title: Monte Carlo-based dose reconstruction in a rat model for scattered ionizing radiation investigations.
abstract: OBJECTIVE
  In radiation biology, rats are often irradiated, but the precise dose distributions are often lacking, particularly in areas that receive scatter radiation. We used a non-dedicated set of resources to calculate detailed dose distributions, including doses to peripheral organs well outside of the primary field, in common rat exposure settings.
  
  
  METHODS
  We conducted a detailed dose reconstruction in a rat through an analog to the conventional human treatment planning process. The process consisted of: (i) Characterizing source properties of an X-ray irradiator system, (ii) acquiring a computed tomography (CT) scan of a rat model, and (iii) using a Monte Carlo (MC) dose calculation engine to generate the dose distribution within the rat model. We considered cranial and liver irradiation scenarios where the rest of the body was protected by a lead shield. Organs of interest were the brain, liver and gonads. The study also included paired scenarios where the dose to adjacent, shielded rats was determined as a potential control for analysis of bystander effects.
  
  
  RESULTS
  We established the precise doses and dose distributions delivered to the peripheral organs in single and paired rats. Mean doses to non-targeted organs in irradiated rats ranged from 0.03-0.1% of the reference platform dose. Mean doses to the adjacent rat peripheral organs were consistent to within 10% those of the directly irradiated rat.
  
  
  CONCLUSIONS
  This work provided details of dose distributions in rat models under common irradiation conditions and established an effective scenario for delivering only scattered radiation consistent with that in a directly irradiated rat.
authors.affiliation: Department of Medical Physics, Jack Ady Cancer Centre, Lethbridge, Alberta, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Kirkby
authors.forename: Esmaeel
authors.initials: E
authors.lastname: Ghasroddashti
authors.forename: Anna
authors.initials: A
authors.lastname: Kovalchuk
authors.forename: Bryan
authors.initials: B
authors.lastname: Kolb
authors.forename: Olga
authors.initials: O
authors.lastname: Kovalchuk
mesh_terms: D000818:Animals; D009010:Monte Carlo Method; D011829:Radiation Dosage; D051381:Rats; D020318:Rats, Long-Evans; D012542:Scattering, Radiation