Effects of proportion of lung target area on lung dose-volume parameters in treatment planning of non-small cell lung cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2022年第3期
- Page:
- 283-288
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Effects of proportion of lung target area on lung dose-volume parameters in treatment planning of non-small cell lung cancer
- Author(s):
- YANG Tao1; ZHANG Dandan2; HU Qiang1; JIN Xiaofeng1; WANG Chuyun1; WANG Yixuan2
- 1. Radiotherapy Center, Huangshi Central Hospital, Edong Healthcare, Huangshi 435000, China 2. Department of Radiation Oncology, Sun Yat-sen University Cancer Center (State Key Laboratory of Oncology in South China/Collaborative Innovation Center for Cancer Medicine), Guangzhou 510060, China
- Keywords:
- Keywords: non-small cell lung cancer volumetric modulated arc therapy size of target area homogeneity lung dose-volume parameter
- PACS:
- R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2022.03.004
- Abstract:
- Abstract: Objective To explore the effects of size of target areas on obtaining better radiotherapy regimen through reducing target dose homogeneity, thereby providing references for limiting the lung dose-volume parameters in the volumetric modulated arc therapy (VMAT) planning of non-small cell lung cancer (NSCLC). Methods A total of 32 NSCLC patients treated with VMAT were randomly selected. The prescription doses for PTV1 and PTV2 were 50.83 and 44.20 Gy, respectively. The original plan was taken as group A and group B was obtained by easing the requirements for PTV homogeneity through canceling the high-dose penalty of target areas in the original plan. After dose normalization, several parameters were analyzed quantitatively, including the volume percentage of normal lung tissues receiving radiation dose above 5 and 20 Gy (V5, V20), as well as the ratio of the lung volume to the PTV (LTR), the ratio of the lung volume to the overlap volume between PTV and lung (LOTR), homogeneity index (HI) and conformity index (CI). Moreover, the variations of lung V5 and V20 with tumor volume were analyzed using scatter plots. Results The lung V5 and V20 in group B were lower by 1.02% and 1.34% than those in group A (P=0.020, 0.001). When LTR1 and LTR2 (the ratio of lung volume to PTV1 or PTV2) were higher than 11 and 6, respectively, the lung V5 and V20 in group B showed an obvious downward trend as compared with the original plan. When LTOR1 and LTOR2 (the ratio of the lung volume to the overlap volume between PTV1 or PTV2 and lung) were greater than 30 and 19, respectively, plan B had a better lung dose reduction. Conclusion LTR and LTOR are two important indicators for assessing whether the strategy of lowering the V5 and V20 of the lungs by reducing target homogeneity works or not. When LTR and LTOR exceed certain critical values, lung V5 and V20 can be effectively reduced, which provides a reference for the clinical practice.
Last Update: 2022-03-28