Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

Takamasa Ota; Masaharu Tsuyuki; Miwa Okumura; Tomonari Sano; Takeshi Kondo; Shinichi Takase

doi:10.1117/12.771099

19 March 2008 Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

Takamasa Ota, Masaharu Tsuyuki, Miwa Okumura, Tomonari Sano, Takeshi Kondo, Shinichi Takase

Author Affiliations +

Proceedings Volume 6913, Medical Imaging 2008: Physics of Medical Imaging; 69134S (2008) https://doi.org/10.1117/12.771099
Event: Medical Imaging, 2008, San Diego, California, United States

Abstract

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.

Citation Download Citation

Takamasa Ota, Masaharu Tsuyuki, Miwa Okumura, Tomonari Sano, Takeshi Kondo, and 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); https://doi.org/10.1117/12.771099

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