Patent ID: 8810416
Filing Date: 2014-08-19
Classification: G01T,H01L,H04N

Abstract:
1. An assembly for monitoring radiation, comprising: a detector substrate for generating electronic charge responsive to incident radiation, said detector substrate configured to form an array of ionising radiation sense volumes; and a circuit substrate supporting an array of read-out circuits corresponding to said sense volumes; wherein a first of said read-out circuits includes photon counting circuitry electronically configurable to respond to a current pulse corresponding to the detection in a corresponding first radiation sense volume of ionising radiation in a first energy range in a first detection period to increment a first count value, and a second of said read-out circuits including photon counting circuitry electronically configurable to respond to a current pulse corresponding to the detection in a corresponding second radiation sense volume of ionising radiation in a second energy range in a second detection period to increment a second count value; wherein said first detection period corresponds to a first frame read-out cycle in which said photon counting circuitry is operative to increment said first count value responsive to detection of ionising radiation in a first window corresponding to said first energy range, and said second detection period corresponds to a second frame read-out cycle in which said photon counting circuitry is operative to increment said second count value responsive to detection of ionising radiation in a second window corresponding to said second energy range, wherein said first and second read-out circuits are operative to read-out frames successively in progressive scanning of successive frames and wherein said second energy range is different from said first energy range; wherein said photon counting circuitry comprises threshold circuitry including a lower current threshold level and an upper current threshold level for defining one or other of said first energy range and said second energy range, said threshold circuitry configured to output a count pulse to said photon counting circuitry responsive to a current pulse having an amplitude within the range defined by said upper current threshold level and lower current threshold level, and wherein said threshold circuitry is operative to adjust said lower current threshold level and said upper current threshold level for each successive read-out cycle such that, in progressive scanning of successive frames, said second window is an increment in the energy spectrum on the previous window.