19 March 2008 Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan
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A novel low-dose ECG-gated helical scan method to investigate coronary artery diseases was developed. This method uses a high pitch for scanning (based on the patient's heart rate) and X-rays are generated only during the optimal cardiac phases. The dose reduction was obtained using a two-level approach: 1) To use a 64-slice CT scanner (Aquilion, Toshiba, Otawara, Tochigi, Japan) with a scan speed of 0.35 s/rot. to helically scan the heart at a high pitch based on the patient's heart rate. By changing the pitch from the conventional 0.175 to 0.271 for a heart rate of 60 bpm, the exposure dose was reduced to 65%. 2) To employ tube current gating that predicts the timing of optimal cardiac phases from the previous cardiac cycle and generates X-rays only during the required cardiac phases. The combination of high speed scanning with a high pitch and appropriate X-ray generation only in the cardiac phases from 60% to 90% allows the exposure dose to be reduced to 5.6 mSv for patients with a heart rate lower than 65 bpm. This is a dose reduction of approximately 70% compared to the conventional scanning method recommended by the manufacturer when segmental reconstruction is considered. This low-dose protocol seamlessly allows for wide scan ranges (e.g., aortic dissection) with the benefits of ECG-gated helical scanning: smooth continuity for longitudinal direction and utilization of data from all cardiac cycles.
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Takamasa Ota, Takamasa Ota, Masaharu Tsuyuki, Masaharu Tsuyuki, Miwa Okumura, Miwa Okumura, Tomonari Sano, Tomonari Sano, Takeshi Kondo, Takeshi Kondo, Shinichi Takase, Shinichi Takase, } "Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan", Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 69134S (19 March 2008); doi: 10.1117/12.771099; https://doi.org/10.1117/12.771099

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