Predictive parameters of symptomatic radiation pneumonitis following stereotactic or hypofractionated radiotherapy delivered using volumetric modulated arcs

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• 作者：Eva M. Bongers ; Angela Botticella ; David A. Palma ; Cornelis J.A. Haasbeek ; Andrew Warner ; Wilko F.A.R. Verbakel ; Ben Slotman ; Umberto Ricardi ; Suresh Senan
• 关键词：Radiation pneumonitis ; Stereotactic radiotherapy ; Lung tumors
• 刊名：Radiotherapy and Oncology
• 出版年：October, 2013
• 年：2013
• 卷：109
• 期：1
• 页码：95-99
• 全文大小：390 K

文摘

Purpose

To identify dosimetric factors that predict development of radiation pneumonitis (RP) following stereotactic or hypofractionated radiotherapy for lung tumors.

Methods

Seventy-nine consecutive patients with either a planning target volume (PTV) > 100 cm³ (n = 69) or prior pneumonectomy or bi-lobectomy (n = 13) were identified. Radiation doses (range: 5-50 Gy, with 5 Gy increments) were converted to equivalent doses (EQD_2 Gy) (伪/尾 = 3). Total lung (TL), ipsilateral (IL) and contralateral lung (CL) volumes minus PTV, receiving 5 Gy (V5) up to 50 Gy (V50) and mean lung dose (MLD) were analyzed. Predictors of grade 猢? RP (CTCAEv4.03) were identified with concordance-statistics (C-statistic) and p-values used to quantify the performance of the model. Factors found to be significant were entered into a recursive partitioning analysis (RPA).

Results

Median PTV was 150 cm³. Grade 猢? RP was observed in 8 patients (10%). In univariable analysis, CL-MLD, CL-V5-15, TL-MLD, TL-V5-V10 and ITV size were predictive of RP (p < 0.05). In multivariable analysis, contralateral MLD (p = .007) and ITV (p = .063) were the strongest predictors of grade 猢? RP, with excellent discrimination (C-statistic: 0.868).

Conclusion

Contralateral MLD and ITV size are both strong predictors of grade 猢? RP post treatment. Planning constraints should aim to keep contralateral MLD below 3.6 Gy.