Local dose-effect relations for lung perfusion post stereotactic body radiotherapy

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• 作者：Alize E.H. Scheenstra ; Maddalena M.G. Rossi ; Jos¨¦ S.A. Belderbos ; Eug¨¨ne M.F. Damen ; Joos V. Lebesque ; Jan-Jakob Sonke
• 关键词：SBRT ; Lung perfusion reduction ; NTCP ; SPECT
• 刊名：Radiotherapy and Oncology
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：107
• 期：3
• 页码：398-402
• 全文大小：503 K

文摘

Purpose

To model the local dose-effect relation for lung perfusion reduction in lung cancer patients treated with stereotactic body radiotherapy (SBRT).

Materials and methods

Forty-two patients having upper-lobe peripheral tumours <5 cm treated with SBRT (3 ¡Á 18 Gy) underwent single-photon emission computed-tomography (SPECT) scans to measure the lung perfusion 2 weeks pre-SBRT, 4-months post-SBRT, and for 8 patients 15-months post-SBRT. The relation between the calculated relative local perfusion reduction and the normalised total dose (¦Á/¦Â = 3 Gy) at 4-months post-SBRT was modeled by 3-parameter logistic model and 2-parameter linear-maximum model.

Results

The relation between local dose and perfusion reduction at 4-months post-SBRT showed a maximum effect of 42.6 % at doses >100 Gy and was best described by the logistic model with parameters (95 % CI): M = 42.6 % (40.7-44.6), D₅₀ = 28.7 Gy (26.3-31.1) and k = 2.2 (1.8-2.5). A significant increase of this maximum effect to 65.2 % was found at 15-months post-SBRT.

Conclusions

The relation between local dose and perfusion reduction in patients treated with SBRT can be modeled by a 3-parameter logistic model. This demonstrated relationship 4-months post-SBRT approaches a plateau for doses >100 Gy, where 90 % of the maximum lung-perfusion reduction is observed at NTD = 78 Gy. A further perfusion reduction compared to 4-months post-SBRT was observed fifteen months post-SBRT.