which of the following MQSA tests must be performed most often? A. Sensitometry “techs must do periodic QC as follows: daily= sensitometry, viewing conditions, darkroom cleaning weekly= phantom evaluation Quarterly= fixer retention and repeat rate analysis Semiannually= darkroom light leakage, film-screen contact, compression B. Repeat Analysis Quarterly C. Film-screen contact Semiannually D. Darkroom fog…. Technically this is also done daily if you are talking about the base+fog done during the sensitometry strip evaluation…

Per MQSA, which of these is tested most frequently? : 

Per MQSA, which of these is tested most frequently? Resolution Peak kVp of tube Measurement of average glandular dose Contrast

Per MQSA, which of these is tested most frequently? : 

Per MQSA, which of these is tested most frequently? Resolution - annually Peak kVp of tube - annually Measurement of average glandular dose - annually Contrast Yes, but tricky as this is one of the steps in the daily sensitometry analysis. To review, the daily things consist of: Prosessor QC This means exposing and developing sensitometry strips and measuring the speed, contrast, base+fog levels Huda p114

Most frequent QC task required in mammo? : 

Most frequent QC task required in mammo? Spatial resolution Contrast resolution Sensitometer Dose Image quality

Most frequent QC task required in mammo? : 

Most frequent QC task required in mammo? Spatial resolution Contrast resolution Sensitometer Dose Image quality

In mammo, what is most important QC factor? : 

In mammo, what is most important QC factor? Processor

30 What target material gives you the highest energy characteristic x-rays at 35 kVp? : 

30 What target material gives you the highest energy characteristic x-rays at 35 kVp? A Molybdenum B Tungsten C Carbon D Beryllium

30 What target material gives you the highest energy characteristic x-rays at 35 kVp? : 

30 What target material gives you the highest energy characteristic x-rays at 35 kVp? A Molybdenum (Molybdenum k-edge = 20 keV)…correct per duke recalls B Tungsten C Carbon D Beryllium

31 Most QC problems or artifacts in mammography occur where? : 

31 Most QC problems or artifacts in mammography occur where? a. processor b. compression c. grid bucky d. kvp c. mas

31 Most QC problems or artifacts in mammography occur where? : 

31 Most QC problems or artifacts in mammography occur where? a. processor“Mammography films have relatively thick single emulsions, which makes them much more sensitive to processor artifacts” Huda 108 b. compression c. grid bucky d. kvp c. mAs d. screen film contact e. dose f. focal spot size

32 How do you measure screen film contact in mammography? : 

32 How do you measure screen film contact in mammography? A Wire mesh

32 How do you measure screen film contact in mammography? : 

32 How do you measure screen film contact in mammography? A Wire mesh

33 A direct digital mammogram is taken at an AEC setting of -2 instead of zero (normal). Which will occur? : 

33 A direct digital mammogram is taken at an AEC setting of -2 instead of zero (normal). Which will occur? A. The noise will increase B. The dose will be higher C. Decreased density of film and the image will be lighter. D. Increased density of film and the image will be darker. E. Resolution will improve

33 A direct digital mammogram is taken at an AEC setting of -2 instead of zero (normal). Which will occur? : 

33 A direct digital mammogram is taken at an AEC setting of -2 instead of zero (normal). Which will occur? A. The noise will increase… (one recall had “Increased quantum mottle” as answer) B. The dose will be higher C. Decreased density of film and the image will be lighter. D. Increased density of film and the image will be darker. E. Resolution will improve

34 To increase the spatial resolution in mammography, what can be attempted? : 

34 To increase the spatial resolution in mammography, what can be attempted? A Change the mA B Change the kVp C Increase the grid ratio

34 To increase the spatial resolution in mammography, what can be attempted? : 

34 To increase the spatial resolution in mammography, what can be attempted? A Change the mA B Change the kVp C Increase the grid ratio ????

35 The most common type of detector used in modern MDCT? : 

35 The most common type of detector used in modern MDCT? A Gas detectors B Solid state detector C NaI(Tl) D Ion chambers E Selenium

35 The most common type of detector used in modern MDCT? : 

35 The most common type of detector used in modern MDCT? A Gas detectors B Solid state detector Only solid-state detectors are used for fourth-generation scanners, which require thin detectors because of the detection geometry…the most common material used in solid-state detectors is cadmium tungstate (CdWO4)” Huda 125 “Multiple detector array CT scanners make use of solid-state detectors” Bush -342 “A solid state detector is composed of a scintillator coupled tightly to a photodetector” Bush -340 C NaI(Tl) D Ion chambers E Selenium

36 What is the maximal spatial resolution of a chest CT? : 

36 What is the maximal spatial resolution of a chest CT? A 0.1-.2 LP/mm B 1-2 LP/mm C 0.01 - .02 LP/mm D > 5 LP/mm

36 What is the maximal spatial resolution of a chest CT? : 

36 What is the maximal spatial resolution of a chest CT? A 0.1-.2 LP/mm B 1-2 LP/mm “spatial resolution of CT scanners is only about 0.5-1.2 LP/mm. The spatial resolution is much worse than that of film-screen or CR/DR systems… the main advantage is that they can visualize low contrast structures in the range of 0.3-0.5%!!! Nickolof p169 C 0.01 - .02 LP/mm D > 5 LP/mm

Duke version:What is the contrast resolution of CT? : 

Duke version:What is the contrast resolution of CT? 0.01% 0.1 % 0.5% 1% 5%

Duke version:What is the contrast resolution of CT? : 

Duke version:What is the contrast resolution of CT? 0.01% 0.1 % 0.5% “spatial resolution of CT scanners is only about 0.5-1.2 LP/mm. The spatial resolution is much worse than that of film-screen or CR/DR systems… the main advantage is that they can visualize low contrast structures in the range of 0.3-0.5%!!! Nickolof p169 “Under ideal circumstances, a lesion that differs by about 5 HU from its surroundings, corresponding to a 0.5% difference in attenuation, can be detected.” Huda 129 1% 5%

37 What is the typical windowing for CT of the brain? : 

37 What is the typical windowing for CT of the brain? A -1000 - +1000 B -20 – 100 C -1000-0 D 0-1000

37 What is the typical windowing for CT of the brain? : 

37 What is the typical windowing for CT of the brain? A -1000 - +1000 B -20 – 100 C -1000-0 D 0-1000

38 MDCT of the chest demonstrates unsharp Pulmonary arteries. Which method will improve resolution of the arteries? : 

38 MDCT of the chest demonstrates unsharp Pulmonary arteries. Which method will improve resolution of the arteries? A) cardiac gating B) increase mas C) appropriate post-processing filtration

38 MDCT of the chest demonstrates unsharp Pulmonary arteries. Which method will improve resolution of the arteries? : 

38 MDCT of the chest demonstrates unsharp Pulmonary arteries. Which method will improve resolution of the arteries? A) cardiac gating B) increase mas C) appropriate post-processing filtration

39 What determines minimal slice thickness in MDCT? : 

39 What determines minimal slice thickness in MDCT? A Collimator width B FOV C Collimator thickness D Detector width E Detector pitch

39 What determines minimal slice thickness in MDCT? : 

39 What determines minimal slice thickness in MDCT? A Collimator width B FOV C Collimator thickness… for single detector CT: “section thickness (collimation) effects resolution in the longitudinal plane and is important in sagittal and coronal reconstructions” Huda 128 D Detector width “section thickness in multislice CT is determined by detector width rather than by collimation thickness” Huda 127 E Detector pitch

What determines the smallest slice thickness possible in MDCT? : 

What determines the smallest slice thickness possible in MDCT? Pre-patient collimation Post-patient collimation Detector size Linear attenuation factor kVp

What determines the smallest slice thickness possible in MDCT? : 

What determines the smallest slice thickness possible in MDCT? Pre-patient collimation Post-patient collimation Detector size Linear attenuation factor kVp

CT pixel values most closely depends on…? : 

CT pixel values most closely depends on…? Mass attenuation coefficient kVp mAs Linear attenuation coefficient Detector size

CT pixel values most closely depends on…? : 

CT pixel values most closely depends on…? Mass attenuation coefficient kVp mAs Linear attenuation coefficient “The brightness of each pixel in the image is directly related to the average attenuation coefficient of the tissue in the voxel…Each pixel is normally represented by 12 bits, or 4,096 gray levels” Huda 122 Detector size

What is the typical smallest CT pixel size? : 

What is the typical smallest CT pixel size? 0.1 mm 0.5 mm 1 mm 5 mm 10 mm

What is the typical smallest CT pixel size? : 

What is the typical smallest CT pixel size? 0.1 mm…duke recall did not give an answer; “CT pixel size is determined by FOV/matrix size which is generally 512 x 512…pixel sizes are 0.5 mm for a 25 cm FOV head scan and 0.8 mm for 40 cm FOV body scan” Huda 122 0.5 mm 1 mm 5 mm 10 mm

40 The CT Houndsfield unit value is linearly related to: : 

40 The CT Houndsfield unit value is linearly related to: a. mass density b. electron density c. linear attenuation coefficient d. mass attenuation coefficient e. effective atomic number

40 The CT Houndsfield unit value is linearly related to: : 

40 The CT Houndsfield unit value is linearly related to: a. mass density b. electron density c. linear attenuation coefficient… “CT images are maps of relative linear attenuation values of tissues” –Huda 121 d. mass attenuation coefficient e. effective atomic number

41 What is the contrast resolution of CT? : 

41 What is the contrast resolution of CT? A 0.2% B 0.5% C 2% D 5% E 10%

41 What is the contrast resolution of CT? : 

41 What is the contrast resolution of CT? A 0.2% B 0.5% “Under ideal circumstances, a lesion that differs by about 5 HU from its surroundings, corresponding to a 0.5% difference in attenuation, can be detected” Huda 129 C 2% D 5% E 10%

42 In CT fluoroscopy, if you halve the slice thickness but keep the signal to noise ratio the same, the patient dose will. : 

42 In CT fluoroscopy, if you halve the slice thickness but keep the signal to noise ratio the same, the patient dose will. A Same B Increase by 4 C Increase by 2 D Decrease by 2 E Increase by 8

42 In CT fluoroscopy, if you halve the slice thickness but keep the signal to noise ratio the same, the patient dose will. : 

42 In CT fluoroscopy, if you halve the slice thickness but keep the signal to noise ratio the same, the patient dose will. A Same B Increase by 4 C Increase by 2 D Decrease by 2 E Increase by 8

An ionization chamber is used to : 

An ionization chamber is used to A measure the activity in the syringe that will be injected in a patient B measure the range of x-ray energies C perform wipe test

An ionization chamber is used to : 

An ionization chamber is used to A measure the activity in the syringe that will be injected in a patient “well-type ionization chambers are called dose calibrators and used in nuc med to assay activities of radiopharmaceuticals to be administered to patients” –Bush p634 B measure the range of x-ray energies C perform wipe test

What is this machine use for? : 

What is this machine use for? Calculating if radioactive waste has fully decayed and can be disposed of Detecting background radiation in a hot lab Measuring contamination in a wipe test Thyroid dose

What is this machine use for? : 

What is this machine use for? Calculating if radioactive waste has fully decayed and can be disposed of Detecting background radiation in a hot lab Measuring contamination in a wipe test (well counter) Thyroid dose

45 Which is directly proportional to the dose from the source organ following the administration of a radiopharmaceutical? : 

45 Which is directly proportional to the dose from the source organ following the administration of a radiopharmaceutical? A Biological half life B Physical half life C Cumulative activity D Organ sensitivity

45 Which is directly proportional to the dose from the source organ following the administration of a radiopharmaceutical? : 

45 Which is directly proportional to the dose from the source organ following the administration of a radiopharmaceutical? A Biological half life B Physical half life C Cumulative activity Acum = Ao x Fraction of dose to organ x 1.44 x Teff….see Primer p 1031 D Organ sensitivity

46 If a Tc-99m generator is eluted at 6 am and noon daily, which of the following is true? : 

46 If a Tc-99m generator is eluted at 6 am and noon daily, which of the following is true? There will be increased aluminum breakthrough at 6 am The eluent will have greater percentage of Tc99 at 6 am (than the noon sample) The generator will be in transient equilibrium at 12 pm The generator will be in secular equilibrium at 6 am. The Tc-99m concentration in the eluants will be the same There will be more Mo contaminant in the 6 am elution

46 If a Tc-99m generator is eluted at 6 am and noon daily, which of the following is true? : 

46 If a Tc-99m generator is eluted at 6 am and noon daily, which of the following is true? There will be increased aluminum breakthrough at 6 am The eluent will have greater percentage of Tc99 at 6 am (than the noon sample) The generator will be in transient equilibrium at 12 pm The generator will be in secular equilibrium at 6 am. The Tc-99m concentration in the eluants will be the same There will be more Mo contaminant in the 6 am elution “Transient equilibrium, in which the activity between the parent (99-Mo) and daughter (99-Tc) are equal, is reached in approximately four half-lives (24 hours)…In transient equilibrium, parent and daughter decay together, with the half-life of the parent” Huda 138 “Secular equilibrium occurs after approximately four half-lives in generator systems in which the half-life of the parent is much greater (100 times) than that of the daughter” Huda 138

47 140 keV photon of Tc99m has what primary interaction with tissue? : 

47 140 keV photon of Tc99m has what primary interaction with tissue? A) Compton scatter B) Photoelectric C) Pair Production D) Coherent scatter

47 140 keV photon of Tc99m has what primary interaction with tissue? : 

47 140 keV photon of Tc99m has what primary interaction with tissue? A) Compton scatter B) Photoelectric C) Pair Production D) Coherent scatter

What is the predominant interaction of an x-ray between 70 and 150 kVp in soft tissue? : 

What is the predominant interaction of an x-ray between 70 and 150 kVp in soft tissue? Photoelectric effect Pair production Compton scattering Others

What is the predominant interaction of an x-ray between 70 and 150 kVp in soft tissue? : 

What is the predominant interaction of an x-ray between 70 and 150 kVp in soft tissue? Photoelectric effect Pair production Compton scattering Others

Regarding diagnostic x-rays from 70 to 120 kVp, what causes the greatest patient dose? : 

Regarding diagnostic x-rays from 70 to 120 kVp, what causes the greatest patient dose? Direct DNA damage Photoelectrons and Compton recoil electrons Tissue heating Scattered x-rays

Regarding diagnostic x-rays from 70 to 120 kVp, what causes the greatest patient dose? : 

Regarding diagnostic x-rays from 70 to 120 kVp, what causes the greatest patient dose? Direct DNA damage Photoelectrons and Compton recoil electrons Tissue heating Scattered x-rays

48 Some SPECT scanners use an internal line radioactive source to… : 

48 Some SPECT scanners use an internal line radioactive source to… A Provide attenuation correction data B Measure dead time C Measure sonogram to detect motion D Assess pixel size

48 Some SPECT scanners use an internal line radioactive source to… : 

48 Some SPECT scanners use an internal line radioactive source to… A Provide attenuation correction data… “…scanning collimated line sources… provide attenuation corrected SPECT images” Bush 710 “several manufacturers provide SPECT cameras with radioactive sources to measure the attenuation through the patient” –Bush p710 B Measure dead time C Measure sonogram to detect motion D Assess pixel size

49 SUV values in PET : 

49 SUV values in PET A) Higher or lower in obese patients B) Decreased in muscle after exercise C) Depends on patient weight, activity administered, region of interest or organ that the activity is being measured in. D) are more accurate if you use the mean instead of the peak

49 SUV values in PET : 

49 SUV values in PET A) Higher or lower in obese patients B) Decreased in muscle after exercise C) Depends on patient weight, activity administered, region of interest or organ that the activity is being measured in… “A number of factors affect SUV measurements. Body weight and composition are obvious factors, with obese patients having higher SUVs than do thin patients for both normal and malignant tissue…” Mettler 375 Body composition and habitus are a source of variability because the conventional SUV normalizes for body weight. Fat, however, has a much lower uptake of FDG (and probably other PET tracers used in oncology) than other tissues. Consequently, the SUV for many tissues shows a strong positive correlation with weight (2, 7). ZasadnyandWahI(2) found, for example, that the SUV of normal liver varied by almost 50% over a range of body weights from 50 to 110 kg. Corrections for this effect have been proposed by Zasadny and Wahl (2) and Kim et al. (7), but such corrections are not used in the majority of published papers that use the SUV. D) are more accurate if you use the mean instead of the peak

50 1 MBq of a radioactive substance will have how many disintegrations? : 

50 1 MBq of a radioactive substance will have how many disintegrations? 1 x 106 per min 3.7 x 106 per min 1 x 106 per sec 3.7 x 106 per sec

50 1 MBq of a radioactive substance will have how many disintegrations? : 

50 1 MBq of a radioactive substance will have how many disintegrations? 1 x 106 per min 3.7 x 106 per min 1 x 106 disintetrations per sec… “The amount of radioactivity present (the number of disintegrations per second) is referred to as activity. In the past, the unit of radioactivity has been the curie (Ci), which is 3.7 x 1010 disintegrations per second…This is being replaced by the becquerel (Bq), which is one disintegration per second.” Mettler 4 1Bq = 1 decay per second Mega = 106 3.7 x 106 per sec

51 Sinogram question. Two figures were given. One figure is a normal sonogram (left), and the other has a horizontal line in the middle and the bottom half was shifted to one side (right). What caused this artifact? : 

51 Sinogram question. Two figures were given. One figure is a normal sonogram (left), and the other has a horizontal line in the middle and the bottom half was shifted to one side (right). What caused this artifact? Motion Non-uniformity Increase pinhole size Photomultiplier tube defect Scintillation crystal defect Power surge

51 Sinogram question. Two figures were given. One figure is a normal sonogram (left), and the other has a horizontal line in the middle and the bottom half was shifted to one side (right). What caused this artifact? : 

51 Sinogram question. Two figures were given. One figure is a normal sonogram (left), and the other has a horizontal line in the middle and the bottom half was shifted to one side (right). What caused this artifact? Motion Non-uniformity Increase pinhole size Photomultiplier tube defect Scintillation crystal defect Power surge

52 Accidental "random" coincidental PET annihilation detection is represented by which diagram? : 

52 Accidental "random" coincidental PET annihilation detection is represented by which diagram?

52 Accidental "random" coincidental PET annihilation detection is represented by which diagram? : 

52 Accidental "random" coincidental PET annihilation detection is represented by which diagram? See fig bush p721

A nuclear medicine technologist wants to measure low counts of activity (in the range of Bqs) in her thyroid, which region of the curve below corresponds to the ideal detector? : 

A nuclear medicine technologist wants to measure low counts of activity (in the range of Bqs) in her thyroid, which region of the curve below corresponds to the ideal detector?

A nuclear medicine technologist wants to measure low counts of activity (in the range of Bqs) in her thyroid, which region of the curve below corresponds to the ideal detector? : 

A nuclear medicine technologist wants to measure low counts of activity (in the range of Bqs) in her thyroid, which region of the curve below corresponds to the ideal detector? 1 = recombination region: not useful as 200-400V are needed to prevent recombination 2= ionization region: collect ALL ion pairs, and this is where EXPOSURE can be measured in mR or R 3= proportional region: creates additional charge by using higher voltages and so the charge is proportional to but greater than the initial ionization and used to assess charged particle radiation like alpha/betas 4= GM region: few ionizations to create large amount of charge – size of charge not related to ionization – used for very small amounts 5= avalanche region: voltage is so high that there are spontaneous discharges

54 What is the difference between PET and SPECT attenuation corrections? : 

54 What is the difference between PET and SPECT attenuation corrections? A. PET depends upon total thickness, while SPECT depends upon depth. B. PET depends upon total thickness, while SPECT depends upon that and depth. C. Both depend upon source depth, but SPECT also depends upon total thickness. D. The only difference is the difference in attenuation from the 511 keV PET photons and the 140 keV SPECT photons.

54 What is the difference between PET and SPECT attenuation corrections? : 

54 What is the difference between PET and SPECT attenuation corrections? A. PET depends upon total thickness, while SPECT depends upon depth. B. PET depends upon total thickness, while SPECT depends upon that and depth. C. Both depend upon source depth, but SPECT also depends upon total thickness. D. The only difference is the difference in attenuation from the 511 keV PET photons and the 140 keV SPECT photons … Don’t know the answer but there is a Great comparison chart Bush 734

55 In PET where is the most variability / greatest degradation of spatial resolution as a result of the kinetic energy of the positron? : 

55 In PET where is the most variability / greatest degradation of spatial resolution as a result of the kinetic energy of the positron? a. brain b. bones c. lungs d.heart

55 In PET where is the most variability / greatest degradation of spatial resolution as a result of the kinetic energy of the positron? : 

55 In PET where is the most variability / greatest degradation of spatial resolution as a result of the kinetic energy of the positron? a. brain b. bones…?? Per duke recall c. lungs d.heart

56 What happens when collimator holes are enlarged? : 

56 What happens when collimator holes are enlarged? Increased sensitivity “Collimators are the major factors in determining the spatial resolution performance, and system sensitivity…Collimator sensitivity is the fraction of gamma rays reaching it from all directions that pass through the holes” “There is generally a tradeoff between collimator sensitivity and spatial resolution” “High-sensitivity collimators are thinner and have larger, and therefore, fewer holes and lower resolution” Huda 143

57 Which of the following components of a gamma camera system has the greatest effect on spatial resolution? : 

57 Which of the following components of a gamma camera system has the greatest effect on spatial resolution? A PMT B Electronics C Collimator D Crystal thickness

57 Which of the following components of a gamma camera system has the greatest effect on spatial resolution? : 

57 Which of the following components of a gamma camera system has the greatest effect on spatial resolution? A PMT B Electronics C Collimator great comparison chart Bush 734 D Crystal thickness

58 What is the main purpose of the PHA : 

58 What is the main purpose of the PHA A Decrease scatter B Decrease pt dose C Improve resolution

58 What is the main purpose of the PHA : 

58 What is the main purpose of the PHA A Decrease scatter The PHA can be set to allow only certain photon energy levels to be counted thus decreasing the Compton scatter…” -Huda p142 B Decrease pt dose C Improve resolution

59 If CT attenuation correction is used for PET : 

59 If CT attenuation correction is used for PET A Must account for different photon energies B Patient dose is decreased C increased quantum mottle D decreased resolution E adjust for different areas of attenuation

59 If CT attenuation correction is used for PET : 

59 If CT attenuation correction is used for PET A Must account for different photon energies B Patient dose is decreased C increased quantum mottle D decreased resolution E adjust for different areas of attenuation

60 3D PET differs from 2D PET in the following regards. : 

60 3D PET differs from 2D PET in the following regards. A Increased sensitivity B Can only do coronal images with 3D C Can only image brain with 2D D More efficient photon detection and counts with 3D E Decreased dead time with 2D images F need septation between detectors in 3D G can’t look at the brain with 2D H 3D uses collimation

60 3D PET differs from 2D PET in the following regards. : 

60 3D PET differs from 2D PET in the following regards. A Increased sensitivity This may also be correct B Can only do coronal images with 3D ?? D More efficient photon detection and counts with 3D This may also be correct. E Decreased dead time with 2D images Yes – “For the same administered activity, the greatly increased interaction rate increases the random coincidence fraction and the dead time count losses… Activity outside the FOV causes few true coincidences but does increase the rate of random (accidental) coincidences and dead-time count losses. Therefore use 3D for low scatter studies like brain or peds.” Bush p727 F need septation between detectors in 3D No. G can’t look at the brain with 2D No. H 3D uses collimation No, 3D has no collimation, 2D does

* Duke alternate: 51. 3D PET imaging differs from 2D PET imaging in which way? : 

* Duke alternate: 51. 3D PET imaging differs from 2D PET imaging in which way? The septa required for 3D are more numerous 3D is more efficient in detecting events 3D PET is far less expensive Coronal reformations are possible only with 3D imaging

* Duke alternate: 51. 3D PET imaging differs from 2D PET imaging in which way? : 

* Duke alternate: 51. 3D PET imaging differs from 2D PET imaging in which way? The septa required for 3D are more numerous 3D is more efficient in detecting events 3D PET is far less expensive Coronal reformations are possible only with 3D imaging

61 If you have an intense region of radiopharmaceutical accumulation outside the region of interest but within the field of view, what can you do? : 

61 If you have an intense region of radiopharmaceutical accumulation outside the region of interest but within the field of view, what can you do? A Put a lead shield over it B Decrease width of pulse height analyzer C Shift the pulse height to greater

61 If you have an intense region of radiopharmaceutical accumulation outside the region of interest but within the field of view, what can you do? : 

61 If you have an intense region of radiopharmaceutical accumulation outside the region of interest but within the field of view, what can you do? A Put a lead shield over it B Decrease width of pulse height analyzer C Shift the pulse height to greater

62 What is the effect of moving a patient closer to the parallel hole collimator? : 

62 What is the effect of moving a patient closer to the parallel hole collimator? Increased spatial resolution Increased sensitivity Increased noise Increased septal penetration

62 What is the effect of moving a patient closer to the parallel hole collimator? : 

62 What is the effect of moving a patient closer to the parallel hole collimator? Increased spatial resolution The size of the image produced by a parallel hole collimator is not affected by the distance of the object from the collimator. However, its spatial resolution degrades rapidly with increasing collimator-to-object distance” Bush 675 Increased sensitivity Increased noise Increased septal penetration

63 What is being tested the adjacent diagram? : 

63 What is being tested the adjacent diagram? Intrinsic flood Extrinsic flood Intrinsic spatial resolution Extrinsic spatial resolution

63 What is being tested the adjacent diagram? : 

63 What is being tested the adjacent diagram? Intrinsic flood … “Intrinsic flood-field images are performed without the collimator. Extrinsic images are performed with the collimator in place” Mettler 50 “Intrinsic uniformity requires removal of the collimator and the placement of Tc99m point source far from the crystal- it measures only crystal uniformity.” –Nickolof p227 Extrinsic flood Intrinsic spatial resolution Extrinsic spatial resolution … “Spatial resolution and linearity are tested weekley, usually by placing a lead grid pattern (bar phantom) between the flood source and the detector head” Mettler 50 “Flood source (Tc99m in water or Co-57 plastic disk directly on collimator = uniformity of both crystal and collimator”

64 One Tesla is how many Gauss : 

64 One Tesla is how many Gauss A 10 B 100 C 1000 D 10,000 E 100,000

64 One Tesla is how many Gauss : 

64 One Tesla is how many Gauss A 10 B 100 C 1000 D 10,000 E 100,000

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? : 

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? A) Ga B) I123 C) Tc99 MAA D) Tc99 HMPAO E) Tl 201

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? : 

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? A) Ga B) I123 C) Tc99 MAA D) Tc99 HMPAO E) Tl 201 See p 554-555 in Mettler

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? : 

65 Which radionuclide if administered to a post partum mother, must she stop breast feeding for two weeks? Tc-99m MAA 12 hours Tc-99m HMPAO ?? I-123 cessation Ga-67 1 monts Xe-33 ?? Ga 1 month I123 If I123 NaI then cessation If I123 MIBG then between 12h and cessation Tc99 Most not needed vs. 6-12h If WBC labeled then between 4h to 2 week to cessation depending on dose I131 Complete cessation In None to one week

66 25 y/o female undergoes 5 MDCT in the past year to rule out Pulmonary embolism. Which tissue/organ is most at risk? : 

66 25 y/o female undergoes 5 MDCT in the past year to rule out Pulmonary embolism. Which tissue/organ is most at risk? a. pericardium b. breast c. bone marrow d. Lungs

66 25 y/o female undergoes 5 MDCT in the past year to rule out Pulmonary embolism. Which tissue/organ is most at risk? : 

66 25 y/o female undergoes 5 MDCT in the past year to rule out Pulmonary embolism. Which tissue/organ is most at risk? a. pericardium b. breast c. bone marrow d. Lungs

67 A female comes to the emergency room with nausea and vomiting and because her radon detector at home read above the normal level. What should you do? : 

67 A female comes to the emergency room with nausea and vomiting and because her radon detector at home read above the normal level. What should you do? A use thyroid detector set at polonium energey level B use thyroid detector set at radon energy level C use Geiger muller detector D get a pregnancy test E Bone scan with level of detector set at polonium F Thyroid uptake test G Administer potassium iodine H Administer activated charcoal

67 A female comes to the emergency room with nausea and vomiting and because her radon detector at home read above the normal level. What should you do? : 

67 A female comes to the emergency room with nausea and vomiting and because her radon detector at home read above the normal level. What should you do? A use thyroid detector set at polonium energey level B use thyroid detector set at radon energy level C use Geiger muller detector D get a pregnancy test E Bone scan with level of detector set at polonium F Thyroid uptake test G Administer potassium iodine H Administer activated charcoal

68 What is the natural incidence of birth defects without any radiation given? : 

68 What is the natural incidence of birth defects without any radiation given? a. 0.6 % b. 6% c. .0006% d. 0.06%

68 What is the natural incidence of birth defects without any radiation given? : 

68 What is the natural incidence of birth defects without any radiation given? a. 0.6 % b. 6% The natural incidence of birth defects is approximately 3 to 6 birth defects per 100 births (3-6%) -Uwisc website “In the US, a congenital abnormality occurs in approximately 5% of live births, which makes the impact of medical xrays difficult to evaluate.” Huda 161 c. .0006% d. 0.06%

69 What procedure gives the highest dose? : 

69 What procedure gives the highest dose? A TIPS B CT Abd/pelvis C CT Thorax D BE E CXR

69 What procedure gives the highest dose? : 

69 What procedure gives the highest dose? A TIPS B CT Abd/pelvis C CT Thorax D BE E CXR

70 What is the monthly dose for a fetus? : 

70 What is the monthly dose for a fetus? A 0.1 mSv B 0.5 mSv C 1 mSv D 5 mSv

70 What is the monthly dose for a fetus? : 

70 What is the monthly dose for a fetus? A 0.1 mSv B 0.5 mSv The fetus of a radiation worker must not exceed a dose of 0.5mSv/month… But “the dose to the fetus is normally taken to be half the skin dose to account for soft tissue attenuation…” –Huda p163 C 1 mSv D 5 mSv

71 What are the units for dose area product? : 

71 What are the units for dose area product? A Gy cm2 B Gy / cm2 D Gy cm E Sv cm2 F Sv cm-2

71 What are the units for dose area product? : 

71 What are the units for dose area product? A Gy cm2 B Gy / cm2 D Gy cm E Sv cm2 F Sv cm-2

72 The most likely consequence of an acute total body exposure to 1Gy of x rays is : 

72 The most likely consequence of an acute total body exposure to 1Gy of x rays is A. Diarrhea B. Decrease in lymphocyte count C. Epilation D. Sterility in a female E. Erythema

72 The most likely consequence of an acute total body exposure to 1Gy of x rays is : 

72 The most likely consequence of an acute total body exposure to 1Gy of x rays is A. Diarrhea B. Decrease in lymphocyte count “Hematologic effects from xrays begin to be apparent at radiation doses around 0.25 – 0.5 Sv” -Nickolof p135 “Lymphocytes are the most radiosensitive cells in the blood and decreased cell counts have been observed after doses of less than 1Gy (100rad)” –Huda p 158 C. Epilation 6Gy D. Sterility in a female ? E. Erythema “Hematologic effects from xrays begin to be apparent at radiation doses around 1-2 Gy. 5Gy

73 What is the lifetime whole body exposure limit to 65 year old radiologist? : 

73 What is the lifetime whole body exposure limit to 65 year old radiologist? A 65 mSv B 200 mSv C 400 mSv D 650 mSv

73 What is the lifetime whole body exposure limit to 65 year old radiologist? : 

73 What is the lifetime whole body exposure limit to 65 year old radiologist? A 65 mSv B 200 mSv C 400 mSv D 650 mSv … based on below 650 seems correct (from NRCP website)

74 Which is not considered when designing a room for radiation safety? : 

74 Which is not considered when designing a room for radiation safety? A Workload B Use-factor C Distance from source to wall D Occupancy factor E # of occupants in the room next door

74 Which is not considered when designing a room for radiation safety? : 

74 Which is not considered when designing a room for radiation safety? A Workload yes B Use-factor yes C Distance from source to wall yes D Occupancy factor yes E # of occupants in the room next door No Plus: Scatter fraction Attenuation

75 What is the likely outcome of a ssDNA break? : 

75 What is the likely outcome of a ssDNA break? A Hereditary defects B Apoptosis C Proliferation D Mutation E Repair

75 What is the likely outcome of a ssDNA break? : 

75 What is the likely outcome of a ssDNA break? A Hereditary defects B Apoptosis C Proliferation D Mutation E Repair

76 Which of the following has a threshold dose of radiation? : 

76 Which of the following has a threshold dose of radiation? A. Cataracts B. Lymphoma C. Colon Cancer D. Breast Cancer

76 Which of the following has a threshold dose of radiation? : 

76 Which of the following has a threshold dose of radiation? A. Cataracts B. Lymphoma C. Colon Cancer D. Breast Cancer

77 The syndrome that is associated with the greatest sensitivity to x rays is : 

77 The syndrome that is associated with the greatest sensitivity to x rays is A. Bloom syndrome B. Ataxia telangiectasia C. Fanconi anemia D. Xeroderma pigmentosum

77 The syndrome that is associated with the greatest sensitivity to x rays is : 

77 The syndrome that is associated with the greatest sensitivity to x rays is A. Bloom syndrome B. Ataxia telangiectasia C. Fanconi anemia D. Xeroderma pigmentosum

78 X-rays cause radiation damage in humans from: : 

78 X-rays cause radiation damage in humans from: A. scattered photons B. photoelectrons and recoil electrons C. direct hits on DNA D. photons which traverse the tissue without any interactions

78 X-rays cause radiation damage in humans from: : 

78 X-rays cause radiation damage in humans from: A. scattered photons B. photoelectrons and recoil electrons C. direct hits on DNA D. photons which traverse the tissue without any interactions

79 Most radioresistant phase of cell cycle? : 

79 Most radioresistant phase of cell cycle? A. late S phase B. G1 C. G2 D. M

79 Most radioresistant phase of cell cycle? : 

79 Most radioresistant phase of cell cycle? A. late S phase B. G1 C. G2 D. M

80 What sets regulatory levels concerning radiation biology? : 

80 What sets regulatory levels concerning radiation biology? A. NRC B. ICRE C. Some other acronyms

80 What sets regulatory levels concerning radiation biology? : 

80 What sets regulatory levels concerning radiation biology? A. NRC “Nuclear regulatory commission is responsible for the rules and regulations regarding nuclear materials” –Huda p161 B. ICRE C. Some other acronyms

81 The LD 50/60 is : 

81 The LD 50/60 is a. 3.5 Gy b. 1 Gy c. 0.5 Gy

81 The LD 50/60 is : 

81 The LD 50/60 is a. 3.5 Gy “320-360 Rad LD 50/60 with minimal care” b. 1 Gy c. 0.5 Gy

82 The most radiosensitive portion of the gastrointestinal tract to cell killing is the : 

82 The most radiosensitive portion of the gastrointestinal tract to cell killing is the A. Esophagus B. Stomach C. Small intestine D. Large intestine E. Oropharynx

82 The most radiosensitive portion of the gastrointestinal tract to cell killing is the : 

82 The most radiosensitive portion of the gastrointestinal tract to cell killing is the A. Esophagus B. Stomach C. Small intestine D. Large intestine E. Oropharynx

83 What is the term for programmed cell death? : 

83 What is the term for programmed cell death? Apoptosis

83 What is the term for programmed cell death? : 

83 What is the term for programmed cell death? Apoptosis

84 If a pregnant woman is exposed to I131 during her babies 4th week of gestation : 

84 If a pregnant woman is exposed to I131 during her babies 4th week of gestation A Neonatal death B No increased risk of hypothyroidism C The baby will have cretinism D The baby has a 5% increase in leukemia

84 If a pregnant woman is exposed to I131 during her babies 4th week of gestation : 

84 If a pregnant woman is exposed to I131 during her babies 4th week of gestation A Neonatal death B No increased risk of hypothyroidism C The baby will have cretinism D The baby has a 5% increase in leukemia

85 What is the most likely abnormality will the fetus acquire after radiation exposure before implantation at less than 2 weeks gestation? : 

85 What is the most likely abnormality will the fetus acquire after radiation exposure before implantation at less than 2 weeks gestation? A Prenatal death B Neonatal death C Congenital anomaly D Mental retardation

85 What is the most likely abnormality will the fetus acquire after radiation exposure before implantation at less than 2 weeks gestation? : 

85 What is the most likely abnormality will the fetus acquire after radiation exposure before implantation at less than 2 weeks gestation? A Prenatal death “most likely result of major radiation exposure during the first 10 days after conception is early intrauterine death” –Huda p161 B Neonatal death C Congenital anomaly D Mental retardation

86 A nuclear disaster occurs. Upon arriving on the scene you should : 

86 A nuclear disaster occurs. Upon arriving on the scene you should Perform basic life support and treat serious injuries

87 How many counts to get 5% uncertainty with 95% confidence interval? : 

87 How many counts to get 5% uncertainty with 95% confidence interval? A) 1600 B) 10,000 C) 20,000 D) 40,000

87 How many counts must be obtained to ensure that the 95% confidence interval lies within 5% of the true value? : 

87 How many counts must be obtained to ensure that the 95% confidence interval lies within 5% of the true value? A) 1600 N = (n/Uncertainty)2 where n is the number of standard deviations required to achieve the given confidence interval (in this case 2 standard deviations from the mean are required to ensure a 95% confidence limit)…see Primer p 1031 = (2/.05) 2 = 1600 B) 10,000 C) 20,000 D) 40,000

88 What happens when you move from A to B on the ROC curve? : 

88 What happens when you move from A to B on the ROC curve? A Decrease sensitivity B Increase specificity C Increase PPV D Increase NPV E Increase false positives

88 What happens when you move from A to B on the ROC curve? : 

88 What happens when you move from A to B on the ROC curve? A Decrease sensitivity B Increase specificity C Increase PPV D Increase NPV E Increase false positives

89 The shaded area below represents which of the following? : 

89 The shaded area below represents which of the following? a. True positives b. False positives c. True negatives d. False negatives e. Selectivity

89 The shaded area below represents which of the following? : 

89 The shaded area below represents which of the following? a. True positives b. False positives c. True negatives d. False negatives e. Selectivity

Which number represents Laminar Flow? : 

Which number represents Laminar Flow? 1 2 3 4 5

Which number represents Laminar Flow? : 

Which number represents Laminar Flow? 1 2 3 4 5

91 How do you correct this ultrasound artifact? : 

91 How do you correct this ultrasound artifact? Increase PRF Increase transducer frequency Change the angle of the probe

91 How do you correct this ultrasound artifact? : 

91 How do you correct this ultrasound artifact? Increase PRF “In a Doppler spectrum, the aliased signals wrap around to negative amplitude, masquerading as reversed flow – the most straightforward method to reduce is for the user to adjust the velocity scale to a wider range or PRF” –Bush –p541 Increase transducer frequency Change the angle of the probe

92 The US transducer scans vessels A and B, : 

92 The US transducer scans vessels A and B, B has less measured velocity than A B appears to have faster flow than A B will appear closer than A really is vessel B will appear to have a larger diameter B A

92 The US transducer scans vessels A and B, : 

92 The US transducer scans vessels A and B, B has less measured velocity than A … due to angle of incidence B appears to have faster flow than A B will appear closer than A really is vessel B will appear to have a larger diameter B A

93 Why do we use harmonics in Ultrasound : 

93 Why do we use harmonics in Ultrasound A To decrease attenuation B To decrease scatter C To increase sensitivity to Rayleigh scatter D To clean up clutter

93 Why do we use harmonics in Ultrasound : 

93 Why do we use harmonics in Ultrasound A To decrease attenuation B To decrease scatter C To increase sensitivity to Rayleigh scatter D To clean up clutter “Harmonic frequencies are integral multiples of the fundamental US pulse frequencies…Harmonic imaging enhances contrast agent imaging by tuning the receiver to the high (harmonic) frequency alone, thereby eliminating the lower frequencies (clutter)” Huda 183 Other duke recalled answer was “to increase weak signal caused by scatter on doppler”

94 Why do you see liver in the Ultrasound? What type of echo is produced? : 

94 Why do you see liver in the Ultrasound? What type of echo is produced? A Specular reflection B Non-specular reflection C Refraction D Attenuation

94 Why do you see liver in the Ultrasound? What type of echo is produced? : 

94 Why do you see liver in the Ultrasound? What type of echo is produced? A Specular reflection … “Specular reflections occur from large smooth surfaces and are the major contributors to ultrasound images. Nonspecular reflections are diffuse scatter from “rough” surfaces where the irregular contours are bigger than the US wavelength” Huda 175 B Non-specular reflection C Refraction D Attenuation

95 As an ultrasound beam travels from fat (velocity 1440 m/sec) to liver (velocity 1550 m/sec) what other change is observed? : 

95 As an ultrasound beam travels from fat (velocity 1440 m/sec) to liver (velocity 1550 m/sec) what other change is observed? A. Increase in wavelength B. Decrease in wavelength C. Increase in frequency D. Decrease in frequency

95 As an ultrasound beam travels from fat (velocity 1440 m/sec) to liver (velocity 1550 m/sec) what other change is observed? : 

95 As an ultrasound beam travels from fat (velocity 1440 m/sec) to liver (velocity 1550 m/sec) what other change is observed? A. Increase in wavelength B. Decrease in wavelength C. Increase in frequency D. Decrease in frequency

96 What determines the axial resolution in US? : 

96 What determines the axial resolution in US? Pulse repetition frequency Pulse length Width of beam

96 What determines the axial resolution in US? : 

96 What determines the axial resolution in US? Pulse repetition frequency Pulse length… “Axial resolution is the ability to separate two objects lying along the axis of the beam and is determined by the pulse length. Axial resolution is limited to half the pulse length and is therefore dependent on pulse frequency and duration” Huda 183 “Axial resolution is determined by the frequency of the ultrasound and the dampening factor of the transducer, which together determine the SPATIAL PULSE LENGTH” –bush 524 Width of beam

97 Doppler US shows what? : 

97 Doppler US shows what? A Compares the transmitted and received ultrasound intensities B Change in frequency C Depth v time

97 Doppler US shows what? : 

97 Doppler US shows what? A Compares the transmitted and received ultrasound intensities B Change in frequency … “Doppler effects refers to the change in frequency that results from a moving sample or ultrasound source” Huda 184 “Doppler ultrasound is based on the shift of frequency in an ultrasound wave caused by a moving reflector” –Bush 531 C Depth v time

98 In a single element transducer, what determines the frequency? : 

98 In a single element transducer, what determines the frequency? A Crystal thickness B Crystal diameter C Current in transducer

98 In a single element transducer, what determines the frequency? : 

98 In a single element transducer, what determines the frequency? A Crystal thickness … “The thickness and acoustic velocity of a piezoelectric crystal determines the resonant frequency of the transducer” Huda 178 B Crystal diameter C Current in transducer

99 How do you decrease metallic artifact in a MRI of a patient with post surgical metallic hardware in the spine? : 

99 How do you decrease metallic artifact in a MRI of a patient with post surgical metallic hardware in the spine? A NEX B Increase TR C Decrease FOV D Increase RF bandwidth E Increase gap distance F Increase matrix size G phase encode gradient H increase reciever bandwidth

99 How do you decrease metallic artifact in a MRI of a patient with post surgical metallic hardware in the spine? : 

99 How do you decrease metallic artifact in a MRI of a patient with post surgical metallic hardware in the spine? NEX Increase TR Decrease FOV Increase RF bandwidth Increase gap distance Increase matrix size phase encode gradient increase reciever bandwidth

100 How is a chemical shift artifact reduced? : 

100 How is a chemical shift artifact reduced? A Increase the tesla strength of magnet B Increase the bandwidth C Increase the echo train legth D Increase the number of acquisitions

100 How is a chemical shift artifact reduced? : 

100 How is a chemical shift artifact reduced? A Increase the tesla strength of magnet B Increase the bandwidth “RF bandwidth/gradient strength and pulse sequences can mitigate chemical shift problems… lower gradient strengths and narrow bandwidths (increased freq) can be used” –Bushp455 C Increase the echo train legth D Increase the number of acquisitions

101 In which direction does motion artifact appear in MRI? : 

101 In which direction does motion artifact appear in MRI? A Phase-encoding direction B Frequency-encoding direction C In the direction of motion D Everywhere

101 In which direction does motion artifact appear in MRI? : 

101 In which direction does motion artifact appear in MRI? A Phase-encoding direction “motion ghosts occur in the phase-encoding direction” –Nickolof 204 B Frequency-encoding direction C In the direction of motion D Everywhere

Chemical shift artifact is in what direction? : 

Chemical shift artifact is in what direction? Frequency encoding Phase encoding

Chemical shift artifact is in what direction? : 

Chemical shift artifact is in what direction? Frequency encoding Phase encoding

102 What happens if you decrease the FOV in MRI? : 

102 What happens if you decrease the FOV in MRI? A Noise increases B Spatial Resolution decreases C Scan time increases D Attenuation increases

102 What happens if you decrease the FOV in MRI? : 

102 What happens if you decrease the FOV in MRI? A Noise increases The smaller the pixel, the greater the noise and the less the contrast of the images B Spatial Resolution decreases (spatial resolution will increase) C Scan time increases D Attenuation increases

103 To increase the spatial resolution in MRI imaging : 

103 To increase the spatial resolution in MRI imaging Increase the FOV Increase the matrix size increasing bandwidth decreasing the matrix size

103 To increase the spatial resolution in MRI imaging : 

103 To increase the spatial resolution in MRI imaging Increase the FOV Increase the matrix size Also can use stronger gradients and more phase-encoding steps increasing bandwidth decreasing the matrix size

104 What part of the MRI machine produces the most noise? : 

104 What part of the MRI machine produces the most noise? A Shim coils B Gradient coils C RF transmitter D RF receiver E Table motion

104 What part of the MRI machine produces the most noise? : 

104 What part of the MRI machine produces the most noise? A Shim coils B Gradient coils “noise of the pulsing gradients can injure hearing” –nickolof p205 C RF transmitter D RF receiver E Table motion

105 If a multislice T1 weighted sequence is being acquired (without a presaturation pulse) and slow flow is present in a vessel, what will be the signal intensity within the vessel? : 

105 If a multislice T1 weighted sequence is being acquired (without a presaturation pulse) and slow flow is present in a vessel, what will be the signal intensity within the vessel? A Brighter on the first few slices B Brighter on the mid slices C Brighter on the last few slices D Always black

105 If a multislice T1 weighted sequence is being acquired (without a presaturation pulse) and slow flow is present in a vessel, what will be the signal intensity within the vessel? : 

105 If a multislice T1 weighted sequence is being acquired (without a presaturation pulse) and slow flow is present in a vessel, what will be the signal intensity within the vessel? A Brighter on the first few slices “repeated excitation of the tissues and blood causes a partial saturation of the spins… blood from outside the imaged volume does not interact with the RF excitations and therefore these unsaturated spins enter the imaged volume and produce large signal compared to blood within the volume. This is known as flow-related enhancement.” –Bush 443 B Brighter on the mid slices C Brighter on the last few slices D Always black

Which of the spin echo sequence represents the slice select gradient? : 

Which of the spin echo sequence represents the slice select gradient?

Which of the spin echo sequence represents the slice select gradient? : 

Which of the spin echo sequence represents the slice select gradient? -RF pulse = Excite protons -SSG = Section select gradient = localize z axis -PEG = Phase encode gradient = localize y axis -FEG = Frequency encode gradient = localize x axis -MR signal/echo

107 MRI sequence with a matrix size of 256 x 256 takes 12 minutes to complete. If the matrix is changed to 128 x 128, what is the new length of images acquisition? : 

107 MRI sequence with a matrix size of 256 x 256 takes 12 minutes to complete. If the matrix is changed to 128 x 128, what is the new length of images acquisition? A 24 minutes B 12 minutes C 6 minutes D 3 minutes

107 MRI sequence with a matrix size of 256 x 256 takes 12 minutes to complete. If the matrix is changed to 128 x 128, what is the new length of images acquisition? : 

107 MRI sequence with a matrix size of 256 x 256 takes 12 minutes to complete. If the matrix is changed to 128 x 128, what is the new length of images acquisition? A 24 minutes B 12 minutes C 6 minutes D 3 minutes

108 Which of the following MRI settings will provide the greatest signal to noise ratio spin-echo brain MRI? : 

108 Which of the following MRI settings will provide the greatest signal to noise ratio spin-echo brain MRI? A TR 2000, TE 20 B TR 2000, TE 80 C TR 1000, TE 80 D TR 500, TE 20 E TR 500, TE 80

108 Which of the following MRI settings will provide the greatest signal to noise ratio spin-echo brain MRI? : 

108 Which of the following MRI settings will provide the greatest signal to noise ratio spin-echo brain MRI? A TR 2000, TE 20 … PD has highest SNR (long TR, short TE) B TR 2000, TE 80 C TR 1000, TE 80 D TR 500, TE 20 E TR 500, TE 80

109 On a brain MRI, the CSF signal compared to brain parenchyma signal has… : 

109 On a brain MRI, the CSF signal compared to brain parenchyma signal has… A Longer T2 B Shorter T2 C Shorter T1

109 On a brain MRI, the CSF signal compared to brain parenchyma signal has… : 

109 On a brain MRI, the CSF signal compared to brain parenchyma signal has… A Longer T2 (and longer T1 as well) B Shorter T2 C Shorter T1

110 Which of the following causes T1 shortening : 

110 Which of the following causes T1 shortening A Administration of gadolinium containing contrast agent “Gadolinium has seven unpaired electrons…acts as a relaxation agent of nearby protons and reduces T1 significantly and T2 slightly. The overall effect is highly dependent on the concentration of gadolinium” Huda 206

111 The region of k-space responsible for the intensity values of each tissue/pixel is where? : 

111 The region of k-space responsible for the intensity values of each tissue/pixel is where? A In the periphery of the image B Mostly in the center of the image C There is a top to bottom gradient D There is a bottom to top gradient E At the corners of the image

111 The region of k-space responsible for the intensity values of each tissue/pixel is where? : 

111 The region of k-space responsible for the intensity values of each tissue/pixel is where? A In the periphery of the image B Mostly in the center of the image “Information near the center of k-space provides the large area contrast in the image, while the outer areas in k-space contribute to the resolution and detail.” –bush430 C There is a top to bottom gradient D There is a bottom to top gradient E At the corners of the image

112 What type of sequence does the following diagram represent? : 

112 What type of sequence does the following diagram represent? Echo planar Gradient echo Fast/Turbo Spin Echo

112 What type of sequence does the following diagram represent? : 

112 What type of sequence does the following diagram represent? Echo planar Gradient echo Fast/Turbo Spin Echo See Nickoloff p 203

Echo planar imaging : 

Echo planar imaging

Gradient echo : 

Gradient echo

113 MRI uses strong gradients with high switching rates because the faster gradient switching means faster scan times and doing more complex types of scanning in reasonable scan times. The ever-stronger gradients can now produce sizeable eddy currents in the patients and lead to: : 

113 MRI uses strong gradients with high switching rates because the faster gradient switching means faster scan times and doing more complex types of scanning in reasonable scan times. The ever-stronger gradients can now produce sizeable eddy currents in the patients and lead to: A Conductors, like implanted electrodes, infusion pumps, biostimulators, and cosmetics on/in the patient to absorb the power and be heated up in response. This may lead to increase SAR, skin burns, or destroy the implanted devices. B Stimulation of peripheral nerves which may causing involuntary twitching of the patient C Missile effect of metallic projectiles D Pacing of the heart via cardiac pacemaker electrodes

113 MRI uses strong gradients with high switching rates because the faster gradient switching means faster scan times and doing more complex types of scanning in reasonable scan times. The ever-stronger gradients can now produce sizeable eddy currents in the patients and lead to: : 

113 MRI uses strong gradients with high switching rates because the faster gradient switching means faster scan times and doing more complex types of scanning in reasonable scan times. The ever-stronger gradients can now produce sizeable eddy currents in the patients and lead to: A Conductors, like implanted electrodes, infusion pumps, biostimulators, and cosmetics on/in the patient to absorb the power and be heated up in response. This may lead to increase SAR, skin burns, or destroy the implanted devices. B Stimulation of peripheral nerves which may causing involuntary twitching of the patient C Missile effect of metallic projectiles D Pacing of the heart via cardiac pacemaker electrodes

114. What is electron binding energy? : 

114. What is electron binding energy? Energy to remove an electron from its orbit

115. Mammo resolution is determined primarily by… : 

115. Mammo resolution is determined primarily by… Focal spot size Motion blur Breast thickness

115. Mammo resolution is determined primarily by… : 

115. Mammo resolution is determined primarily by… Focal spot size Motion blur Breast thickness

116 The average energy should be slightly greater than the Kedge of the contrast material for optimal contrast. : 

116 The average energy should be slightly greater than the Kedge of the contrast material for optimal contrast.

At what x-ray photon energy is the probability of the photoelectric effect the highest? : 

At what x-ray photon energy is the probability of the photoelectric effect the highest? Much lower than the k-edge At the k-edge Slightly above the k-edge Slightly below the k-edge Much higher than the k-edge

At what x-ray photon energy is the probability of the photoelectric effect the highest? : 

At what x-ray photon energy is the probability of the photoelectric effect the highest? Much lower than the k-edge At the k-edge Slightly above the k-edge Slightly below the k-edge Much higher than the k-edge

Which is true about the half value layer? : 

Which is true about the half value layer? A It must meet or exceed FDA standards B Measured in mm of copper C Equals linear attenuation coefficient over ln2

Which is true about the half value layer? : 

Which is true about the half value layer? A It must meet or exceed FDA standards B Measured in mm of copper C Equals linear attenuation coefficient over ln2

What increases when you open the aperture of the II keeping the FOV overall the same? : 

What increases when you open the aperture of the II keeping the FOV overall the same? A Noise B Resolution C Dose D Magnification E Brightness

What increases when you open the aperture of the II keeping the FOV overall the same? : 

What increases when you open the aperture of the II keeping the FOV overall the same? A Noise B Resolution C Dose D Magnification E Brightness

If you double kVp on a digital film, what do you do? : 

If you double kVp on a digital film, what do you do? A Make it lighter B Make it darker C Increase latitude D Decrease noise

If you double kVp on a digital film, what do you do? : 

If you double kVp on a digital film, what do you do? A Make it lighter B Make it darker C Increase latitude D Decrease noise

What is the effect of opening the optical aperture of an image intensifier? : 

What is the effect of opening the optical aperture of an image intensifier? Reduced patient dose Increased contrast Increased resolution

What is the effect of opening the optical aperture of an image intensifier? : 

What is the effect of opening the optical aperture of an image intensifier? Reduced patient dose Increased contrast Increased resolution

121 Which target has the highest characteristic radiation? : 

121 Which target has the highest characteristic radiation? A Calcium B Molybdenum C Rhodium D Tungsten

121 Which target has the highest characteristic radiation? : 

121 Which target has the highest characteristic radiation? A Calcium B Molybdenum C Rhodium D Tungsten ???

Decrease dose in CT by increasing what? : 

Decrease dose in CT by increasing what? A Kvp B mAs C Pitch

Decrease dose in CT by increasing what? : 

Decrease dose in CT by increasing what? A Kvp B mAs C Pitch

In MDCT which will decrease quantum mottle? : 

In MDCT which will decrease quantum mottle? A decreasing mAs B decreasing patient thickness C decreasing pixel size D decreasing kVp

In MDCT which will decrease quantum mottle? : 

In MDCT which will decrease quantum mottle? A decreasing mAs B decreasing patient thickness C decreasing pixel size D decreasing kVp

Between 70-120 keV, what is the dominant source of patient dose? : 

Between 70-120 keV, what is the dominant source of patient dose? A Compton B Photoelectric

Between 70-120 keV, what is the dominant source of patient dose? : 

Between 70-120 keV, what is the dominant source of patient dose? A Compton B Photoelectric

Greatest man made medical dose to population is from : 

Greatest man made medical dose to population is from A CXR B fluoro D CT E NM F MRI

Greatest man made medical dose to population is from : 

Greatest man made medical dose to population is from A CXR B fluoro D CT E NM F MRI

A radiation worker wants to test herself for low level thyroid uptake (approx 1 Bq). Which instrument should she use? : 

A radiation worker wants to test herself for low level thyroid uptake (approx 1 Bq). Which instrument should she use? Ionization chamber GM counter TLD NaI scintillator

A radiation worker wants to test herself for low level thyroid uptake (approx 1 Bq). Which instrument should she use? : 

A radiation worker wants to test herself for low level thyroid uptake (approx 1 Bq). Which instrument should she use? Ionization chamber GM counter TLD NaI scintillator

Regarding T1 values of different tissues…? : 

Regarding T1 values of different tissues…? T1 is essentially independent of magnetic field strength T1 increases with increasing resonance frequency of the tissues T1 is shorter than T2

Regarding T1 values of different tissues…? : 

Regarding T1 values of different tissues…? T1 is essentially independent of magnetic field strength T1 increases with increasing resonance frequency of the tissues T1 is shorter than T2

If one wants to determine the energy spectrum of a radioactive sample, one should use an… : 

If one wants to determine the energy spectrum of a radioactive sample, one should use an… Dose calibrator NaI well counter GM counter

If one wants to determine the energy spectrum of a radioactive sample, one should use an… : 

If one wants to determine the energy spectrum of a radioactive sample, one should use an… Dose calibrator NaI well counter GM counter

In CT fluoro, if the slice width is halved while keeping the SNR the same, what happens to patient dose? : 

In CT fluoro, if the slice width is halved while keeping the SNR the same, what happens to patient dose? Halved Unchanged Doubled Quadrupled Increases 16-fold

In CT fluoro, if the slice width is halved while keeping the SNR the same, what happens to patient dose? : 

In CT fluoro, if the slice width is halved while keeping the SNR the same, what happens to patient dose? Halved Unchanged Doubled Quadrupled Increases 16-fold

Quantum mottle in digital fluoro can be reduced by…? : 

Quantum mottle in digital fluoro can be reduced by…? Decreasing the technique Increasing the patient to II distance Multi-frame averaging

Quantum mottle in digital fluoro can be reduced by…? : 

Quantum mottle in digital fluoro can be reduced by…? Decreasing the technique Increasing the patient to II distance Multi-frame averaging

The yearly occupational dose limit to the thyroid gland is…? : 

The yearly occupational dose limit to the thyroid gland is…? 1 mSv 50 mSv 150 mSv 500 mSv 4 Sv

The yearly occupational dose limit to the thyroid gland is…? : 

The yearly occupational dose limit to the thyroid gland is…? 1 mSv 50 mSv 150 mSv 500 mSv 4 Sv

If a low pass filter is applied to an image, and this image is subtracted from the original, this is referred to as what technique? : 

If a low pass filter is applied to an image, and this image is subtracted from the original, this is referred to as what technique? Modulation transfer function Unsharp masking Focused blurring Contrast enhancement

If a low pass filter is applied to an image, and this image is subtracted from the original, this is referred to as what technique? : 

If a low pass filter is applied to an image, and this image is subtracted from the original, this is referred to as what technique? Modulation transfer function Unsharp masking Focused blurring Contrast enhancement

During digital subtraction angiography (DSA) of the carotid arteries, the patient moves. What post processing measure can improve the subsequent subtraction images? : 

During digital subtraction angiography (DSA) of the carotid arteries, the patient moves. What post processing measure can improve the subsequent subtraction images? Logarithmic transformation Increase frame averaging Energy subtraction Change of mask image Change visual optics

During digital subtraction angiography (DSA) of the carotid arteries, the patient moves. What post processing measure can improve the subsequent subtraction images? : 

During digital subtraction angiography (DSA) of the carotid arteries, the patient moves. What post processing measure can improve the subsequent subtraction images? Logarithmic transformation Increase frame averaging Energy subtraction Change of mask image Change visual optics

For a low contrast 4 cm hepatoma on noncontrast CT, visibility will be increased by… : 

For a low contrast 4 cm hepatoma on noncontrast CT, visibility will be increased by… Increasing slice thickness Increasing cutoff frequency of ramp filter Decreasing mAs Decreasing scan time

For a low contrast 4 cm hepatoma on noncontrast CT, visibility will be increased by… : 

For a low contrast 4 cm hepatoma on noncontrast CT, visibility will be increased by… Increasing slice thickness Increasing cutoff frequency of ramp filter Decreasing mAs Decreasing scan time

How do you decrease noise in CT? : 

How do you decrease noise in CT? Decrease pitch Decrease mA Decrease kVp Decrease slice thickness

How do you decrease noise in CT? : 

How do you decrease noise in CT? Decrease pitch Decrease mA Decrease kVp Decrease slice thickness

Regarding electron binding energy, what is true? : 

Regarding electron binding energy, what is true? It is the energy needed to remove an orbital electron Decreases with increasing Z Increases with outer shell electrons

Regarding electron binding energy, what is true? : 

Regarding electron binding energy, what is true? It is the energy needed to remove an orbital electron Decreases with increasing Z Increases with outer shell electrons

Rate of decay of a radiopharmaceutrical is… : 

Rate of decay of a radiopharmaceutrical is… Constant over time

Heel effect decreases resolution where? : 

Heel effect decreases resolution where? Anode side Cathode side

Heel effect decreases resolution where? : 

Heel effect decreases resolution where? Anode side Cathode side

What increases noise most in DSA? : 

What increases noise most in DSA? Significant motion between mask and contrast shot

Why can’t you just increase geometric mag (SID) in mammo? : 

Why can’t you just increase geometric mag (SID) in mammo? Increased focal spot blur

What does CR use to hold its latent image? : 

What does CR use to hold its latent image? Photostimulable Phosphor Solid state detector Xenon gas

What does CR use to hold its latent image? : 

What does CR use to hold its latent image? Photostimulable Phosphor Solid state detector Xenon gas

Slide 311: 

The spatial resolution is better at what side? Anode Cathode

Slide 312: 

1. Regarding mammography, what quality control test must be performed daily? Processor sensitometry mAs reciprocity mAs linearity kVP accuracy

Slide 313: 

1. Regarding mammography, what quality control test must be performed daily? Processor sensitometry mAs reciprocity mAs linearity kVP accuracy

Slide 314: 

2. The definition of 1 MBcq is: 3.7 x 106 disintegrations per second. 1 x 106 disintegrations per second. 1 x 10-6 disintegrations per second. 3.7 x 1010 disintegrations per second. 1 x 10 disintegrations per second.

Slide 315: 

2. The definition of 1 MBcq is: 3.7 x 106 disintegrations per second. 1 x 106 disintegrations per second. 1 x 10-6 disintegrations per second. 3.7 x 1010 disintegrations per second. 1 x 10 disintegrations per second.

Slide 316: 

3. The ability of a system to differentiate high contrast resolution at different spatial frequencies is represented by: Contrast-detail curve MTF Bar phantom test Linear dose response Tube power loading curve

Slide 317: 

3. The ability of a system to differentiate high contrast resolution at different spatial frequencies is represented by: MTF A modulation transfer function is the relationship of an object’s contrast (y-axis) to its spatial resolution (x-axis). According to BUSHBERG Chapter 10 page 271: “The MTF illustrates the fraction (or percentage) of an object’s contrast that is recorded by the imaging system, as a function of the size (i.e., spatial frequency) of the object.)

Slide 318: 

Where will laminar flow occur? 1 2 3 4 5

Slide 319: 

Where will laminar flow occur? 1 2 3 4 5

Slide 320: 

A technologist changes the automatic exposure control (AEC) dial on a mammography tube to the – 2 (negative 2) setting from 0 (normal). What will this due to the ensuing images? Increase radiation dose Increase the amount of image noise Increase tube loading Increase the amount of contrast Increase exposure time

Slide 321: 

A technologist changes the automatic exposure control (AEC) dial on a mammography tube to the – 2 (negative 2) setting from 0 (normal). What will this due to the ensuing images? Increase radiation dose Increase the amount of image noise Apparently moving the AEC dial to negative numbers will terminate the exposure earlier or more quickly, which would result in less photons making up the image, thus decreasing dose at the expense of INCREASING IMAGE NOISE. Increase tube loading Increase the amount of contrast Increase exposure time

Slide 322: 

How can you get rid of the artifact shown below? Increase the PRF Increase the frequency of the transducer Increase the gain Decrease the Doppler angle

Slide 323: 

How can you get rid of the artifact shown below? Increase the PRF Increase the frequency of the transducer Increase the gain Decrease the Doppler angle

Slide 324: 

Plain film of the abdomen at 80 kVp, on 20 cm patient. What is the exit dose? 2% 99% 75% 50% 0.01%

Slide 325: 

Plain film of the abdomen at 80 kVp, on 20 cm patient. What is the exit dose? 2% 99% 75% 50% 0.01%

Slide 326: 

Which of the following interactions predominate for Tc-99m in tissue? Compton scattering Pair Production Rayleigh (classical) Scattering Photoelectric effect Nuclear Disintegration

Slide 327: 

Which of the following interactions predominate for Tc-99m in tissue? Compton scattering BUSHBERG Chapter 3 page 38: “…Compton scattering not only predominates in the diagnostic energy range above 26 keV in soft tissue, but continues beyond diagnostic energies to approximately 30 MeV…”) Pair Production Rayleigh (classical) Scattering Photoelectric effect Nuclear Disintegration

Slide 328: 

If the grid that is used for a radiograph is laterally de-centered, what will the resultant image look like? Increased image noise Low spatial resolution Overexposed Dark in the center of the image and lighter towards the periphery

Slide 329: 

If the grid that is used for a radiograph is laterally de-centered, what will the resultant image look like? Increased image noise (probably…poor choices it seems) Christensen’s Physics of Medical Imaging: “…Lateral decentering results from the x-ray tube being positioned lateral to the convergent line but at the correct focal distance. All the lead strips cut off the same amount of primary radiation, so there is a uniform loss of radiation over the entire surface of the grid, producing a uniformly light radiograph. This is probably the most common kind of grid cutoff, but it cannot be recognized by inspection of the film. All we see is a light film that is usually attributed to incorrect exposure factors. The films become progressively lighter as the amount of lateral decentering increases, but the exposure is still uniform. The center and both edges of the film are equally exposed, and it’s impossible to recognize the cutoff from inspection of the film…” See primer for pics

Slide 330: 

When obtaining an MRI series of images of a knee replacement, which of the following is the most effective way to reduce the magnetic susceptibility artifact? Increase the receiver bandwidth Increase the magnetic field strength Decrease the slice thickness Decrease the FOV Increase the image matrix

Slide 331: 

When obtaining an MRI series of images of a knee replacement, which of the following is the most effective way to reduce the magnetic susceptibility artifact? Increase the receiver bandwidth The visual distortion created by metallic implants on MR images cannot be completely eliminated, but its effect can be minimized by a large receiver bandwidth and a decreased echo time. Fast SE acquisitions with a high bandwidth typically work well in such cases. However, care should be taken to avoid the heating of tissue that is adjacent to the metal (RSNA physics tutorial for residents)

Slide 332: 

When acquiring a fast spin echo MRI which demonstrates chemical shift artifact, which of the following is the most effective way to reduce this artifact? Increase the receiver bandwidth Decrease the field of view Increase slice thickness Decrease the size of the matrix

Slide 333: 

When acquiring a fast spin echo MRI which demonstrates chemical shift artifact, which of the following is the most effective way to reduce this artifact? Increase the receiver bandwidth “Chemical shift artifacts were common on T2-weighted images obtained before the invention of fast SE imaging. The overall signal intensity on a normal T2-weighted image was low, and in order to increase the signal-to-noise ratio, it was a common practice to use a low receiver bandwidth for the T2-weighted echo. With the use of fast SE sequences, in contrast, the goals are to minimize the echo spacing and to maximize the decaying T2 signal. These goals are usually achieved by using a shorter RF pulse and a higher-bandwidth receiver window. “ RSNA tutorial

Slide 334: 

Which of the following is responsible for eliminating scatter in a nuclear medicine planar image? The collimator The pulse height analyzer The crystal thickness Dynodes A grid

Slide 335: 

Which of the following is responsible for eliminating scatter in a nuclear medicine planar image? The collimator The pulse height analyzer The crystal thickness Dynodes A grid

Slide 336: 

What property of the ultrasound beam is responsible for the visualization of parenchyma such as the liver on an ultrasound image? Nonspecular reflections Specular reflections Scatter Refraction Absorption

Slide 337: 

What property of the ultrasound beam is responsible for the visualization of parenchyma such as the liver on an ultrasound image? Nonspecular reflections From BUSHBERG Chapter 16 page 480: “Small particle reflectors within a tissue or organ cause a diffuse scattering pattern that is characteristic of the particle size, giving rise to specific tissue or organ “signatures”. “Acoustic scattering arises from objects within a tissue that are about the size of the wavelength or smaller, and represent a rough or nonspecular reflector surface. Most organs have a characteristic structure that gives rise to a defined scatter “signature” and provides much of the diagnostic information contained in the ultrasound image.”)

Slide 338: 

Which of the following regarding the electon binding energy is correct? Is given by (A – Z) Is equal to Z2 Is not dependent on Z The k edge of barium is less than the k-edge of iodine. The amount of energy required to remove an electron from the k-shell to outside of the atom.

Slide 339: 

Which of the following regarding the electon binding energy is correct? Is given by (A – Z) Is equal to Z2 Is not dependent on Z The k edge of barium is less than the k-edge of iodine. The amount of energy required to remove an electron from the k-shell to outside of the atom.

Slide 340: 

All of the following are used when calculating the room shielding required for an xray room except: Amount of x-rays that are produced per week. Fraction of time during which radiation is directed at a particular barrier. Fraction of time that an individual spends in an adjacent room. Distance that the tube is from the primary barrier. Number of individuals occupying adjacent room.

Slide 341: 

All of the following are used when calculating the room shielding required for an xray room except: Number of individuals occupying adjacent room. The number of people in the next room is irrelevant for calculation of room shielding. The important thing to realize is that they are trying to trick you with an incorrect definition of occupancy factor. Occupancy is the FRACTION of time an individual spends in an adjacent room, NOT the number of individuals. Make sure you watch the difference between these two descriptions very very very closely so you don’t trick yourself into the wrong answer. A = Definition of Workload; B = Definition of Use Factor; C = Definition of Occupancy Factor; D = Definition of distance. These four factors determine room shielding requirement! BUSHBERG Chapter 23, page 761

Slide 342: 

What does the following device perform/do? -Wipe test analysis OR Multi-Channel --Analysis -Radiation Surveying -Radionuclide dose measurements -Nuclear Waste Disposal

Slide 343: 

What does the following device perform/do? -Wipe test analysis OR Multi-Channel –Analysis The arrow points to a portable NaI well counter

Slide 344: 

Compared with the brain parenchyma (gray and white matter) the CSF has a:  Shorter T1 Shorter T2 Longer T2 Same T1 Same T2

Slide 345: 

Compared with the brain parenchyma (gray and white matter) the CSF has a:  Longer T2 The T2 time will be longer, because as the T2 magnetization decays, the CSF decays more slowly, and therefore with have higher signal than that of the parenchyma.

Slide 346: 

For which of the following radiopharmaceutical administrations would you recommend that the mother discontinue breast feeding for two weeks after administration? Tc-99m MAA I-125 Tc-99m DTPA Ga67 Xe133

Slide 347: 

For which of the following radiopharmaceutical administrations would you recommend that the mother discontinue breast feeding for two weeks after administration? Tc-99m MAA I-125 Tc-99m DTPA Ga67 Xe133

Slide 348: 

33. Which of the following will using harmonic ultrasound without contrast agents result in? Improved Axial Resolution Decreased bandwidth Removal of clutter from returning echoes Improved temporal resolution Improved lateral resolution

Slide 349: 

Which of the following will using harmonic ultrasound without contrast agents result in? Improved Axial Resolution Decreased bandwidth Removal of clutter from returning echoes Improved temporal resolution Improved lateral resolution from an AAPM/RSNA Physics Tutorials for Residents article: “The strongest harmonic signals also originate in regions of the ultrasound pulse with the greatest pressure amplitudes, that is, near the pulse center. This often provides harmonic images with superior lateral and elevational resolution relative to fundamental images.”

Slide 350: 

With a kVp of 35, which of the following anode target materials will yield the greatest amount of k-characteristic x-rays? Beryllium (Z = 4) Carbon (Z = 6) Aluminum (Z = 13) Molybdenum (Z = 42) Tungsten (Z = 74)

Slide 351: 

With a kVp of 35, which of the following anode target materials will yield the greatest amount of k-characteristic x-rays? Molybdenum (Z = 42) Molybdenum’s k-characteristic peaks at energies of 17.5 keV and 19.6 keV, and we know that the average energy of the photons emitted by an anode target is approximately 1/3 to1/2 of the kVp. So in the case of a kVp of 35, most of the incident photons will be right in the perfect energy to produce the maximum amount of k-characteristic photons. Tungsten is much too high, and according to BUSHBERG, at 30 kVp, Tungsten targets don’t even produce any k-characteristic because in order to pull off a k-shell electron, you need to have at least 69.5 keV, and that’s not even possible with a kVp that is much too low even at Emax! According to Chapter 8 BUSHBERG, the tungsten target at kVp = 30 produces L-characteristic and Bremsstrahlung x-rays, not k-characteristic x-rays.

Slide 352: 

What is the approximate amount of contrast resolution that is achievable by computed tomography (CT)? 0.05% 0.5% 5% 10% 50%

Slide 353: 

What is the approximate amount of contrast resolution that is achievable by computed tomography (CT)? 0.05% 0.5% According to BUSHBERG Chapter 13 page 367 in Computed Tomography chapter: “It is generally accepted that the contrast resolution of screen-film radiography is approximately 5%, whereas CT demonstrates contrast resolution capability of about 0.5%.” 5% 10% 50%

Slide 354: 

Which of the following is most likely to be performed with a GdO6­S2 (Gadolinium Screen)? Direct Radiography (DR) Digital Subtraction Radiography Computed Radiography (CR) Digital Mammography

Slide 355: 

Which of the following is most likely to be performed with a GdO6­S2 (Gadolinium Screen)? Direct Radiography (DR) Digital Subtraction Radiography Computed Radiography (CR) Computed Radiography uses basically the same setup from a screen standpoint as film-screen radiography, the only difference is that the receptor plate is different such that it absorbs and traps light photons to be read out at a later time by a laser device. Digital Mammography

Slide 356: 

When performing a fluoroscopic examination with the automatic exposure control, what effect will opening the optical aperture have? Increase quantum mottle Increase the amount of dose to the patient Increase the amount of magnification Decrease the Field of View (FOV) Decrease the amount of image noise

Slide 357: 

When performing a fluoroscopic examination with the automatic exposure control, what effect will opening the optical aperture have? Increase quantum mottle Also note that it will result in less dose to the patient just in case they change this question slightly for your year to try to trick you. Basically, when you open the optical aperture which is located nearly at the end of the imaging chain in fluoroscopy (see pg 239 BUSHBERG), you end up allowing much more light into the video camera to produce your pictures up on the screen, and when that happens, the AEC will then act to decrease the amount of photons producing the image, which in turn reduces the amount of dose to the patient, and therefore less photons producing the image also means that the amount of NOISE WILL INCREASE therefore INCREASE QUANTUM MOTTLE.

Slide 358: 

If it takes 12 minutes to scan MRI study with matrix of 256 x 256, how many minutes does it take to scan with a matrix of 128 x128? 3 6 9 12 24

Slide 359: 

If it takes 12 minutes to scan MRI study with matrix of 256 x 256, how many minutes does it take to scan with a matrix of 128 x128? 6 According to HUDA/Bushberg: Scan time = # phase encode steps x number of signal averages x TR. In this example, the number of phase encode steps is only dependent on the shortest matrix dimension, and thus when you decrease the matrix by a factor of 2 in each direction, it only matters for the phase encode gradient since the frequency encode gradient has no bearing on the scan time.

Slide 360: 

The majority of the energy received by biologic material from x rays is transferred by electrons degraded gamma photons protons spallation products

Slide 361: 

The majority of the energy received by biologic material from x rays is transferred by electrons degraded gamma photons protons spallation products

Slide 362: 

How can you increase detection of a low contrast 4 cm hepatoma in a noncontrast abdominal CT? Increase kVP Increase slice thickness Filter out low frequency Decrease couch mm/360 degree rotation Increase the scan time.

Slide 363: 

How can you increase detection of a low contrast 4 cm hepatoma in a noncontrast abdominal CT? Increase slice thickness They basically are asking you to show what will increase SNR, since increasing SNR will improve contrast. (BUSHBERG Chapter 13, page 369 has an excellent summary entitled FACTORS AFFECTING CONTRAST RESOLUTION – if you look at the paragraph heading ‘Slice thickness’: “The slice thickness has a strong (linear) influence on the number of photons used to produce the image. Thicker slices use more photons and have better SNR. For example, doubling of the slice thickness doubles the number of photons used (at the same kV and mAs), and increases the SNR by 2, or 41%.” I would definitely sit down and read all of these factors as they will likely show up on the test!)

Slide 364: 

The syndrome that is associated with greatest sensitivity to X-rays is Fanconi’s Anemia Bloomberg’s syndrome Ataxia Telangiectasia Xeroderma Pigmentosa

Slide 365: 

The syndrome that is associated with greatest sensitivity to X-rays is Fanconi’s Anemia Bloomberg’s syndrome Ataxia Telangiectasia Xeroderma Pigmentosa

Slide 366: 

Variation in radiofrequency pulses can result in cause the following some patients: Induction of intense pain (brain stimulation) Cardiac stimulation Peripheral nerve stimulation All of the above

Slide 367: 

Variation in radiofrequency pulses can result in cause the following some patients: Induction of intense pain (brain stimulation) Cardiac stimulation Peripheral nerve stimulation All of the above

Slide 368: 

Edge enhancement is used to better visualize the vascular structures. This technique will increase contrast. increase noise. smooth the image. blur the image.

Slide 369: 

Edge enhancement is used to better visualize the vascular structures. This technique will increase contrast. increase noise. smooth the image. blur the image.

Slide 370: 

Gadolinium contrast will increase T2. decrease T2. increase T1. decrease T1. not affect T1.

Slide 371: 

Gadolinium contrast will increase T2. decrease T2. increase T1. decrease T1 Gadolinium only shortens T1, that’s all you need to know. not affect T1.

Slide 372: 

Contrast is improved in digital subtraction angiography with increased frame of view. frame integration. edge enhancement. decreased frame rate. placement of a test infant into the beam for ½ hour.

Slide 373: 

Contrast is improved in digital subtraction angiography with increased frame of view. frame integration BUSHBERG Chapter 9, page 245: “Frame averaging (integration) can cause very noticeable image lag, but the noise in the image is reduced as well.” As you will see, reducing noise will lead to increased contrast. edge enhancement. decreased frame rate. placement of a test infant into the beam for ½ hour.

Slide 374: 

What is the main limitation on spatial resolution for direct digital radiography? Focal spot size Screen thickness Patient thickness Radiation dose Detector element width

Slide 375: 

What is the main limitation on spatial resolution for direct digital radiography? Focal spot size Screen thickness Patient thickness Radiation dose Detector element width Bushberg 302: “The size of the detector element on a flat panel largely determines the spatial resolution of the detector system…”

Slide 376: 

Effective dose limit for the thyroid gland in a radiation worker is 5 mSv per year. 50 mSv per year. 500 mSv per year. 150 mSv per year. 5 Sv per year.

Slide 377: 

Effective dose limit for the thyroid gland in a radiation worker is 5 mSv per year. 50 mSv per year. 500 mSv per year. 150 mSv per year. 5 Sv per year.

Slide 378: 

Geometric is unsharpness surrounding an object on a radiograph is approximately 0.25 mm on both sides. What is the limiting spatial resolution in lp/mm? 0.5 2 10 20 25

Slide 379: 

Geometric is unsharpness surrounding an object on a radiograph is approximately 0.25 mm on both sides. What is the limiting spatial resolution in lp/mm? 2 F = 1 / (2 x ), where F is frequency and  (delta) is the distance spanned by one-half cycle of a sine wave, gives us 1 / (2 x 0.25 mm) = 2 lp/mm.

Slide 380: 

Beam filtration: usually uses silver. decreases the average energy of the remaining x-rays. increases radiation dose to the patient. increases contrast. decreases the amount of low energy radiation to the patient.

Slide 381: 

Beam filtration: decreases the amount of low energy radiation to the patient. BUSHBERG Chapter 5 page 114: “Added filtration refers to sheets of metal intentionally placed in the beam to change its effective energy. In general diagnostic radiology, added filters attenuate the low-energy x-rays in the spectrum that have virtually no chance of penetrating the patient and reaching the x-ray detector. Because the low-energy x-rays are absorbed by the filters instead of the patient, the radiation dose is reduced. Aluminum (Al) is the most common added filter material. Other common filter materials include copper and plastic (e.g, acrylic). In mammography, molybdenum and rhodium filters are used to help shape the x-ray spectrum. Rare earth filters such as erbium are sometimes employed in chest radiography to reduce the patient dose.” Beam filtration increases the average energy of the beam and, therefore, decreases contrast secondary to increased Compton effect in this scenario.

Slide 382: 

The following diagram depicts which MR sequence? Echo Planar Imaging Fast Spin Echo Gradient Recalled Echo Fluid Attenuated Inversion Recovery Short Tau Inversion Recovery

Slide 383: 

The following diagram depicts which MR sequence? Echo Planar Imaging Fast Spin Echo Gradient Recalled Echo Fluid Attenuated Inversion Recovery Short Tau Inversion Recovery

Slide 384: 

Compton scatter produces an alpha particle. a positron. a photoelectron and a photon. a photon and a positron a recoiled electron and a photon.

Slide 385: 

Compton scatter produces an alpha particle. a positron. a photoelectron and a photon. a photon and a positron a recoiled electron and a photon.

Slide 386: 

In fluoroscopy the dose to the center of the patient is what percent of the entrance skin exposure? 100% 50% 20% 10% 1%

Slide 387: 

In fluoroscopy the dose to the center of the patient is what percent of the entrance skin exposure? 100% 50% 20% 10% 1%

Slide 388: 

Compared with 2-D PET imaging, 3-D PET imaging uses a collimator. has greater count rates. detects less scatter. suffers from less dead-time count loses. worse for pediatric imaging.

Slide 389: 

Compared with 2-D PET imaging, 3-D PET imaging has greater count rates. BUSHBERG Chapter 22 page 726: “In three-dimensional (volume) data acquisition, axial collimators are not used and coincidences are detected between many and all detector rings. Three-dimensional acquisition greatly increases the number of true coincidences detected and may permit smaller activities to be administered to patients. There are disadvantages to three-dimensional data acquisition. For the same administered activity, the greatly increased interaction rate increases the random coincidence fraction and the dead-time count losses. Thus, three-dimensional acquisition may require less activity to be administered, compared to two-dimensional image acquisition. Furthermore, the scatter coincidence fraction is much larger and the number of interactions from activity outside the FOV is greatly increased. (Activity out of the FOV causes few true coincidences, but increases the rate of random coincidences detected and dead-time count losses.) Thus, three-dimensional acquisition is likely to be most useful in low-scatter studies, such as pediatric and brain studies, and low-activity studies.”

Slide 390: 

Given the following SPECT diagram, what is being measured? intrinsic uniformity system resolution collimator resolution extrinsic uniformity intrinsic resolution

Slide 391: 

Given the following SPECT diagram, what is being measured? intrinsic uniformity system resolution collimator resolution extrinsic uniformity intrinsic resolution Bushberg 678-79: “Intrinsic uniformity is measured by placing a point radionuclide source (typically 150 Ci of Tc-99m) in front of the uncollimated camera. The source should be placed at least four times the largest dimension of the crystal away to ensure uniform irradiation of the camera surface and at least five times away if the uniformity image is to be analyzed quantitatively using a computer… The intrinsic resolution is determined quantitatively by acquiring an image with a sheet of lead containing thin slits placed against the uncollimated camera using a point source.”

Slide 392: 

Which diagram correctly describes true random coincidences in PET?

Slide 393: 

Which diagram correctly describes true random coincidences in PET? BUSHBERG Chapter 22 page 720-21: “A true coincidence is the simultaneous interaction of emissions resulting from a single nuclear transformation (choice C). A random coincidence (also called accidental or chance coincidence), which mimics a true coincidence, occurs when emissions from different nuclear transformations interact simultaneously with the detectors (choice A)… Random coincidences and scatter coincidences result in misplaced coincidences, because they are assigned to lines of response that do not intersect the actual locations of the annihilations (choice B). They are therefore sources of noise, whose main effect is to reduce image contrast.”

Slide 394: 

Given the following diagram, the shaded area corresponds to: True positives True negatives False positives False negatives Selectivity

Slide 395: 

Given the following diagram, the shaded area corresponds to: True positives True negatives False positives False negatives Selectivity

Slide 396: 

Which of the following accurately describes the standardized uptake values (SUV)? A. Is a measure of attenuation B. Characterizes a lesion with respect to its density C. SUVs based on average pixel value are recommended rather than maximal pixel value D. SUVs greater than 3.5 are considered normal E. SUVs are affected by body weight, composition, and administered activity

Slide 397: 

Which of the following accurately describes the standardized uptake values (SUV)? A. Is a measure of attenuation B. Characterizes a lesion with respect to its density C. SUVs based on average pixel value are recommended rather than maximal pixel value D. SUVs greater than 3.5 are considered normal E. SUVs are affected by body weight, composition, and administered activity

Slide 398: 

In a fluoroscopic system with automatic brightness control (ABC), contrast is improved by increasing the mA. kV. anode angle. focal spot size. beam filtration.

Slide 399: 

In a fluoroscopic system with automatic brightness control (ABC), contrast is improved by increasing the mA. kV. anode angle. focal spot size. beam filtration. BUSHBERG Chapter 9 pages 246-248: “In situations where contrast is crucial (eg., angiography), the generator can increase the mA instead of the kV; this preserves subject contrast at the expense of higher patient dose.” Know and understand ABC Curves on page 247.

Slide 400: 

Regarding the k-space in sequential MRI, which of the following is correct? It is filled from the center to the outer edges It is filled from the outer edges towards the center It is filled from the top right outer edge to the left outer edge It is filled from the top left outer edge to the right outer edge Faithfully represents the 2-D visible image

Slide 401: 

Regarding the k-space in sequential MRI, which of the following is correct? It is filled from the center to the outer edges It is filled from the outer edges towards the center It is filled from the top right outer edge to the left outer edge It is filled from the top left outer edge to the right outer edge Faithfully represents the 2-D visible image

Slide 402: 

Technetium-99m pertechnetate is eluted from a molybdenum/technetium generator at 0600 AM and 1200 PM daily. Which of the following is correct? More technetium is available at 0600 AM than at 1200 PM. Technetium is in transient equilibrium with molybdenum at 0600 AM. Technetium is in secular equilibrium with molybdenum at 1200 PM. Aluminum breakthrough will be greatest at 1200 PM. Less technetium is available at 0600 AM than at 1200 PM.

Slide 403: 

Technetium-99m pertechnetate is eluted from a molybdenum/technetium generator at 0600 AM and 1200 PM daily. Which of the following is correct? More technetium is available at 0600 AM than at 1200 PM. Technetium is in transient equilibrium with molybdenum at 0600 AM. Technetium is in secular equilibrium with molybdenum at 1200 PM. Aluminum breakthrough will be greatest at 1200 PM. Less technetium is available at 0600 AM than at 1200 PM. BUSHBERG Chapter 19: “After approximately 23 hours (~ 4 half lives) the Tc-99m (t1/2 = 6 hours) activity reaches a maximum, at which time the production rate and the decay rate are equal and the parent and daughter are said to be in transient equilibrium… Transient equilibrium occurs when the half-life of the parent is greater than that of the daughter by a factor of approximately 10.” Choice B is incorrect as the samples are taken daily and, therefore, transient equilibrium is NEVER reached. “When the half-life of the parent is much longer than that of the daughter (i.e., more than about 100x longer), secular equilibrium occurs after approximately five to six half-lives of the daughter.” Choice C is also incorrect and, furthermore, the rubidium 81/krypton 81m generator demonstrates secular equilibrium NOT molybdenum/technetium. Alumina (presumably from the resin in the generator) can contaminate the Tc-99m eluate, but this is generally thought to be rare and choice D is incorrect. Of the two remaining, choice A is the best answer because 0600 AM represents the time of highest Tc-99 m activity since Mo has 18 hours (from 1200 PM on the previous day to 0600 AM the next morning) to decay.

Slide 404: 

A point source used during a SPECT acquisition is for improving spatial resolution. attenuation correction in the patient. spatial registration. center of rotation calibration. filter backprojection computations.

Slide 405: 

A point source used during a SPECT acquisition is for improving spatial resolution. attenuation correction in the patient. Bushberg 710: “Several manufacturers provide SPECT cameras with radioactive sources to measure the attenuation through the patient. The sources are used to acquire transmission data from projections around the patient. After acquisition, the transmission projection data are reconstructed to provide maps of tissue attenuation characteristics across transverse sections of the patient, similar to x-ray CT images.” spatial registration center of rotation calibration. filter backprojection computations.

Slide 406: 

Artifacts caused by motion in MR images are generally manifested in which direction? Frequency axis Phase Axis Fourier Transform Slice Select

Slide 407: 

Artifacts caused by motion in MR images are generally manifested in which direction? Frequency axis Phase Axis Fourier Transform Slice Select

Slide 408: 

A technologist obtains a screen film radiograph using AEC phototiming where the majority of the image is overexposed. What is the most likely reason? Phototimer is too sensitive Wrong phototimer selected The kVp is too low The mAs is too high The kVp is too high

Slide 409: 

A technologist obtains a screen film radiograph using AEC phototiming where the majority of the image is overexposed. What is the most likely reason? Phototimer is too sensitive Wrong phototimer selected The kVp is too low The mAs is too high The kVp is too high

Slide 410: 

You decrease the slice width in CT by ½ and keep the SNR the same. This will cause which of the following? Decreased noise Increased noise No change Increased radiation dose Improved contrast

Slide 411: 

You decrease the slice width in CT by ½ and keep the SNR the same. This will cause which of the following? Decreased noise Increased noise No change Increased radiation dose Bushberg 369 (This page and the page before it are crucial for this exam. Know these pages!): “Slice thickness: the slice thickness has a strong (linear) influence on the number of photons used to produce the image. Thicker slices use more photons and have better SNR. For example, doubling of the slice thickness doubles the number of photons used (at the same kV and mAs), and increases the SNR by 2, or 41%.” Therefore choice A, B, and E are incorrect because we are told that SNR is kept the same. Since decreasing slice width by ½ should increase noise (lower SNR), we MUST increase kVp and mAs to keep SNR the same and choice C is, therefore, also incorrect. Improved contrast

Slide 412: 

Which of the following is the most frequently encountered quality control issue in mammography? Screen films Automatic exposure controls Film processing Compression devices X-ray field / light field alignment

Slide 413: 

Which of the following is the most frequently encountered quality control issue in mammography? Screen films Automatic exposure controls Film processing Bushberg 214-17: “Because of the high sensitivity of mammography film quality to slight changes in processor performance, routine monitoring of proper film contrast, speed, and base plus fog values is import. A film-process quality control program is required by MQSA regulations, and daily sensitometric tests prior to the first clinical images must verify acceptable performance.” Compression devices X-ray field / light field alignment

Slide 414: 

For a CT image, how much would you have to increase the dose to increase the SNR by 4? 2 4 8 16 32

Slide 415: 

For a CT image, how much would you have to increase the dose to increase the SNR by 4? 2 4 8 16 BUSHBERG Chapter 13 page 367: “In CT there is a well-established relationship among SNR, pixel dimensions (), slice thickness (T), and radiation dose (D): D  SNR2 / 3T. Therefore, an increase in SNR by a factor of 4 would require a dose increase of 42 = 16. There is an excellent article on CT and dose at the following link: http://radiographics.rsnajnls.org/cgi/content/full/22/6/1541. 32

Slide 416: 

With regard to the diagram above, which of the following represents the region corresponding to a Geiger-Mueller Counter? A. B. C. D. E.

Slide 417: 

With regard to the diagram above, which of the following represents the region corresponding to a Geiger-Mueller Counter? A. B. C. D. E.

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