Topic 10 QA Radiation Protection Flashcards
how often must you replace an HDR source?
There is no regulation.
how often to check the CBCT phantom and check shifts?
Daily
How often to check image quality for MV and kV?
Monthly
How often to check for geometric accuracy?
Monthly
How often to check for CBCT shifts?
Monthly
frequency of picket fence test?
Weekly
Is external scatter greater with metal blocks or with static MLCs?
metal blocks
What is a TVL? how much will 3 TVLs decrease the dose?
A tenth value layer. 3 TVLs will decrease dose by 0.1^3 Or in order to reduce the dose by a factor of 5, 10^n =5. or n=log10(5)
Does scatter or leakage increase with IMRT over 3D?
leakage, due to increased MUs
in FMEA (failure mode effects analysis, what is prioritized?
severity
frequency
detectability
to release a patient with a permanent implant what is the maximum allowable dose to another individual?
5 mSv
Who certifies the training needed to receive radioactive packages?
Dept of Transportation
Sv is the SI unit of _____.
Equivalent dose
Just like Gy, it is J/kg
What is not suitable for in vivo dosimetry?
- Diodes
- TLDs
- OSLDs
- MOSFETs
- Ion Chambers
Ion chambers - they require high voltage
What is the most accurate way to measure surface dose?
Extrapolation chamber
What measures dosimetry for electron beams <10 MeV?
Parallel plate chambers
What is a parallel plate chamber used for?
dosimetry for electron beams <10 MeV
surface dose for photons
depth dose for photon/electron beams
How often must survey meters be sent for calibration?
1 year
how often must therapy dosimeters (chambers used to calibrate therapy beams) be sent for calibration?
2 years
AAP recommends brachy souces are specifies in terms of their _____.
Air kerma strength
How often are brachy souces leak tested?
q6 months
How often/ who calibrates the Farmer Chamber?
Annually, in-house physicist
How often do well chambers need to be calibrated?
every 2 years
WHat energy beam produces unwanted neutrons?
higher energies like 15 MV
