TY - JOUR T1 - Relationship Between Radiation Pneumonitis Following Definitive Radiotherapy for Non-small Cell Lung Cancer and Isodose Line JF - In Vivo JO - In Vivo SP - 3441 LP - 3448 DO - 10.21873/invivo.12644 VL - 35 IS - 6 AU - SHIGENOBU WATANABE AU - ICHIRO OGINO AU - DAISUKE SHIGENAGA AU - MASAHARU HATA Y1 - 2021/11/01 UR - http://iv.iiarjournals.org/content/35/6/3441.abstract N2 - Background/Aim: It is important to identify radiation pneumonitis above Common Terminology Criteria for Adverse Events Grade 2 (G2) in order to safely continue durvalumab maintenance after chemoradiotherapy for advanced lung cancer. The aim of this study was to discover factors that predict pneumonitis above G2. Patients and Methods: A follow-up computed tomography (CT) image was superimposed on the planning CT image using deformable image registration (DIR). The pneumonitis area was contoured on follow-up CT after DIR and the dose-volume histogram parameters of the contoured pneumonitis area were calculated. Results: V5 (Percentage of total volume receiving ≥5 Gy) to V50 of pneumonitis were significantly lower in patients with G2 pneumonitis than in those with G1 pneumonitis. The pneumonitis V15 was the most significant. The group with pneumonitis V15 <87.10% had significantly more G2 pneumonitis than the group with pneumonitis V15 ≥87.10%. Conclusion: Pneumonitis V15 <87.10% was a risk factor for G2 pneumonitis. ER -