Determination of the Weighted Computed Tomography Dose Index in Coronary Multidetector Computed Tomography Angiography

Multislice computed tomography (CT) angiography is a robust imaging method for noninvasive assessment of coronary artery diseases, which is associated with high radiation dose. Having knowledge of the various parameters used to estimate the dose plays an important role in increasing the understanding of dose delivered to patients and help operators and technologist to reduce the dose. In this research, the amounts of Weighted Computed Tomography Dose Index (CTDIW) for coronary CT angiography exams were measured in Isfahan city, Iran.
To calculate the dose, an ionization chamber (Piranha, X-ray Analyzer, RTI Electronics and Sweden) and acrylic body phantom were used. Common conditions of coronary CT angiography used in two centers were applied for this project. Finally, CTDIW of all the scans were calculated using the related formulation.
Findings: The amount of mean CTDIW for calcium score exams in Sina and Alzahra hospitals were 0.468 ± 0.190 and 2.354 ± 0.610 mGy, respectively (P = 0.007); and for coronary CT angiography scans in Sina and Alzahra hospitals were 6.221 ± 1.290 and 5.299 ± 0.840 mGy, respectively (P = 0.860).
CTDIW for the calcium score was significantly different in the two centers, but there was not significant difference in the two centers for coronary CT angiography scans. In this study, the amount of CTDIW was much lower than the measured in other centers. Since scan parameters have an important effect on the dose value, training and precision of technologist result in dose reduction and patient radiation protection.