三度空間電腦放射治療計劃系統之驗收與測試

3-D Radiotherapy Treatment Planning System Acceptance Test

林盈釧(Ying-Chuan Lin) ； 吳簡坤(Jian-Kuen Wu) ； 黃英強(David Y.C. Huang) ； 簡哲民(James J.M. Jian)

《放射治療與腫瘤學》 5卷4期 (1998/12) Pp. 303-310

https://doi.org/10.6316/TRO/199805(4)303

摘要

目的：如何使三度空間電腦放射治療計劃系統(3-D radiotherapy Treatment Planning System, 3-D RTP)計算所得之等劑量曲線分佈與水假體量測出來之結果取得合理的一致性，是RTP驗收過程(Acceptance Test Procedure, ATP)中重要的課題，也是病人接受高品質放射線治療的重要因素。
材料與方法：本文係針對Computerized Medicals System-Focus 1.4.0 及Helax-TMS 4.0版系統逐項作一驗收測試，並且評估其間之誤差值是否合理以及運用於臨床上之治療是否可行。ATP分成硬體及軟休兩部份，硬體包括網路之連結及影像之傳輸功能，屬於3-D RTP本身數位板(digitizer)的準確性，繪圖機的放大率及準確度及病人資料保存(backup)之完整性與方便性。軟體部份有光子及電子射束的百分深度劑量(Percentage Depth Dose)、等劑量曲線分佈(isodose distribution)及射束剖面圖(beam profile)的比對；以及針對光子射東的開放性照野(open-field)、楔形濾板(wedge)、組織填充物(bolus)、非均勻密度組織(inhomogenities)、鉛擋塊(block)及多葉型準直儀(Multi-Leaf collimator, MLC)修正後的劑量比對；另外電子的斜角度劑量分佈(oblique incidence)也是驗收項目。由於治療計畫是以電腦斷層影像為基礎，因此院內放射治療網路系統(SIEMENS LANTIS)之連結及影像傳輪系統之設施亦需針對其特點逐一驗收測試，以利於整體之應用操作。
結果:以Helax-TMS而言，開放性照野部份，若照野大於功 20×20則觭角效應(horn effect)會明顯增大，最大約2%的劑量誤差。而楔形濾板部份照野不宜過大，若照野大於10×10則45°及60°楔形濾板會有約3%之劑量誤差。鉛擋塊及多葉型準直儀的半影區則較水假休所量測之值有大約2~3 平方公厘之誤差。對CMS-Focus而言，在開放性照野部份，觭鳥效應並不會隨照野之大小而有所改變，其劑量誤差值有2%。楔形濾板之劑量誤差值約在2%，照野適用範圍可開至最大值20 cm 。而鉛檔塊及多葉型準直儀之半影區則有 1~2 mm 之誤差。
討論：對於以上驗收測試的結果，網路之連結及影像之傳輸皆可正常之運作，而劑量分佈之誤差值皆在放射線治療可接受的範圍內，因此也確定本院兩套3－D RTP可應用於臨床放射線之治療。

關鍵字

三度空問電腦放射治療計劃系統 ； 驗收過程 ； 射束資料 ； 臨床應用

並列摘要

Purpose: The important subject of 3-D radiotherapy treatment planning system (3-D RTP) acceptance test procedure (ATP) is to get the reasonable agreement between the calculated isodose distribution of 3-D RTP and the measured results of water phantom, before the clinical use of 3-D RTP system.
Materials & Methods: This report is a acceptance test results of Computerized Medical System - Focus 1.4.0 and Helax-TMS 4.0. Acceptance test procedure includes hardware and software. Hardware includes the function of the link of Network system, the function of the image transfer system, the accuracy of the digitizer, the magnification and accuracy of the plotter, the function of the printer and the patient data backup facility. Software includes the comparison of percentage depth dose for photon beam and for electron beam, isodose distribution check and beam profile check. The comparisons of photon beam include open-field, wedge-field, half-beam, asymmetric jaws, irregular-field, bolus, inhomogeneities, block-field and Multi-Leaf Collimator MLC). The electron oblique incidence is also one of the test items.
Results: For Helax-TMS, if the field size is more than 20×20, the open-field horn effect will be increased, the maximum dose deviation about 2%. It's about 3% dose deviation of 45° and 60° wedge filter of the field size more than 10×10. The penumbra error of block and MLC is 2-3 mm compared with water phantom data, For CMS-Focus, the horn effect is independent of field size and the dose deviation about 2%. The field size of wedge filter can open to a maximum of 20 cm and the dose deviation is 2%. The penumbra error of block and MLC, compared to water phantom, about 1-2 mm.
Conclusion: In conclusion, the functions of network and include image-transfer are acceptable and the isodose distribution discrepancies are also acceptable for the clinical radiotherapy treatment application.

並列關鍵字

3-D RTP ； ATP ； Beam data ； Clinical application