Homework 5 Flashcards
1
Q
the alignment of the light field to the radiation field can not be measured using A. the cross sectional isodose curves B. the central axis depth dose C. the profile D. none fo the answers are correct
A
B. the central axis depth dose
2
Q
the lines on a two dimensional isodose distribution represent locations of A. maximum absorption B. equal dose C. equal depth D. constant energy
A
B. equal dose
3
Q
the portion of the dose distribution which primarily represents scatter radiation is called the A. umbra B. profile C. penumbra D. dmax
A
C. penumbra
4
Q
which of the following is a use for the 3D scanning water phantom?
A. measure beam data for treatment planning computer
B. measure central axis depth dose
C. measure profile of radiation beam
D. all of the answers are correct
A
D. all of the answers are correct
5
Q
the primary purpose of the flattening filter is to
A. make the profile of the radiation beam more uniform
B. harden the beam to create less penetration
C. make the enrgy more uniform off axis
D. none of the answers are correct
A
A. make the profile of the radiation beam more uniform
6
Q
which of the following is an advantage of soft wedges? A. less scatter dose to the patient B. more time efficiency C. safer for patient and therapist D. all of the answers are correct
A
D. all of the answers are correct
7
Q
as energy increases the \_\_\_\_\_ decreases A. point of electronic equlibrium B. depth of Dmax C. PDD at 10 cm D. surface dose
A
D. surface dose
8
Q
to adequately treat the entire target volume with uniform dose the target must be within the A. central axis B. depth dose at 10 cm C. penumbra D. umbra
A
D. umbra
9
Q
dosimetric penumbra is primarily due to A. radiaiton field size B. source to measurement distance C. scatter radiaiton D. none of the answers are correct
A
C. scatter radiaiton
10
Q
calculate the geometric penumbra, in cm, if the: source size, s=3 mm SSD = 100 cm SDD= 63 cm d= 5 cm
A
0.2
