[1] Draw an ionisation chamber.
[2] What is
it measuring?
[3] Where is the charge collected?
[4] What effects do temperature and pressure have on the readings?
[5] Prior to an Sr-90 check, what else do you need
to consider about the electrometer? (Leakage test).
[6] Asked about the Heel Effect on the orthovoltage machine?
What is it, explain the curve and how do we overcome this is our measurements?
[7] Draw an electron depth dose curve.
[8] Explain each part of the curve.
[9] How does the curve vary with energy? Why?
[10] Draw a treatment head (linac).
[11] What are the purposes of the secondary collimators?
[12] How is the field size defined? Is it a 10 x 10 cm field
at the isocentre or at 100cm FSD?
[13] How would you measure the field size? Film? (50%).
[14] Can you determine the beam flatness from this film?
[15] How would you do that?
[16] Asked about head scatter measurements.
Why are they performed?
[17] Are they utilised in the treatment planning system?
[18] Why do we do dmax profile scans and measurements?
[19] If you had a particular area of a field blocked out,
how would you calculates the required treatment time?