title: Reproducible rat model for comparing late rectal toxicity from different brachytherapy techniques.
abstract: OBJECTIVE
  Newer brachytherapy techniques, such as pulse-simulated low dose rate (PDR) and high dose rate (HDR) offer clinical and technical advantages over the conventional continuous low dose rate (CLDR) irradiation. The impact of these techniques on late normal tissue toxicity has remained largely undefined, with mathematical modeling and limited clinical experience providing some guidelines. We sought to develop a reproducible rat model for quantifying and comparing late rectal toxicity from different brachytherapy techniques.
  
  
  METHODS
  An intrarectal applicator has been designed and techniques have been developed to deliver clinically relevant doses of CLDR to allow comparison to PDR and HDR. Female Wistar rats are utilized. The endpoints assessed are rectal obstruction and a histological grading of late rectal injury.
  
  
  RESULTS
  Analysis of 65 rats given either sham or single acute pulse irradiation has demonstrated the model to be reproducible and reliable in evaluating late rectal toxicity.
  
  
  CONCLUSIONS
  The use of this rat model to compare late rectal injury from various doses, dose rates, and fractionation parameters utilized by CLDR, PDR, and HDR will provide another tool for safely implementing these techniques into the clinical setting.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: White
authors.forename: E P
authors.initials: EP
authors.lastname: Armour
authors.forename: A R
authors.initials: AR
authors.lastname: Armin
authors.forename: C C
authors.initials: CC
authors.lastname: Dewitt
authors.forename: P M
authors.initials: PM
authors.lastname: Corry
authors.forename: A
authors.initials: A
authors.lastname: Martinez
mesh_terms: D000818:Animals; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D004195:Disease Models, Animal; D005260:Female; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D012002:Rectal Diseases / Q000473:pathology*; D012007:Rectum / Q000473:pathology / Q000528:radiation effects*; D015203:Reproducibility of Results