- 作者：Kambiz Ghafourian ; MD ; MPH鈦?/sup> ; Desiree Younes ; MD&dagger ; ; Lauren A. Simprini ; MD鈦?/sup> ; Wm. Guy Weigold ; MD鈦?/sup> ; Gaby Weissman ; MD鈦?/sup> ; Allen J. Taylor ; MD&dagger ; ; Allen.Taylor@gunet.georgetown.edu
- 关键词：cardiac computed tomographic angiography ; radiation exposure
- 刊名：JACC ; Cardiovascular Imaging
- 出版年：2012
- 期刊代码：pca197_1936878X
- 类别：med
- 出版时间：June, 2012
- 卷：5
- 期：6
- 页码：589-595
- 文件大小：734 K
Objectives
The study evaluated the relationship between cardiac computed tomography (CT) scout view x-ray attenuation and CT image noise compared with weight or body mass index (BMI).Background
Decreasing peak tube voltage from 120 to 100 kVp on the basis of body size reduces radiation exposure. Methods to better predict CT image noise may lead to more effective selection of reduced tube voltage in cardiac CT.
Methods
Image quality was graded subjectively (1 [excellent] to 4 [nondiagnostic]) and objectively (SD of the aortic attenuation value) in cardiac CT angiograms (N = 106) acquired at either 100 or 120 kVp. X-ray attenuation characteristics on the scout view (120 kVp, 30 mA) were measured within a 3-cm region of interest across the chest in the frontal x-ray. Receiver-operating characteristic curve analysis was performed comparing scout view attenuation versus weight and BMI in predicting CT image noise and quality.
Results
CT image noise correlated with both BMI (r = 0.40; p < 0.001) and the scout view attenuation value (r = 0.52; p < 0.001). In linear regression models with controlling for BMI (or weight) and tube potential, scout view attenuation was the best predictor of the CT image noise (p < 0.001), and increased model fit statistic from 0.23 to 0.41 (p model <0.001). At 120 kVp, scout view attenuation predicted CT image noise <30 Hounsfield units (HU) more accurately than BMI (area under the curve: 0.89 vs. 0.77). For CT images acquired at 120 kVp, those with a scout view attenuation <鈭?20 HU had significantly lower noise and higher signal-to-noise ratios, with similar mean aortic attenuation values. A majority (89.3%) of 鈥渓ow-noise鈥?CT images at 120 kVp had scout view attenuation values of <鈭?20 HU.
Conclusions
Scout view attenuation predicts cardiac CT image noise better than weight or BMI and could enable broader application of reduced x-ray tube voltage as a radiation sparing technique.