Siemens Aktiengesellschaft

Roland Ziegler

Rolf Lindner

Martin Schmidt

Werner Kuhlmann

In a photodiode array suitable for use in an x-ray detector for computed tomography, the influences of direct conversion of x-rays into contributions to the electrical output signal and optical cross-talk between channels in the photodiode array are significantly reduced by integrating a number of extraction diodes into the photodiode array, with one extraction diode disposed between each two neighboring photodiodes. The anodes of all of the extraction diodes are connected together at a common anode contact, the common anode contact being connected to a voltage source which applies a voltage across all of the extraction diodes for operating the extraction diodes reverse biased, i.e. so as to block current flow.

Photodiode array

A solid-state radiation detector, including a photodiode array, is suitable for use in computed tomography, with the dark current of the photodiodes being compensated. The compensation is accomplished by an adjustable voltage source connected to the photodiode, the voltage of the adjustable voltage source being set by a regulator so that the dark current becomes zero. The regulator receives a signal corresponding to the dark current from a measured value transducer in the form of a current-driven voltage source. The voltage supplied by the adjustable voltage source to the photodiode is maintained constant while x-rays are incident on the overall detector which cause illumination of the photodiode.

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Erlangen, Germany

Roland Ziegler