1
Q
Multileaf collimator
A
field shape or aperture shape
2
Q
Shaping the beam - pre MLC
A
jaws that formed differing sizes of squares and rectangles. However this treated too much NTT
3
Q
3 types of mlc
A
- in bound coverage - inside PTV
- Out-bound coverage - does not cover enough NTT
- cross - bound - follows the tumour shape
4
Q
Edge of MLC
A
curved - brings the light field edge and the penumbra edge closer together
reduces width of penumbra allowing more accurate dosimetry of shapes created by MLC
5
Q
Why are there grooves on MLC leaf
A
limit interleaf leakage or X-rays penetrating between the leaves in the bank
6
Q
QA tests staff need to complete
A
- double check MLC field by therapists of each fraction
- review of procedures an in service with therapists
7
Q
Positioning of MLCs
A
below primary jaws
