- 期刊
以不同身體質量指標的成人胸部電腦斷層檢查估算體型特異性劑量值與有效劑量
Size-Specific Dose Estimation and Effective Doses Using Chest Computed Tomography Examinations of Adults with Different Body Mass Indexes
摘要
電腦斷層掃描（Computed Tomography; CT）應用於成人健檢為放射診斷科常見檢查項目之一。因此本研究將探討成人健檢電腦斷層掃描，使用容積電腦斷層劑量指數（CTDIvol）與體型特異性劑量評估（Size-specific Dose Estimates, SSDE）兩種不同方式，評估接受的輻射劑量之差異性。本研究經由人體試驗委員會的核准，於 2019年3月至10月之間，共回溯性分析288位執行成人胸部電腦斷層檢查之患者。並依據身體質量指數（BMI）（kg/m2），由BMI≧16.0 kg/m2至BMI≦33.0 kg/m2，以每1單位數值BMI進行分組，共17組。本研究為了確保不受顯影劑因素影響，皆選擇未使用顯影劑之電腦斷層影像作為比較。其掃描參數皆設定管電壓固定為120 kVp及管電流固定為220 mAs﹝實際管電流為自動曝光控制系統（automatic exposure control, AEC）依據患者體型自動調控﹞。研究將透過電腦斷層掃描系統收集身體前後直徑、左右直徑、與CTDIvol相關數據。並依據美國醫學物理學家協會第204號報告換算成SSDE。研究結果顯示使用CTDIvol與SSDE方式兩種來評估劑量有顯著差異（p＜0.0001）。而臨床常使用之CTDIvol方法，評估患者所接受之輻射劑量會比較低1.22至2.28 mGy之間。而根據CTDIvol與SSDE 之平均差異值與BMI之線性關係圖，我們導出其線性迴歸之公式y = -0.0632 x + 3.351（x為BMI，y為CTDIvol與SSDE 之平均差異值；R2 = 0.8185）。建議臨床使用，推算出病患受檢一次胸部電腦斷層檢查之有效劑量﹝effective dose, E；E（mSv）﹞。
並列摘要
Computed Tomography (CT) is used in adult health examination and is one of the common examination items in the diagnostic radiology department. Therefore, this study will explore adult health check-up computed tomography, using two different methods: volumetric computed tomography dose index (CTDIvol) and size-specific dose estimates (SSDE) to evaluate the difference in radiation dose received. This study, with the approval of the institutional review board, retrospectively analyzed 288 patients who underwent adult chest computed tomography between March and October 2019. According to the body mass index(BMI；kg/m2), from BMI > 16.0 kg/m2 to BMI< 33.0 kg/m2, each unit is divided into a group, which is divided into 17 different BMI groups. In order to ensure that it is not affected by developer factors, this study selected computer tomography images without developer for comparison. The scanning parameters are all set with the tube voltage fixed at 120 kVp and the tube current fixed at 220 mAs with the actual tube current adjusted by the automatic exposure control system (AEC) according to the subject body size. The study will collect data related to the body's anterior posterior(AP), lateral dimension and CTDIvol through a computed tomography system. According to the American Association of Medical Physicists Report No. 204, the formula is proposed to convert to SSDE. The results of the study show that there is a significant difference between using CTDIvol and SSDE to assess dose (p < 0.0001). The CTDIvol method, which is commonly used in clinical practice, estimates that the radiation dose received by patients will be relatively low, with a difference between 1.22 and 2.28 mGy. Based on the linear relationship between the average difference between CTDIvol and SSDE and BMI, we derived the linear regression formula y = -0.0632 x + 3.351 (x is BMI, y is the average difference between CTDIvol and SSDE; R2 = 0.8185). It is recommended to be used clinically to calculate the effective dose of a chest computed tomography examination for patients.