Abstract: A CT scanner having an outer circular array of stationary radiation detectors for an inner concentrically revolving source of radiation emitted in a fan pattern subtending a number of the detectors. Each grouping of 15 consecutive detectors is housed in a detector module, each one of which is provided with an electro-optical device which is arranged to normally deactivate the output of each of the detectors in the module. The detectors are arranged in exclusive groups of four nonconsecutive detectors each equiangularly disposed about the array connected in daisy chain fashion with the output of each of said nonconsecutive detector groups applied to a single signal cable defining a corresponding signal processing channel.

Abstract: A curved beam apparatus adapted for mounting thereon a scintillation detector. The apparatus comprises a circular C-arm which is balanced with a counterweight at one end and a scintillation detector pivotally mounted by means of a yoke at the other end. The C-arm is mounted in a carrier member which in turn is attached to a base. The carrier member is rotatable about an axis passing through its center. In addition, the C-arm rotates circumferentially along a plane defined by the shape of the C-arm and intersecting said axis. The combination of the rotation of the C-arm and the rotation of the carrier member permits the scintillation detector to be quickly and easily manually positioned to any desired location on an imaginary sphere surrounding a portion of patient to be examined.

Abstract: A cardiac output computer which measures cardiac output by the indicator method involving the estimation of the area under either a thermodilution of a luminous transmission curve with automatic bolus detection. Evaluation of the area under the curve is made relative to a true baseline and is independent of, in the case of thermodilution, blood temperature as of the time the bolus is injected into the patient. A series of blood temperature samples are read and stored with the magnitude of each successive signal compared to the one received immediately before. As soon as a plurality of successive comparisons, preferably five, of six successively acquired blood temperatures indicate monotonically decreasing blood temperature values, a test for monotonicity is confirmed, with the highest temperature of the six being designated as the baseline. Once the test is confirmed the computer proceeds to evaluate the area under the curve.

Abstract: A fluorophotometer for determining the concentration of a fluorescent material in an eye, including a light source producing a beam of light traversing a path in the eye to excite the material to emit fluorescence, optics for imaging the path and fluorescence at a detecting plane, a linear photodiode array at the detecting plane for detecting the fluorescence along the path, and a microprocessor for collecting data from the array and producing information of the concentration of the fluorescent material.

Abstract: A brake mechanism for decelerating and positively stopping the support apparatus of a rotating scintillation detector subsequent to completion of a full 360.degree. of rotation as needed for a tomographic study. There is provided a laterally deflectable striker member positioned between two shock absorbers. The support structure of the scintillation detector is either manually rotated or is motor driven by a gear which is provided with a laterally extending striker pin configured and arranged to rotate with said gear and deflect the striker member in a lateral direction as the gear is completing its rotation in either the clockwise or counterclockwise direction. Once the striker pin engages the striker, the striker is deflected either to the right or to the left depending on whether the gear is rotating in a clockwise or counterclockwise direction. In either direction, the striker contacts one of the shock absorbers which serves to decelerate the rotating mass and safely slow it down.

Abstract: A radiation detector or detector array which has a non-constant spatial response individually and in combination with a tomographic scanner. The detector has a first dimension which is oriented parallel to the plane of the scan circle in the scanner. Along the first dimension, the detector is most responsive to radiation received along a centered segment of the dimension and less responsive to radiation received along edge segments. This non-constant spatial response can be achieved in a detector comprised of a scintillation crystal and a photoelectric transducer. The scintillation crystal in one embodiment is composed of three crystals arranged in layers, with the center crystal having the greatest light conversion efficiency. In a preferred embodiment, the non-constant spatial response is achieved in a detector comprised of a single scintillation crystal whose response is shaped by inducing along said first dimension a scintillation conversion efficiency gradient.

Abstract: A method is disclosed for manufacturing a sealed-off RF excited CO.sub.2 laser with a longer operating life. The invention, which relates to the method and the resulting laser, comprises means for stabilizing the laser gas chemistry otherwise affected by CO.sub.2 dissociation, O.sub.2 consumption, and outgassing of H.sub.2 and H.sub.2 O. More specifically, the aluminum housing of the laser assembly is nickel-plated and then passivated by an oxidation technique using concentrated nitric acid. In addition, novel gettering substances, comprising either a group B metal or cellulose, are employed to adsorb hydrogen and/or water vapor to alleviate the outgassing problem.

Abstract: A waveguide gas laser of improved stability and efficiency resulting from novel improvements. Such improvements, including longitudinal RF excitation, unique ballasting techniques, a novel drive circuit design that is immediately responsive to defeat unstable hot spot problems, and a controlled power excitation function, result in an RF excited waveguide gas laser that substantially overcomes disadvantages of prior art devices.

Abstract: A shadowgraphic scanner for producing electronic two-dimensional shadowgraphic images of an examined region of a patient. A source of radiation produces a generally planar beam of radiation which is scanned along the examined region. A two-dimensional array of radiation detectors fixed relative to the source of radiation, but movable in unison therewith relative to the patient. The two-dimensional array of radiation detectors includes a plurality of columns of detectors arranged transverse to the direction in which the beam of radiation is scanned. A first collimator is placed between the source and the patient and a second collimator is placed between the patient and the array of detectors. Both collimators are fixed relative to the source and the detectors and are configured and dimensioned to permit passage therethrough of a beam of radiation of a cross section which corresponds in size to the array of detectors to irradiate the entire array, as the patient is being scanned.

Abstract: The radiographic system includes an x-ray source for irradiating a patient with x-radiation. An image intensifier receives the x-radiation which has traversed the patient and produces an optical image of a radiation shadowgraph of the examined area of the patient. A television camera converts the optical image into a video signal. An image processor stores each frame of the video signal generated by the television camera as an electronic image of the optical image viewed on the image intensifier. Alternately, a plurality of frames from the television camera may be combined to produce a composite image. A bias light is provided adjacent the target of a television camera to illuminate the target before an optical image from the image intensifier is monitored by the television camera. This improves the linearity of the response of the television camera, particularly to low amplitude light intensities on the first few video frames generated by the camera.

Abstract: In a radiographic digital subtraction system utilizing a contrast agent for enhancing a difficult-to-image anatomic region of interest, a method of selecting a superior difference image. The difference image selected represents the differential between a pair of digitized radiographic images selected from a series of such images acquired before and after the contrast appears in the region of interest during a dynamic imaging study.

Abstract: A method of minimizing a streaking effect found in reconstructed images obtained from high resolution CT scanning of a small scan circle that corresponds to a limited region of interest, such as portions of the spinal cord of a patient, particularly in scans that include concentrated high density material, such as bone, situated outside the small scan circle. The approximate range of view angles that will project bone from outside the limited region of interest is determined. Detectors corresponding to the determined region are selected out. The projection data acquired by the selected detectors is filtered. The filtering is accomplished by convolving the projection data with a preselected filter function or in machine implemented form by passing the electrical signal representing the projection data through a low pass filter.

Abstract: A method of preprocessing incomplete or truncated projections obtained from high resolution CT scanning of a small scan circle corresponding to a limited region of interest within the scanned object. An air calibration is performed to obtain a set of air values. The intensity values obtained during the partial area scan are subtracted from the air values to convert the intensity values to attenuation values. The approximate slope at either end of the truncated projection is then calculated. Based on the attenuation values and the slope the necessary extrapolation of the truncated projection is performed to complete the projection. No measurements, ionizing or otherwise, are required from the region outside of the small scan circle.The completed projection is ready for conventional reconstruction techniques involving convolution and back projection.

Abstract: A method of emission tomography using a gamma camera and a rotating collimator having an array of a large number of slanted, small diameter holes. A planar projection corresponding to each angular orientation assumed by the collimator is recorded. From these series of planar projections, a three-dimensional simulation model is reconstructed by an iterative algorithm which approximates the emitting object. The simulated model comprises multiple separable planes.