Changes in Prostate Shape and Volume and Their Implications for Radiotherapy After Introduction of Endorectal Balloon as Determined by MRI at 3T

ERC introduction as observed by 3T MRI changed the prostate shape and volume significantly. The mean anteroposterior diameter was reduced by nearly one-sixth of its original diameter, and the mean total prostate volume was decreased by approximately 18%. This could cause difficulties and should be considered when using ERC-based MRI for MRI-computed tomography fusion and radiotherapy planning.