於VMAT治療計畫下，肺癌患者之正常器官劑量評估

Evaluating Equivalent Dose of Normal Organs for Lung Cancer Patients Undergoing VMAT Treatment

陳芯鈺(Hsin-Yu Chen)

指導教授 ： 陳健懿

中山醫學大學/醫學科技學院/生物醫學科學學系碩士班/碩士(2014年)

https://doi.org/10.6834/CSMU.2014.00068

摘要

根據民國101年行政院衛生福利部主要癌症死亡率趨勢統計報告，肺癌死亡率逐年攀升，許多肺癌患者選用以直線加速器 (linear accelerator, linac)為基礎且融合強度調控和影像導引的弧形調控放射治療 (Volumetric Modulated Arc Therapy, VMAT)，因此，我們開始研究肺癌患者行弧形調控放射治療時的全身有效劑量(Effective dose, E) 和器官/組織等價劑量 (Equivalent dose, EDT)，評估照野外散射對其他器官組織的損害及危險度。以熱發光劑量計 (Thermoluminicent dosimeters, TLD-100H) 評估肺癌患者行弧形調控放射治療時之劑量。TLD-100H經過靈敏度篩選和線性校準後，佈植於參考國際輻射單位與度量衡委員會48號報告 (International Commission on Radiation Units and Measurements, ICRU-48) 和亞當數學假體 (Germany’s National Research Center for Environment and Health Institute for Radiation Protection Adam, GSF Adam) 而設計的五個不同公斤數自研假體 (Self-Developed Mathematic Phantom, SDM)及侖道假體 (Alderson Radiation Therapy phantom, ART Rando phantom)之模擬肺癌患者。使用中山醫學大學附設醫院放射腫瘤科Elekta Axesse型直線加速器進行照射，能量為6MV，弧形數目為二，腫瘤體積治療療程為3次分次，總治療劑量共2100 cGy。參考Cheung等人及Kawaura等人之文獻佈點熱發光劑量計於各器官/組織位置。等價劑量和有效劑量根據國際放射防護委員會 (International Commission on Radiological Protection, ICRP) 60號報告和103號報告計算。ICRP 60及ICRP103計算結果，有效劑量前者較後者低，E (mSv)= -0.0214 X(kg)+ 2.497 (ICRP 60); E (mSv)= -0.0204 X(kg)+ 2.662 (ICRP 103)。 10公斤自研假體具有最高之有效劑量。實驗用每顆熱發光劑量計之間有相當良好的線性關係，各假體肺臟、心臟和乳房之等價劑量偏高。最低等價劑量在腦部。離治療照野越遠，劑量越低。距離腫瘤約5.4cm，劑量大幅減少。藉由VMAT治療肺癌患者，得到各體重的有效劑量隨著體重上升而有減少的趨勢，未來可提供臨床劑量評估卓參。

關鍵字

熱發光劑量計 ； 自製研發數學假體 ； ICRP 60 ； ICRP 103 ； 弧形調控放射治療 ； 侖道假體

並列摘要

According to the 101st report of main cancer death rate by Ministry of Health and Welfare, Executive Yuan, ROC, death rate of lung cancer has increased these days. Volumetric Modulated Arc Therapy (VMAT) of linear accelerator (linac), Axesse of Elekta Comp. was carried out on lung cancer treatment of patients. Effective dose (E) and Equivalent dose (EDT) of patients undergoing lung treatments were evaluated. To investigate the possible risk of secondary radiations, the contribution of photon doses delivered outside the treatment field will be been measured on these phantoms. Thermoluminescent dosimeter (TLD-100H) was used to evaluate the E and EDT of lung cancer patients at Radiation Oncology Department of Chung Shan Medical University Hospital. For sensitivity and linearity calibration, TLDs were calibrated using 6 MV photons from AXESSE, then inserting into five different body-weight Self-Developed Mathematic phantoms (SDM) derived from ICRU-48 and ICRU-44 as well as a male Alderson Radiation Therapy phantom (ART Rando phantom). These SDM phantoms ranging from 10 to 90 kg had been developed corresponding to the GSF (Forschungszentrum fur Umwelt und Gesundheit, Germany) mathematical phantoms. The radiation was delivered with 6 MV X-ray, 2 Arcs, from Axesse linac. A total treatment dose of 2100 cGy in 3 fractions was prescribed to the tumor volume. The locations of sensitive organs and tissues were determined by visually comparing sections to an atlas of cross-sectional anatomy published by Cheung and Kawaura. E and EDT were calculated and recommended by International Commission on Radiological Protection, ICRP 60 and 103. It has good linearity between each TLD. E calculated by ICRP 60 was lower than that of 103. E (mSv)= -0.0214 X(kg)+ 2.497 (ICRP 60); E (mSv)= -0.0204 X(kg)+ 2.662 (ICRP 103). The 10-kg SDM has the highest E than other phantoms. The EDheart and EDbreast were the highest among organs. The minimum EDT is in the brain. The farther away from the treatment field, the lower ED it was. The distance, 5.4 cm, from tumor center, the EDT is significantly decreased. The E decreased exponentially in an inverse correlation with increasing phantom weight. These findings were useful and recommended to patients, physicians, radiologists and the public.

並列關鍵字

Effective doses（E） ； TLD ； self-developed mathematic phantom ； Rando phantom ； VMAT ； ICRP 60 ； ICRP 103

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