Can diet combined with treatment scheduling achieve consistency of rectal filling in patients receiving radiotherapy to the prostate?

Background and purpose: This pilot study investigates whether an individualized fluid and fibre prescription combined with a constant treatment can improve rectal filling consistency during radiotherapy. Methods and materials: Fibre, fluid intake and bowel function were assessed in 22 patients at a standard planning scan (SCT) and individualized dietary advice was prescribed to regularize bowel habit. Patients were requested to record frequency and type of bowel movements, fibre and fluid intake daily. Two subsequent CT scans were acquired at 7 (CCT1) and 10 days (CCT2) after SCT at a similar time. Rectal volume and gas were measured planning CT's and 'on treatment' cone beam CT scans. We hypothesised that the difference in volume between CCT1 and CCT2 would be less than the difference between SCT and CCT1. Results: The mean (SD) change in volume between SCT to CCT1 and CCT1 to CCT2 was 5.68 cm(3) (26.2) and -8.6 cm(3) (40.1), respectively (p = 0.292). Of the 22 patients scanned 20 provided a complete record of dietary intake and bowel motion. The majority of patients either achieved or exceeded prescription. Change in rectal gas was the only correlation with change in rectal volume. Conclusion: Patient self reporting of bowel motion, fibre, fluid intake was achievable but consistency of rectal filling was not improved. Improved understanding of the aetiology and management of rectal gas is indicated. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 101 (2011) 471-478