A special device (double-hole belly board) and optimal radiation technique to reduce testicular radiation exposure in radiotherapy of rectal cancer.

PURPOSE: Patients with rectal cancer are treated in prone position on a belly board to reduce the volume of irradiated small bowel. With this technique the testes obtain radiation doses, which often result in partial or complete impairment of the spermatogenesis and a dose-dependent decrease of testosterone levels. We developed a double-hole belly board (DHBB) and evaluated its potential to reduce testicular dose. METHODS AND MATERIALS: In nine consecutive male patients (3 very low tumor localisations [inguinal RT], 3 low [RT perineum], 3 high [lower border ischial tuberosities]) CT scans were performed on a conventional single-hole belly board (SHBB) and on a DHBB. Dose-volume histograms of the testes were analysed for both belly boards and for different treatment techniques (3-field and 4-field).
RESULTS: To reduce testicular dose in high tumors, positioning on DHBB was most effective (V(1.5Gy) 20-30% vs. 60% for SHBB, V(4Gy) 7% vs. 35%). In low tumors, a 3-field technique reduced high testicular doses (V(14Gy) 0-6% vs. 28-34% for 4-fields). In very low tumors a combination of DHBB and 3-fields led to a decrease of high dose exposure (V(33Gy) 0% vs. 24-78%).
CONCLUSION: In male patients with rectal cancer the use of a DHBB and a 3-field technique is recommended to reduce testicular radiation exposure.