Pixel Value Measurement of Microcalcification Specks in Digitized X-ray Film Images for Image Quality Assessment: Automatic Procedure Developed Using Excel Functions.

We previously reported a method of pixel value averaging for microcalcification specks on digitized mammographic phantom images. These average values are considered to represent the pixel value of a speck for quality control in comparison to its maximal peak value. In this report, we described an automatic processing procedure using a spreadsheet to derive the average and peak values of the pixel value of a speck. A hundred and twenty specks in 10 phantoms were processed using the spreadsheet, and average and peak values were compared. In the examination of the digitized mammography images of RMI 156 phantoms for two calcification speck groups, the average and peak values showed good correlation. Therefore, we concluded the peak values could be used as substitutes for the average values for a quality control purpose. However, as the regression coefficients of the two speck groups were significantly different, the relationship between the average and peak value seemed to depend on speck sizes.