評估不同年齡及BMI接受64切冠狀動脈電腦斷層攝影之合理劑量

Evaluation of Feasible Radiation Dose for 64 Slice CTCA under Different Ages and BMIs

張育瑜(Yu-Yu Chang)

指導教授 ： 黃詠暉

共同指導教授 ： 陳泰賓(Tai-Bean Chen)

義守大學/電機資訊學院/資訊工程學系/碩士(2014年)

https://doi.org/10.6343/ISU.2014.00353

摘要

研究動機與目的:本研究動機為探討受測者在接受電腦斷層造影時之合理輻射劑量。目的係根據受測者之年齡與身體質量指數(Body Mass Index, BMI)，在不影響影像品質下，尋求最適之劑量。
材料與方法:本研究收集的樣本共161位，包括因健檢或追蹤冠狀動脈疾病而至放射線部接受64切電腦斷層檢查，其所收集樣本數以曾經做過一次且不重複之同一樣本收集，按年齡(Age)分成二組:年齡≦55歲、年齡>55歲，按BMI分成四組:BMI≦19kg/m²、19< BMI ≦24kg/m²、24< BMI ≦26kg/m²、BMI >26kg/m²。利用影像軟體OsiriX估算受測者進行電腦斷層冠狀動脈攝影時之體積;同時，從影像中量測訊雜比(Signal to Noise Ratio, SNR)並請醫師對影像之品質進行評分(Score)。病人所接受之劑量係利用標準化電腦斷層劑量指標(Volume Computed Tomography Dose Index, CTDIvol)除以病人所造影之體積視為標準化CTDIvol，即每一c.c.有多少吸收劑量(單位:mGy/c.c.)。之後將取得的資料運用T檢定、相關性分析及迴歸分析並建立迴歸評估模型。
結果:劑量評估模型之依變數為標準化CTDIvol，其餘自變數如BMI群組、年齡群組、SNR及Score。標準化CTDIvol對於自變數之間皆具有顯著性(P<0.05)，所建立之合理劑量迴歸評估模型為標準化CTDIvol=0.23BMI+0.03Age。
結論: 按照估算出的合理劑量在不同年齡及BMI時所給予的標準化CTDIvol分別為在年齡≦55歲及BMI≦19kg/m²時4.32~5.79mGy/c.c.;在年齡≦55歲及19< BMI ≦24kg/m²時6.23~6.49mGy/c.c.;在年齡≦55歲及24< BMI ≦26kg/m²時7.32~7.5mGy/c.c.;在年齡≦55歲及BMI>26kg/m²時7.41~8.4mGy/c.c.;在年齡>55歲及BMI≦19kg/m²時5.37~6.33mGy/c.c.;在年齡>55歲及19< BMI ≦24kg/m²時7.14~7.36mGy/c.c.;在年齡>55歲及24< BMI ≦26kg/m²時7.95~8.16 mGy/c.c.;在年齡>55歲及BMI>26kg/m²時7.75~8.13 mGy/c.c.。根據上述結果，未來可估算病人胸部實際體積的大小，再運用該病人之BMI及年齡代入合理劑量評估迴歸模型去推算會得到標準化CTDIvol，使得病人所接受之劑量更趨合理化，以提供下修劑量之參考依據。

關鍵字

電腦斷層 ； 冠狀動脈 ； 體積電腦斷層劑量指標 ； 影像品質 ； 訊號雜訊比

並列摘要

Motivation and Objective: The motivation was explored the subjects reasonable radiation dose undergoing Computed Tomography. The purpose of this study was using the subjects ages and BMIs(Body Mass Index)to compromised between the optimal dose and the image quality.
Materials and Methods: In this study,161 subjects were collected,including any health examination or track coronary artery disease and accepted the 64-slice CT exam to the radiation department. They collected a number of done and not repeat sample collection,by ages were divided into two groups:age≦55 years,age>55 years and divided into four groups according to BMI:BMI≦19kg/m²、19< BMI ≦24kg/m²、24< BMI ≦26kg/m²、BMI>26kg/m². When subjects undergoing CTCA(Computed Tomography Coronary Artery),to estimated the scanning volume using software OsiriX from the images; measuring SNR(Signal to Nosie)and recording the scored by doctors. Subjects dose were evaluated from standardized CTDIvol(Volume Computed Tomography Dose Index),that defined as divided patient imaging volume from every subjects(unit: mGy/c.c.). Then would be using T-test, correlation analysis and regression analysis.
Results: The dependent variable of assessment model was standardized CTDIvol, the independent variable were BMI groups, age groups, SNR and score. Standardized CTDIvol for all have significant(P<0.05)between the independent variables,the regression model used for resonable dose assessment was:Standardized CTDIvol==0.23BMI+0.03Age.
Conclusion:Acoording to the estimated reasonable doses at different ages and BMIs were given standardized CTDIvol. At age≦55 years and BMI≦19kg/m², 4.32~5.79mGy/c.c.. At age≦55 years and 19< BMI ≦24kg/m², 6.23~6.49mGy/c.c.. At age≦55 years and 24< BMI ≦26kg/m², 7.32~7.5mGy/c.c.. At age≦55 years and BMI>26kg/m², 7.41~8.4mGy/c.c.. At age>55 years and BMI≦19kg/m², 5.37~6.33mGy/c.c.. At age>55 years and 19< BMI ≦24kg/m², 7.14~7.36 mGy/c.c.. At age>55 years and 24< BMI ≦26kg/m², 7.95~8.16mGy/c.c.. At age>55 years and BMI>26kg/m², 7.75~8.13mGy/c.c.. In this study,model established could provide different ages and BMIs that were given to operate the instrument in the clinical exam and provided a downward revision in radiation dose.

並列關鍵字

CT ； Coronary Artery ； CTDIvol ； Image Quality ； SNR

參考文獻

27. JP Su. Comparison of Automatic Tube Current Modulation with Fixed Tube Current in Multi-Detector Row CT of the Liver. Kaohsiung Medical University Institute of Radiological Sciences Master Thesis. 2006.

2. TQ Callister, B Cooil, SP Raya, et al. Coronary Artery Disease: Improved Reproducibility of Calcium Scoring with an Electron-Beam CT Volumetric Method. Radiology. 1998; 208(3), 807-814.

3. JW Li. Quantitative Assessment of Image Quality in 64-Slice Computed Tomography of Coronary Arteries in Subjects Undergoing Screening for Coronary Artery Disease Thesis. 2011.

4. FA Mettler, PW Wiest, JA Locken, et al. CT Scanning:Patterns of Use and Dose. J Radiol. 2000; 20(4), 353-359.

6. AW Leber, A Knez, A Becker, et al. Quatification of Obstructive and Non Obstructive Coronary Lesions by 64-Slice Computed Tomography: A Comparative Study With Coronary Angiography and Intravascular Ultrasound. J Am Coll Cardiol. 2005; 46(1), 147-154.