Abstract: A method for automatically locating microcalcifications indicating breast cancer. The invention assists mammographers in finding very subtle microcalcifications and in recognizing the pattern formed by all the microcalcifications. It also draws attention to microcalcifications that might be overlooked because a more prominent feature draws attention away from an important object. A new filter has been designed to weed out false positives in one of the steps of the method. Previously, iterative selection threshold was used to separate microcalcifications from the spurious signals resulting from texture or other background. A Selective Erosion or Enhancement (SEE) Filter has been invented to improve this step. Since the algorithm detects areas containing potential calcifications on the mammogram, it can be used to determine which areas need be stored at the highest resolution available, while, in addition, the full mammogram can be reduced to an appropriate resolution for the remaining cancer signs.

Abstract: In a computed tomography apparatus which irradiates an X-ray ray fan beam to a slice of a subject body from various directions around the slice, detects the image data of the X-ray ray that has passed the subject body to obtain projection data, and performs reconstruction computation on the projection data to acquire the tomographic image of the slice of the subject body, a main detector which has a plurality of rows of detection elements are aligned in association with a plurality of slices of the subject body and detects projection data of a plurality of slices at a time, a profile detector which has the same number of rows of detection elements as the main detector and measures a profile in the slice direction of the amount of X-ray ray incident to the main detector, and a data processing device for compensating the projection data output from the main detector in accordance with the output of the profile detector.

Abstract: In a method for detecting a prospective abnormal pattern, a stimulable phosphor sheet, on which a radiation image of an object has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected by a photoelectric read-out device, and an image signal representing the radiation image is thereby obtained. A prospective abnormal pattern is detected from the radiation image in accordance with the obtained image signal. During the detection of the prospective abnormal pattern, in accordance with the image signal, calculations are made to find a normalized read-out sensitivity and a normalized latitude, which are equivalent to read-out conditions appropriate for obtaining a visible image reproduced from the radiation image.

Abstract: A method and apparatus are disclosed for predicting prior to injection an organ specific contrast enhancement in a patient for a preselected contrast injection protocol for pre-determining a computed tomography scan. The invention is preferably implemented in a computer program which creates a mathematical model of human cardiovascular physiology in a hypothetical patient with a specific body habitus subjected to the pre-selected contrast injection protocol. The predicted contrast enhancement is then displayed for operator approval and may be then used to control a CT scanner to perform the scan with the pre-selected injection protocol. The mathematical model includes models of organs and vessels using differential equations to describe mass transport of contrast agent through the cardiovascular system.

Abstract: Two digital radiologic images taken from different viewing directions of a same region, notably a mammogram study of the same breast, are automatically processed by a computer to identify suspect masses by producing processed mammogram images in which suspect spots, the skinline and the nipple are marked or enhanced. Candidate suspect spots are initially identified by individually processing each mammogram image separately. Then characteristics of the candidate spots identified in the mammogram images taken from different viewing directions are compared to eliminate false positives. The characteristics compared include position of the spots relative to the explicitly detected nipple, and their size, shape, brightness and brightness variance.

Abstract: A computerized tomography (CT) system includes a stationary frame, an annular rotating frame and apparatus that includes a phase splitter having an input port coupled to receive a modulated carrier having a relatively wide bandwidth. The phase splitter has first and second output ports for supplying, respectively, first and second modulated carrier constituents having a uniform phase angle differential, such as 180.degree., between one another while maintaining a uniform amplitude over the bandwidth for the modulated carrier. A transmission line is attached to the rotating frame and is positioned around the annular rotating frame. The transmission line comprises one or more individual segments having first and second conductors respectively coupled to the output ports of the phase splitter to receive the first and second modulated carrier constituents from the phase splitter.

Abstract: The present invention, in one form, is a method for determining and applying a ZCAL correction vector to the channel outputs from the detector array in a multi-slice CT system. More specifically, and in accordance with one embodiment of the present invention, the signal gain for each detector cell, or channel, at multiple z-axis locations is measured. For each channel, a correction polynomial Q.sub.n is fitted to the signal variation curve as a function of z-axis position so that the correction polynomial value multiplied by its channel signal produces a constant value over the operational range of z-axis positions. Beam positions (Z.sub.r) are measured as a function of each position reference signal (D.sub.r) and the Z position of the beam at the sensor channel and the location of the focal spot are determined. The z-axis location for each channel and the ZCAL correction vector are then determined. The ZCAL correction vector is then multiplied by the channel signal to calibrate the channel signal.

Abstract: A wavelet based neural network (WNN) is proposed for image restoration using a nuclear gamma camera. The WNN first segments the image noise from the detected signal using a wavelet or multi-resolution method and then restores the detector resolution using the neural network. An example of methods is described for detecting beta particles (bremsstrahlung radiation) but the proposed WNN can be applied to either the detection of positrons or gamma rays using the gamma camera.

Abstract: A high repetition-rate laser plasma target source system wherein ice crystals are irradiated by a laser and lithography system. The target source system comprises in a preferred embodiment a liquid tank source and freezer means which freezes microscopic particles into crystal shapes which are projected by a nozzle jet from a high repetition rate liquid-droplet injector into the path of a flashing laser beam, which results in producing soft x-rays of approximately 11.7 nm and 13 nm. Uncollected and unshot target crystals are collected and reliquified by a heater source in order to be recycled back to the liquid tank source. Optionally an auxiliary source and detector system can be used to allow for instantaneous triggering of the laser beam. The target source system can be incorporated into well known EUV lithography systems for the production of wafer chips.

Abstract: A dosimetry system and method characterized by use a plurality of radiation sensitive elements to monitor exposure to a radiation field composed of one or more types of radiation at one or more different energies; reading the radiation sensitive elements in a reader after irradiation by the radiation field to obtain element outputs; and supplying the element outputs to a trained neural network computer apparatus wherein the element outputs are analyzed to provide an output indicative of the radiation field.

Abstract: Digital mammograms are automatically segmented into background, corresponding to the region external of the breast, and foreground, corresponding to the region within the breast, by the detection of the skinline which forms a border between these regions. A binary array is produced representing an initial coarse segmentation between foreground and background in which a binary one value is assigned to each pixel in the binary array whose intensity exceeds an intensity threshold and/or whose gradient amplitude exceeds a gradient threshold.

Abstract: A method for automatically editing a plurality of CT image slices to provide a three dimensional view of a selected object located within a patient's body comprises providing at least one slab of CT image slices produced by CT scanning system and computing a top MIP image of the slab. An undesirable object is automatically removed from the top MIP image by first detecting all the pixels having illuminating intensity values which represent the undesirable object. Then all the pixels of the object to be removed are set to a substantially zero illuminating intensity value in order to remove the object from the top MIP image of the slab. After the undesirable object is removed from the top MIP image, the edits made thereto are applied to each CT image slice in the slab. The present invention also includes apparatus for performing a 3D reconstruction of CT angiographic images to visualize a selected object located within a patient's body.

Abstract: An X-ray computed tomography apparatus in which detection signals based on X-rays transmitted through an object to be examined are repeatedly integrated at predetermined intervals. The integral signal is sampled a plurality of times in an initial period of the interval, and the sampled signals are averaged. The integral signal is also sampled a plurality of times in a final period of the interval, and the sampled signals are averaged. Projection data are created by subtracting the initial average value from the final average value. Circuit noise can be reduced according to the increase in number of times of sampling with a detioration in X-rays available for processing since the integration time is substantially shortened. Circuit noise becomes conspicuous when the dose of transmitted X-rays is relatively small, and becomes latent when the dose of X-rays is relatively large.

Abstract: A cassette containing an x-ray film with a latent image is placed in a camera having a memory which receives data relating to the image. The cassette is provided with a window which is closed by a cover and, once the cassette is in the camera, the window is sealed from external light. A moving mechanism then slides away the cover to open the window. The moving mechanism carries a printed circuit board which supports the memory, two parallel rows of LEDs and a microprocessor connected to the memory and the LEDs. The rows extend perpendicular to the direction of movement of the moving mechanism, and the LEDs of the rows are offset relative to one another. After the window has been opened completely, the moving mechanism begins to close the window. As the window closes, the microprocessor activates the LEDs so that the latter print the data in the memory on the portion of the film in the window.

Abstract: A method of obtaining scatter-corrected images from a nuclear imaging apparatus such as a gamma-ray camera involves the use of a calibration step which measures the energy spectrum response of the apparatus to unscattered gamma-ray events as a function of spatial location, and a correction step which deconvolves the unscattered distribution from a distribution measured in the presence of scatter by using the calculated calibration response function. The method eliminates the necessity of performing a spatially dependent energy correction for detected radiation image events.

Abstract: The present invention, in one form, is a method for improving image quality in CT helical scan systems by using a post reconstruction filtering algorithm. In accordance with one embodiment of the algorithm, image data is segmented into sharp structure data and background data. The background data is then filtered to remove reconstruction and data artifacts. The filtered background data is then combined with the sharp structure data. The combined data can then be used to generate an artifact reduced image.

Abstract: An arrangement for CT imaging of an object is provided, wherein a cone-beam X-ray source traverses a scan path to acquire line integral data at a plurality of view positions, a set of Radon data points in Radon space being associated with the arrangement, and it being necessary to compute the Radon derivative for each Radon data point in order to construct an image of the object. The arrangement includes a specified number of processors greater than one. The Radon space is partitioned by a number of coaxial planes separated from one another by an angle of .pi. divided by the specified number. A set of view positions likewise separated from one another by an angle equal to .pi. divided by the specified number are selected from the plurality of view positions, and each view position in the view position set is projected into a different one of the coaxial planes to define a subset of Radon data points corresponding to one of the planes, and also to one of the processors.

Abstract: A method of reconstructing selected features of a part manufactured according to a CAD model involves acquiring a set of linear push broom (LPB) projection images of the part acquired at different angles about an axis of rotation passing through the part. Acquiring a set of matrices M.sub.j j=1 . . . N, each of which maps 3D coordinates of the part to screen coordinates of one of the projection images. Reconstruction of 3D structures from the projection images requires identification of screen coordinates of each image which correspond to a point of the structure of the part to be reconstructed. Back projecting these screen coordinates modified by the distortion inherent in the LPB imaging device. This is accomplished by selecting a screen coordinate on a feature desired to be reconstructed. Computing a ray passing through the selected screen coordinate through an imaging center. Using each M matrix to map this ray to a hyperbola on the other images.

Abstract: In a computed tomography apparatus having a gantry, on which a rotating anode x-ray tube and a radiation detector are disposed, the gantry being rotatable around a system axis and being tiltable relative to an axis extending perpendicularly to the system axis, the direction of rotation of the gantry is opposite the direction of rotation of the rotating anode in the x-ray tube. Gyroscopic forces acting on the bearing of the rotating anode are thereby at least partially cancelled, significantly reducing mechanical stress on the anode bearing.

Abstract: A subject (12) in an examination region is injected with a radioisotope that emits radiation. A detector head (18) receives emission radiation projections (28a) from the radioisotope and transmission radiation projections (28b) from a transmission radiation source (22) disposed opposite the subject from the detector head. A volume memory (50) stores an estimated volume image. For each actually collected image emission data projection set, a projector (52) reprojects a set of projection of the volume image from the image memory (50) along each of the same projection directions as the emission data projections. Each projection is rotated (80) and warped (82) such that rays which converge with the same angle as the convergence of the collimator on the detector head become parallel. The layers are each convolved with a point response function (84) weighted in accordance with a depth of the corresponding layer in the volume image and corresponding points are summed (92) to create a reprojected projection.