Abstract: A multiple layer multileaf collimator for shaping a radiation beam. The collimator comprises first and second layers of a plurality of elongated radiation blocking leaves. The leaves of each layer are arranged adjacent one another so as to form two opposed rows of adjacently positioned leaves and are movable in a longitudinal direction (Y) which is generally traverse to the direction of the beam so as to define a radiation beam shaping field between the opposed ends of the leaves. The layers are arranged one above another in the beam direction and offset in a lateral direction (X) generally transverse to the beam direction and orthogonal to the longitudinal direction (Y) so that spaces between adjacent leaves of the first and second layers are positioned over and under, respectively, leaves of the second and first layers, respectively.

Abstract: Human body structures, for example, of a fetus, are automatically measured using ultrasound by first using an ultrasonic transducer or prestored ultrasound scan to generate an image frame as a pattern of pixels. Each pixel has a brightness value corresponding to an echo signal from a corresponding portion of an interrogation region of the patient's body, which includes the body structure. The image frame is displayed on a screen and includes a structure frame portion that corresponds to the body structure. The user then designates a general geometry feature of the displayed body structure and at least one measurement parameter associated with the designated geometry feature. For curved, closed structures such as the head or abdomen, the measurement parameters may, for example, be the circumference or at least one diameter. For mainly straight structures such as the femur or humerus, the measurement parameter will normally be the end-to-end length.

Abstract: A region of tissue is scanned as a series of 2-D frames. The correlation of substantially homogeneous speckle regions in the frames is determined and is compared with a precalibrated speckle correlation-versus-distance function to give an estimate of the distance between the frames. In some applications, the frames are partitioned into sub-frames, whose correlation values and distances are combined according to predetermined functions to give a distance estimate between the frames as a whole. The reliability of the distance estimates is improved and evaluated in various ways, for example, by comparing combinations of possible distances from end frames via intermediate frames, and by comparing computed frame or sub-frame velocities with a known or estimated transducer velocity. Once the relative distances of the 2-D frames are estimated, a 3-D image is compiled using registration techniques. Image frames need not be parallel.

Abstract: An image registration method and apparatus is provided in which consecutive ultrasonic image frames are correlated in order to derive transducer motion information. Since ultrasonic images from real-time scanning operations are highly correlated from one frame to another, the individual images can be divided into several smaller sub-image regions and a very fast and robust image motion detection algorithm utilized to measure the sub-image motion. This algorithm uses a fast adaptive coarse/fine minimum-sum-absolute-difference (MSAD) search strategy to compute an initial estimation of the local motion vectors. The initial estimation is combined with two measurement parameters by use of a fuzzy logic technique to derive a final estimation of the local motion vectors. The final local motion vectors are applied to a least-squares (L-S) process in order to estimate global image motion. Finally, a fast display technique generates compound images based on the derived global image motion.

Abstract: The ultrasound transducer array defines an average row spacing along the elevation for receiving transducer elements that differs from an average row spacing along the elevation for transmitting transducer elements. In one embodiment a relatively "coarse" row spacing is used for reception and a relatively "fine" row spacing is used for transmission. The differing spacings lead to different transmit-elevation and receive-elevation beam-patterns. In one configuration the number of transducer elements, and correspondingly the number of ultrasound processing channels, is reduced. In an alternative configuration the beam-pattern "footprint" is increased without increasing the number of transducer elements or processing channels. The array includes dedicated transmit-only elements and/or dedicated receive-only elements, together with coincident, time-shared transmit/receive elements.

Abstract: In a system which corrects for attenuation artifacts in a SPECT study, a line source is parallel to the axis of rotation of the scintillation camera detector(s) and is scanned in a plane which is parallel to the detector. Advantageously, the line source is initially scanned at high speed across the detector to acquire preliminary transmission CT data and is subsequently scanned across the detector at lower speed to acquire additional transmission CT data. During rescanning, the shuttering of the line source, and/or the speed of the line source, is varied. This acquires transmission CT data which is more reliable and from which the attenuation of the patient may be more accurately calculated.

Abstract: An ultrasonic imaging system is provided that effectively corrects for inhomogeneities in the imaged media. The ultrasonic imaging system comprises a transducer array having a plurality of transducer elements each being separately operable to provide an ultrasonic pulse in response to a driving signal and to provide a corresponding echo signal in response to a received echo based on the ultrasonic pulse. A transmitter is coupled to the transducer array and provides the driving signal to each respective one of the transducer elements. The driving signals define a steered beam of the transducer array. A receiver is coupled to the transducer array and receives the echo signal from each respective one of the transducer elements. The receiver includes a beamformer section that produces a single matched and summed signal from the echo signals of the plurality of transducer elements. The beamformer section comprises a plurality of processing modules coupled in a cascading arrangement with separate processing stages.

Abstract: A method and apparatus is provided for generating a spatially compounded ultrasonic image using an image registration method (IR-SC). In the image registration method, a current image frame is correlated with a previously generated IR-SC image in order to derive the transducer motion information for IR-SC image generation. Specifically, the current image frame is divided into several smaller sub-frame regions, and a very fast and robust image motion detection algorithm is utilized to measure the sub-frame motion. This algorithm uses a fast adaptive coarse/fine minimum-sum-absolute-difference (MSAD) search strategy to compute an initial estimation of the local motion vectors. The initial estimation is combined with two measurement parameters by use of a fuzzy logic technique to derive a final estimation of the local motion vectors. The final local motion vectors are applied to a least-squares (L-S) process in order to estimate global image motion.

Abstract: A data acquisition device is disclosed for use in a patient monitoring system which includes a display device. The system also includes a pressure transducer which produces patient blood pressure signals. The data acquisition device includes terminals for receiving signals representing blood pressure from the pressure transducer. Circuitry in the data acquisition device, including multiplexers and a digital to analog converter conditions the signals representing blood pressure. The pressure transducer and the circuitry are collocated. The device also includes circuit paths for electrically coupling the pressure transducer and the conditioning circuitry. The conditioning circuitry is selectably coupled to the display to provide the conditioned signals to the display. The data acquisition device may be positioned independently of the display device.

Abstract: This invention addresses the aliasing and range ambiguity artifact trade-off occurring in pulsed doppler ultrasound applications. By increasing pulse repetition frequency to avoid aliasing and by implementing non-coinciding transmit and receive beam-patterns, range ambiguity effects are reduced. Separate transmit and receive apertures define respective transmit and receive beam-patterns. These separate transmit and receive beam-patterns intersect at a primary range gate. Secondary range gates may occur along the receive beam-pattern. The transmit beam-pattern does not intersect such secondary gates. Weaker dispersed ultrasound energy may intersect the secondary gates, however, and reflect back to the receive aperture. Relatively stronger samples are obtained from the primary range gate than from the secondary range gates.

Abstract: A method and apparatus of operating an ultrasound imaging apparatus so as to obtain continuous wave (CW) Doppler data from a user selected area comprises operating a multiple element transducer array and its associated delay and signal processing circuitry so as to develop and display in substantially real-time a two-dimensional ultrasound image, operating a user controllable device so as to cause a display of at least one controllable position marker in substantially real-time within the displayed two-dimensional ultrasound image, which marker selects an area of sensitivity within the ultrasound image for which it is desired to obtain CW Doppler data, operating the multiple element transducer array and its associated delay signal processing circuitry based upon the position of the selected area so that,1) a given number of the multiple elements are used to transmit a steered beam of CW ultrasound through the selected area, and2) a given number of the multiple elements of the array are used to receive a steer

Abstract: In a radiation emitting device, particularly in a radiation treatment device, the actual radiation delivered to an object via a radiation beam is adjusted dependent on the dimensions of an opening in a plate arrangement provided between a radiation source and an object so that the radiation output has a constant wedge factor over an irradiation field, regardless of the size of the opening. The wedge factor is defined as the ratio between a reference radiation output along a reference axis of the beam with a predetermined physical wedge in the beam path and an actual radiation output of the beam in a substantiallylossless beam path.

Abstract: An ultrasonic diagnostic system is provided that automatically measures a volumetric flow rate of a vessel presented on a graphical display by estimating the vessel size and direction. The Doppler information signals received from an ultrasonic transducer include frequency components representing fluid flow through a region of interest. The operator selects a vessel represented graphically on the display in which a volumetric flow rate measurement is desired. The ultrasonic diagnostic system then performs a search in a plurality of directions that extend radially outward from a location within the vessel for an upper and a lower set of edge points that correspond to inner wall surfaces of the vessel. Once the upper and lower set of edge points are identified, curves are fitted through the respective sets of edge points to define respective estimates of the inner wall surfaces. Next, an angular difference between the respective curves and a beam direction of the Doppler information signals is measured.

Abstract: A Doppler audio dealiasing system has a zero inserter that inserts zeros between input samples of signal. The resultant signal is then processed in various ways. After the zeros are inserted and a new signal is formed, the newly formed signal is filtered and otherwise processed to remove inappropriate parts.

Abstract: Ultrasound imaging system providing automatic activation of a probe, which ultrasound system includes: (a) a motion sensor for detecting motion of the probe and for generating a signal in response to the motion; (b) a signal detector for detecting the signal; and (c) a probe activator, in response to a detector signal from the detector, for activating the probe. In a preferred embodiment of the present invention, the motion sensor is an accelerometer which is affixed to the probe.

Abstract: A Platz-Heinzelmann collimator is produced by introducing strips of material between the dies of a die press, heating the material to below its extrusion temperature, applying pressure, removing the strips and adhesively securing them together.The collimator may be of the focussing type.

Abstract: Reflected-back ultrasound waves are recorded and rebinned in accordance with a particular data classification scheme. In a post processing step, the data is processed to remove the effect of stationary scatterers (such as slowly-moving body structure) and features of the processed data are computer-traced to determine e.g. the velocity of the patient's blood stream.

Abstract: A spatial-temporal doppler velocity estimation method expands the detectable frequency range by extending the frequency boundary at which aliasing artifacts may occur. In various embodiments the detectable frequency range is extended beyond the Nyquist limit. To do so, multiple velocity estimation functions are defined. One function is the conventional function typically bound by the Nyquist limit. For additional functions, the (n-1)-th echo is spatially shifted with respect to the n-th echo, (i.e., temporal/spatial pulse-pairs are averaged). For example, in one embodiment a shift of +.DELTA. is inserted to define one additional estimation function, while a shift of -.DELTA. is inserted to define another additional estimation function. A power function then is calculated for each velocity estimation function. The estimation function having the highest power is selected for use in deriving the doppler shift frequency of a given sample point.

Abstract: An ultrasonic Doppler flow (e.g. blood) imaging and/or measuring system capable of adaptively suppressing stationary or slowly-moving non-flow (e.g. tissue) signals having variable spectra from the recovered ultrasonic echoes. In accordance with the invention, the tissue signals are suppressed using a tissue rejection filter arrangement having an attenuation characteristic which is controlled based upon measured estimates of at least one spectral characteristic of the tissue signals to be removed, thereby maximizing the rejection of tissue movement signals and minimizing undesired attenuation of the blood flow signals. In accordance with an embodiment of the invention, signal routing out of the corner-turning buffer memory component in prior art systems is advantageously modified, so as to provide during a first mode of operation, the echo signal data to a Doppler velocity processor, for forming estimates of tissue signal motion.