腦部雙能電腦斷層輻射劑量評估

Assessment dual energy computed tomography radiation dose of brain

鍾昆賢(Qsen-Shian Chung)

指導教授 ： 張寶樹

高雄醫學大學/健康科學院/醫學影像暨放射科學系碩士在職專班/碩士(2015年)

https://doi.org/10.6832/KMU.2015.00029

摘要

由於電腦斷層攝影(computed tomography, CT)的影像清晰、解析度高，因此在放射診斷上的應用愈來愈普遍。然而CT 造成的病患劑量往往是傳統X光照相的數十乃至數百倍，至今已發展出使用雙X光源掃描之雙能量電腦斷層掃描儀，藉由人體對不同放射線能量吸收度的差異，可呈現出多元的醫學影像。
本文探討頭部雙能電腦斷層攝影的劑量，使用10公分筆形游離腔和電腦斷層PMMA 直徑16公分假體來測量一部CT掃描儀，在使用單一球管或兩顆球管以模擬病人進行頭部檢查的劑量，採用三次連續性量測劑量，加上一連串公式手算運算，來了解病人在兩種使用模式下的等價劑量的情形。
使用SPSS 18.0軟體，以t-Test的獨立樣本檢定來進行統計分析，設定P<0.01有顯著性差異，發現在成人頭部劑量分析上使用單能及雙能的模式，顯示有顯著性差異，故接受虛無假設。兒童5-12歲頭部劑量分析上使用單能及雙能的模式，顯示有顯著性差異，故接受虛無假設。兒童0-5歲頭部劑量分析上使用單能及雙能的模式，顯示有顯著性差異，故接受虛無假設。

關鍵字

雙能電腦斷層 ； 游離腔偵檢器 ； 假體 ； 輻射劑量 ； 虛無假設

並列摘要

The CT (computed tomography) study had been used widely in diagnostic radiology due to its clear images and high spatial resolution; however, the radiation dose of CT was tens or hundreds times than conventional X ray study. Today, the dual energy computed tomography study had been developed to demonstrate various medical imaging through the difference of radiation absorption by human body.
This study was mainly to investigate the radiation dose of dual energy computed tomography in brain. We used a 10 cm pencil ion chamber and a PMMA 16 cm phantom to measure a CT scanner; and using single tube and double tubes in the same CT scanner to stimulate the radiation dose absorbed by patient during brain CT.
Through three continuous measurements to examine the equivalent dose absorbed by patient under those two modes, and using t-test by SPSS ver.18 software to test statistical hypothesis,P<0.01 is defined as significant difference. The results showed that the equivalent dose absorbed by adult patient, children patient who were 5-12 years-old and children patient who were under 5 years-old during brain CT was significant difference both in single tube and double tubes; therefore, all the null hypothesis in three groups were accepted.

並列關鍵字

dual energy CT ； ion chamber ； phantom ； radiation dose ； null hypothesis

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