Page 52 - Fisica In Medicina n° 1/2017

^Äëíê~Åí=cáëáÅá= =Lung SBRT: treatment verification with a transmission detectorsystemE. GALLIO1, F.R. GIGLIOLI1, C. FIANDRA2, O. HAMMAD ALI3, R. ROPOLO1, R.RAGONA21 A.O.U. Città della Salute e della Scienza, Department of Medical Physics, Torino, Italy2 University of Turin, Radiotherapy Unit Department of Oncology, Torino, Italy 3 International Center for Theoretical Physics, Trieste, ItalyIntroductionThe new IBA Dolphin (IBA Dosimetry, Germany) is a transmission detector mounted on the gantry for online treatment verification. Dolphin includes the Compass software (v. 4.0) that permits the 3D dose distribution reconstruction on a patient CT. The system consists of a beam model for the calculation of the fluence and a collapsed cone dose engine for the dose deposition. The dose is predicted according to the RT plan and/or can be reconstructed based on Dolphin measurements. In this study, we tested the use of Dolphin/Compass for lung stereotactic body radiation therapy treatments and we evaluated the detector attenuation.Materials and MethodsTen patients affected by lung cancer were included in the study. The doses (prescription at 80% isodose) varied from 26 Gy in 1 fraction to 60 Gy in 8 fraction. All treatment plans were verified with Dolphin detector.To validate the beam modelling, Compass dose computation was compared with Monaco treatment planning (v. 5.0, Elekta, Sweden) based on Monte Carlo calculation, in term of dose to PTV (D98%, mean dose, D2%).Afterward the Compass reconstructed doses from measurements were compared with Compass plan computation ones. Gamma index (2%-2mm), PTV coverage (V80%, D98%, mean dose, D2%) and43