Validation of clearcalc for efficient patient specific QA.

Abstract

Uganda's only radiotherapy center is a very busy facility treating about 210 patients daily on three linear accelerators making it sometimes hard to have machine time for pretreatment QAs. This study was aimed at validating an independent calculation software, ClearCalc (ICS) for second checks of the treatment planning system (TPS) calculations. The validation of ICS started with simple phantom test plans consisting of square, irregular, open and wedged fields designed in the TPS and measured in phantoms. Doses and monitor units (MUs) calculated by ICS were compared with TPS calculated doses and with measured doses. ICS was then validated on clinically approved treatment plans: comparison with TPS calculations and with pretreatment QA measurements performed with electronic portal imaging devices (EPIDs) and analyzed using Gamma passing criteria of 3%/3 mm and 3%/2 mm. Results for test plans were within the passing level of 3.0% except for 2 outliers (-3.1% and 3.1%). As for the clinically approved treatment plans, they show good agreement between MUs (0.2 ± 1.8%), reference point doses (0.2 ±1.5%) and mean PTV doses (0.5 ± 1.4%). ICS calculated (3D) mean gamma pass rates were 98.1±1.6% and 98.4±1.0% for 3%/2 mm and 3%/3 mm criteria. No correlation was seen between gamma analysis results from ICS and EPID. This study validated ClearCalc on phantom and clinically approved plans. The result show that ICS based patients specific QA is quick, promising and potentially allows significant time saving that can be utilized for patient treatments.