Abstract: An ultrasound front end circuit (1000) according to the present invention includes a single transformer core which performs all of the pulse and transmit/receive switching functions. A transmit pulser (1102) is formed by a pair of transistor switches in combination with a transformer having first windings (N1, N2) driven by a DC source. A secondary winding (N3) provides a voltage step up for transmitted wave forms and a pair of anti-parallel shunt diodes (1014) on the receiver terminal direct the transmitted 0 waveform to the ultrasound transducer (1024). A floating third winding (N4) shunted by a current biased diode bridge (1002) provides an effective open circuit across the secondary winding while transmitting high amplitude signals. The third winding (N4) and diode bridge (1002) act to short circuit the secondary winding (N3) while receiving small amplitude signals, thus providing a direct connection between the transducer (1024) and receiver (1020).

Abstract: An amplifier (32) is provided which allows for reduced system power dissipation. The amplifier (32) can dynamically draw power from different supply voltages in response to an input voltage signal. The amplifier (32) includes a plurality of complementary transistor pairs (40-46), where each transistor pair is coupled to a respective power supply. Each transistor pair provides output current when the input voltage signal is within a respective predetermined voltage range. This arrangement permits the amplifier (30) to interpolate between the supply voltages to generate a continuous amp output. System power is conserved by selecting the power supply which can most efficiently supply the required current within the voltage range.

Abstract: A transmit/receive circuit employing passive elements. A transmit/receive circuit according to an embodiment of the present invention includes a transformer having a primary winding coupled to an input stage and an output stage. A transducer is coupled to the secondary winding of the transformer. A diode limiter is coupled to the input stage and a diode bridge is coupled to a node at the output stage. The input and output stages are alternatingly grounded. An output switch including an inverse parallel circuit of two diodes having opposite polarities may be connected at the output stage between a transmitter and the transformer. Alternatively, a complementary common emitter amplifier may be provided at the output stage. The circuit thus electrically couples the transducer element to the receiver during reception and electrically decouples both the transducer and the transmitter from the receiver during transmission.

Abstract: An intravascular MR contrast agent is administered to a living patient. A series of three-dimensional dynamic MR datasets is acquired from the Volume of Interest ("VOI"), beginning after administration of the contrast agent and continuing for a sufficiently long time as to reflect contrast agent enhancement of all arterial and venous blood vessels within the VOI. A three-dimensional MR angiogram of the VOI is acquired after the contrast agent has reached equilibrium. For each voxel within the VOI, enhancement of that voxel as a function of time post administration of the contrast agent is computed. Parameters that distinguish enhancement of voxels relating to the patient's arteries from enhancement of voxels relating to the patient's veins are selected, and the intensity of each voxel in the MR angiogram is scaled in accordance with the selected parameters. A maximum intensity projection reconstruction of the VOI is generated from the MR angiogram in which voxel intensity has been scaled.

Abstract: A method and apparatus for creating an electrically conductive path between ground conductors on a printed circuit board (PCB) and downwardly facing walls of an electromagnetic interference (EMI) housing, uses surface mountable conductive spring-like strips. A plurality of surface mount device receiving areas are provided at predetermined spaced positions along the ground conductors on the PCB, and a pick and place device is used for automatically positioning a plurality of the conductive spring-like strips at each of the surface mount device receiving areas, each strip having at least one upwardly facing engagement portion. Thereafter, the conductive spring-like strips are affixed on the PCB by, for example, wavesolder techniques. The engagement portion is adapted to engage and make electrically conductive contact with an abutting portion of an EMI housing during fastening of the EMI housing to the PCB.

Abstract: An ultrasound front end circuit (2000) which includes a multiple winding transformers (N1, N2, N3, N4) to accomplish both transmit pulse generation and transmit/receive switching. An additional set of transformer windings and switching transistors (1103) allows logical selection between one of two transmit levels.

Abstract: A system and method for radiation therapy delivery. Prior to the delivery of the actual treatment, a run up is executed in order to stabilize the RF system. The run up is accomplished by initiating the triggers with the injector and RF pulses out of phase so that the electrons, for example, in the accelerating waveguide do not get accelerated even though the RF system is being pulsed. The RF warm up period during which the injector and RF pulses are out of phase, ends at RAD ON (Radiation On) with the injector pulse being phase-shifted to coincide in time with the RF pulse thereby resulting in the production of electron beam pulses. Following the application of this run up period, precise and rapid disabling and enabling of the treatment beam between IMRT fields can be accomplished. The electron injection is phase-shifted in and out without affecting either the injector or the RF pulse amplitudes, thereby allowing transitions between a stable RAD ON beam and no beam between one pulse and the next.

Abstract: A system and method for dynamic subspace intensity modulation. Portions around the edges of a multi-leaf collimator-defined static radiation field are expanded or shrunk during part or all of the delivery of radiation at constant velocity. In order to match some or all of the sloping regions (502) of an intensity profile, the individual leaves (41, 42) of the multi-leaf collimator are moved at a fixed velocity over the sloping portions (502) of the intensity profile. By keeping the major portion of the field static and by only moving the leaves at one fixed velocity over a small subspace of the intensity profile, it is relatively easier to know what dose the patient receives and it is also relatively easier to resume treatment since it can be determined exactly how many more monitor units of radiation must be delivered and what the leaf positions were when the radiation was turned off.

Abstract: A system and method for radiation therapy delivery. Known delays are compensated for by applying a compensation factor to the dose at the start of the beam cycle. According to one embodiment of the invention, a dosimetry controller is configured to sense radiation on (RAD ON) and monitor the dose rate at the beginning of the beam cycle. The dosimetry controller then multiplies the dose rate by a compensation factor. Thus, for each beam cycle, the dosimetry controller resolves the magnitude of the lost dose rate data and compensates each segment accordingly.

Abstract: A heart rate value determined from a first physiological signal that is acquired independently from a second physiological signal, is used to control a band pass filter for controllably bandpass filtering the second physiological signal. In a system having sensors for independently acquiring both electrocardiogram (ECG) and pulse oximetry (SpO2) signals, a heart rate value determined from the ECG signal is used to controllably bandpass filter the red and infrared SpO2 signals, thereby reducing the level of artifact signal in the SpO2 signals.

Abstract: A radiation treatment apparatus (10) including a stand (12), a gantry (14) movably supported on the stand (12), the gantry (14) having a vertical section (16) and a generally linear cantilevered strut section (18), the cantilevered strut section (18) having a supported end adjacent the vertical section (16) and a projecting end opposite the supported end, a substantially linear particle accelerator (30) disposed within and longitudinally supported in generally parallel relationship with the cantilevered strut section (18), the accelerator (30) having a predetermined injection point (32) where particles are launched in the accelerator and a predetermined exit point (34) where the particles are discharged from the accelerator, a treatment head (22) coupled to the remote end of the cantilevered strut section proximate the exit point (34), the treatment head (22) for emitting a radiation beam (27), and a tuneable stiffening apparatus (40) attached to the accelerator (30) for substantially maintaining alignment be

Abstract: A probing apparatus for probing a large pin count integrated circuit mounted on a circuit board is disclosed. The probing apparatus uses a mounting block and an interconnecting probe body to provide proper alignment of the probing apparatus to pins or pads of the integrated circuit. Since the probing apparatus can be connected while the integrated circuit to be tested is powered up and operational, the probing apparatus facilitates testing of the integrated circuit in real-time. A method for probing a large pin count integrated circuit is also disclosed.

Abstract: A monitor system of the type including at least one portable patient monitor for acquiring, processing and transferring patient data monitored from a patient, the system being distributed over at least two geographically separate patient monitoring areas which are interconnected via a communication network having a network node connection in each of the areas. A patient monitor docking station located in one of the patient monitoring areas provides for transmission of patient data from the portable patient monitor to the network via a selective coupling of the portable patient monitor to the network node connection. The docking station provides, in addition to the selective coupling to the portable monitor and apparatus for transferring patient data between the portable monitor and the docking station, a memory for storing network related information and transferring the network related information to the portable monitor when it is coupled to the docking station.

Abstract: A line type modulator for modulating an RF power device in a medical linear accelerator is described. The modulator employs a low voltage DC power source and a flyback transformer. Current sensing circuitry senses current in the primary winding of the flyback transformer and generates a current sense signal indicative thereof. A solid-state switching stage is coupled between the DC power source and the flyback transformer which electrically connects and disconnects the DC power source and the primary winding in response to a control signal. Control circuitry coupled to the current sensing circuitry and the switching stage generates the control signal in response to the current sense signal. The anode of a charge diode assembly is coupled to the secondary winding of the flyback transformer. A delay element is coupled to the cathode of the charge diode assembly. A pulse forming network is coupled to the delay element and generates an energy pulse.

Abstract: A needle guide mount has a main guide body, with a knob arm and a pivot arm each attached at one end to the main guide body. A gate assembly is pivotably in the pivot arm and has an open position, in which the gate assembly can pivot freely away from the knob arm, and a closed position, in which the gate assembly is secured in the knob arm. The gate assembly preferably has a shaft, a knob that can move longitudinally and rotatably on the shaft, and a locking arrangement that permits the gate assembly to enter the closed position only when the central axis of the gate assembly lies less than a predetermined maximum misalignment angle away from a correct mounting alignment axis. If the guide mount is not properly positioned on the probe, then the gate assembly is out of correct alignment and the locking arrangement is unable to engage. The operator can then easily feel that she is not able to mount the guide.

Abstract: A high voltage pulse generating circuit for powering klystrons, and the like. The circuit includes a source of D.C. power having positive and negative terminals, a flyback transformer having a primary winding and a secondary winding, the primary winding having first and second terminals for connection to the source of D.C. power, a sensor for generating a signal indicating the amplitude of the current in the primary winding, and a solid state switching circuit for coupling the source of D.C. power to the primary winding of the flyback transformer. The primary winding is coupled to the power source in response to a control signal, and decoupled from the power source when a predetermined level of current is detected in the primary winding.

Abstract: A method of providing connections to an arrangement of multilayer transducer elements of an ultrasonic transducer array includes patterning an electrically conductive layer on a substrate to define a number of traces and a wide-area continuous region. At least a portion of the substrate is then removed to expose both of the upper and lower surfaces of the wide-area conductive region. The exposed upper and lower surfaces are captured between first and second piezoelectric layers such that the conductive layer electrically contacts both of the piezoelectric layers. The captured wide-area continuous region and at least one of the piezoelectric layers are diced to define the array of transducer elements. The traces that are formed during the patterning step are arranged such that there is a one-to-one correspondence between the traces and the electrodes that are defined by segmenting the wide-area continuous region during the dicing step.

Abstract: Data from a nuclear medicine study is classified in real time into categories which include image data relating to image pixels which are essential covarient. The results of the classification process permit a determination of, e.g., whether the camera is properly positioned at an early stage of the study and long before the study is completed. It is then possible to reposition the camera so as to obtain data which will be useful. As a result, it is unnecessary to wait until the end of a prolonged study in order to determine whether the study was taken under appropriate conditions.

Abstract: Apparatus for synchronizing a reference clock signal received from a host system with an A/D converter clock signal generated in a data acquisition pod. The pod includes a decoder responsive to communication received from the host for extracting a host reference signal, and a clock signal source for developing an A/D reference clock signal having a frequency that is different from the frequency of the host reference signal. A pulse modifying digital phase-locked loop (PLL) is responsive to the A/D reference clock signal and the host reference signal for developing an A/D clock signal for an A/D converter in which one of its clock periods is periodically modified, thereby locking the rate at which the A/D converter develops samples to the rate at which the host system requests samples.

Abstract: A static switching scheme along transducer elevation for obtaining beam line from multiple firings. Between firings for an associated beam line the elevation aperture is changed depending upon the image plane focus depth. For a single image plane focus beyond a deepest break point, a widest elevation aperture is used during one firing. During other firings for the beam line the elevation aperture is narrowed. Each of multiple break points separate a distinct depth region. Echo data for a beam line includes echo data from one firing for one region and from another firing for another region. Echo data from multiple firings is blended in vicinity of region boundaries. For multiple image plane foci applications, the elevation aperture for a given firing is determined by the target image plane focus for such firing.