1. What is the percent depth dose (also sometimes called DDR or depth dose ratio) for each of the following situations. Assume 100 cm SSD. See appendices in Kahn.
a. 4 MV photons, 10×10 cm field, d = 2 cm
b. 10 MV photons, 12×12 field, d = 3.5 cm
c. 10 MV photons, 8×8 field, d = 7.3 cm
d. 4 MV photons, 13×13 field, d = 5 cm
2. Recalculate the value in problem 1b for SSDs of 110 cm and 80 cm.
3. A dose of 200 cGy is prescribed at dmax for a 10×10 field, 100 cm SSD, and 4 MV photons. What is the dose 5 cm beyond dmax?
4. A dose of 150 cGy is prescribed at a depth of 7 cm for a 6×6 field, 100 cm SSD, and 10 MV photons. What is the dose at dmax?