134. DynaLog file-based Procedure for a daily monitoring of IMRT dose delivery

Abstract

PurposeThanks to the intensity modulated radiation therapy (IMRT) it is possible to achieve highly conformal dose distribution with an important shield to the adjacent organs at risk. Nevertheless, the complex nature of such treatments requires a comprehensive Quality Assurance (QA). The last decade witnessed a proliferation of QA method based on machine log files (DynaLogs Files) since their several advantages [1,2]. In this study we propose a DynaLog file-based method to ensure a daily monitoring of the correct dose delivery. MethodsThe delivery of one prostate IMRT treatment has been daily monitored thanks to the DynaLogs Files. These files are generated for each field delivery and record many useful information [1,2]. Herein the DynaLogs information about planned and actual cumulative dose fraction is taken into account. The prostate IMRT plan consists of 5 fixed field arrangements using a dynamic delivery technique (sliding window). It was calculated using the Varian Eclipse TPS (version 13.6; Varian, Palo Alto) with the analytical anisotropic algorithm (AAA) and it was delivered on a Varian Clinac2100CD. Target dose prescription is 80 Gy in 40 fractions. ResultsThe deviation between planned and actual dose fraction was calculated, for each field, as a function of both fraction numbers and delivery time. The mean and maximum dose deviations were 0.1 and 0.3 Monitor Units, respectively. ConclusionsUsually the IMRT QA is performed before the treatment beginning and it is assumed that no further variations will occur. The proposed method allows to daily assess the correct dose delivery thanks to DynaLogs Files in a no time-consuming way.