title: Variability of bladder filling in patients receiving radical radiotherapy to the prostate.
abstract: OBJECTIVE
  Patients receiving radical radiotherapy to the prostate are requested to maintain a full bladder to displace the dome of the bladder and small bowel from the target volume. This study investigated patients' ability to consistently maintain a full bladder throughout planning and treatment before (Study 1) and after (Study 2) the introduction of a patient information sheet.
  
  
  METHODS
  Bladder volumes were measured on 41 patients at CT scanning, simulation and once weekly during treatment using a portable ultrasound device, BladderScan BVI 3000. Patients were asked their assessment of bladder fullness, time since last urination and the volume of fluid drank. A patient information sheet on bladder filling was then introduced and the study repeated on 25 patients (Study 2). The ultrasound bladder volumes measured at CT were compared to the CT scan data.
  
  
  RESULTS
  There was a strong correlation between the ultrasound and CT bladder volumes r = 0.88 (P < 0.01). There was a significant decrease between the volume at CT (mean 362 ml, SD 229 ml) and treatment (mean 251 ml, SD 171 ml) in Study 1 (P = 0.002). In Study 2 the mean volume at CT was 286 ml (SD 164 ml) compared to a mean of 312 ml (SD 196 ml) during treatment. The measured volume correlated with patient self-assessment (r = 0.47, P < 0.01). The median volume drank by patients in Study 2 was 350 ml (range 50-825 ml) compared to 450 ml (range 75-1500 ml) in Study 1.
  
  
  CONCLUSIONS
  Our initial results showed patients were unable to maintain a constant bladder volume during planning and treatment. Implementation of written bladder filling instructions was shown to improve bladder volume consistency.
authors.affiliation: Radiotherapy Department, Royal Marsden NHS Foundation Trust, Sutton, UK.
authors.forename: Una M
authors.initials: UM
authors.lastname: O'Doherty
authors.forename: Helen A
authors.initials: HA
authors.lastname: McNair
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Norman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miles
authors.forename: Simon
authors.initials: S
authors.lastname: Hooper
authors.forename: Mark
authors.initials: M
authors.lastname: Davies
authors.forename: Naomi
authors.initials: N
authors.lastname: Lincoln
authors.forename: Jan
authors.initials: J
authors.lastname: Balyckyi
authors.forename: Peter
authors.initials: P
authors.lastname: Childs
authors.forename: David P
authors.initials: DP
authors.lastname: Dearnaley
authors.forename: Robert A
authors.initials: RA
authors.lastname: Huddart
mesh_terms: D019583:Dose Fractionation, Radiation; D004326:Drinking; D006801:Humans; D008297:Male; D015588:Observer Variation; D009929:Organ Size; D010349:Patient Compliance; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011859:Radiography; D014463:Ultrasonography; D001743:Urinary Bladder / Q000000981:diagnostic imaging*