隨著科技的日新月異，放射治療技術也隨之進步。放射治療的目標為利用輻射殺死腫瘤細胞但盡可能降低正常組織的受照劑量。目前常用的先進治療技術為強度調控放射治療，但目前之放射治療技術均獲多或少會造成腫瘤週遭之正常組織接受到輻射劑量，而這些正常組織受到的輻射劑量會正比於日後誘發二次癌症之風險。因此，本研究使用熱發光劑量計評及侖道、自製假體，模擬評估鼻咽癌症病患接受先進(強度調控)放射治療技術進行治療後，其日後正常組織之輻射健康效應風險。藉由量測治療假體其照野外正常組織之個別等價劑量，進行計算並比較強度調控放射治療之下在不同假體造成之正常組織劑量和風險；依據2007 年新輻射建議報告書中之器官與1991 年ICRP 所發表第60 號報告之器官風險係數可評估病患日後發生二次惡性腫瘤之風險。研究結果顯示估鼻咽癌病患接受強度調控放射治療後，導致的輻射誘發癌風險為0.29-3.6%，腫瘤體積及治療MU 較大時，導致之風險亦較高。

By means of the fast development of sciences and technologies, the technologies of radiotherapy are also advanced. The goal of radiotherapy is killing tumor cells with radiation but delivering the dose to normal tissues as low as possible. Intensity modulated radiation therapy, IMRT, is one of the most popular techniques. However, it’s almost impossible to
deliver no dose to normal tissues (or organs) using any technique of modern radiotherapy. The doses delivered to the normal tissues outside the tumor targets will increase the probabilities of inducing secondary cancers after the treatments. This research investigated the absorbed doses, equivalent doses and effective doses delivered to the patients in
Nasopharyngeal Carcinoma (NPC) radiotherapy using IMRT technique by means of the Rando phantom and the thermoluminscent dosimeter (TLD). Specific organs and risk coefficients recommended by the International Commission on Radiological Protection (ICRP) (ICRP, 1991 and 2007) These health risks can be assessed by means of estimating the doses of normal tissues during the treatment courses of radiotherapy. Results of this research showed that the normal tissue secondary cancer risks of NPC patients would increased 0.29-3.6% after IMRT. Large tumor size and monitor unit (MU) caused higher risks.