The patient setting up comparison between using two immobilization devices for lung cancer patient

Abstract

Background Lung cancer radiotherapy requires high accuracy of radiation dose to the target volume. Thus, setup reproducibility in the lung area is particularly important because there are surrounding critical organs such as heart and healthy lung tissue. Currently, there are 2 types of the immobilizations including; long mask (covered chest region) and wing board used to reduce patient setup error in our radiotherapy center. This study would like to evaluate the accuracy of the used of long mask and wing board for patient setup error. Objectives The objectives of this study were to compare the patient setup error between using extended long mask and wing board setting up and to monitor the patient pain level in different areas when long mask and wing board were used. Materials and methods The 30 cases of lung cancer patients treated with TrueBEAM linear accelerator using VMAT technique were collected. The patients were divided into 2 groups that used extended long mask group and wing board group. The weekly CBCT images were taken to evaluate the patient setup error. For the patient pain level in different areas of using immobilization, the 5 score level (from 1 to 5) in 4 areas including forehead, shoulder, neck, and back were selected to evaluate the results. Results The total of 180 CBCT images was analyzed. The average results of patient setup errors from long mask group and wing board group was -0.04±0.37, -0.06±0.40, -0.05±0.33 cm. and 0.08±0.48, 0.14±0.52, 0.11±0.45 cm. for vertical, longitudinal and lateral directions, respectively. The patient setup errors using long mask were significantly lesser than wing board for all directions supported by p-values, with the reduction in patient pain at shoulder region. However, the patient pain at forehead region increased when the mask was used. Conclusion The weekly CBCT can be performed to verify the patient position error. Using the extended long mask immobilization can reduce in patient setup error for all directions with lesser pain at shoulder level for lung cancer patient treatment.