Monte Carlo analysis of relation between patient dose and noise characteristic of a flat-panel detector for cone-beam CT

We have examined the characteristic of a flat-panel detector used for our cone-beam CT scanner. We calculated detection efficiency, the modulation transfer function and the noise characteristic of flat-panel detector by the Monte Carlo method, and compared the results with experiment data. From these data, we estimate the relation between the patient dose and signal-to-noise ratio of projection data of CT image. Furthermore, to reduce the patient dose, we have examined the effect of removing the noise from projection degraded by quantum mottle, by the wavelet analysis. Our preliminary results show that de-noising of projection data with wavelet analysis has an effect to reduce the patient dose to less than 1/10, without decreasing the quality of CT image.