A randomized crossover study evaluating two immobilization devices for prostate cancer treatment

Abstract

Purpose: To compare the Combifix® immobilization device with a conventional double-leg cushion in terms of patient comfort, therapist feedback and systematic/random error outcomes. Materials and Methods: This prospective block-randomised crossover study enrolled 18 high-risk prostate cancer patients who received whole pelvic plus prostate radiotherapy. Treatment consisted of a prostate boost with one immobilization device followed by whole pelvic radiation using the other device. Our primary endpoints were device ease-of-use and patient comfort. Secondary endpoints included treatment time and systematic/ random error assessments. Results: While our patients found both devices equally comfortable and easy to use, the therapists preferred the leg cushion for ease of set-up (p = 0.04). Patient treatment time was similar for the two devices. In terms of electronic portal imaging (EPID)-based isocentre shifts, statistically, but not clinically, significant differences in systematic and random errors between the two devices exist in the superior-inferior directions (p = 0.05). Conclusions: No clinically important advantage was seen with the Combifix® device versus our standard double-leg cushion in terms of patient/therapist preference, patient comfort, and bony pelvic immobilization. However, this research project confirmed the feasibility of mounting a small single-institution randomised crossover technology assessment related to a practical radiotherapy issue. © 2008 Cambridge University Press.