Quantitative radiographic imaging using a photostimulable phosphor system

We have evaluated a photostimulable phosphor x‐ray imaging system [Philips Computed Radiography (PCR) system] for use in quantification of x‐ray exposure in diagnostic radiography. An exponential function was fitted to data yielding quantitative x‐ray exposure values as a function of digital pixel values. We investigated several factors that affect the accuracy of exposure measurement using the PCR including repeatability, background noise as a function of time delay between plate erasure and use, sensitivity variation between different plates, nonuniformity of sensitivity within a plate, decay of the latent image between time of exposure and readout (observed as a change in sensitivity), and the accuracy with which the (exponential) calibration function yields exposure values as a function of digital pixel values. The calibration was performed over the exposure range from 5.1×10 −9 to 2.0×10 −5 C/kg (0.02–75 mR). The accuracy of exposure measurements made with a single imaging plate is between 1.6% and 4.2%. If measurements from several plates are involved, the uncertainty in the final measurement will be between 5% and 5.9%.