Abstract: A subject (10) is disposed adjacent a detector array (18) of a nuclear camera. The subject (10) is injected with a radioactive isotope (14) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array (18). Individual detectors (22) are monitored in groups of 64. When one of them detects a nuclear event, it produces an electrical spike that is filtered into a Gaussian with about a 1.2 &mgr;sec peaking time. A 10 bit analog to digital converter (44) 10 repeatedly digitizes the amplitude of the Gaussian pulse, e.g. at a 20 MHz clock rate. The 10 bit digitized pulse amplitudes are monitored by a 10 bit comparitor (46), which monitors consecutive values of the digitized signal, looking for the peak value, e.g. for the amplitude to stop rising. When the peak is detected, the most recent four digital pulse amplitudes contiguous to the peak are summed in a 12 bit accumulator (106) to generate a 12 bit peak amplitude value.

Abstract: A penetrating radiation source (14) is disposed on one side of a object (10) which is on a object support (12). A flat panel radiation detector (18) is stationarily disposed on the opposite side of the object (10) than the source (14). A moving system (16, 50, 52) moves the source (14) with respect to the object (10). In each position (Xi, Yi, Zi) of the source (14) a center ray of the x-ray beam strikes the detector (18) at a corresponding location (xi, yi, 0). For each position (Xi, Yi, Zi) of the source (14), the image (xi, yi, 0) of an object located on a focal plane offsets by a vector displacement (Di) relative to a reference position (xo, yo, zo) of the image when the source is at (X0, Y0, Z0). A processor (28) shifts and interpolates each view by the different vector displacements corresponding to each of the focal planes (L1, L2, . . . ) and integrates the images to generate a series of slice image representations which are stored in a volume image memory (30).

Abstract: A radiographic imaging system is comprised of a radiation source 12, a radiation adsorbing grid assembly 18, an image producing element 22 a controller 34, an exposure sequence start means 28 and a grid assembly oscillation means 20. The radiation source and grid define a subject receiving gap, wherein an object under examination is disposed, and through which the source propagates a beam of radiation onto the face of the image producing element. The controller recognizes when the exposure sequence start means is activated and starts the exposure sequence. The exposure sequence is comprised of an exposure preparation interval and an exposure interval. The exposure preparation interval is comprised of a radiation source preparation time and a point-in-time when the grid assembly oscillation commences oscillating the grid assembly.

Abstract: An improved phototimer control and compensation scheme is provided. The control monitors electrical signals produced by a plurality of photomultiplier tubes. PMT dark current is sampled prior to exposure and is compensated for as exposure begins. Each PMT produces a signal proportional to incident radiation which is integrated by separate integrator means to produce first ramp signals. Switching means are provided for selecting any one or combination of first ramp signals. Mixing means combines selected first ramp signals. Amplifier means amplifies mixed signals as a function signals selected to produce a second ramp signal. Gain selection means compensates the gain of the second ramp signal to the speed with the film-screen combination chosen. An exposure compensation scheme produces an exposure reference signal defining the net effect of system variables. Equations defining kV reference curves are stored in a first storage means.

Abstract: In a photoconductive image processing system, consistent copy quality is possible if the charge necessary for the transfer of a toner image is produced by a source of substantially constant current. Changes in transfer material or humidity will not affect the current and thus the charge delivered. As a result, readjustment of the charge source is obviated.