The objective of this study was to investigate accuracy of the United Imaging Healthcare's uRT treatment planning system (uRT-TPS), by creating AAPM TG 119 test plans with respectively IMRT and VMAT techniques by homogeneous and heterogeneous phantom.
Materials and Methods
The plans were delivered to the homogeneous and heterogeneous phantom using the United Imaging Healthcare's uRT-Linac 506C. The overall dose calculation accuracy by uRT-TPS with Collapsed Cone Convolution (CC) and Monte Carlo (MC) algorithm was measured and analyzed by creating IMRT and VMAT plans for the 5 test geometries specified in TG 119, by using two kinds of beams FF photon beam and FFF photon beam. The point doses were measured with a Farmer type ion chamber and the fluences were measured with films respectively.
The result of position accuracy was shown that the worst position accuracy is 0.36 mm and the repeated positioning accuracy of MLC field location was less than 0.25mm. The symmetry deviation of MLC was less than 0.08mm. In this study, the CLs of sMLC, dMLC and VMAT plans with FF photon beams were 2.74%, 2.12%, and 1.36% respectively. As for FFF photon beams, they were 3.76%, 2.14% and 2.90% respectively, whereas the counterpart CL specified in TG119 were 4.5% for the high dose regions and 4.7% for OAR regions. The CLs of Gamma Passing rates for sMLC, dMLC and VMAT plans were 4.59%, 5.35% and 2.15% for FF beam mode, and were 1.82%, 6.12% and 4.82% for FFF beam mode. For the heterogeneous phantom, the maximum deviation is 2.35% for CC and 2.63% for MC algorithm respectively.
Based on this analysis which were performed in accordance with the TG 119 recommendations, it is evident that the URT treatment planning system and URT-Linac 506C have commissioned IMRT and VMAT techniques with adequate accuracy. and all uRT_TPS treatment plans were recognized as clinically acceptable.