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| Impact of statistical uncertainty on esophagus cancer plan for dose to water and dose to medium |
| WANG Yun1, GU Peihua1, WANG Jiehua1, CAO Can2, LI Qinghao2, CHEN Li2, ZHANG Xiaoxiao2, WANG Lu2 |
1. Department of Radiotherapy, Shanghai Shidong Hospital, Shanghai 200438 China;
2. Department of Radiotherapy, Anshan Cancer Hospital, Anshan 114000 China |
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Abstract Objective To study the dosimetry effect of Dw and Dm middle and lower esophageal cancer in Monaco treatment planning system (TPS).Methods 30 patients with T3N0M0StageⅡa middle and lower esophageal cancer were selected for experiment. For each patient, optimize the plan using dose to water (Dw) and dose to medium (Dm) dose calculation mode, then rescale prescription dose to 95% volume of PTV. Compare the difference in the two mode, conformity index (CI), Homogeneity index (HI), Mean dose (Dmean), Minimum dose (Dmin), Maximum dose (D2), Dose to Organ at risk (OAR), MU, Optimization time, photon usage, and QA results of MatriXX and Arc Check. Use SPSS for multivariate analysis.Results In the dose evaluation of the middle and lower esophageal cancer cases under different dose calculation methods, the spinal cord, trachea, V20 of the whole lung, and D2 of the liver have significant dosimetric differences, the dose value, the sequential dose results were compared as (37.92 ±1.11)/(35.85 ±1.08), (59.91 ±1.43)/(60.25 ±0.98), (22.52 ±1.75)/(21.38 ±2.01), (42.89 ±0.52)/(41.73 ±0.58). In the comparison of dose cloud distribution, the difference is mainly located in the cavity and the inner wall of the lung in the target area, the dose in the target cavity in the Dw group is higher than that in the Dm group. The dose in the inner and outer walls of the lung cavity in the Dw group are slightly adducted than that in the Dm group, especially in the central area.Dose QA of MartiXX (3%-3 mm) and Arc Check (2%-2 mm) with different dose calculation methods of 60 plans of 30 cases have all passed clinical requirements. Dm Group is better than Dw group.Conclusion It is recommended to use Dm dose calculation method for Monaco 5.11 TPS in the condition of treatment planning for middle and lower esophageal cancer.
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Received: 03 January 2021
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