Influence of volumes of prostate, rectum, and bladder on treatment planning CT on interfraction prostate shifts during ultrasound image-guided IMRT.

Purpose: The purpose of this study was to analyze the relationship between prostate, bladder, and rectum volumes on treatment planning CT day and prostate shifts in the XYZ directions on treatment days.

Methods: Prostate, seminal vesicles, bladder, and rectum were contoured on CT images obtained in supine position. Intensity modulated radiation therapy plans was prepared.