Calculation of the contrast of the calcification in digital mammography system: Gate validation

Purpose: Validation of the Gate tool in digital mammography image simulation from the viewpoint of image quality (contrast of calcifications).

Materials and methods: The polymethyl methacrylate (PMMA) phantom containing aluminum foils in different thicknesses is used for measuring the contrast of calcifications in a real system. In this research, the phantom and mammography system have been simulated by the Gate tool with the maximum possible details. The contrast of the aluminum foil in simulations and practical method has been compared with each other and the standard errors in the mean (SEM) for various voltages of X-ray tube, aluminum foil, and PMMA thicknesses have been reported.

Results: Based on the obtained results, by increasing the X-ray tube voltage from 20 to 39 kVp, the image contrast has been decreased in both simulation and practical methods. The minimum and maximum average SEM of the contrast of the aluminum foils among various voltages between two simulations and practical methods for different PMMA thicknesses of 2, 4, and 6 cm have been reported as 0.0105 and 0.0117, 0.0049 and 0.0154, and 0.0037 and 0.0072, respectively.

Discussion: According to the SEM rate reported in this research for calculating the contrast of the aluminum foils in the mammography system based on simulation and practical methods, the capability of the Gate tool for simulating digital mammography system and the images created in it from the viewpoint of image contrast can be confirmed.