Question

A dose of 19 Gy is to be delivered with a 6 MeV beam to a tumour located at a depth of 11 cm. An 11 ? 11 cm field is to be used with a 100 cm SSD. For this beam in this geometry, you are given the following additional data: PDD for a 10 ? 10 cmfield at depth of 10 cm = 66.0%, PDD for a 12 ? 12 cm field at depth of 10 cm = 67.8%, PDD for a 10 ? 10 cm field at depth of 15 cm = 50.5%, and PDD for a 12 ? 12 cm field at depth of 15 cm = 52.3%. Compute the maximum dose (in Gy) received at any location within the patient's anatomy. (For all field sizes and depths stated above, the dose at depth d, D(d), is linear with respect to field size and linear with respect to depth.)

Answer 1