Application of COMPASS 3D Dose Validation System in Volumetric Modulated Arc Therapy of Esophageal Cancer

Objective To explore the feasibility of COMPASS 3D dose verification system in volumetric modulated arc therapy of esophageal cancer.

Methods We selected 37 patients newly diagnosed as esophageal neoplasm to make VMAT design based on the Oncentra planning system, and then transferred the treatment plan to the COMPASS validation system and the accelerator.We compared the calculated results in the planned system with the actual measurements in the COMPASS validation system.We obtained the Gamma passing rate, separately D95 and Dmean of the gross tumor volume(GTV) and the planning target volume(PTV), and compared the V20 and V30 dose values of the total lung.

Results The calculated results and the measured results of the γ pass rate were higher than 92% respectively.The average dose difference for D95 was less than 3% for most treatment plans and the average difference for the target volumes(Dmean) was less than 1%.The average difference for V20 and V30 of the total lung were (9.86±2.18, 20.03±2.21)% and (12.35±2.61, 12.40±2.52)% in the calculated results and the measured results, respectively.

Conclusion  COMPASS 3D validation system could analyze the results accurately and quickly, ensure the safety of esophageal cancer treatment.