| 摘要 |
<p>A device in a gamma camera for automatic amplification control of the photomultiplier tubes thereof. A plurality of light emitting diodes are supplied power from a continuously working pulse generator and the light therefrom impinges directly or after reflection, on the cathodes of the photomultiplier tubes. A control circuit for each photomultiplier tube acts to control the potential difference between two dynodes in the tube and comprises a peak detector coupled to the output of the associated photomultiplier tube, with the output signal thereof going to a comparator for comparison with an adjustable stable reference voltage. The output of the comparator is connected to a resistance control circuit connected over the two dynodes, such that a continuous recalibration of the amplification of each photomultiplier tube is made during use of the gamma camera.</p> |
