顱內多發腫瘤病患使用電腦刀多葉準直儀與動態準直儀之放射治療計畫劑量輸出效能比較

Dosimetric Delivery Efficiency Comparison between CyberKnife M6 InCise MLC and Iris Treatment Modes for Intracranial Multiple Tumors

陳怡任(Yi-Ren Chen) ； 郭仕賢(Shih-Sian Guo) ； 黃郁傑(Yu-Je Huang) ； 黃俊杰(Chun-Chieh Huang) ； 張寶樹(Pao-Shu Chang) ； 李財福(Tsair-Fwu Lee)

《中華放射線技術學雜誌》 42卷2期 (2018/06) Pp. 69-78

摘要

比較顱內多發腫瘤患者接受CyberKnife M6多葉準直儀（InCise multileaf collimator, MLC）或動態準直儀（Iris variable aperture collimator）放射治療計劃之劑量指標參數與治療效率差異。研究對象為10位多發（mutiple）顱內腫瘤患者同時規劃CyberKnife M6 InCise MLC與Iris系統之兩組不同放射治療計畫（InCise MLC:Iris = 10:10）；其處方劑量為14 Gy-30 Gy、次數為1-3次，皆使用相同之腫瘤包覆率與危急器官（organs at risk, OARs）劑量限制條件，用以評估劑量品質與傳遞效率。研究評估利用魏克森符號等級檢定（Wilcoxon signed-rank test）進行分析及比較以下之各項腫瘤指標參數包括：順形指數（conformity index, CI）、新順形指數（new conformity index, nCI）、勻稱指數（homogeneity index, HI）、靶體積包覆率（target coverage）、危急器官品質指數（quality index, QI）、腫瘤外的劑量梯度（R10 - R90）以及射束傳遞效率包括：射束（beams）、節點（nodes）、監控單位（monitor unit, MU）、傳遞時間（delivery time）。研究結果顯示CyberKnife InCise MLC及Iris系統對於顱內腫瘤之CI、nCI、HI和coverage無顯著差異，且於危急器官之QI上擁有相具同的保護效力，而在腫瘤外的劑量梯度（R10-R90）比較上，InCise MLC最高可減少48% R50劑量，而最低可減少22% R90劑量，在治療效率方面，InCise MLC可有效減少1/3的治療時間（71% beams、48% nodes、50% MU及32%治療時間）。兩種技術給予腫瘤包覆／危急器官保護之劑量指標上具備相同的治療／保護效力，然而InCise MLC放射治療計畫在腫瘤外治療劑量梯度下降率及治療效率優於Iris。本研究可提供CyberKnife於臨床放射治療規劃之參考指標，以提升患者治療品質及放射治療效率。

關鍵字

顱內多發腫瘤 ； 電腦刀（CyberKnife M6） ； 多葉準直儀（InCise MLC） ； 動態準直儀（Iris） ； 治療效率

並列摘要

This study aimed to compare the dosimetric quality and treatment delivery efficiency in the patients for multiple intracranial tumors by the InCise MLC and Iris treatment planning. Ten patients with multiple intracranial tumors for CyberKnife treatment were enrolled. Both CyberKnife InCise MLC and Iris treatment planning were designed for each patients with prescribed dose 14-30 Gy; fractions 1-3. The same constraints were guided for PTV coverage and organs at risk (OARs) sparing. Thus 20 plans (InCise MLC: Iris = 10:10) were created for comparison. The following indices were used to compare the quality of dosimetry and delivery efficiency, e.g., conformity index (CI), new conformity index (nCI), homogeneity index (HI), coverage, quality index (QI), dose gradient outside the tumor (R10 - R90), and treatment efficiency (beams, nodes, MU, delivery time). Statistical analysis was performed using Wilcoxon signed-rank test. No significant difference was found between CyberKnife InCise MLC and Iris mode on the CI, nCI, HI and PTV coverage analysis. The InCise MLC and Iris had the same sparing effects on the OARs with QI comparison. For the dose gradient outside the tumor (R10-R90), 40% dose reduction can be seen in InCise MLC mode averagely. For the treatment efficiency, InCise MLC was able to reduce the treatment time of 1/3 effectively (71% beams, 48% nodes, 50% MU and 32% treatment time). The PTV coverage/OAR sparing effects of these two techniques were the same; however, the CyberKnife M6 InCise MLC mode has a steeper dose gradient outside the tumors and with better overall treatment efficiency.

並列關鍵字

intracranial multiple tumors ； CyberKnife M6 ； Iris variable aperture collimator ； InCise multileaf collimator ； treatment efficiency