A radiographic imaging system based upon a 2-D silicon microstrip sensor

A high resolution, direct-digital detector system based upon a 2-D silicon microstrip sensor has been designed, built and is undergoing evaluation for applications in dentistry and mammography. The sensor parameters and image requirements were selected using Monte Carlo simulations. Sensors selected for evaluation have a strip pitch of 50 /spl mu/m on the p-side and 80 /spl mu/m on the n-side. Front-end electronics and data acquisition are based on the APV6 chip and were adapted from systems used at CERN for high-energy physics experiments. The APV6 chip is not self-triggering so data acquisition is done at a fixed trigger rate. This paper describes the mammographic evaluation of the double sided microstrip sensor. Raw data correction procedures were implemented to remove the effects of dead strips and non-uniform response. Standard test objects (TORMAX) were used to determine limiting spatial resolution and detectability. MTFs were determined using the edge response. The results indicate that the spatial resolution of the sensor can achieve at least 6 1p/mm with detectability performance comparable to a mammographic film/screen and amorphous silicon array. Due to the operational characteristics of the data acquisition system conventional dose estimates were not possible; instead image quality was compared on an event per pixel basis.