The Effects of Detector Gain Capacitances on Image Quality and Radiation Doses

In this paper, we studied the effects on image quality and radiation doses when varying the detector gain capacitances provided in a flat panel detector. The responses between the radiation dose and the output signal at the detector according to both low and high capacitance values were analyzed and they both found to have a linear relationship with different slopes. The high capacitance can receive more radiation dose than the low capacitance. Moreover, the contrast to noise ratio (CNR) along with the standard deviation were measured in the cross-section images. The experimental results showed that with the low capacitance gain mode, the CNR was higher, while the standard deviation was lower. In case of high radiation doses as commonly required in the soft tissue applications, the high capacitance gain mode seems to be more suitable. On the other hand, since bone applications prefer high contrast with low doses, the low capacitance gain mode tends to be applicable. Choosing the right capacitance according to the desired application would improve image quality of reconstructed images.