Method and apparatus of detecting ionizing radiation

An imaging system comprising a semiconductor detector, said imaging system comprising:

• a pixilated semiconductor substrate responsive to ionizing radiation, said substrate including a first surface pixilated with at least one pixel anode, a grid electrode coupled to said pixilated surface, said grid electrode circumscribing a central region of the at least one pixel anode, and a cathode coupled to a second surface of said pixelated surface, said cathode substantially covering said second surface;
• and
• a controller configured to;
• measure a first signal between said at least one pixel anode and said cathode by applying a first bias voltage to said at least one pixel anode;
• measure a second signal between said grid electrode and said cathode by applying a second bias voltage to said grid electrode wherein said second bias voltage is less than said first bias voltage;
• and
• combine the magnitude of the first signal and the magnitude of the second signal to obtain a total signal from the semiconductor substrate.

A radiation detector, comprising:

• a semiconductor substrate comprising at least one pixel anode defined in a first surface of said substrate, said at least one pixel anode configured to receive a first bias voltage;
• a cathode electrically coupled to a second surface of said substrate, said cathode substantially covering said substrate;
• a grid electrode coupled to said first surface, said grid electrode circumscribing a central region of said at least one pixel anode and configured to receive a second bias voltage;
• a first measurement circuit configured to measure a first signal;
• a second measurement circuit configured to measure a second signal;
• and
• a summing circuit configured to combine the magnitude of the output of the first measurement circuit and the magnitude of the output of the second measurement circuit, the combination proportional to a total charge in the pixel.