title: Bladder filling variations during concurrent chemotherapy and pelvic radiotherapy in rectal cancer patients: early experience of bladder volume assessment using ultrasound scanner.
abstract: OBJECTIVE
  To describe the early experience of analyzing variations and time trends in bladder volume of the rectal cancer patients who received bladder ultrasound scan.
  
  
  METHODS
  We identified 20 consecutive rectal cancer patients who received whole pelvic radiotherapy (RT) and bladder ultrasound scan between February and April 2012. Before simulation and during the entire course of treatment, patients were scanned with portable automated ultrasonic bladder scanner, 5 times consecutively, and the median value was reported. Then a radiation oncologist contoured the bladder inner wall shown on simulation computed tomography (CT) and calculated its volume.
  
  
  RESULTS
  Before simulation, the median bladder volume measured using simulation CT and bladder ultrasound scan was 427 mL (range, 74 to 1,172 mL) and 417 mL (range, 147 to 1,245 mL), respectively. There was strong linear correlation (R = 0.93, p < 0.001) between the two results. During the course of treatment, there were wide variations in the bladder volume and every time, measurements were below the baseline with statistical significance (12/16). At 6 weeks after RT, the median volume was reduced by 59.3% to 175 mL. Compared to the baseline, bladder volume was reduced by 38% or 161 mL on average every week for 6 weeks.
  
  
  CONCLUSIONS
  To our knowledge, this study is the first to prove that there are bladder volume variations and a reduction in bladder volume in rectal cancer patients. Moreover, our results will serve as the basis for implementation of bladder training to patients receiving RT with full bladder.
authors.affiliation: Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jee Suk
authors.initials: JS
authors.lastname: Chang
authors.forename: Hong In
authors.initials: HI
authors.lastname: Yoon
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Cha
authors.forename: Yoonsun
authors.initials: Y
authors.lastname: Chung
authors.forename: Yeona
authors.initials: Y
authors.lastname: Cho
authors.forename: Ki Chang
authors.initials: KC
authors.lastname: Keum
authors.forename: Woong Sub
authors.initials: WS
authors.lastname: Koom
keywords: Observer variation; Radiotherapy; Rectal neoplasms; Ultrasonography; Urinary bladder