Coplanar intensity-modulated radiotherapy class solution for patients with prostate cancer with bilateral hip prostheses with and without nodal involvement

Abstract

Dose distributions for prostate radiotherapy are difficult to predict in patients with bilateral hip prostheses in situ, due to image distortions and difficulty in dose calculation. The feasibility of delivering curative doses to prostate using intensity-modulated radiotherapy (IMRT) in patients with bilateral hip prostheses was evaluated. Planning target volumes for prostate only (PTV1) and pelvic nodes (PTV2) were generated from data on 5 patients. PTV1 and PTV2 dose prescriptions were 70Gy and 60Gy, respectively, in 35 fractions, and an additional nodal boost of 65Gy was added for 1 plan. Rectum, bladder, and bowel were also delineated. Beam angles and segments were chosen to best avoid entering through the prostheses. Dose-volume data were assessed with respect to clinical objectives. The plans achieved the required prescription doses to the PTVs. Five-field IMRT plans were adequate for patients with relatively small prostheses (head volumes<60cm3) but 7-field plans were required for patients with larger prostheses. Bowel and bladder doses were clinically acceptable for all patients. Rectal doses were deemed clinically acceptable, although the V50Gy objective was not met for 4/5 patients. We describe an IMRT solution for patients with bilateral hip prostheses of varying size and shape, requiring either localized or whole pelvic radiotherapy for prostate cancer.