There are two main performance indicators for evaluating the quality of flat panel detectors: Detective Quantum Efficiency (DQE) and spatial resolution. DQE determines the resolution of flat panel detectors for differences in tissue density; spatial resolution determines the resolution of tissue microstructure. Investigating DQE and spatial resolution can evaluate the imaging capabilities of flat panel detectors.
For the same flat panel detector, the DQE is variable at different spatial resolutions; the extreme DQE is high, not equal to the high DQE at any spatial resolution. The formula for DQE is as follows:
S: average signal intensity; MFT: modulation transfer function; X: X-ray exposure intensity; NPS: system noise power spectrum; C: X-ray quantum coefficient
It can be known from the calculation formula that different MFT values correspond to different DQEs, which means that there are different DQEs at different spatial resolutions.
The limit DQE of indirect conversion flat panel detector is relatively high, but with the increase of spatial resolution, its DQE decreases more; the limit DQE of direct conversion flat panel detector is not as high as the limit DQE of indirect conversion flat panel detector, but it is high. At spatial resolution, the DQE of the direct conversion flat panel detector is high.