Patient dose reduction in CT Angiography (CTA)
A study published in the AJR by Matsuoka et al. at Harvard Medical School investigated the use of 100 or 110 kV rather than 120 or 130 kV in CT angiography (CTA) examinations. The authors estimated that the 20 kVp reduction led to a 40 to 50% reduction in radiation dose. 200 patients each were in the standard kVp and the reduced kVp group. All underwent multidetector-row CT (MDCT) examinations. Although there was no significant difference in image quality scores in the two groups, the mean vascular enhancement in the main pulmonary artery had significantly higher attenuation values in the low kVp group. Authors document improved vascular enhancement.
Another CTA study published in the Journal of the American College of Cardiology by Pontone et al in Italy has shown that prospective electrocardiogram (ECG) triggering of computed tomography angiography (CTA) scans can allow accurate detection of coronary stenosis with a large reduction in radiation dose when compared with retrospective ECG triggering of CTA. 160 patients were studied with 80 in the prospective ECG triggering group and 80 in the retrospective triggering group. The diagnostic performance of multidetector computed tomography (MDCT) angiography for both groups was similar, with greater than 92% accuracy in both groups, but with an estimated radiation dose of 5.7 ± 1.5 mSv for the prospective group vs. 20.5 ± 4.3 mSv for the retrospective group.
References
MATSUOKA, S., HUNSAKER, A.R., GILL, R.R., OLIVA, I.B., TROTMAN-DICKENSON, B., JACOBSON, F.L., HATABU, H., Vascular enhancement and image quality of MDCT pulmonary angiography in 400 cases: Comparison of standard and low kilovoltage settings, Am. J. Roentgenol. 192 6 (Jun. 2009) 1651-1656.
PONTONE, G., ANDREINI, D., BARTORELLI, A.L., CORTINOVIS, S., MUSHTAQ, S., BERTELLA, E., ANNONI, A., FORMENTI, A., NOBILI, E., TRABATTONI, D., MONTORSI, P., BALLERINI, G., AGOSTONI, P., PEPI, M., Diagnostic accuracy of coronary computed tomography angiography: A comparison between prospective and retrospective electrocardiogram triggering, J. Am. Coll. Cardiol. 54 4 (Jul. 2009) 346-355.
