Question

a) A tumour located at a depth of 10 cm is treated using a non-isocentic technique with a Co-60 machine, to a dose of 1.8 Gy, with a single 5 cm x 5 cm beam. Compute the maximum dose received anywhere in the patient's anatomy. Refer to the attached table for PDD data. (5 pts)

b) At what depth does the maximum dose occur? Explain. (5 pts)

c) Compute the dose at a depth of 5 cm along the beam axis. (5 pts)

d) Would this be a good treatment strategy? Explain.

Percent Depth dose (in %) table for Co-60 beam for different depths and field sizes.

	Field Size (cm^2)	5 x 5	10 x 10	20 x 20
Depth (cm)
0.5		100	100	100
5.0		76.7	80.4	83.0
10.0		53.3	58.7	63.3

Answer 1