Wieland H. Sommer, Edda Albrecht, Fabian Bamberg, Jan C. Schenzle, Thorsten R. Johnson, Klement Neumaier, Maximilian F. Reiser, Konstatin Nikolaou
OBJECTIVE. The objective of this study was to compare image quality and radiation dose between high-pitch and established retrospectively and prospectively gated cardiac CT protocols using an Alderson-Rando phantom and a set of patients.
MATERIALS AND (METHODS. An anthropomorphic Alderson-Rando phantom equipped with thermoluminiscent detectors and a set of clinical patients underwent the fol-lowing cardiac CT protocols: high-pitch acquisition (pitch 3.4), prospectively triggered acqui-sition, and retrospectively gated acquisition (pitch 0.2). For patients with sinus rhythm below 65 beats per minute (bpm), high-pitch protocol was used, whereas for patients in sinus rhythm between 65 and 100 bpm, prospective triggering was used. Patients with irregular heart rates or heart rates of > 100 bpm, were examined using retrospectively gated acquisition. Evaluabil-ity of coronary artery segments was determined, and effective radiation dose was derived from the phantom study.
RESULTS. In the phantom study, the effective radiation dose as determined with ther¬moluminescent detector (TLD) measurements was lowest in the high-pitch acquisition (1.21, 3.12, and 11.81 mSv, for the high-pitch, the prospectively triggered, and the retrospectively gated acquisition, respectively). There was a significant difference with respect to the percent¬age of motion-free coronary artery segments (99%, 87%, and 92% for high-pitch, prospec-tively triggered, and retrospectively gated, respectively (p < 0.001), whereas image noise was lowest for the high-pitch protocol (p < 0.05).
CONCLUSION. High-pitch scans have the potential to reduce radiation dose up to 61.2% and 89.8% compared with prospectively triggered and retrospectively gated scans. High-pitch protocols lead to excellent image quality when used in patients with stable heart