title: Use of a prospective cohort study in the development of a bladder scanning protocol to assist in bladder filling consistency for prostate cancer patients receiving radiation therapy.
abstract: BACKGROUND
  Evidence of variations in bladder filling effecting prostate stability and therefore treatment and side-effects is well established with intensity modulated radiation therapy (IMRT). This study aimed to increase bladder volume reproducibility for prostate radiation therapy by implementing a bladder scanning (BS) protocol that could assist patients' bladder filling at computed tomography (CT) simulation and treatment.
  
  
  METHODS
  Based on a retrospective review of 524 prostate cancer patients, a bladder volume of 250-350 mL was adopted as 'ideal' for achieving planning dose constraints. A prospective cohort study was conducted to assess the clinical utility of measuring patients' bladder volumes at CT simulation using an ultrasound bladder scanner (Verathon 9400 BladderScan(®)). A revised bladder preparation protocol was utilised by a bladder scan group (BS) and a non-BS group followed the standard departmental bladder preparation protocol. Time and volume data for the BS group (n = 17) were compared with the non-BS group (n = 17).
  
  
  RESULTS
  The BS cohort had a CT bladder volume range of 221-588 mL; mean 379 mL, SD 125 mL. The non-BS group had a larger range: 184-757 mL; mean 373 mL, SD 160 mL (P = 0.9171). There was a positive correlation between CT volume and BS volume in the BS group (r = 0.797; P = 0.0002) although BS volumes were smaller: range 160-420 mL; mean 251 mL; SD 91 mL; P < 0.0001). The maximum bladder volume receiving 50 Gy (V50) from the BS group was 46.4%, mean 24.5%. The maximum bladder V50 from the non-BS group was 50.9%, mean 27.3% (P = 0.5178). Treatment data from weekly cone beam CT scans were also compared over 6 weeks. They were assessed as being a pass if bladder and bowel requirements were acceptable. The BS group proceeded to treatment on the basis of a pass 92.7% of the time, whereas the pass rate for non-BS group was 75%; difference 17.7% (P < 0.0001).
  
  
  CONCLUSIONS
  The BS is a useful tool for achieving consistent, appropriately sized bladder volumes in prostate cancer patients.
authors.affiliation: Department of Radiation Oncology North Coast Cancer Institute Coffs Harbour Health Campus Coffs Harbour New South Wales Australia.
authors.forename: Leah
authors.initials: L
authors.lastname: Cramp
authors.affiliation: Department of Radiation Oncology North Coast Cancer Institute Coffs Harbour Health Campus Coffs Harbour New South Wales Australia.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Connors
authors.affiliation: Department of Radiation Oncology North Coast Cancer Institute Coffs Harbour Health Campus Coffs Harbour New South Wales Australia.
authors.forename: Maree
authors.initials: M
authors.lastname: Wood
authors.affiliation: Department of Radiation Oncology North Coast Cancer Institute Coffs Harbour Health Campus Coffs Harbour New South Wales Australia.
authors.forename: Justin
authors.initials: J
authors.lastname: Westhuyzen
authors.affiliation: North Coast Cancer Institute Lismore Health Campus Lismore New South Wales Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: McKay
authors.affiliation: Department of Radiation Oncology North Coast Cancer Institute Coffs Harbour Health Campus Coffs Harbour New South Wales Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Greenham
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods; D001743:Urinary Bladder / Q000000981:diagnostic imaging* / Q000528:radiation effects
keywords: Diagnostic imaging; prostate; radiotherapy; ultrasonography; urinary bladder