Vessel-sparing prostate radiotherapy: Dose limitation to critical erectile vascular structures (internal pudendal artery and corpus cavernosum) defined by MRI

The distance between the prostate apex and critical vascular structures is highly variable. Current empiric rules for CT contouring (apex 1.5 cm above PB) overestimate or underestimate the distance between the prostate apex and critical vascular structures. When defined by MRI T2 and MRI angiogram with CT registration, limitation of dose to critical erectile structures is possible, with a more significant gain than has been previously reported using dose limitation by commonly applied intensity modulated radiation therapy studies based on CT imaging. These techniques make “vessel-sparing” prostate radiotherapy feasible.