Absorbed Radiation Dose in Radiosensitive Organs During Coronary CT Angiography Using 320-MDCT: Effect of Maximum Tube Voltage and Heart Rate Variations

作者：Nikolic Boris; Khosa Faisal; Lin Pei Jan Paul; Khan Atif N; Sarwar Sheryar; Yam Chun Shan; Court Laurence E; Raptopoulos Vassilios; Clouse Melvin E^*

来源：American Journal of Roentgenology, 2010, 195(6): 1347-1354.

DOI：10.2214/AJR.10.4333

• 320-MDCT
• absorbed radiation dose
• cardiac imaging
• cardiac MDCT
• CT dose index
• dose-length product
• metal oxide semiconductor field effect transistor dosimetry

OBJECTIVE. The purpose of this article is to estimate the absorbed radiation dose in radiosensitive organs during coronary MDCT angiography using 320-MDCT and to determine the effects of tube voltage variation and heart rate (HR) control on absorbed radiation dose.
MATERIALS AND METHODS. Semiconductor field effect transistor detectors were used to measure absorbed radiation doses for the thyroid, midbreast, breast, and midlung in an anthropomorphic phantom at 100, 120, and 135 kVp at two different HRs of 60 and 75 beats per minute (bpm) with a scan field of view of 320 mm, 400 mA, 320 x 0.5 mm detectors, and 160 mm collimator width (160 mm range). The paired Student's t test was used for data evaluation.
RESULTS. At 60 bpm, absorbed radiation doses for 100, 120, and 135 kVp were 13.41 +/- 3.59, 21.7 +/- 4.12, and 29.28 +/- 5.17 mGy, respectively, for midbreast; 11.76 +/- 0.58, 18.86 +/- 1.06, and 24.82 +/- 1.45 mGy, respectively, for breast; 12.19 +/- 2.59, 19.09 +/- 3.12, and 26.48 +/- 5.0 mGy, respectively, for lung; and 0.37 +/- 0.14, 0.69 +/- 0.14, and 0.92 +/- 0.2 mGy, respectively, for thyroid. Corresponding absorbed radiation doses for 75 bpm were 38.34 +/- 2.02, 59.72 +/- 3.13, and 77.8 +/- 3.67 mGy for midbreast; 26.2 +/- 1.74, 44 +/- 1.11, and 52.84 +/- 4.07 mGy for breast; 38.02 +/- 1.58, 58.89 +/- 1.68, and 78 +/- 2.93 mGy for lung; and 0.79 +/- 0.233, 1.04 +/- 0.18, and 2.24 +/- 0.52 mGy for thyroid. Absorbed radiation dose changes were significant for all organs for both tube voltage reductions as well as for HR control from 75 to 60 bpm at all tube voltage settings (p < 0.05). The absorbed radiation doses for the calcium score protocol were 11.2 +/- 1.4 mGy for midbreast, 9.12 +/- 0.48 mGy for breast, 10.36 +/- 1.3 mGy for lung, and 0.4 +/- 0.05 mGy for thyroid.
CONCLUSION. CT angiography with 320-MDCT scanners results in absorbed radiation doses in radiosensitive organs that compare favorably to those previously reported. Significant dose reductions can be achieved by tube voltage reductions and HR control.

• 出版日期2010-12