title: The impact of emphysema on dosimetric parameters for stereotactic body radiotherapy of the lung.
abstract: The purpose of this study was to evaluate the impact of emphysematous changes in lung on dosimetric parameters in stereotactic body radiation therapy (SBRT) for lung tumor. A total of 72 treatment plans were reviewed, and dosimetric factors [including homogeneity index (HI) and conformity index (CI)] were evaluated. Emphysematous changes in lung were observed in 43 patients (60%). Patients were divided into three groups according to the severity of emphysema: no emphysema (n = 29), mild emphysema (n = 22) and moderate to severe emphysema groups (n = 21). The HI (P < 0.001) and the CI (P = 0.029) were significantly different in accordance with the severity of emphysema in one-way analysis of variance (ANOVA). The HI value was significantly higher in the moderate to severe emphysema group compared with in the no emphysema (Tukey, P < 0.001) and mild emphysema groups (P = 0.002). The CI value was significantly higher in the moderate to severe emphysema group compared with in the no emphysema group (P = 0.044). In multiple linear regression analysis, the severity of emphysema (P < 0.001) and the mean material density of the lung within the PTV (P < 0.001) were significant factors for HI, and the mean density of the lung within the PTV (P = 0.005) was the only significant factor for CI. The mean density of the lung within the PTV was significantly different in accordance with the severity of emphysema (one-way ANOVA, P = 0.008) and the severity of emphysema (P < 0.001) was one of the significant factors for the density of the lung within the PTV in multiple linear regression analysis. Our results suggest that emphysematous changes in the lung significantly impact on several dosimetric parameters in SBRT, and they should be carefully evaluated before treatment planning.
authors.affiliation: Department of Radiation Oncology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan sochiai1981@gmail.com.
authors.forename: Satoru
authors.initials: S
authors.lastname: Ochiai
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Nomoto
authors.affiliation: Department of Radiation Oncology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Yamashita
authors.affiliation: Department of Radiation Oncology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Radiology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan.
authors.forename: Shuuichi
authors.initials: S
authors.lastname: Murashima
authors.affiliation: Department of Radiology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hasegawa
authors.affiliation: Department of Radiology, Matsusaka Central Hospital, 102 Kobou Kawai-machi, Matsusaka, Mie 515-8566, Japan.
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Kurita
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Toyomasu
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kawamura
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Takada
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.lastname: Noriko
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Sakuma
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D016014:Linear Models; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000150:complications*; D011874:Radiometry; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D012307:Risk Factors
keywords: chronic obstructive pulmonary disease; conformity index; dosimetric parameter; emphysema; homogeneity index; lung cancer; stereotactic ablative radiation therapy; stereotactic body radiation therapy