Because you don’t need the lights on when you’re managing prostate motion with electromagnetic transponders. That’s the technique used in this trial of prostate SBRT to deliver 7.4 Gy x 5. The early grade 2 GU toxicity rate of 23% fell to 9% “long-term” (with a median follow-up of 36 months). Acute and “chronic” grade 2 GI toxicity rates were in the single-digits. Zero grade 3 bladder or bowel toxicities were recorded. Ultimately, baseline issues predicted respective toxicities. This should help your next risk-benefit discussion on prostate SBRT be more than a shot in the dark.