牙科電腦斷層攝影與64切/4切電腦斷層攝影之頭頸部輻射劑量評估

The evaluation of head and neck radiation dose in dental CT compared with 64/4 multi slice CT

黃耀德(Yao-De Huang)

指導教授 ： 鄭凱元

中臺科技大學/健康科學院/放射科學研究所/碩士(2008年)

https://doi.org/10.6822/CTUST.2008.00007

摘要

自從1970年代電腦斷層攝影(computed tomography)問世以來，在放射診斷上成就了新一代的里程碑，隨著醫學科技的發展更新，有愈來愈多快速掃描以及多元應用的機型誕生，如今已經成為醫學影像不可或缺的利器。
本研究中將探討牙科電腦斷層攝影的i-CAT、ASAHI-PSR9000NT兩種型號，比較64切電腦斷層攝影(TOSHIBA-Aquillion)、4切電腦斷層攝影(GE-LightSpeed)兩種型號，藉由改變FOV、kVp、mAs等參數合理抑低所產生的輻射劑量；實驗中使用片狀熱發光劑量計(thermoluminescent dosimeter; TLD-100薄型)量測，鑲嵌或貼附於擬人假體(Alderson-Rando phantom)，對頭頸部重要器官或組織進行評估，透過游離腔測讀儀的絕對劑量轉換及ICRP第60號報告之組織或器官加權因數表可計算有效劑量，在相關性、再現性、線性度等方面皆有良好表現。
結果顯示牙科電腦斷層攝影有效劑量為0.025~0.384 mSv，一般電腦斷層攝影的有效劑量為0.278~2.248 mSv；牙科電腦斷層攝影透過照野的縮小，有效劑量在不同mAs下至多可以減少52.34%；透過mAs的降低，有效劑量至多可以減少73.46%；透過kVp的降低，有效劑量至多可以減少25.23%。而64切一般電腦斷層攝影與4切一般電腦斷層攝影在不同mAs的操作下，有效劑量可以差距到七倍以上。

關鍵字

4切電腦斷層攝影 ； 64切電腦斷層攝影 ； 有效劑量 ； 牙科電腦斷層攝影 ； 熱發光劑量計

並列摘要

Since Computed Tomography was invented in 1970s, it has turned to be a landmark in medical images of radiological diagnosis. As medical technology evolves, more and more high-speed scanners and extensive application mechanisms are generated. Nowadays, Computed Tomography is an invaluable tool in the department of radiology.
The purpose of this study is to evaluate the radiation dose of head and neck in dental CT: i-CAT and ASAHI-PSR9000NT, compared with 64/4 multi slice CT: TOSHIBA-Aquillion 64 slice and GE-LightSpeed 4 slice. The experiments to get the radiation dose in anthropomorphic Alderson-Rando phantom were performed by changing parameters of FOV, kVp, and mAs. Thermoluminescent dosimeters (TLD-100: thin type) were used in this study. TLDs were inserted or pasted on the Rando phantom, and the doses were estimated in critical organs or tissue of head and neck, then the effective dose could be calculated according to ion chamber with electrometer measurement, and summarized the equivalent dose with tissue weighted factor of ICRP60 report.
In this study, the doses of head and neck contributed by dental CT is 0.025~0.384 mSv, and the dose contributed from 64/4 multi slice CT is 0.278~2.248 mSv. For dental CT, the effective dose descends about 52.34% when the FOV is smaller. The one descends 73.46% when mAs is cut down, and the one descends at most 25.23% when kVp adjusted lower. Besides, doses could descend over seven times as mAs is cut down in 64/4 multi slice CT. Moreover, dose undulated in skin and neck could add shielding to protect it.

並列關鍵字

64 multi slice CT ； 4 multi slice CT ； TLD ； dental CT ； effective dose

參考文獻

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