The reused mask application for extremity soft tissue sarcoma immobilization

Abstract

In radiotherapy, the accuracy and reproducibility for patient setup using immobilization is very important. At present, the vacuum styrofoam named Vac-Lok is usually used in case of extremity cancer treatment at department of radiation oncology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, however, there are some problems of treatment fields drawing on patient’s skin and inconvenience of patient setup with Vac-Lok. Therefore, the purpose of this study was to compare the patient setup accuracy between using Vac-Lok and reused-mask using image guided radiation therapy for extremity soft tissue sarcoma treatment. The data were collected from 6 patients who treated with each immobilization device during April to December 2017. The patients were verified the setup error using daily electronic portal imaging device in AP and lateral directions. The results showed that vertical direction presented the least error in both methods. The patient setup errors using Vac-Lok in vertical, longitudinal and lateral directions were -0.01±0.05, -0.21±0.28 and 0.23±0.47 cm, respectively, while the errors using reused-mask were 0.00±0.03, 0.08±0.30 and -0.14±0.27, respectively. In conclusion, the reused-mask can be applied to immobilize the extremity soft tissue sarcoma cases with the high accuracy and reproducibility and could replace the Vac-Lok. The institutes that have no Vac-Lok are possible to apply the reused-mask to increase the efficiency of extremity soft tissue sarcoma treatment.