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題名 | Evaluate the Differences between Displayed and Measured CTDIvol on Computed Tomography=電腦斷層掃描儀之體積劑量指標與實測的劑量差異評估 |
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作 者 | 汪志偉; 王俊聰; 林鼎裕; 黃武達; 杜俊元; | 書刊名 | 中華放射線技術學雜誌 |
卷期 | 35:3 2011.09[民100.09] |
頁次 | 頁159-162 |
分類號 | 416.14 |
關鍵詞 | 圓柱形均勻壓克力假體; 筆型空氣游離腔; 電腦斷層體積劑量指標; Cylindrical acrylic phantoms; Pen-shaped ionization chamber; Computed tomography dose index; CTDIvol; |
語文 | 英文(English) |
中文摘要 | 本研究比較實際量測與螢幕所顯示的電腦斷層體積劑量指標差異,於兩部Siemens及一部Toshiba電腦斷層掃描儀上實測,使用16或32公分直徑圓柱形均勻壓克力假體及10公分長筆型空氣游離腔,不開啟自動曝露調控功能,針對美國放射學院有提出劑量標準的三種檢查部位(成人頭部、成人腹部及五歲以下小兒腹部)實測,並紀錄掃描前控制器螢幕上所顯示預估的劑量,得到每臺機器各種掃描部位的劑量誤差比率(比較實測與螢幕顯示),在西門子的兩部機器上小兒腹部的掃描螢幕上所顯示的劑量低估了約55%,在三部機器上成人頭部及腹部的劑量誤差約在-7% ~ +10%。調整掃描參數的設定,螢幕上所顯示的病人曝露會立即明顯地隨之改變,身體掃描的輻射劑量計算時係採用標準的身體假體體型,並無法將每位病人的實際身體大小計算進去,特別是在小兒的檢查,因為程式計算時所使用的身體假體大小與小兒體型的差別導致相當大的劑量誤差估計,所以臨床小兒腹部掃描時,使用螢幕所顯示的估計值必須特別小心。 |
英文摘要 | The aim of this research was to survey differences between the actual dose measurement and the dose displayed on the computed tomography (CT) monitor during routine CT examinations. Two uniform cylindrical acrylic phantoms (either 16- or 32- cm in diameter), equipped with a pen-shaped ionization chamber, were scanned without Automatic Exposure Control on two Siemens and one Toshiba CT scanners. Three standard examinations using an adult head protocol, an adult abdomen protocol, and a child under five years old abdomen protocol were performed on the phantoms and the radiation doses were compared. The computed tomography dose index (CTDIvol) value displayed on the monitor was underestimated by 55% for the child’s abdomen on both CT scanners, and the dose difference ratio was approximately -7% to +10% for the adult head and abdomen on all three CT scanners. Changes in scan parameter settings and their implications for patient exposure are obvious. The dose values for examinations carried out during body scanning have always been based on body CTDI regardless of patient size. In pediatric CT examinations, error in the CTDIvol calculating program results in large dose differences. The displayed values must be carefully adjusted for clinical pediatric abdominal scanning. |
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