Premium
A combined dose calculation and verification method for a small animal precision irradiator based on onboard imaging
Author(s) -
Granton Patrick V.,
Podesta Mark,
Landry Guillaume,
Nijsten Sebastiaan,
Bootsma Gregory,
Verhaegen Frank
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4725710
Subject(s) - collimated light , monte carlo method , optics , detector , dosimetry , offset (computer science) , medical imaging , materials science , beam (structure) , medical physics , nuclear medicine , physics , computer science , medicine , radiology , mathematics , laser , statistics , programming language
Purpose: 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.