1. Ionization chambers if not sealed require their readings to be corrected for temperature and pressure because:
A. Walls of the chamber expand and shrink with temperature
B. The collecting electrodes electrical conductivity changes
C. The volume of the air changes
D. Mass of the air in the chamber changes
2. Thimble chambers are used to calibrate radiation beams because:
A. These are sturdy
B. They have good spatial resolution
C. They do not significantly perturb the beams
D. All of the above
3. Thimble chamber walls:
A. Are made from high Z atomic number material
B. Need be very thick
C. Are air-equivalent
D. Are made of ferromagnetic material
4. Parallel-plate ionization chambers are primarily used to measure:
A. Ionization at deeper locations in a phantom
B. Surface dose
C. Scattered radiation dose
D. Interstitial dose
5. Which of the following is not a desirable characteristic of an ionization chamber:
A. Energy independence
B. High signal to noise ratio
C. Change in sensitivity with the direction of the incident beam
D. Reproducibility
6. Calibration of an ionization chamber means it has been:
A. Exposed to radiation to stabilize
B. Compared against a national standard to establish a correction factor
C. Tested against leakage and electrical shorts
D. Made waterproof
7. An electrometer is an instrument used to measure:
A. Charge, current
B. Voltage, resistance
C. Capacitance
D. AIl of the above.