Performance evaluation of carbon-interspaced anti-scatter grids in mammography: Empirical formula and Monte Carlo simulation studies

Anti-scatter grids show various performances depending on complicated design parameters. However, it takes a long time and high cost to fabricate grids and perform experiments to evaluate the performance of grids. Therefore, to replace actual measurements, we performed a Monte Carlo simulation study and obtained Tp (transmission of primary radiation) and Tt (transmission of total radiation) values, which represent grid performance. A beam quality check was done to validate our simulation results. Although the simulation lowers the cost, it is still time-consuming work. To solve those problems, we derived empirical formulae for Tp and Tt by analyzing the results of the simulation. Design parameters for grids were setup in order to derive the empirical formulae. The derived empirical formulae helped us estimate the Tp and the Tt values of an arbitrary grid without a complicated experiment or a tedious simulation and to easily obtain the contrast improvement factor (CIF) and the Bucky factor (BF), which axe commonly used to evaluate the performance of a grid. The design parameters of a grid for the minimum patient's dose can be proposed while maintaining the image quality within the designable range by using the derived empirical formulae.