Personal Monitoring Devices, Extremity Monitoring :Personal Monitoring Devices, Extremity Monitoring Presented by: Jorge Artamendi Daniel Ferro Karina Caboverde


Objectives :Objectives Describe and discuss devices Personnel monitoring Film badge, Pocket ionization, and Thermoluminescent dosimeters Discuss instruments use for monitoring Ionization chamber,Scintillation instruments, Geiger-Mueller (survey meter), Proportional counter, Victoreen condenser R-meter


Personal Monitoring Devices, Extremity Monitoring :Personal Monitoring Devices, Extremity Monitoring Occupational worker must keep below the allowed 5 REM a year Lens of eye 15 REM Extremities 50 REM Embryo-fetus 0.5 REM Types of monitoring devices Film badges Pocket ionization chambers (pocket dosimeter) Thermoluminescent dosimeter


Film Badge :Film Badge Record Radiation exposure accumulated at low rate over a long period of time Consists of three period: Durable light weight plastic film holder, an assortment of metals and a film packet The plastic holder is made for a low atomic number to filter low energy x-rays and background


Film badge con’t :Film badge con’t Metal filters are usually of aluminum or copper Measure the approximate energy of the radiation reaching the device Penetrating radiations cast faint shadows on the filters Sensitive to doses as low as .0002Sv or 1mSv (10mrem) to as high as 5Sv or 5000mSv. Provides Permanent Legal Record


Pro’s and Con’s of Film badge :Pro’s and Con’s of Film badge Light weight and easy to carry Cost effective Provides a permanent legal record Detects and records large and small exposures Can detect X, gamma and beta rays Temperature and humidity can cause film in the badge to fog over long periods of time, causing inaccurate exposure reading. Decreased film sensitivity above and below 50 keV Accuracy limited to + or – 20% Results in a month


Pocket Ionization :Pocket Ionization Are the most sensitive personnel monitoring devices 2 types of ionization chambers: Self-reading and non-self reading Self reading has a built in electrometer Measures electrical charge Gives instant reading of radiation absorbed Non-self reading which requires a special accessory electrometer to read the device.


Pocket Ionization con’t :Pocket Ionization con’t Looks like a pen Chamber contains two electrodes when charged the electrodes in the device are exposed to ionizing radiation, the air surrounding to central electrode (+) becomes ionized and discharges the mechanism in direct proportion to the amount of radiation to which it has been exposed. No legal documentation is recorded or provided


Pro’s and Con’s of Pocket Ionization :Pro’s and Con’s of Pocket Ionization Small compact and easy to use Accurate Self reading provides accurate on the spot reading Expensive Readings don’t provide legal documentation Records only exposure received in the body area which its worn Unit can discharge subjected to some type of mechanical shock and give false reading


Thermoluminescent Dosimeters :Thermoluminescent Dosimeters Measures the amount of radiation absorbed Looks like a film badge but completely different It is a light free device mostly contains a crystalline form powder or small chips of lithium fluoride. When irradiated the electrons in the crystalline lattice structure absorb energy and excited to higher energy levels or bands.


Thermoluminescent Dosimeters con’t :Thermoluminescent Dosimeters con’t When the crystals are heated the trapped electrons receive energy to rise above their present locations into a region called the conduction band. From the conduction band the electrons return to normal state and the emission of energy in the form of visible light is how the absorbed radiation dose is determined Can be worn for 3 months Only one reading


Pro’s and Con’s of Thermoluminescent Dosimeters :Pro’s and Con’s of Thermoluminescent Dosimeters Crystals in TLD interact with ionization radiation the same way human tissue does Not affected by humidity, pressure, or normal temperature Can wear for 3 months TLD crystals can be resued Results can be lost Records exposure in area of the body which it is worn Read out process destroys information stored in TLD, which prevents the read TLD from serving as permanent, legal record.


Personal Monitoring Devices, Extremity Monitoring :Personal Monitoring Devices, Extremity Monitoring Follow ALARA – as low as reasonably achievable Instruments: Ionization chamber Scintillation instruments Geiger-Mueller (survey meter) Proportional counter Victoreen condenser R-meter


Ionization Chamber :Ionization Chamber Is a gas-filled radiation detector Survey instruments operated in the ionization region of the gas amplification curve are designed to measure radiation exposure or exposure rate. Unable to detect very small amounts of activity Ex. Contamination Used to measure high exposure Generator or patient that has been injected


Scintillation Instruments :Scintillation Instruments A type of detector that is based on the property of using certain crystals to emit light photons after deposition of energy in the crystal by ionizing radiation. Used to measure low levels of activity Activity of a thyroid of personnel cared for with I131 therapy With window- detects gamma-emitting radionuclides in diagnostic energy region No window- detects high energy, gamma-emitting radionuclides.


Geiger-MuellerSurvey Meter :Geiger-MuellerSurvey Meter Is a portable survey meter to survey areas of contamination, ionization chamber measuring radiation in the region where the charge produced per ionizing event is indeprndent of the number of primary ions produced by the initial ionizing event. With the cap off it can detect, all except the lowest energy beta particles and with the cap in place only higher-energy beta particles and x-rays and gamma rays penetrate.


Proportional counter :Proportional counter Used in a laboratory to detect alpha and beta radiation and other small amounts of low level radioactive material Can discriminate between alpha and beta because alpha travel a short distance in air.


Victoreen condenser R-meter :Victoreen condenser R-meter Measures radiation by recording the total exposure received during a given period of time; tiny electric currents prodeced in the chamber when ions are liberated by radiation exposure Is adaptable to wide range of exposures Mostly used to calibrate X-ray equipment


Summary :Summary Understood the different types of personnel monitoring devices Aware of the Pro’s and Con’s of the different personnel devices Understood the different types of instruments used for personnel monitoring Aware of there different functions


References :References Saha, Gopal. Physics and Radiobiology of nuclear medicine. New York: Springer Science + Business media Inc., 2006. Waterstram-Rich, Christian. Nuclear Medicine and PET/CT. St. Louis: MOBY Elsevier, 2007.


Question 1 :Question 1 What is the Occupational dose allowed for whole body, lens of eye, extremities and embryo-(fetus)?


Answer 1 :Answer 1 Whole Body 5 REM Lens of eye 15 REM Extremities 50 REM Embryo-fetus 0.5 REM


Question 2 :Question 2 What are the three types of Personnel monitoring devices?


Answer 2 :Answer 2 Film badges Pocket ionization chambers (pocket dosimeter) Thermoluminescent dosimeter


Question 3 :Question 3 What is a film badge? How long can it be worn for? What metal filters can be used in a film badge?


Answer 3 :Answer 3 Record Radiation exposure accumulated at low rate over a long period of time 1 month Aluminum or copper


Question 4 :Question 4 T or F A pocket ionization provides legal documentation? Measures the charge of protons? Chamber contains 2 electrodes?


Answer 4 :Answer 4 False- does not provide legal Documentation False-Measures Electrons True- Chamber contains 2 electrodes


Question 5 :Question 5 What happens to the crystalline in the Thermoluminescent dosimeters when irradiated?


Answer 5 :Answer 5 When irradiated the electrons in the crystalline lattice structure absorb energy and excited to higher energy levels or bands.


Question 6 :Question 6 T or F Thermoluminescent dosimeters can be worn for 5 months? Thermoluminescent dosimeters uses a powder and/or small chips of lithium fluoride? The crystals can be reuesd after a reading?


Answer 6 :Answer 6 False-3 months True- uses crystalline in a form powder or small chips of lithium fluoride. True-Crystals my be reused


Question 7 :Question 7 What types of instruments are used as part of personnel and extremity monitoring?


Answer 7 :Answer 7 Ionization chamber Scintillation instruments Geiger-Mueller (survey meter) Proportional counter Victoreen condenser R-meter


Question 8 :Question 8 Ionization chamber detects what type of exposure?


Answer 8 :Answer 8 High exposure


Question 9 :Question 9 A scintillation detector can detect what type of energies? With and with out a window. What type of energy can a GM survey meter detect?


Answer 9 :Answer 9 Used to measure low levels of activity With window- detects gamma-emitting radionuclides in diagnostic energy region No window- detects high energy, gamma-emitting radionuclides With the cap off it can detect, all except the lowest energy beta particles and with the cap in place only higher-energy beta particles and x-rays and gamma rays penetrate


Question 10 :Question 10 What is a porportional counter used for? What is a Victoreen Condenser R-meter used for?


Answer 10 :Answer 10 Used in a laboratory to detect alpha and beta radiation and other small amounts of low level radioactive material Mostly used to calibrate X-ray equipment Measures radiation by recording the total exposure received during a given period of time