Photon PDD Flashcards
1
Q
Dmax PDD for Co60
A
0.5cm
2
Q
Dmax PDD for 6MV Photon
A
1.5cm
3
Q
Dmax PDD for 18MV Photon
A
3.3cm
4
Q
How does Photon PDD measured?
A
Using Scanning water phantom
Moving detector up and down while the beam is on
5
Q
Describe PDD curve
A
A
6
Q
What are percentage of dose deposited at the surface of 120kVp, Co60, 6MV, 18MV photon
A
0% 120kVp
30% Co60
15% 6MV
10% 18MV
7
Q
What are percentage of dose deposited at the the depth of 10cm in 120kVp, Co60, 6MV, 18MV photon
A
21% 120kVp
55% Co60
67% 6MV
80% 18MV
8
Q
Describe buildup effect curve
A
A
9
Q
Formula for surface dose
A
Dose at the surface
——————– x 100%
Dmax
