title: Morphologic change of rectosigmoid colon using belly board and distended bladder protocol.
abstract: OBJECTIVE
  This study investigates morphologic change of the rectosigmoid colon using a belly board in prone position and distended bladder in patients with rectal cancer. We evaluate the possibility of excluding the proximal margin of anastomosis from the radiation field by straightening the rectosigmoid colon.
  
  
  METHODS
  Nineteen patients who received preoperative radiotherapy between 2006 and 2009 underwent simulation in a prone position (group A). These patients were compared to 19 patients treated using a belly board in prone position and a distended bladder protocol (group B). Rectosigmoid colon in the pelvic cavity was delineated on planning computed tomography (CT) images. A total dose of 45 Gy was planned for the whole pelvic field with superior margin of the sacral promontory. The volume and redundancy of rectosigmoid colon was assessed.
  
  
  RESULTS
  Patients in group B had straighter rectosigmoid colons than those in group A (no redundancy; group A vs. group B, 10% vs. 42%; p = 0.03). The volume of rectosigmoid colon in the radiation field was significantly larger in group A (56.7 vs. 49.1 mL; p = 0.009). In dose volume histogram analysis, the mean irradiated volume was lower in patients in group B (V45 27.2 vs. 18.2 mL; p = 0.004). In Pearson correlation coefficient analysis, the in-field volume of rectosigmoid colon was significantly correlated with the bladder volume (R = 0.86, p = 0.003).
  
  
  CONCLUSIONS
  Use of a belly board and distended bladder protocol could contribute to exclusion of the proximal margin of anastomosis from the radiation field.
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Yeona
authors.initials: Y
authors.lastname: Cho
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Jee Suk
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Mi Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Icheon Public Health Center, Icheon, Korea.
authors.forename: Jaehwan
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Hwakyung
authors.initials: H
authors.lastname: Byun
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Nalee
authors.initials: N
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Ki Chnag
authors.initials: KC
authors.lastname: Keum
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
authors.forename: Woong Sub
authors.initials: WS
authors.lastname: Koom
keywords: Anastomotic leakage; Anastomotic strength; Belly board; Bladder volume; Preoperative radiotherapy; Rectal cancers