取像條件對錐狀射束電腦斷層影像定位準確性之影響

Comparison of Different Image Conditions Will Affect The Accuracy of CBCT Positioning

陳文凱(Wen-Kai Chen) ； 康誠麟(Chen-Lin Kang) ； 謝致瑋(Chih-Wei Hsieh) ； 張軒銘(Hsuan-Ming Chang) ； 廖宗義(Tzung-Yi Liao) ； 阮國榮(Kuo-Jung Juan)

《中華放射線技術學雜誌》 35卷4期 (2011/12) Pp. 227-232

https://doi.org/10.30045/CJRT.201112.0005

摘要

本研究主要統計分析若改變取像條件是否會影響錐狀射束電腦斷層影像（Cone-Beam Computed Tomography，CBCT）定位的準確性。Synergy®是一部同時備有能量為仟伏能取得三度空間CBCT與自動影像導引定位驗證系統的直線加速器，執行治療前可進行影像融合比對，比對結束後可將位移偏差修正，使得每次治療時的擺位偏差能進一步的降低，分次間的擺位偏差主要以骨骼解剖特徵進行比對而得。總共收集20位胸腹部患者與40組修正資料來進行分析，藉由影像導引定位系統取得三維位移修正數值，分析並計算兩組條件三維各軸的擺位偏差，其中X、Y、Z分別代表了左右，頭腳，前後方向的偏差數值，所測得兩組條件X、Y、Z 三軸Mean±SD，分別為2.38±1.83mm、4.64±3.61mm、2.01±1.7mm與2.88±1.76mm、4.7±4.19mm、2.5±2.03mm，均在合理範圍內，結果顯示改變取像條件並不會影響CBCT定位的準確性。近年來CBCT在腫瘤治療的應用上越來越廣泛，但CBCT取像費時、病患須吸收較多額外輻射劑量，常造成影像上有較多雜訊與動態假影、影像儲存空間大等因素而造成使用上的困擾。本研究試著改變CBCT操作時的取像參數及掃瞄角度且在不影響比對結果的情況下確實可以達到縮短掃瞄時間、減少病患吸收劑量、改善影像品質及減少儲存空間的目的。

關鍵字

錐狀射束電腦斷層影像 ； 影像導引 ； 擺位偏差 ； 影像融合

並列摘要

This study analyzed whether the conditions as if the change will take affect Cone-Beam Computed Tomography (CBCT) positioning accuracy. Synergy ® is an energy kilovoltage will also have to obtain 3D CBCT and automatic image-guided positioning verification system of the linear accelerator, before treatment, image fusion can be compared. After comparing the displacement error correction can be made for each treatment of setup deviation can be further reduced. Fractional setup deviation mainly derived from bone anatomy for comparison. We collected 20 of chest and abdomen in patients with 40 group's setup deviation data for analysis. Use of image-guided positioning system to obtain 3D displacement correction data, analysis and calculation of two conditions X、Y、Z axis setup deviation.The measured two conditions X (LR), Y (SI), Z (AP) axis Mean ± SD, were 2.38±1.83mm, 4.64±3.61mm, 2.01±1.7mm and 2.88±1.76mm, 4.7±4.19mm, 2.5±2.03mm. all at a reasonable range, the results show that take as conditions change will not affect the positioning accuracy of the CBCT. In recent years CBCT applications in radiotherapy more widely. Resulting in the use of trouble because CBCT time-consuming. Patients had to absorb more additional radiation dose, often resulting images have more noise and dynamic artifacts, and the images are stored in a large space. This study tried to change the CBCT image capture operation parameters and scan angle does not affect the outcome of the case than, Indeed can achieve shorter scan time, reduce patient absorbed dose, improving image quality and reduce the storage space.

並列關鍵字

cone-beam computed tomography ； image-guided ； setup deviation ； image fusion