Characteristic curve measurement based on bootstrap method using a new calcium phosphate stepwedge in mammography

A method for measuring the characteristic curves generated by the mammography imaging systems has not yet been well established due to poor quality control over X-ray exposure in the range of kV values, which is lower than the conventional quality. In this paper, we proposed a bootstrap method using a “stepwedge” designed for characteristic curve measurement in mammography. A ten-step stepwedge containing calcium phosphate, with each step having a different density of material, was employed. In our experiment, the tube voltage and mA values were changed in the range of 25 to 32 kV at increments of 1 kV and in the range of 20 to 100 mAs at increments of 20 mAs, respectively. The results of the curve measurements indicated that our method might be useful to both screen-film mammography and computed radiography (CR), although additional experiments to evaluate the accuracy and precision of the acquired data are required.