title: PEG spacer gel and adaptive planning vs single plan in external prostate radiotherapy--clinical dosimetry evaluation.
abstract: OBJECTIVE
  Spacer gel is used to reduce the rectal dose in prostate radiotherapy. It is injected to increase the distance between the prostate and rectum. During the course of external radiotherapy treatment, physiological changes in rectal volume exist. When using polyethylene glycol material, such as DuraSeal(®) (Covidien, Mansfield, MA), gel resorption also occurs. Together, these factors alter the original dose plan distribution.
  
  
  METHODS
  External dose planning and calculations were simulated using images acquired from 10 patients who were treated with brachytherapy and gel. The CT series was taken relative to gel injection: pre 1 day, post 1 day, post 1 month and post 2 months. Adaptive planning was compared with a single plan.
  
  
  RESULTS
  Adaptive planning shows better results compared with the single plan used in the total treatment course; however, the effect is minor.
  
  
  CONCLUSIONS
  Gel usage is clearly favourable to rectal DVH. Using adaptive planning with gel improves rectal DVH but is not necessary according to this study.
  
  
  CONCLUSIONS
  Spacer gel is used in prostate radiotherapy to increase distance between the prostate and the rectum, thus reducing the rectal doses. During the treatment course, gel resorption exists which affects the rectal doses. The usefulness of adaptive planning to compensate this resorption effect has not been studied before.
authors.affiliation: Department of Oncology and Radiotherapy, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: Vesa-Pekka
authors.initials: VP
authors.lastname: Heikkilä
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D005782:Gels / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D011092:Polyethylene Glycols / Q000008:administration & dosage*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
chemical_list: D005782:Gels; D011092:Polyethylene Glycols