Treatment planning comparison of high-dose-rate brachytherapy vs. robotic and conventional stereotactic body radiotherapy for ultrahypofractionated treatment of prostate cancer.

Abstract

Ultrahypofractionated radiation therapy is increasingly used in the treatment of prostate cancer. High-dose-rate brachytherapy (HDR-BT) and stereotactic body radiotherapy (SBRT) are representative methods of ultrahypofractionation. This study was performed to compare clinically applied treatment plans for patients who had been treated using HDR-BT vs. conventional or robotic SBRT. Calculated dose-volume indices between HDR-BT without a perirectal spacer (n=20), robotic SBRT without a spacer (n=40), and conventional (non-robotic) SBRT with a spacer (n=40) were compared. Percentages against the prescription dose regarding the planning target volume (PTV), bladder, rectum, and urethra were statistically compared. The D50% of the PTV with HDR-BT (140.5%±4.9%) was significantly higher than that with robotic or conventional SBRT (116.2%±1.6%, 101.0%±0.4%, p<0.01). The D2cm3 of the bladder with HDR-BT (65.6%±6.4%) was significantly lower than those with SBRT (105.3%±2.9%, 98.0%±1.3%, p<0.01). The D2cm3 of the rectum with HDR-BT (60.6%±6.2%) was also significantly lower than those with SBRT (85.1%±8.8%, 70.4%±9.6%, p<0.01). By contrast, the D0.1cm3 of the urethra with HDR-BT (117.1%±3.6%) was significantly higher than those with SBRT (100.2%±0.7%, 104.5%±0.6%, p<0.01). HDR-BT could administer a higher dose to the PTV and a lower dose to the bladder and rectum, at the cost of a slightly higher dose to the urethra compared with SBRT.