What are the units of Exposure Rate constant?
Exposure Rate Constant is expressed in terms of R.cm2/hr.mCi
Thursday, November 30, 2006
Wednesday, November 29, 2006
Tuesday, November 28, 2006
Window and Level
Oral Question 2002 pg 233
Examinee was shown two pictures and asked what the difference was between them. They were the same CT slice with different window and levelling.
DEFINE WINDOW AND LEVEL
Examinee was shown two pictures and asked what the difference was between them. They were the same CT slice with different window and levelling.
DEFINE WINDOW AND LEVEL
Major components of a linac
What are the major components of a linac? Describe each of them and how they operate.
ACCELERATOR STRUCTURE which is either a Traveling wave or a standing wave.
Traveling Wave- High freq microwaves of 3000 MHz are transmitted down an evacuated tube through evenly spaced accelerating cavities (Lambda/4 which is approximately 2.5 cm) in length
A prebuncher is used to reduce velocity of the electromagnetic wave in order to correspond to the speed of the injected electron, so that the electron remains on the crest of the wave ("surfing") and undergoes acceleration. Electromagnetic waves are absorbed in a dummy load at the end of the guide to prevent them from reflecting and interfering with incoming waves.
Standing Wave- Standing wave is produced when two traveling waves of equal amplitude and period travel through a waveguide in opposite directions. Standing wave accelerator structures are used in most modern LINACS.
Electron Gun- Cathode that provides a source of bunched or pulsed electrons injected into an accelerator structure
Magnetron- "Makes Microwaves" . Produces them with frequency of 3000 MHz
Klystron- Carries Microwaves. It's a microwave amplifier driven by a low power microwave oscillator.
Modulator- Simulatenously produces high voltage direct current pulses to the magnetron or klystron and the electron gun.
Waveguide- Carries microwave power from a magnetron or klystron through the accelerator structure.
Accelerator Structure- Accelerates electrons from an electron gun using microwave power from a magnetron or klystron.
Treatment Head (Bending Magnet, Scattering foil, Target, Flattening Filter)
Add Schematic
ACCELERATOR STRUCTURE which is either a Traveling wave or a standing wave.
Traveling Wave- High freq microwaves of 3000 MHz are transmitted down an evacuated tube through evenly spaced accelerating cavities (Lambda/4 which is approximately 2.5 cm) in length
A prebuncher is used to reduce velocity of the electromagnetic wave in order to correspond to the speed of the injected electron, so that the electron remains on the crest of the wave ("surfing") and undergoes acceleration. Electromagnetic waves are absorbed in a dummy load at the end of the guide to prevent them from reflecting and interfering with incoming waves.
Standing Wave- Standing wave is produced when two traveling waves of equal amplitude and period travel through a waveguide in opposite directions. Standing wave accelerator structures are used in most modern LINACS.
Electron Gun- Cathode that provides a source of bunched or pulsed electrons injected into an accelerator structure
Magnetron- "Makes Microwaves" . Produces them with frequency of 3000 MHz
Klystron- Carries Microwaves. It's a microwave amplifier driven by a low power microwave oscillator.
Modulator- Simulatenously produces high voltage direct current pulses to the magnetron or klystron and the electron gun.
Waveguide- Carries microwave power from a magnetron or klystron through the accelerator structure.
Accelerator Structure- Accelerates electrons from an electron gun using microwave power from a magnetron or klystron.
Treatment Head (Bending Magnet, Scattering foil, Target, Flattening Filter)
Add Schematic
Wednesday, November 8, 2006
Tandem and ovoid quick facts
DRR writes:
Location of point A and point B
Point A is located 2 cm laterally from the uterine canal and 2 cm above the lateral fornix. Point B is located on the pelvic wall 3 cm lateral to point A. The total dose to points A and B is the sum of the contributions from each source. WMK writes: It's a little more complicated than this. I'll comment later.
Location of point A and point B
Point A is located 2 cm laterally from the uterine canal and 2 cm above the lateral fornix. Point B is located on the pelvic wall 3 cm lateral to point A. The total dose to points A and B is the sum of the contributions from each source. WMK writes: It's a little more complicated than this. I'll comment later.
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