Dose-Volume Metrics Associated With Radiation Pneumonitis After Stereotactic Body Radiation Therapy for Lung Cancer

Journal Article · Sun Jul 15 04:00:00 EDT 2012 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2012.01.018· OSTI ID:22058978

Matsuo, Yukinori ^[1]; Shibuya, Keiko; Nakamura, Mitsuhiro; Narabayashi, Masaru; Sakanaka, Katsuyuki; Ueki, Nami; Miyagi, Ken; Norihisa, Yoshiki; Mizowaki, Takashi ^[1]; Nagata, Yasushi ^[2]; Hiraoka, Masahiro ^[1]

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1. Department of Radiation Oncology and Image-applied Therapy, Kyoto University, Kyoto (Japan)
2. Division of Radiation Oncology, Hiroshima University Hospital, Hiroshima (Japan)

Purpose: To identify dose-volume factors associated with radiation pneumonitis (RP) after stereotactic body radiation therapy (SBRT) for lung cancer. Methods and Materials: This study analyzed 74 patients who underwent SBRT for primary lung cancer. The prescribed dose for SBRT was uniformly 48 Gy in four fractions at the isocenter. RP was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) v.3. Symptomatic RP was defined as grade 2 or worse. Optimal cut-offs dividing the patient population into two subgroups based on the incidence of symptomatic RP were sought using the following dose-volume metrics: PTV volume (ml), mean lung dose (Gy), and V5, V10, V15, V20, V25, V30, V35, and V40 (%) of both lungs excluding the PTV. Results: With a median follow-up duration of 31.4 months, symptomatic RP was observed in 15 patients (20.3%), including 1 patient with grade 3. Optimal cut-offs for pulmonary dose-volume metrics were V25 and V20. These two factors were highly correlated with each other, and V25 was more significant. Symptomatic RP was observed in 14.8% of the patients with V25 <4.2%, and the rate was 46.2% in the remainder (p = 0.019). PTV volume was another significant factor. The symptomatic RP rate was significantly lower in the group with PTV <37.7 ml compared with the larger PTV group (11.1% vs. 34.5%, p = 0.020). The patients were divided into three subgroups (patients with PTV <37.7 ml; patients with, PTV {>=}37.7 ml and V25 <4.2%; and patients with PTV {>=}37.7 ml and V25 {>=}4.2%); the incidence of RP grade 2 or worse was 11.1%, 23.5%, and 50.0%, respectively (p = 0.013). Conclusions: Lung V25 and PTV volume were significant factors associated with RP after SBRT.

• OSTI ID: 22058978
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 83; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
LUNGS
METRICS
NEOPLASMS
PATIENTS
PNEUMONITIS
RADIATION DOSES
RADIOTHERAPY