- 期刊
立體定位放射治療，使用標靶儀或影像導引系統定位治療中心點的誤差比較
Evaluation of Stereotactic Localizer Box and Image Guided System for Patient Setup in Stereotactic Radiosurgery/Radiotherapy for Intracranial Lesions
摘要
目的：評估在立體定位放射治療技術(stereotactic radiotherapy)中，使用標靶儀(stereotactic localizer box)或是影像導引(image guided system)定位系統，對於治療中心點的準確度的影響。 材料及方法：本研究以諾力刀(BrainLAB Novalis, Feldkirchen, Germany)為工具，分成兩個主要部份：一、將人頭假體分別以BrainLAB的headring與mask headring(maskring)兩種固定頭部的模具，輔以標靶儀與影像導引兩種定位系統，模擬臨床治療過程，比較兩種定位系統的治療中心點何者準確。二、在2007年5月至2008年10月之間，22位腦瘤病患進行立體定位放射治療，其中8位進行立體定位放射手術(stereotactic radiosurgery, SRS)，14位進行分次立體定位放射治療(stereotac ticradiotherapy, SRT)。每位病人均先經過標靶儀定位後，再以影像導引系統攝影定位，紀錄影像導引系統軟體對治療中心點的位移修正值，分析兩者位移修正值在臨床上的意義。 結果與討論：在假體實驗中，以假體中埋入的針頭作為標準治療中心點，標靶儀呈現的誤差：headring在A-P方向是1.0mm；maskring在A-P與Lateral方向，分別是1.1mm與1.0mm；影像導引系統呈現的誤差：headring在A-P方向是0.6mm；maskring在A-P與Lateral方向，分別是0.2mm與0.4mm。因此影像導引系統定位的準確性較用標靶儀定位系統來的準確；但對假體而言，兩定位系統彼此的相對差異幾近，而且對位準確性均符合立體定位系統在治療中心點的誤差需小於1mm的標準。 臨床病人數據在兩定位系統彼此的相對位移修正值，以headring固定者，在SRS除在頭部前後方向位移修正值微大於1mm外，其餘所有方向的位移修正值均接近或小於1mm與1度，與假體實驗結果符合；而maskring固定者，在SRS與SRT的治療中心點的位移修正值則全部均小於3mm與2度。誤差產生的原因在比較系統誤差、隨機誤差、再現性、空間向量及與其他文獻報告的佐證後，研判標靶儀定位準確性，會受到不同模具固定效果或治療床位置的影響，而影像導引系統因為以解剖構造為基準做為比較，較不易受到外在因素影響，因此便產生兩者在臨床定位上的差異。 結論：為了降低定位時的誤差，確保每次治療時的治療中心點與治療計畫中治療中心點相同的正確性，使用maskring配合標靶儀定位系統在需要高準確性的立體定位放射治療時，建議使用影像導引定位系統。
並列摘要
Purpose: The study is to investigate the spatial difference of the treatment center between setup by the stereotactic localizer box and by ExacTrac x-ray verification system in the treatments of stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SRT) for intracranial lesions. Materials and Methods: Between May 2007 to October 2008, 22 patients were enrolled in this study, including 8 patients each treated by single fraction SRS, and 14 other patients treated by SRT. All patients were treated by dedicated Novalis radiosurgery system coupled with ExacTrac image guided system. At first, we performed head phantom test to compare the accuracy of each setup method to predefined isocenter, and then to compare the spatial difference between these two setup methods from patients' data. Due to the software’s limitation, treatment setup can be proceeded only by one method at a time, either by stereotactic localizer box or ExacTrac image guided system, therefore, the phantom and each patient had two treatment plans of the same treatment center. We started to setup by the traditional SRS procedure first, i.e., matching the treatment center in the stereotactic localizer box from the first plan, and then we took two fixed angled oblique radiographs to check the difference between this treatment center and that from the digital reconstructed radiographs of the second treatment plan. Results: In phantom's test, the setup error of stereotactic frame box with maskring is 1.1 mm in AP direction, and 1mm in lateral direction, in contrast to 0.2 mm in AP, and 0.4 mm in lateral direction by ExacTrac x-ray verification system. Patients with immobilization using headring had less displacement error, all were smaller than 1 mm or within 1 degree of rotation except in vertical direction. In contrast, immobilization using maskring had larger displacement, but all of them were smaller than 3 mm or within 2 degrees. The setup accuracy of localizer box could be affected by the reproducibility of maskring, and this factor can be corrected in ExacTrac image guided system. Conclusion : For SRS, the setup error is usually required to be within 1 mm for rapid dose fall-off outside of the target, and headring can meet this requirement; maskring, usually used in the SRT, had larger setup error, and this should be taken into account in defining treatment target. The adoption of image guided system for double-check of the treatment center could be beneficial in reducing the setup error, especially in the SRT treatment.
延伸閱讀
- 陳咨縈、林招膨、賴源淳、熊敬業、游惟強（2009）。影像引導放射治療之人體位置準確度探討。台灣應用輻射與同位素雜誌，5(1)，571-577。https://doi.org/10.29832/TJARI.200903.0001
- Li, S. T., Liu, W. S., Chou, Y. H., Hsiung, P. W., Hsu, H. T., & Chang, H. C. (2008). 以導航螺旋式光子刀之影像導引放射治療程序驗證病患定位誤差. 放射治療與腫瘤學, 15(2), 119-128. https://doi.org/10.6316/TRO/200815(2)119
- 蕭凱嘉、溫舒瑜、杜昭遠、黃國明、成佳憲、許峯銘（2013）。立體定位軀體放射治療位移誤差影響因子之分析。台灣應用輻射與同位素雜誌，9(3)，681-689。https://www.airitilibrary.com/Article/Detail?DocID=18156290-201309-201311010045-201311010045-681-689
- 陳韋霖、梁雲、張寶樹、劉明祥、張瑛真（2019）。Comparison of Peripheral Low Dose with or without Flattening Filter in Stereotactic Ablative Body Radiotherapy and in Volumetric Modulated Arc Therapy。南臺灣醫學雜誌，15(1)，35-47。https://doi.org/10.6726/MJST.201906_15(1).0004
- Que, J., Ho, H. W., Lin, H. M., Huang, C. C., Lin, L. C., & Hernandez, L. N. (2017). STEREOTACTIC BODY RADIATION THERAPY FOR HUGE HEPATOCELLULAR CARCINOMA: DOSIMETRIC COMPARISON OF 3D CONFORMAL RADIOTHERAPY, INTENSITY-MODULATED RADIOTHERAPY AND CYBERKNIFE. 放射治療與腫瘤學, 24(1), 35-47. https://doi.org/10.6316/TRO/201624(1)35