[Radiation dose reduction effects of prospective ECG-gated helical scan with high helical pitch in coronary multidetector computed tomography].

Background: High radiation dose of conventional retrospective ECG-gated coronary MDCT (multidetector computed tomography) with regular helical pitch (HP) continuous scan has disturbed wide clinical use. The purpose was to estimate the radiation dose reduction effects of FlashScan, which was a prospective ECG-gated helical scan with high HP.

Method: Coronary MDCT was performed by Aquilion 64 Super Heart (Toshiba) in 474 patients (M/F=280/194, mean age: 65+/-11 years old, mean height: 161+/-10 cm, body weight: 62+/-13 kg, BMI: 23.9+/-3.4) with HR
Result: Mean HP (BP) which was automatically decided by the FlashScan system was 15.3+/-1.0 (0.239+/-0.016) when the gantry rotation speed was 0.35 s/rot. In 6 patients, arrhythmias occurred during scan and data deficits were observed on their images. In the remaining 468 patients, image quality was excellent. Mean DLP of the FlashScan (499+/-119 mGy.cm) was significantly (P<0.0001) lower than that of retrospective continuous scan with regular HP (1281+/-286 mGy.cm) or than that of modulation scan (927+/-202 mGy.cm), and mean scan time of the FlashScan (6.9+/-0.6 s) was also significantly (P<0.0001) shorter than that of retrospective continuous scan with regular HP (8.8+/-0.6 s).

Conclusion: The FlashScan was a useful method to reduce patients' radiation dose and scan time in patients with HR