(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: Conventional Patient Specific Quality Assurance (PSQA) is commonly performed by using 2D ion chamber array (2D-array). This current PSQA procedure has two big drawbacks. First, set-up of the phantom and measuring of the dose are quite time consuming and labor intensive. The other is that we cannot confirm those actual dose distributions in the patient. We developed the system to check the daily dose distributions and assessed the dose calculation accuracy of the SMC.
Methods: To verify the accuracy of the system, we compared 2D dose distributions calculated by the SMC to dose distributions measured with the 2D-array for 10 real patient plans. We also compared the 3D dose distributions with those from TPS and verified the dose delivery accuracy. 2D and 3D gamma analysis were used for the verifications.
Results: The gamma passing rate were almost 100% for the 3mm/3% criteria for the 2D analysis. For the 3D dose analysis, the gamma passing rate were around 95% for the 3mm/3% criteria. The major reason of the discrepancy of the 3D analysis is due to the different dose calculation algorithm used in the LB3D-DVS (SMC) and the TPS (PBA). The calculation time of the SMC was on average 4 minutes using a windows workstation with 8 cores and 64GB memory.
Conclusion: We developed the LB3D-DVS. This system enables reasonably fast and accurate dose verification on patient images. Therefore, we believe that this system has the potential to increase the chance of patients’ receiving IMPT, which requires long PSQA time.
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