Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320？mAs per rotation, 100 and 120？kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5？cm, collimation ？mm with z-flying focal spot, gantry rotation time 280？ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1？mSv to 1.6？mSv and from 1.2 to 1.8？mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of % compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively ( ). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable. 1. Introduction At present, computed tomography coronary angiography (CTCA) is an important, widely accepted diagnostic tool for the assessment of coronary artery disease. Several studies have shown the potential of different dose-saving strategies to keep the radiation exposure as low as reasonablly achievable. Hausleiter et al. reported in an international multicenter trial (PROTECTION I) a mean effective dose of 12？mSv in CTCA, ranging from 5 to 30？mSv . Radiation exposure can be reduced substantially by currently available strategies, but these possibilities are used infrequently . Since the introduction of a second-generation dual-source scanner system, a new scanning mode with increased table feed is available. Compared to retrospective ECG-gated and prospective ECG-triggered CTCA, this high-pitch, prospective triggered scanning mode has the potential for drastic dose reduction due to a gapless imaging of the heart within one heartbeat with no overlapping data acquisition. The aim of the study was to estimate effective whole-body dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. 2. Material and Methods 2.1. Dosimetry The experiments were performed by using an anthropomorphic,
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