The dosimetric impact to bladder utilizing the Varian Edge linear accelerator for prostate stereotactic body...

Stereotactic body radiation therapy (SBRT) is increasingly utilized for low and intermediate grade prostate cancer, offering advantages in reducing toxicities to critical structures and improving dose conformity. However, minimizing bladder toxicity remains challenging due to the organ's close proximity to the target. The Varian Edge linear accelerator utilizes high-resolution 2.5 mm multileaf collimators, enabling enhanced beam shaping and potentially improving organ at risk sparing. Limited data exist on the dosimetric impact of prostate SBRT planned with the Varian Edge linear accelerator. The goal of this study was to evaluate bladder toxicity in prostate SBRT planning by comparing treatment plans generated for delivery on the Varian TrueBeam and Varian Edge linear accelerators. It was hypothesized that plans utilizing the Varian Edge linear accelerator would result in a volume of the bladder receiving 34 Gy (V_{34 Gy}) ≤ 5 cubic centimeters (cc), volume of the bladder receiving 37 Gy ≤ 5 cc, dose to the most exposed 1 cc (D_{1 cc)} of the bladder ≤ 38.06 Gy, and maximum dose to 0.03 cc (D_{0.03 cc}) of the bladder ≤ 38.06 Gy. Ten patients were retrospectively analyzed, and the results demonstrated significant reductions in the V_{34 Gy} and V_{37 Gy} of the bladder for the plans designed for delivery on the Varian Edge linear accelerator. There were no meaningful differences observed for the D_{1 cc} and D_{0.03 cc.} While the Varian Edge linear accelerator provides measurable dosimetric advantages in reducing intermediate dosing to the bladder, larger prospective studies with long-term follow-up are needed to determine whether these reductions translate into improved quality of life and reduced urinary toxicity.