logging in or signing up X-RAYS louise.woolford Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 669 Category: Entertainment License: All Rights Reserved Like it (5) Dislike it (0) Added: July 14, 2009 This Presentation is Public Favorites: 3 Presentation Description No description available. Comments Posting comment... By: nazim_gee (13 month(s) ago) its a good presentation and it is related to my interest so i want to get this presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: nilakshi1016 (14 month(s) ago) I'am a medical student.this is very interesting field for student like us. and also I need this powerpoint presentation. Saving..... Post Reply Close Saving..... Edit Comment Close By: gayukal (29 month(s) ago) SIR IT IS VERY USEFUL I NEED A PPT OF THIS PRESENTATION Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: JP© 1 X - RAYS Slide 2: JP© 2 Cathode Ray Discharge Tube ROENTGEN 1895 X – RAYS !! Slide 3: JP© 3 Early cold cathode X-ray tube Slide 4: JP© 4 Heater current X-Ray Tube BASIC PRINCIPLE Thermionic Emission of Electrons X-Ray Photons Slide 5: JP© 5 On Average 99% of each electron’s energy is converted into heat energy. X-RAYS ARE PRODUCED IN TWO WAYS. 1. A BACKGROUND BREMSSTRAHLUNG SPECTRUM 2. A FINE LINE SPECTRUM Wavelength range : 10-9 - 10-11 metres Slide 6: JP© 6 BREMSSTRAHLUNG RADIATION SPECTRUM ACCELERATING CHARGES RADIATE ELECTROMAGNETIC RADIATION When a fast-moving electron swings around a heavily charged nucleus, its acceleration changes rapidly. BREMSSTRAHLUNG radiation Photon Energy, E = hf Slide 7: JP© 7 BREMSSTRAHLUNG BACKGROUND SPECTRUM Many X-Ray wavelengths [ down to a certain minimum ] may be produced by a particular X-Ray tube, depending upon how much of the electron’s energy is converted in this way. Maximum electron energy available = eV Slide 8: JP© 8 FINE [ LINE ] SPECTRUM DEPENDS UPON THE TARGET METAL IN THE ANODE Slide 9: JP© 9 LINE SPECTRUM Produced after an electron knocks out an inner electron from one of the target atoms e e Electrons from a higher energy level can then fall in to a vacant energy level. Excess energy is lost as an X-Ray photon e e Slide 10: JP© 10 X-RAY SPECTRUM AS A FUNCTION OF TUBE P.D. Intensity Voltage / kV 100 kV 150 kV Slide 11: JP© 11 ROTATING ANODE X-RAY TUBE 6.3 V A.C. hot filament focusing cathode 0 V 100 000V vacuum motor stator motor rotor ball race bearings rotating anode tungsten target electron beam X-RAYS THE ANODE ROTATES AT 3000 RPM Slide 12: JP© 12 THE ANODE IS ROTATED SO THAT IT DOES NOT MELT. ROTATING ANODE X-RAY TUBE THE TUBE IS IMMERSED IN OIL TO ASSIST COOLING. X-Ray QUALITY [= penetrating power] is increased by increasing the p.d. across the tube. X-Ray INTENSITY [ number of photons per second] is increased by increasing the filament current. This is the way in which the exposure time to produce a photographic plate is controlled. Slide 13: JP© 13 ATTENUATION OF X-RAYS IN A VACUUM, OR AIR, ATTENUATION OBEYS THE INVERSE SQUARE LAW IN A MATERIAL OF THICKNESS X metres Where I = the transmitted intensity in Wm-2 , I0 = the incident intensity and µ = the linear attenuation coefficient. the half thickness Slide 14: JP© 14 the half thickness is the thickness of material that halves the X-Ray intensity The mass attenuation coefficient, µm, is the attenuation per unit mass of material. Slide 15: JP© 15 X-RAY IMAGING X-rays cannot be focused. They only make shadow images. We therefore need to produce a point source. The geometry of the anode restricts the angular beam width to about 17o. The width of the beam is further limited with strips of lead. Narrow X-Ray Beam Slide 16: JP© 16 X-RAY IMAGING Lead GRID absorbs scattered X-Rays Slide 17: JP© 17 IMAGE INTENSIFIER TUBE X RAYS electrons to TV camera Screen A converts X – Rays into light Light releases photoelectrons from the photocathode Electrons accelerated by anodes The energy gained by the electrons increases the intensity produces in screen B by a factor of 100 Slide 18: JP© 18 Barium sulphate is used for X-rays of the digestive system. It is given as a white liquid drink (barium meal) or into the back passage (barium enema). X-rays cannot go through it, so when the X-ray pictures are taken, the outline of the stomach or bowel shows up on the X-ray. Contrast Media Slide 19: JP© 19 X – Ray source moves around the circular tube sending X - Rays through the patient in a fan shaped beam. X –Ray detector moves around in time with the source and measures the X – Ray strength in each position. CT SCANNER Slide 20: JP© 20 Each time the x-ray tube and detector make a 360 degree rotation and the x-ray passes through the patient's body, the image of a thin section is acquired. During each rotation, the detector records about 1,000 images (profiles) of the expanded x-ray beam. Each profile is then reconstructed by a computer into a two-dimensional image of the section that was scanned. Computed Tomography Imaging (CT Scan, CAT Scan) You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
X-RAYS louise.woolford Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 669 Category: Entertainment License: All Rights Reserved Like it (5) Dislike it (0) Added: July 14, 2009 This Presentation is Public Favorites: 3 Presentation Description No description available. Comments Posting comment... By: nazim_gee (13 month(s) ago) its a good presentation and it is related to my interest so i want to get this presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: nilakshi1016 (14 month(s) ago) I'am a medical student.this is very interesting field for student like us. and also I need this powerpoint presentation. Saving..... Post Reply Close Saving..... Edit Comment Close By: gayukal (29 month(s) ago) SIR IT IS VERY USEFUL I NEED A PPT OF THIS PRESENTATION Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: JP© 1 X - RAYS Slide 2: JP© 2 Cathode Ray Discharge Tube ROENTGEN 1895 X – RAYS !! Slide 3: JP© 3 Early cold cathode X-ray tube Slide 4: JP© 4 Heater current X-Ray Tube BASIC PRINCIPLE Thermionic Emission of Electrons X-Ray Photons Slide 5: JP© 5 On Average 99% of each electron’s energy is converted into heat energy. X-RAYS ARE PRODUCED IN TWO WAYS. 1. A BACKGROUND BREMSSTRAHLUNG SPECTRUM 2. A FINE LINE SPECTRUM Wavelength range : 10-9 - 10-11 metres Slide 6: JP© 6 BREMSSTRAHLUNG RADIATION SPECTRUM ACCELERATING CHARGES RADIATE ELECTROMAGNETIC RADIATION When a fast-moving electron swings around a heavily charged nucleus, its acceleration changes rapidly. BREMSSTRAHLUNG radiation Photon Energy, E = hf Slide 7: JP© 7 BREMSSTRAHLUNG BACKGROUND SPECTRUM Many X-Ray wavelengths [ down to a certain minimum ] may be produced by a particular X-Ray tube, depending upon how much of the electron’s energy is converted in this way. Maximum electron energy available = eV Slide 8: JP© 8 FINE [ LINE ] SPECTRUM DEPENDS UPON THE TARGET METAL IN THE ANODE Slide 9: JP© 9 LINE SPECTRUM Produced after an electron knocks out an inner electron from one of the target atoms e e Electrons from a higher energy level can then fall in to a vacant energy level. Excess energy is lost as an X-Ray photon e e Slide 10: JP© 10 X-RAY SPECTRUM AS A FUNCTION OF TUBE P.D. Intensity Voltage / kV 100 kV 150 kV Slide 11: JP© 11 ROTATING ANODE X-RAY TUBE 6.3 V A.C. hot filament focusing cathode 0 V 100 000V vacuum motor stator motor rotor ball race bearings rotating anode tungsten target electron beam X-RAYS THE ANODE ROTATES AT 3000 RPM Slide 12: JP© 12 THE ANODE IS ROTATED SO THAT IT DOES NOT MELT. ROTATING ANODE X-RAY TUBE THE TUBE IS IMMERSED IN OIL TO ASSIST COOLING. X-Ray QUALITY [= penetrating power] is increased by increasing the p.d. across the tube. X-Ray INTENSITY [ number of photons per second] is increased by increasing the filament current. This is the way in which the exposure time to produce a photographic plate is controlled. Slide 13: JP© 13 ATTENUATION OF X-RAYS IN A VACUUM, OR AIR, ATTENUATION OBEYS THE INVERSE SQUARE LAW IN A MATERIAL OF THICKNESS X metres Where I = the transmitted intensity in Wm-2 , I0 = the incident intensity and µ = the linear attenuation coefficient. the half thickness Slide 14: JP© 14 the half thickness is the thickness of material that halves the X-Ray intensity The mass attenuation coefficient, µm, is the attenuation per unit mass of material. Slide 15: JP© 15 X-RAY IMAGING X-rays cannot be focused. They only make shadow images. We therefore need to produce a point source. The geometry of the anode restricts the angular beam width to about 17o. The width of the beam is further limited with strips of lead. Narrow X-Ray Beam Slide 16: JP© 16 X-RAY IMAGING Lead GRID absorbs scattered X-Rays Slide 17: JP© 17 IMAGE INTENSIFIER TUBE X RAYS electrons to TV camera Screen A converts X – Rays into light Light releases photoelectrons from the photocathode Electrons accelerated by anodes The energy gained by the electrons increases the intensity produces in screen B by a factor of 100 Slide 18: JP© 18 Barium sulphate is used for X-rays of the digestive system. It is given as a white liquid drink (barium meal) or into the back passage (barium enema). X-rays cannot go through it, so when the X-ray pictures are taken, the outline of the stomach or bowel shows up on the X-ray. Contrast Media Slide 19: JP© 19 X – Ray source moves around the circular tube sending X - Rays through the patient in a fan shaped beam. X –Ray detector moves around in time with the source and measures the X – Ray strength in each position. CT SCANNER Slide 20: JP© 20 Each time the x-ray tube and detector make a 360 degree rotation and the x-ray passes through the patient's body, the image of a thin section is acquired. During each rotation, the detector records about 1,000 images (profiles) of the expanded x-ray beam. Each profile is then reconstructed by a computer into a two-dimensional image of the section that was scanned. Computed Tomography Imaging (CT Scan, CAT Scan)