- 期刊
鼻咽癌強度調控放射治療全身重要器官之劑量評估
Estimated the Whole Body Critical Organs Dose in Nasopharyngeal Cancer Treated by Intensity Modulated Radiotherapy (IMRT)
摘要
病患執行強度調控放射治療(IMRT)時，由於直線加速器的監控單位(MU)比傳統放射治療或三度空間順形放射治療高出許多，所以病患各部位重要器官可能接受比傳統放射治療還高的散射劑量。本篇以鼻咽癌病患為例，利用熱發光劑量計(TLDs)測量各部位重要器官接受的劑量。首先須對醫用直線加速器(Elekta, Precise-Sli)所產生的6 MV高能X射束的能量及劑量輸出做校正，將1 MU的劑量輸出校正成1 cGy的吸收劑量。建立熱發光劑量計(TLD-100H)的準確度及劑量響應靈敏度，其誤差須小於3%。將TLD-100H置入Rando假體中，按照一般治療照射條件，測量各部位的平均吸收劑量。在40個分次(fraction)放射治療療程共72Gy的總劑量中，眼睛水晶體接受到4.03Gy，對誘發白內障有較高的風險，而心臟及腎臟分別是0.86Gy及0.19Gy，遠低於它們所能接受的耐受劑量(tolerance dose)。對於治療照野靠近危急器官或耐受劑量較低的器官，或者是總監控單位(MU)比較高的每個病人，尤其是可治癒(curable)的年輕病患，在其接受整個療程裡應該評估各個重要器官之劑量。
並列摘要
The patients received more radiation monitor units (MU) by using IMRT technique than the conventional or 3-D conformal techniques. Thus, the patients receive higher whole body dose in the IMRT technique. In this study, we use thermoluminescent dosimeters (TLDs) to measure the nasopharyngeal cancer (NPC) patients who are treated by the IMRT technique. The organs dose were estimated. To calibration the energy and output factor for 6 MV x-ray from an Elekta linear accelerator (model: Precise-Sli). One monitor unit (MU) output was calibrated as 1 cGy. The accuracy, sensitivity and blank test of TLD-100H dosimeters were also measured within 3%. To place these calibrated dosimeters to different positions in the Rando phantom, then irradiated the head and neck area of Rando phantom by IMRT technique. The data of different organ doses were obtained separately for each of IMRT irradiation. Total radiation dose in the IMRT treatment course was 72 Gy in 40 fractions. Lens was received 4.03 Gy, which had relatively high risk to induce cataract. Heart and kidney received 0.86 Gy and 0.19 Gy. We need to estimate the organs dose which near the edge of irradiation field or lower tolerance dose, especially. However, a long term evaluation for young cancer patients with curable attempt is feasible.
延伸閱讀
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