An X-ray detecting apparatus comprising: at least one X-ray detector module (100-1, 100-n) configured to detect an X-ray irradiated from an X-ray generator to an object , and to convert the X-ray irradiated to the object into an electric signal according to a photograph protocol to obtain X-ray data about the object; a storage configured to store a setting parameter value comprising information about offset calibration of the at least one X-ray detector module and about a feedback capacitor included in the at least one X-ray detector module, said information comprising an offset value of the at least one X-ray detector module (100-1, 100-n) and a feedback capacitor value of the feedback capacitor; a power supply configured to supply an electric power to the at least one X-ray detector module (100-1, 100-n); a controller configured to receive a signal for starting an X-ray tomography scan with respect to the at least one X-ray detector module (100-1, 100-n), and to control the power supply to supply an electric power to the at least one X-ray detector module (100-1, 100-n) when an X-ray tomography scan starts based on the signal for starting the X-ray tomography scan and to shut off the electric power supplied to the at least one X-ray detector module when the X-ray tomography scan is finished; and a detector module controller configured to receive the setting parameter value from the storage and correct the offset value and the feedback capacitor value comprised in the received setting parameter value after the supplying of the electric power to the at least one X-ray detector module (100-1, 100-n); wherein the X-ray detecting apparatus is further configured to obtain the X-ray data of the object based on the corrected offset calibration value and corrected feedback capacitor value. at least one X-ray detector module (100-1, 100-n) configured to detect an X-ray irradiated from an X-ray generator to an object , and to convert the X-ray irradiated to the object into an electric signal according to a photograph protocol to obtain X-ray data about the object; a storage configured to store a setting parameter value comprising information about offset calibration of the at least one X-ray detector module and about a feedback capacitor included in the at least one X-ray detector module, said information comprising an offset value of the at least one X-ray detector module (100-1, 100-n) and a feedback capacitor value of the feedback capacitor; a power supply configured to supply an electric power to the at least one X-ray detector module (100-1, 100-n); a controller configured to receive a signal for starting an X-ray tomography scan with respect to the at least one X-ray detector module (100-1, 100-n), and to control the power supply to supply an electric power to the at least one X-ray detector module (100-1, 100-n) when an X-ray tomography scan starts based on the signal for starting the X-ray tomography scan and to shut off the electric power supplied to the at least one X-ray detector module when the X-ray tomography scan is finished; and a detector module controller configured to receive the setting parameter value from the storage and correct the offset value and the feedback capacitor value comprised in the received setting parameter value after the supplying of the electric power to the at least one X-ray detector module (100-1, 100-n); wherein the X-ray detecting apparatus is further configured to obtain the X-ray data of the object based on the corrected offset calibration value and corrected feedback capacitor value. <EOS>