| Abstract: | 國内各醫學中心近年來加快裝設醫用直線加速器(Linear accelerator, linac)，如亞瑟 刀（AXESSE, Elekta)進行強度調控弧形放射治療(Volumetric-Modulated Arc Therapy, VMAT)。惟運轉中的高能電子加速器會有巨量光子自靶區外釋，造成肺癌患者的額外散 射劑量，且這些並不是治療計畫的一部分，對有效劑量與危險度實屬重要，只有少數論 文，討論侖道假體，卻無不同體重下患者及散射劑量及危險度，實不得不加以詳查。 本計畫分成二年計畫：第一年計畫(1)設計/建構完成10至90公斤，五座自行研發擬 人型假體（Sels-developed mathematic phantom)研發，這些假體是參照GSF (Forschungszentrum fur Umwelt und Gesundheit, Germany)數學假體研發，假體身高、體重 及肺部重量、密度是依據ICRP參考人及ICRU 44、ICRU 48報告設計。（2)為了模擬女 性患者，重量50、70、90公斤胸部假體之研發。（3)電腦斷層模擬腫瘤定位(CT simulator, General electric, Hi speed)由資深醫學物理師張席昌完成。（4)肺癌治療計畫由曾顯群主任 /醫師完成，50公斤假體腫瘤深度為左侧5公分、距皮膚5公分、深度2.4公分、大小為 3x3x3立方公分。(5)進行TLD-100H的校正，劑量範圍由1 cGy到1000 cGy由6 MV的 光子劑量，每分鐘400 mU速度。第二年計畫(6)完成10及90公斤自研及侖道假體實驗， AXESSE加速器由放射師朱欣怡操作，每個假體要三重覆實驗。（7)重量50、70、90公 斤女性假體實驗。（8) ICRP 60號及103號報告組織加權因數來評估全身的有效劑量 (effective dose, E);由ICRP 60報告評估照野外的散射輕射之危險度。
In resent years, domestic medical center pushed to assemble medical electron linear accelerator (linac) of AXESSE in order to Volumetric-Modulated Arc Therapy (VMAT). However, running linac will generate high energy x-ray, which will induce extra secondary radiations. These radiations are not detailed in routine treatment planning. But it is potentially important to estimate effective dose (E) and risks. There is limited data currently available for assessing radiations and risk of rando phantom. No equations derived from effective dose-body weight of patients. In this two year projects, the first year is (1) Five self-developed mathematic phantoms (SDM) ranging from 10 to 90 kg had been constructed and developed corresponding to the GSF (Forschungszentrum fur Umwelt und Gesundheit, Germany). These phantoms’ height, weight, lung mass and density are designed based on the ICRP reference man and ICRU 44 and ICRU 48. (2)For simulate female patient, breast phantoms of 30, 50, 90 kg were developed. (3) An archival computed tomography simulator (CT simulator, General electric, Hi speed) of these phantoms were conducted by senior radiotherapist (H. C. Chang). (4) Lung cancer treatment plans of 50 kg phantom had been developed and reviewed by Medical Doctor, (H.C. Tseng, MD) at CSMUH. Lung cancer tumor was centered at depth of 2.4 cm, out of gentry of 5 cm and left 5 cm, dimension 3x3x3 cm . (5) TLDs were calibrated by photon dose ranging from 1 cGy to 1000 cGy were delivered in 6 MV photon beam of dose rate of 400 mU/min. The second year, (6) complete these experiments of 10 to 90 SDM and rando phantoms. Axesse linac will be operated by senior radiotherapist (H. Y. Chu) during three times investigations. (7) complete 30, 50, 90 female phantoms. (8) ICRP-60 and 103 tissue weighting factors were used for evaluating effective dose. Risk coming from the contribution of photon doses delivered outside the treatment field will be recommend by ICRP 60. This work will derive a simple equation for effective dose-body weight of patients undergoing VMAT. These involved equivalent doses of organ of tissue (EDt), E and risks. This project will be useful and recommended to the relatives, physicians and radiologists and AEC-ROC. |
