Abstract: Because the mobility ratio of thin film transistors is too low, it is recognized that flat detector can not be used in CT machine.The current research direction is to find the detector material with higher mobility ratio, but with little success. This study puts forward a new scheme to solve the core problem that limits the application of CT, which is the mobility of thin film transistors:by moving various TFT functions in the thin film transistor to the peripheral circuit, the restriction of the mobility of thin film transistor on the CT machine is completely overcome, and the reading speed of the flat panel detector becomes very fast, which can perfectly meet the requirements of the scanning speed of the CT machine.This will provide new research ideas for the application of flat panel detector in CT machine.