背景: 利用參考人假體模型評估的體內劑量，應用於甲狀腺腫瘤或甲動腺機能亢進的治療上，通常與個體所接受的真實劑量有著極大的差異，主要原因在於甲狀腺組織異常增生，而造成體積與幾保形狀之改變。本研究提出一種結合參考人假體與個人器官體素假體的方法，用以建構個人混合型假體(personal hybrid phantom)，並比較其劑量評估上的差異。
方法: 在本研究中，首先利用核能研究所建立的參考人數學假體模型與蒙地卡羅方法，評估口服碘-131所造成的體內劑量，並與MIRDOSE程式評估之結果比較。接著，評估三個不同質量甲狀腺的臨案例，並利用個人混合型假體與核研所參考人假體進行劑量之比較。
結果: 在核研所參考人劑量與MIRDOSE的比較上，甲狀腺劑量差異小於1%，有效劑量差異小於6%。在三組個人混合型假體與參考人假體的比較上，甲狀腺劑量差異最大可達53%，其餘器官劑量差量最大亦可達到25%，其中以胸腔官所受到的影響較大。
結論: 應用核研究參考人假體與蒙地卡羅技術於體內劑量評估是準確而且可行的。在核醫治療上，使用個人混合型假體取代參考人假體進行治療劑量之評估有其必要性。

Beckground: In the treatment of thyroid using 131I, the difference in evaluated dose and real dose is very large due to the variance of mass and geometry between reference man and a real person. The aim of this paper is to compare the dose estimated from reference man and the voxel phantom of thyroid in the treatment of thyroid tumor or hyperthyroidism, and propose a method to construct a personal hybrid phantom from mathematical phantom and voxel phantom.
Methods: In this study, the reference man was constructed and a Monte Carlo method was used to evaluate internal dose caused by 131I. Acomparison was made with MIRDOSE program. Then, three personal hybrid phantoms with different thyroid masses were constructed and compared with reference man.
Results: In the comparison of reference man and MIRDOSE, the dose variation for thyroid is less than 1%, and less than 6% for effective dose. In the comparisons between three hybrid phantoms and reference man, the dose variation for thyroid reached 53% and the maximum dose difference of other organs reached 25%.
Conclusion: Applying INER reference man and a Monte Carlo method to evaluate internal dose is feasible and accurate. In the therapeutic purpose of nuclear medicine, using personal hybrid phantom to instead reference mathematical phantom in dose estimation is necessary.