An Analysis of the Accuracy of the Robotic Respiratory Tracking Radiosurgical System in Extracranial Tumor

機械手臂呼吸追踪系統運用在顱外腫瘤之立體定位放射線手術治療之準確性分析

蔡若婷(Jo-Ting Tsai) ； 林家瑋(Jia-Wei Lin) ； 朱唯勤(Woei-Chyn Chu)

《中華民國癌症醫學會雜誌》 25卷3期 (2009/06) Pp. 184-194

https://doi.org/10.6588/JCOS.2009.25.3.4

摘要

放射線手術(SRS)運用於顱外腫瘤治療，可減少腫瘤週圍重要器官受放射線影響的體積。電腦刀( CyberKnife(上標 ®))系統中的Synchrony(上標 TM)呼吸同步追蹤系統(RTS)是運用腫瘤與植入於體內的定位標記物(fiducial markers)，在呼吸時位移之相對關係，建立出數學對應模式，來預估腫瘤的移動。RTS可連續追踪腫瘤的位置、預期腫瘤之移動、並即時自動同步修正放射線投予之方位。我們使用一個內部已植入了定位標誌物及驗證片(Gafchromic film)的球型假體來驗證RTS在即時追踪胸部腫瘤移動之準確性。本實驗於呼吸靜態期、呼吸運動期及運用呼吸追踪系統補償後，分別作實驗研究。將球型假體放置於模擬呼吸週期用的移動假體上，放置於中心位置時為呼吸週期之中心點，置於上端時為吐氣終點，下端為吸氣終點。在未使用RTS 時，電腦刀定位於呼吸週期的中心點，吐氣終點及吸氣終點的整體誤差分別為0.76±0.14mm，10.86±0.29mm 及11.16±0.45mm。在使用RTS後，整體誤差分別為0.33±0.13mm，0.42±0.66mm 及0.30±0.66mm。本研究驗證了運用Synchrony(上標 TM) RTS，可建立胸腔腫瘤於呼吸週期時位移，與植入的定位標誌物位置之非線性對應模式，並有效提供放射線手術治療時同步追踪定位腫瘤位置，以達到毫米下之整體定位準確度。

關鍵字

電腦刀 ； 呼吸同步追踪系統

並列摘要

Stereotactic radiosurgery (SRS) has been used to minimize the volume of the surrounding critical structures irradiated during extracranial tumor treatment. The Synchrony(superscript TM) Respiratory Tracking System (RTS) of the CyberKnife estimates tumor position by building a correlation model between the tumor respiration motion and implanted fiducial markers locations with a predictive algorithm. RTS is able to continuously track the tumor position, anticipate the tumor motion and facilitate real time automatic realignment of the radiation beam. A ball cube phantom with preloaded fiducial markers and Gafchromic films was used in this study to verify the accuracy of the Synchrony(superscript TM) RTS in real-time tracking of moving thoracic tumor. Three stages of respiratory tracking were tested, including static, motion and compensation experiment. The systemic errors of targeting with Synchrony(superscript TM) RTS switch off and moving phantom located in the center, end expiration and end inspiration respiratory cycle were 0.76+0.14 mm, 10.86+0.29 mm and 11.16+0.45 mm, respectively. With Synchrony(superscript TM) RTS switch on, the errors were 0.33+0.13 mm, 0.42+0.66 mm and 0.30+0.66 mm, respectively. There was no significant accuracy difference between taking x-ray images at every node or every four-node interval. By using the Synchrony(superscript TM) RTS to build nonlinear correlation models of inspiratory and expiratory phases of the respiratory cycle, simultaneous real-time tracking of the thoracic tumor position in all three directions can achieve sub-millimeter accuracy.

並列關鍵字

CyberKnife ； Respiratory Tracking System