Performance Evaluation of Carbon-Interspaced Anti-Scatter Grids inMammography: Empirical Formula and Monte Carlo Simulation Studies

摘要

Anti-scatter grids show various performances depending on complicated design parameters. How-ever, it takes a long time and high cost to fabricate grids and perform experiments to evaluate theperformance of grids. Therefore, to replace actual measurements, we performed a Monte Carlo sim-ulation study and obtained Tp (transmission of primary radiation) and Tt (transmission of totalradiation) values, which represent grid performance. A beam quality check was done to validateour simulation results. Although the simulation lowers the cost, it is still time-consuming work. Tosolve those problems, we derived empirical formulae for Tp and Tt by analyzing the results of thesimulation. Design parameters for grids were setup in order to derive the empirical formulae. Thederived empirical formulae helped us estimate the Tp and the Tt values of an arbitrary grid withouta complicated experiment or a tedious simulation and to easily obtain the contrast improvementfactor (CIF) and the Bucky factor (BF), which are commonly used to evaluate the performanceof a grid. The design parameters of a grid for the minimum patient's dose can be proposed whilemaintaining the image quality within the designable range by using the derived empirical formulae.