(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: Small animal image-guided radiotherapy (SA-IGRT) systems have the potential to significantly improve the accuracy and precision of preclinical radiation research. A major concern in precision SA-IGRT is validating the accuracy of dose calculations in preclinically applied treatment planning systems (TPSs). Here, we perform a quantitative analysis on the accuracy of a preclinical TPS integrated into a commercial small animal radiation research platform (SARRP, Xstrahl, Inc.).
Methods: We validated the dose calculation accuracy of MuriPlan (V2.1.2) in homogeneous slab phantoms. We quantified the dose calculation accuracy in various phantom thicknesses and distances from x-ray source and compared them with EB3 film measurements. We also evaluated the TPS performance in heterogenous phantoms. We conducted these tests with custom-made inhomogeneous slab phantoms, comprised of cork, water, graphite, and aluminum with 0.25, 1.0, 1.7, 2.69 g/cm3 as roughly similar to the range of physical densities encountered in tissue e.g., lung, fat, and bone, which have densities of 0.25, 0.95, and 1.92 g.cm–3, respectively.
Results: TPS-calculated dose values showed close agreement with film measurements in varying depth of homogeneous phantom (0.3–53.3 mm), with difference of 4.64% (in superficial depths) to -5.54% (in deeper depths). Our results indicate that the MuriPlan overestimates surface dose, which is almost independent of distance from source (325–347.5 mm). Discrepancy between calculated and measured entrance dose values was constant (~10%). We found that TPS-calculated dose values were in good agreement with film measurements at exit surface of homogeneous phantom (average≤3.3%). For inhomogeneous phantom, the TPS and film exit dose measurements agreed within ≤2%.
Conclusion: We validated accuracy of the MuriPlan as a kV dedicated TPS for small animal radiotherapy application. The MuriPlan showed potential to calculate dose accurately, however, it requires accurate material definitions to have correct influence of the material segmentation on the dose distributions.
Keywords
Validation, Treatment Planning, Phantoms
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