Page 43 - Fisica In Medicina n° 1/2017

^Äëíê~Åí=cáëáÅá= =ACUROS XB validation (v.13.6) for lung and spine SBRT treatmentsN. CA V ALLI1, E. BONANNO1, A.M. GUELI2, N. RICOTTONE1, G. PISASALE1, A. D’AGOSTINO1, A. GIRLANDO1, C. MARINO1,21 HUMANITAS-Centro Catanese di Oncologia, CATANIA, ITALY2 School of Medical Physics, University of Catania, CATANIA, ITALYIntroductionSBRT requires a very high precision level and an appropriate choice of the calculation algorithm.In this study accuracy of the latest version of the Acuros XB (AXB 13.6.23) algorithm was tested with the purpose of using it for SBRT treatments in critical anatomical districts, such as lung and spine.Materials and MethodsTaking into account results obtained from Fogliata et al. 2011 “Dosimetric evaluation of Acuros XB Advanced Dose Calculation algorithm in heterogeneous media”, a comparison between AXB and AAA (v. 13.6.23) have been performed, using the same set of virtual phantoms.In a second step, SBRT lung (18 Gy x3) and spine (24 Gy x1) treatments plans (in VMAT mode with AAA and AXB) were achieved using 10MV FFF photon beam provided by a TrueBeam 2.5. Plans were calculated using an anthropomorphic phantom and pre-treatment verifications were performed on a slab phantom (RW3) using pin point chamber and thermoluminescent dosimeters (CaF2:Mn TLD-400), previously characterized.Finally, in order to complete the verification from the end-to-end point of view, SBRT plans were verified with anthropomorphic phantom containing inserts for the TLDs. Dose was verified for PTV and for some points close to the PTV.ResultsDigital phantom measurements confirm results of the previous version of AXB, showing most substantial deviations from AAA at bone-water interfaces and in extreme cases of materials with very low density and small fields.34