title: A combined dose calculation and verification method for a small animal precision irradiator based on onboard imaging.
abstract: OBJECTIVE
  Novel small animal precision microirradiators (micro-IR) are becoming available for preclinical use and are often equipped with onboard imaging (OBI) devices. We investigated the use of OBI as a means to infer the accuracy of the delivered treatment plan.
  
  
  METHODS
  Monte Carlo modeling of the micro-IR including an elliptical Gaussian electron beam incident on the x-ray tube was used to score dose and to continue photon transport to the plane of the OBI device. A model of the OBI detector response was used to generate simulated onboard images. Experimental OBI was performed at 225 kVp, gain∕offset and scatter-glare were corrected. Simulated and experimentally obtained onboard images of phantoms and a mouse specimen were compared for a range of photon beam sizes from 2.5 cm down to 0.1 cm.
  
  
  RESULTS
  Simulated OBI can be used in small animal radiotherapy to determine if a treatment plan was delivered according to the prescription within an uncertainty of 5% for beams as small as 4 mm in diameter. For collimated beams smaller than 4 mm, beam profile differences remain primarily in the penumbra region of the smallest beams, which may be tolerable for specific preclinical micro-IR investigations.
  
  
  CONCLUSIONS
  Comparing simulated to acquired OBI during small animal treatment radiotherapy represents a useful treatment delivery tool.
authors: Department of Radiation Oncology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors: Patrick V
authors: PV
authors: Granton
authors: Mark
authors: M
authors: Podesta
authors: Guillaume
authors: G
authors: Landry
authors: Sebastiaan
authors: S
authors: Nijsten
authors: Gregory
authors: G
authors: Bootsma
authors: Frank
authors: F
authors: Verhaegen
mesh_terms: D000818:Animals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005373:Film Dosimetry / Q000295:instrumentation* / Q000662:veterinary*; D051379:Mice; D011874:Radiometry / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity