Background and purpose: This study was aimed to identify the clinical and dosimetric parameters that predict symptomatic radiation pneumonitis (SRP, radiation pneumonitis≥2 grade) in patients with pulmonary metastasis from hepatocellular carcinoma (HCC) after helical tomotherapy (HT) hypofractionated simultaneous multitarget radiotherapy.
Materials and methods: 62 patients with 407 pulmonary metastases from HCC were consecutively treated with HT. The median radiation dose was a 49.7Gy in 4.0Gy/fraction to 95% of the planning target volume (PTV). The associations between the clinical and dosimetric data and incidences of SRP were analyzed. The dose-pneumonitis relationship was analyzed based on Biologically Effective Dose (BED).
Results: Univariate analysis showed that the gross tumor volume (GTV), PTV, median lung dose (MLD), the number of pulmonary metastatic lesions (NPML), and the percentage of non-target normal lung (NTNL) volume receiving more than a BED of 3-50Gy (VBED3-50) were associated with SRP. Multivariate logistic regression analysis showed that VBED20 and NPML were significant parameters (both P<0.001) CONCLUSIONS: Our findings indicated that SRP can be predicted with NPML>5 and VBED20≥30.4% with the α/β ratio of 3Gy.
Keywords: Helical tomotherapy; Hepatocellular carcinoma; Hypofractionated radiotherapy; Pulmonary metastases; Radiation pneumonitis.
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