A radiation detection apparatus, comprising: a radiation detector (101,301,401) which generates an electrical signal by interacting with X-rays, wherein scintillators generate photon signals by interacting with transmitted X-rays, and the radiation detector (101,301,401) converts photon signals into electrical signals; a high speed Analog-to-Digital Converter (102, 302, 403, 500) which is coupled to the radiation detector and converts the electrical signal to a waveform data; and a data processor (103, 303, 505) which determines the number of single photon signals according to the waveform data from the high speed ADC, and determines whether an integral signal and/or a count signal of the waveform data will be used for imaging according to the number of the single photon signals, characterized in that the single photon signals are signals which peak amplitude is less than a predetermined single photon amplitude threshold, and the data processor (103, 303, 505) is configured to determine whether an integral signal and/or a count signal of the waveform data will be used for imaging according to the number of the single photon signals by: comparing the number of the single photon signals with a predetermined lower threshold and a predetermined upper threshold; using the integral signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is less than the predetermined lower threshold; and using the count signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is greater than the predetermined upper threshold. a radiation detector (101,301,401) which generates an electrical signal by interacting with X-rays, wherein scintillators generate photon signals by interacting with transmitted X-rays, and the radiation detector (101,301,401) converts photon signals into electrical signals; a high speed Analog-to-Digital Converter (102, 302, 403, 500) which is coupled to the radiation detector and converts the electrical signal to a waveform data; and a data processor (103, 303, 505) which determines the number of single photon signals according to the waveform data from the high speed ADC, and determines whether an integral signal and/or a count signal of the waveform data will be used for imaging according to the number of the single photon signals, characterized in that the single photon signals are signals which peak amplitude is less than a predetermined single photon amplitude threshold, and the data processor (103, 303, 505) is configured to determine whether an integral signal and/or a count signal of the waveform data will be used for imaging according to the number of the single photon signals by: comparing the number of the single photon signals with a predetermined lower threshold and a predetermined upper threshold; using the integral signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is less than the predetermined lower threshold; and using the count signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is greater than the predetermined upper threshold. comparing the number of the single photon signals with a predetermined lower threshold and a predetermined upper threshold; using the integral signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is less than the predetermined lower threshold; and using the count signal of the waveform data as an imaging signal to perform imaging if the number of the single photon signals is greater than the predetermined upper threshold.