Exam (elaborations)
RAD 400 FINAL QUESTIONS AND ANSWERS
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RAD 400 FINAL QUESTIONS AND ANSWERS
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Name: Score:71 Multiple choice questions
Term 1 of 71
if the patient was planned in prior times with a homogenous calculation algorithm, but there
was a fair amount of lung tissue to transverse, then how would their actual dose be considered
in more modern times which utilize heterogeneity in the algorithm
patient was over dosed
it increases the hotspot
wider, wider
it increases
Term 2 of 71
T/F: The block margin for electrons is often slightly larger than the block margin for photon
beams.
true
it decreases
3 cm
photons
Term 3 of 71
what is another term for segmentation
wider, wider
image fusion
image contouring
scaling
,Term 4 of 71
T/F: Electrons may be preferred for some instances because they do not penetrate deep and
can spare deeper normal structures
true
it decreases
it increases
wider, wider
Term 5 of 71
what is true concerning the benefits of a dynamic wedge over a physical wedge?
- inelastic
- elastic
- in the nucleus
- not in the nucleus
on the KV side because electrons repel each other
- the edge of the light field represents the 50% isodose line
- a field size of 4x4 cm is more difficult to measure than a 20x20
- a cobalt machine has wider penumbra compared to a linac beam
- less scatter on the patient w/a dynamic wedge
- less chance of error w/respect to the wedge direction
- physical wedges are less efficient due to their static size
-a wedge factor must be applied to the MU setting for both
Term 6 of 71
if a patient was planned in prior times with a homogenous calculation algorithm but there was
a fair amount of bone to transverse, then how would their actual dose be if considered in more
modern times which utilize heterogeneity in the algorithm
patient was over dosed
it would be located in the valley
the patient would be underdosed
wider, wider
,Term 7 of 71
what is the GTV
POI dose / RX
the gross tumor volume or actual tumor
2.5 cm
its a wedge that is 60 degrees but only places the wedg in the beam path half of the time
Term 8 of 71
Why is a 6x sometimes preferred to an 18x
- TomoTherapy doesn't utilize a flattening filter
- a 10 FFF beam has a lower energy than a 10x beam w/a flattening filter
- flattening filter free beams are very useful for high dose per fx
if the treatment depth is shallow, it might not buildup in enough time for an 18x and it
could miss the tumor
sources are concentrated more in the middle because the ends on a catheter are filtered
- the edge of the light field represents the 50% isodose line
- a field size of 4x4 cm is more difficult to measure than a 20x20
- a cobalt machine has wider penumbra compared to a linac beam
Term 9 of 71
What is the Dmax of a 10 mv beam
1.0 cm
2.5 cm
1.5 cm
3 cm
, Term 10 of 71
What is the Dmax for 4 mv beam
1.5 cm
2.5 cm
3 cm
1.0 cm
Term 11 of 71
Concerning penumbra, for electrons it is ___________________, which means the blocks must be
___________________ compared to photon blocks.
wider, wider
scaling
narrower, narrower
image contouring
Term 12 of 71
if you increase beam energy what happens to the peripheral midpoint ratio
it decreases
it stays the same
no effect
it increases
Term 13 of 71
what is another term for image registration
image fusion
fusion therapy
conversion
image registration
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