title: A randomized study of the use of a customized immobilization system in the treatment of prostate cancer with conformal radiotherapy.
abstract: OBJECTIVE
  To evaluate the impact of a customized immobilisation system on field placement accuracy, simulation and treatment delivery time, radiographer convenience and patient acceptability.
  
  
  METHODS
  Thirty men receiving radical radiotherapy for prostate cancer were randomised using a cross over trial design to have radiotherapy planning and treatment given either in a conventional treatment position (CTP) or using an immobilisation system (IMS). The randomisation was to have either the CTP or IMS for the initial 3 weeks of radiotherapy after which patients were replanned and changed to the alternative treatment set-up. Treatment accuracy was measured using an electronic portal imaging device. Radiographers and patients completed weekly questionnaires.
  
  
  RESULTS
  Median simulation time was 22.5 min (range 20-30 min) in the CTP and 25 min (range 15-40 min) for the IMS (P < 0.001). Median treatment time was 9 min for CTP (range 8-10 min), and 10 min (range 8.5-13.5 min) for IMS (P < 0.001). Median isocentre displacement for anterior fields was 1.7 mm from the simulated isocentre for the CTP compared to 2.0 mm for IMS (P = 0.07). For left lateral fields values were 1.8 and 1.8 mm (P = 0.98), and for right lateral fields 2.1 and 1.7 mm (P = 0.06), respectively. No clinically significant reduction in either systematic or random field placement errors was demonstrated. Radiographers reported that patients found the IMS more comfortable than CTP (P < 0.001), but when using the IMS, they noticed greater difficulty in patient positioning (P < 0.001), and alignment to skin tattoos (P < 0.001).
  
  
  CONCLUSIONS
  Although IMS may have been more comfortable, treatment accuracy was not improved compared to the CTP in our department. In addition, treatment took longer and patient set-up was more difficult.
authors.affiliation: Academic Unit of Radiotherapy and Oncology, Institute of Cancer Research, Sutton, Surrey, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Nutting
authors.forename: V S
authors.initials: VS
authors.lastname: Khoo
authors.forename: V
authors.initials: V
authors.lastname: Walker
authors.forename: H
authors.initials: H
authors.lastname: McNair
authors.forename: C
authors.initials: C
authors.lastname: Beardmore
authors.forename: A
authors.initials: A
authors.lastname: Norman
authors.forename: D P
authors.initials: DP
authors.lastname: Dearnaley
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D006801:Humans; D007103:Immobilization; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017060:Patient Satisfaction; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D016896:Treatment Outcome