Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography

Scanner- and protocol-specific k-factors, in units of mSv·mGy⁻¹cm⁻¹, were calculated for cardiac CT using ICRP Publication 103 definition of effective dose, for 12 scanners and 120 scan protocols with standard tube potentials of 80, 100, and 120 kVp. k-Factors here are summarized in 5 categories of axial and helical CT angiography protocol types, and calcium score. Per-scanner averages of the k-factors across all protocol types and energy levels are displayed along with the CV in the 2 right-most columns. Scan length for all scans is 13.3 to 14.2 cm. Heart rate is 60 beats/min for all scans, except where otherwise noted. A detailed description of each protocol here is also provided in Online Table 1, as are additional k-factors and detailed descriptions for very low (70 kVp) and high (135 or 140 kVp) tube potential protocols for selected scanners.

CV = coefficient of variation (ratio of standard deviation to mean in percentage values); other abbreviations as in Tables 1, 2, and 3 .

• ↵∗ Tube current modulation.

• ↵† Average of 2 beams with 20- and 40-mm widths.

• ↵‡ Heart rate = 80 beats/min (all others are 60 beats/min).

• ↵§ Average of high and standard resolution modes.

• ↵‖ Target mode volume scan.

• ↵¶ Continuous volume scan with exposure throughout a full cardiac cycle.