A clinical application research of 3D dose verification for esophageal carcinoma intensity-modulated radiation therapy with Compass ®

Objective To study the clinical application of Compass ® system, a novel 3 D quality assurance system for the verification of esophageal carcinoma intensity-modulated radiotherapy (IMRT) plan. Methods 12 esophageal carcinoma IMRT plans were optimized with Eclipse 8. 6 treatment planning system (TPS), and then Compass ® reconstructed 3D dose distributions with the patient anatomy. Comparison was performed among the reconstructed and calculated with TPS, Dose-volume parameters (γ pass rate、average dose deviation) to the planning target volume (PTV) and critical structures were quantitative valuated. Furthermore two-dimensional dose verification were performed use MatriXX, γ pass rate were evaluated with 3%/3 mm criteria. Results The γ pass rate of actual gantry angle was found generally declined seemingly compared with 0 degree gantry angle in two dimensional verification, difference was statistically significant (P =0.018 -0. 001). In 3D dose verification, the γ volume of PTV were exceed 93%, the deviation of D95, D50, D2 were less than 3% ; The γ volume of lungs and heart were exceed 95%, the average dose deviation were less than 3% ; The γ pass rate of spinal cord and trachea were exceed 98%. The independent check verified more conformed with the TPS calculated. Dose deviations appeared in the radiation field edge area. Conclusions 3D dose verification can provide more information to comprehensively evaluate the plan which is benefit for evaluating the clinical value of verification. Key words: Dose verification; Quality assurance; Esophageal neoplasms/radiotherapy