肺部腫瘤立體定位全身放射治療設定靶體積外擴緣範圍之經驗評估

The Evaluation of Planning Target Volume Margins for Lung Tumor by Stereotatic Body Radiation Therapy

謝震球(Chun-Kau Tse) ； 劉明祥(Ming-Hsiang Liou) ； 張瑛真(Ying-Chen Chang) ； 陳佑旻(Yu-Min Chen) ； 莊文佐(Wen-Tso Chuang) ； 梁雲(Stephen Wan Leung)

《南臺灣醫學雜誌》 17卷2期 (2021/12) Pp. 98-105

https://doi.org/10.6726/MJST.202112_17(2).0005

摘要

目的：研究中收集4D錐狀斷層掃描（4-Dimensional Cone Beam Computed Tomography, 4DCBCT）影像導引的位移量數據，來分析並計算出更符合本科治療靶體積外擴緣範圍的參考值。方法：回溯由2013年至2018年共21位肺部轉移且完整接受SBRT治療的病患，收集直線加速器影像軟體XVI（X-Ray Volume Imaging）數據，計算擺位誤差，22最後以公式M=2.5Σ+β√σ^2+σ^2_p-βσ_p推估靶體積外擴緣之參考值。結果：由XVI數據結果分析出系統誤差Σ為0.07、0.12、0.09 cm分別代表Tx，Ty，Tz；而0.24、0.3、0.31度則分別代表Rx，Ry，Rz。隨機誤差σ方面為0.13、0.28、0.15 cm分別代表Tx，Ty，Tz；而0.46、0.5、0.55度則分別代表Rx，Ry，Rz，以公式演算後靶體積外擴緣計算結果分別為0.20、0.35、0.24 cm分別代表R-L，S-I，A-P平面方向，0.72、0.89、0.94度則分別代表Rx，Ry，Rz旋轉方向。結論：臨床上SBRT治療的過程中之擺位誤差，能借此公式推算出日後所有治療SBRT病患靶體積外擴緣為ITV+0.35 cm為最理想的安全範圍，最終能減少正常肺部組織的傷害。

關鍵字

立體定位全身放射治療 ； 靶體積外擴緣 ； 4D錐狀斷層掃描 ； 擺位誤差

並列摘要

Objective: We calculated our patient specific PTV treatment margins to compensate for these respiratory motion variations using four-dimensional cone beam computed tomography (4D CBCT) set-up error data. Methods: We retrospectively reviewed SBRT with lung tumor patients from 2013 to 2018, a total of 21 patients set-up error data results were collected which included a pretreatment and post-treatment data by using 4D CBCT images. All datas were computed by formulaM=2.5Σ+β√σ^2+σ^2_p-βσ_p. Results: The systematic error (Σ) and random error (σ) were 0.07, 0.12,0.09 cm and 0.13, 0.28, 0.15 cm in the R-L , SI, and A-P translational directions, respectively. 0.24,0.3,0.31° and 0.46,0.5,0.55° in the Rx ,Ry and Rz in rotational directions, respectively. PTV margin recipe was 0.20,0.35 and 0.24cm in the R-L, S-I, and A-P in translational directions, respectively. 0.72, 0.89 and 0.94° in the Rx, Ry and Rz in rotational directions ,respectively. Conclusion: These formula can be used to accurately to calculate the ITV+0.35cm with PTV margins that is reliable for SBRT patient set-up errors in our department . The ultimately could be determined the appropriate PTV margins of the less normal lung tissue is irradiated and less toxicity may be expected.

並列關鍵字

stereotatic body radiation therapy ； planning target volume ； 4D CBCT ； set-up error