Page 78 - Fisica In Medicina n° 1/2017

^Äëíê~Åí=jÉÇáÅá= =differences while, for central tumors, the PTV coverage reduction is less pronounced. In order toobtain the same PTV coverage of RT plans, MC plans were re-prescribed to a significantly lowerprescription isodose. Particularly it decreases from [80-84]% to [64-76]% with a subsequentegli OCR calcolati e misurati per il collimatore fisso da a) 5 mm, b) 60 mm; confronto dei TPRcalcolati e misurati per il collimatore fisso da c) 5 mm, d) 60 mm;enhancement of the maximum dose to the target.1 – Confronto d– Copertura del PTV, nelle proiezioni assiale, coronale e sagittale, risultante dai piani di tra mediante algoritmi RT e MC.Fig. 2 PTV coverage with RT and MC algorithmsttamento ottimizzatiConclusionMC method shows a higher accuracy in the dose calculation thanks to the ability to take intoaccount tissues heterogeneity and to simulate the radiation transport within tissues.Thus, MC algorithm seems to be more suitable in case of NSCLC worthy of SBRT treatment withPag. 85 di 118CK. Dose distributions obtained with the MC method, and the consequent need to operateprescription at lowest isodose in order to ensure a PTV coverage of at least 95%, leave space for further careful clinical evaluations.69.2