目的：頭頸部腫瘤因腫瘤之型態與淋巴之流向關係，在治療時常考慮下頸部與鎖骨上窩淋巴結之照射，其照射方法多為前方單一門之預防性照射。由於現今電腦治療計劃與直線加速器之進步，頭頸部腫瘤放射治療擺位方式多採用單一等中心點（mono-isocenter）來取代過去非單一等中心點的擺位方式，本研究即評估頸部表面劑量因技術不同其皮膚劑量之變化與影響。材料與方法：本實驗以熱發光劑量計（TLD-100）置於RT-HUMANOID似人假體表面，評估以TMR公式計算之非單一等中心點、與電腦治療計劃計算之單一等中心點這兩種計算與擺位方式於頭頸部腫瘤治療時的頸部皮膚劑量，希望能瞭解其皮膚劑量變化。結果：實驗發現今使用的電腦治療計劃配合單一等中心點擺位的頸部皮膚劑量較TMR公式與非單一等中心點擺位之頸部皮膚劑量高出約6%。使用相同之擺位（非單一點中心擺位），不同計算方式（TMR公式與電腦治療計劃），則電腦治療計劃給予劑量之假體的頸部皮膚劑量較TMR公式計算給予劑量之假體的頸部皮膚劑量高出約8%。結論：皮膚劑量因治療方式或計算方式不同、其輸出劑量也不同，利用電腦治療計畫來給予治療輸出劑量時會比利用TMR計算給予之劑量高，因此產生較高之皮膚劑量，統計學上是有意義的。

Purpose : In radiotherapy of head and neck cancer, regional lympha mode of lower-neck and supraclavicular fossa was taken into the irradiation field because of the tumor type and lymphatic drainage always in high risk. A conventional anterior low-neck and supercalaviculer field was
performed regularly during radiotherapy. Owing to the remarkable progressing advances in linear accelerator and treatment planning system, there were a lot of achievement in radiotherapy in recent decades, the patient setup technique of radiotherapy in head and neck cancer have changed from multicenters technique to mono-isocenter technique.Materials and Methods : Ther moluminescent dosimeters (TLDs) were used to place on RT-HUMANOID phantom to evaluate the skin dose of head and neck field. Multi-centers and monoisocenter techniques were performed in setup with anthropomorphic phantom during the experiment. TMR formula and Pinnacle radiotherapy planning system were used to calculate the output monitorunit (MU). Results : We found that the neck skin doses in mono-isocenter technique was calculated in treatment planning system as 6% higher than multi-centers technique when that of calculated with TMR formula. The neck skin doses of mono-isocenter were 3% higher than that of multi-centers setup technique using the same calculation method (which is Pinnacle radiotherapy planning system). The neck skin doses of Pinnacle radiotherapy planning system were 8% higher than that of TMR formula using the same setup technique (which is multi-centers).
Discussions : The calculation methods and the SSD (source-surface distance) might cause the different of the neck skin doses.