The Effect of Dose Grid Resolution on Dose Volume Histograms for Slender Organs at Risk during Pelvic Intensity-modulated Radiotherapy

摘要

Purpose: There are enduring uncertainties regarding the optimal dose grid resolution for use with pelvic intensity-modulated radiotherapy (IMRT) plans in which the adjacent organs at risk are slender and transect the field edge. Therefore, this study evaluated the effect of dose grid resolution on bladder wail dose-volume histogram (DVH) calculations for prostate IMRT plans.Materials and Methods: The planning computed tomography scans and clinical plans from 15 prostate cancer patients were included in this analysis. For each study computed tomography, the entire inner and outer bladder surfaces were delineated. Nine versions of the clinical plan were created, varying interval between the dose grid calculation points uniformly in three dimensions, whereas all other plan parameters were kept constant. The dose grid increments tested were 1-10 mm. The plans were recalculated and the bladder wall DVH compared against the study benchmark (1 mm grid).