III기 폐암 치료에서 체적조절호형방사선치료(VMAT)에 기초한 새로운 하이브리드 방사선 치료기술의 유용성에 대한 검증

Abstract

Purpose: It is occasionally difficult to deliver sufficient radiation dose by using existing 3-dimensional conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT), or volumetric modulated arc therapy (VMAT) techniques in stage III lung cancer patients. To address this problem, we developed a new hybrid VMAT (hVMAT) technique. This study aimed to demonstrate the usability of the new hVMAT technique in stage III lung cancer treatment. Methods and Materials: 32 consecutive patients with stage III lung cancer who had been treated with hVMAT were included. The hVMAT plan was made by adding two static beams to the original VMAT plan. To evaluate the superiority of the hVMAT plan, we compared the three techniques (3DCRT vs. VMAT vs. hVMAT) using the conformity index (CI), conformation number (CN), homogeneity index (HI), and the dosimetric parameters of organs at risk (OARs). Results: The mean V20 of the lung from the hVMAT plans (27.2%) was significantly lower than 3DCRT plans (40.5%) and VMAT plans (35.0%). Additionally, the hVMAT plans showed the best results for other lung dose parameters (V5, V10, mean lung dose) among the three plans, while maintaining an irradiated dose at an acceptable level for the spinal cord, esophagus, and heart. In addition, hVMAT also showed non-inferior results for CI, CN, and HI compared with the VMAT plans. Conclusion: This novel hybrid technique can improve all dosimetric parameters of lung while maintaining the acceptable dose for other OARs. Therefore, the new hVMAT could be a useful planning technique for treating stage III lung cancer and it might be a solution for patients who cannot receive a sufficient dose with the existing 3DCRT or VMAT plans.