Delta three-dimensional semiconductor array verification for intensity modulated planning of helical tomotherapy

Objective To investigate the feasibility of dose verification of intensity modulated planning of helical tomotherapy (HT) using three-dimensional semiconductor array (Delta4) and find a more time-consuming and accurate method to validate the delivery dose.Methods Delta4 detector array was used to verify the HT plan dose distribution of 10 patients.The precise setup of detector array was guided and registered by MVCT imaging.After the implementation of delivery,the measured dose distributions on the corresponding planes were compared with those calculated by the treatment planning system (TPS).According to the different acceptance criteria combination of dose difference or distance to agreement at different threshold level including 3％/2 mm,3％/3 mm,3％/4 mm,3％/5 mm at TH5,TH10,TH20,TH30,TH70,TH90,the γ analysis method was utilized to evaluate the dose verification.Results The dose distribution measured by the Delta4 was well consistent with that calculated by the TPS.The mean γpassing rates were all above 94.89％.Conclusions Delta4 detector array can get satisfying results when used in HT plan dose verification and is a viable tool to replace traditional film dosimetry system in clinical quality assurance work. Key words: Dose verification;  Three-dimensional detector array;  Helical tomotherapy