title: Reduced dose to small bowel with the prone position and a belly board versus the supine position in neoadjuvant 3D conformal radiotherapy for rectal adenocarcinoma.
abstract: BACKGROUND
  No consensus exists regarding the optimal treatment setup for neoadjuvant radiotherapy of rectal cancer using a 3D conformal (3D CRT) technique. Positioning the patient prone with a belly board aims to reduce the amount of small bowel irradiated.
  
  
  METHODS
  Twenty-five patients with locally advanced rectal cancer underwent computed tomography (CT) planning for neoadjuvant chemoradiotherapy. Patients were simulated prone with a belly board and then in the supine position. Questionnaires rating the comfort of each position were completed. 3D CRT plans were generated for both positions to a prescribed dose of 50.4 Gy in 1.8 Gy daily fractions. Dose-volume parameters in 5 Gy increments for small bowel, large bowel and bladder wall were compared.
  
  
  RESULTS
  Small bowel V5 Gy, V10 Gy, V15 Gy and V20 Gy values were significantly higher in the supine position (398, 366, 245, 151 cm3for supine vs. 243, 213, 161, 122 cm3for prone respectively; P < 0.001, <0.001, <0.001 and 0.025). Large bowel V5 Gy, V10 Gy and V15 Gy values were significantly higher in the supine position (266, 209, 147 cm3supine, 175, 139, 108 cm3prone respectively; P = 0.001, <0.001, 0.003). There was a significant difference in comfort scores favouring the supine position (P = 0.015).
  
  
  CONCLUSIONS
  A significant increase in small and large bowel dose was seen in the supine plans. Treatment in the prone position with a belly board may reduce toxicity when using a 3D CRT technique. Whilst both setup positions were tolerable the supine was more comfortable.
authors.affiliation: Radiation Oncology Department, Olivia Newton John Cancer and Wellness Centre, Heidelberg, Victoria, Australia.
authors.forename: Rohen
authors.initials: R
authors.lastname: White
authors.affiliation: Radiation Oncology Department, Olivia Newton John Cancer and Wellness Centre, Heidelberg, Victoria, Australia.
authors.forename: Farshad
authors.initials: F
authors.lastname: Foroudi
authors.affiliation: Radiation Oncology Department, Olivia Newton John Cancer and Wellness Centre, Heidelberg, Victoria, Australia.
authors.forename: Joseph
authors.initials: J
authors.lastname: Sia
authors.affiliation: Radiation Oncology Department, Olivia Newton John Cancer and Wellness Centre, Heidelberg, Victoria, Australia.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Marr
authors.affiliation: Radiation Oncology Department, Olivia Newton John Cancer and Wellness Centre, Heidelberg, Victoria, Australia.
authors.forename: Daryl
authors.initials: D
authors.lastname: Lim Joon
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000009:adverse effects; D058958:Organs at Risk / Q000528:radiation effects*; D056888:Patient Positioning / Q000295:instrumentation / Q000379:methods*; D016684:Prone Position; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D016683:Supine Position
keywords: Chemoradiotherapy; gastrointestinal tract; radiotherapy conformal; radiotherapy dosage; rectal neoplasms