CT dose management of adult patients with unknown body weight using an effective diameter

To assess the usefulness of effective diameter (D_eff) for CT dose management of adult patients with unknown body weight.

A total of 642 adult patients whose height and weight had been measured before CT examination (chest CT using Aquilion Prime SP, 428 patients; chest CT using Biograph mCT, 100 patients; and abdominal CT using Aquilion Prime SP, 114 patients) were retrospectively examined between April 2018 and September 2019. The D_eff was automatically calculated from the lateral diameter on a CT localizer radiograph by a dose management software (Radimetrics). In order to determine the correlation between body weight and D_eff, we compared volume CT dose index and dose length product between patients with body weight between 50 and 70 kg and those with D_eff equivalent to body weight between 50 and 70 kg. Correlation analysis was performed by Pearson's product-moment correlation, and statistical analyses were performed by using t-test.

The correlation coefficient values between body weight and D_eff were 0.920 for chest CT using Aquilion Prime SP, 0.929 for chest CT using Biograph mCT, and 0.805 for abdominal CT using Aquilion Prime SP. In both chest and abdominal CT scans, there were no significant differences in volume CT dose index and dose length product between patients with body weight between 50 and 70 kg and those with D_eff equivalent to body weight between 50 and 70 kg.

The D_eff may be useful as a somatometric parameter for CT dose management of adult patients with unknown body weight.