Quantitative analysis of imaging performance for computed radiography systems

The computed radiography (CR) system consists of three processes: reading, image processing, and display. Image noise from the reading process consists of quantum noise and fixed noise. Quantum noise is dependent on exposure but fixed noise is independent of it. Quantum noise can be divided into light photon noise and x-ray photon noise. The former is inversely proportional to the light detection efficiency and the latter is independent of it. We separated the noise components of the Fuji computed radiography (FCR) 7000 system. At a spatial frequency of 1 cycle/mm, the ratio of x ray photon noise to light photon noise to fixed noise was about 8:1:1 at 1 mR(2.58 X 10-7 C/kg). In the new CR system (FCR9000), we decreased x-ray photon noise and fixed noise. As a result, the FCR9000 system yields DQE of approximately 1.4 times higher at a spatial frequency of 0.5 cycle/mm and approximately 1.2 times higher at 1.0 cycles/mm at 1 mR (2.58 X 10-7 C/kg).