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Proceedings Paper

Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan
Author(s): Takamasa Ota; Masaharu Tsuyuki; Miwa Okumura; Tomonari Sano; Takeshi Kondo; Shinichi Takase
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Paper 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.

Paper Details

Date Published: 19 March 2008
PDF: 10 pages
Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 69134S (19 March 2008); doi: 10.1117/12.771099
Show Author Affiliations
Takamasa Ota, Toshiba Information Systems Corp. (Japan)
Masaharu Tsuyuki, Toshiba Medical Systems Corp. (Japan)
Miwa Okumura, Toshiba Medical Systems Corp. (Japan)
Tomonari Sano, Takase Clinic (Japan)
Takeshi Kondo, Takase Clinic (Japan)
Shinichi Takase, Takase Clinic (Japan)

Published in SPIE Proceedings Vol. 6913:
Medical Imaging 2008: Physics of Medical Imaging
Jiang Hsieh; Ehsan Samei, Editor(s)

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