A dosimetric comparison of ultra-hypofractionated passively scattered proton radiotherapy and stereotactic body radiotherapy (SBRT) in the definitive treatment of localized prostate cancer.

AbstractBackground. We compared target and normal tissue dosimetric indices between ultra-hypofractionated passively scattered proton radiotherapy and stereotactic body radiotherapy (SBRT) in the definitive treatment of localized prostate cancer.Material and methods. Ten patients were treated definitively for localized prostate cancer with SBRT to a dose of 36.25 Gy in 5 fractions prescribed to a volume encompassing the prostate only. Dose-volume constraints were applied to the rectum, bladder, penile bulb, femoral heads, and prostatic and membranous urethra. Three-field passively scattered proton plans were retrospectively generated using target volumes from the same patients. Dosimetric indices were compared between the SBRT and proton plans using the Wilcoxon signed rank test.Results. All dose constraints were achieved using both ultra-hypofractionated passively scattered proton and SBRT planning. Proton plans demonstrated significant improvement over SBRT in mean dose delivered to the penile bulb (5.2...