title: The effect of bowel preparation regime on interfraction rectal filling variation during image guided radiotherapy for prostate cancer.
abstract: BACKGROUND
  This study aimed to investigate the tolerability and impact of milk of magnesia (MoM) on interfraction rectal filling during prostate cancer radiotherapy.
  
  
  METHODS
  Two groups were retrospectively identified, each consisting of 40 patients with prostate cancer treated with radiotherapy to prostate+/-seminal vesicles, with daily image-guidance in 78Gy/39fractions/8 weeks. The first-group followed anti-flatulence diet with MoM started 3-days prior to planning-CT and continued during radiotherapy, while the second-group followed the same anti-flatulence diet only. The rectum between upper and lower limit of the clinical target volume (CTV) was delineated on planning-CT and on weekly cone-beam-CT (CBCT). Rectal filling was assessed by measurement of anterio-posterior diameter of the rectum at the superior and mid levels of CTV, rectal volume (RV), and average cross-sectional rectal area (CSA; RV/length).
  
  
  RESULTS
  Overall 720 images (80 planning-CT and 640 CBCT images) from 80 patients were analyzed. Using linear mixed models, and after adjusting for baseline values at the time of planning-CT to test the differences in rectal dimensions between both groups over the 8-week treatment period, there were no significant differences in RV (p = 0.4), CSA (p = 0.5), anterio-posterior diameter of rectum at superior (p = 0.4) or mid level of CTV (p = 0.4). In the non-MoM group; 22.5% of patients had diarrhea compared to 60% in the MoM group, while 40% discontinued use of MoM by end of radiotherapy.
  
  
  CONCLUSIONS
  The addition of MoM to antiflatulence diet did not reduce the interfraction variation in rectal filling but caused diarrhea in a substantial proportion of patients who then discontinued its use.
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Hosni
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Tara
authors.initials: T
authors.lastname: Rosewall
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Timothy
authors.initials: T
authors.lastname: Craig
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada.
authors.forename: Vickie
authors.initials: V
authors.lastname: Kong
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bayley
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Berlin
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Bristow
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Catton
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
authors.forename: Padraig
authors.initials: P
authors.lastname: Warde
authors.affiliation: Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, 610 University Ave, Toronto, ON, M5G 2M9, Canada. Peter.Chung@rmp.uhn.on.ca.
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005414:Flatulence / Q000517:prevention & control; D006801:Humans; D007421:Intestine, Small / Q000502:physiology*; D054368:Laxatives / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009038:Motion; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012007:Rectum / Q000502:physiology; D012189:Retrospective Studies
chemical_list: D054368:Laxatives
keywords: Bowel preparation; Laxative; Prostate cancer; Radiotherapy; Rectum