Novel method of attenuation-based estimating patient size from single CT localizer radiograph

This study developed a novel attenuation-based method that employs the absorption coefficient ( μt ) of the single localizer radiograph images. The anterior–posterior (AP) and lateral (LAT) dimensions were estimated using the beam hardening-corrected μt and area under the curve. Based on the reconstructed axial CT images of abdominal CT scans of five patients, we compared the results of the new attenuation-based method with the effective diameter calculated by the geometry-based method recommended in the American Association of Physicists in Medicine (AAPM) Report 204. The diameter values exhibited average differences of 1 and 34.3% for the two methods, respectively. When the results of the AP and LAT dimensions calculation using the attenuation-based method were compared with the reconstructed axial CT images, there were average differences of 0.4 and 1.5% in the AP and LAT dimensions. The proposed attenuation-based method can be used to obtain a more accurate measurement of patient size by correcting the geometric magnification and μt value of the localizer radiograph for physical attenuation.