Picker International, Inc.

Other

Hugh T Morgan

Gengsheng Lawrence Zeng

Grant T Gullberg

Bryce G Thornton

Steven J Plummer

Chi-Hua Tung

Paul E Christian

Gregory G Cooley

Jerome John Griesmer

Carl J Brunnett

Gary G Jarkewicz

Stephen D Miller

Darrell M Smith

Piotr J Maniawski

Steven G Plummer

Roger N Lexa

A CT scanner includes a stationary gantry (A) defining an examination region (,) and a rotating gantry (C) which rotates about the examination region. Multiple fan beam generators (B), each capable of producing a beam of radiation directed through the examination region, are mounted to the rotating gantry. The radiation beams are collimated (,) into a plurality of parallel thin fan shaped beams (,) that are projected through the examination region. X-rays are detected by at least an arc of x-ray detectors (,) or a plurality of parallel rings of detectors (,). The detectors generate signals indicative of the radiation received which are processed by a reconstruction processor (,) into a volumetric image representation for display on a monitor (,). In one embodiment, the signals are reconstructed into a series of spaced parallel slices. The object is indexed and additional slices are collected and reconstructed between previously reconstructed slices. In another embodiment, the region of interest moves such that each beam traverses a spiral path spanning one of a plurality of contiguous slabs. The multiple fan beam generators may be contained within a single elongated x-ray tube (,). Alternatively, the multiple fan beams can be generated by a plurality of angularly displaced x-ray tubes.

Multiple fan beam computed tomography system

A multi-modality diagnostic imaging system includes a first imaging subsystem (A), such as a computed tomographic (CT) system, for performing a first imaging procedure on a subject. A second imaging subsystem (B), such as a nuclear medicine system (NUC), performs a second imaging procedure on a subject. The second imaging subsystem (B) is remote from the first imaging system (A). A patient couch (,) supports a subject. A patient transfer subsystem (C) transfers a patient couch (,) between the first imaging subsystem (A) and the second imaging subsystem (B). The first and second imaging subsystems (A, B) can be operated concurrently to perform different imaging procedures on different subjects supported by separate patient couches. Data generated by the first imaging subsystem (A) can be used to correct emission data generated by the second imaging subsystem (B).

Separate and combined multi-modality diagnostic imaging system

An x-ray tube (10) includes a body (16) defining a vacuum envelope. A plurality of anode elements (18) each defining a target face are rotatably disposed within the vacuum envelope. Mounted within the vacuum envelope, a plurality of cathode assemblies (22) are each capable of generating an electron stream (36) toward an associated target face. A filament current supply (32) applies a current to each of the cathode assemblies, and is selectively controlled by a cathode controller (34) which powers sets of the cathodes based on thermal loading conditions and a desired imaging profile. A collimator (C) is adjacent to the body and defines a series of alternating openings (42) and septa (44) for forming a corresponding series of parallel, fan-shaped x-ray beams or slices (46).

Rotating anode x-ray tube with multiple simultaneously emitting focal

A gamma camera system includes two or more radiation detector heads and which are mounted opposite each other to a gantry for rotation about a subject. A transmission radiation source assembly is mounted to the front face of at least one of the detectors and can be moved across the face of the detector. The source assembly includes a radiation attenuating housing, a leaded bronze source holder, and a radionuclide source. The radionuclide source is retained in a longitudinal groove disposed in the source holder. The source holder may be rotated into open, closed, and access positions. The transmission radiation emitted by the source assembly is directed across the examination region, attenuated by the subject, and detected by the opposed detector. The gamma camera system also includes a filter which selectively attenuates the transmission radiation to obtain a desired attenuation profile which prevents saturation of the opposed detector. The filter includes at least one layer of radiation attenuating material of uniform thickness but varying in width in a direction substantially parallel to a direction of motion of the source assembly. An image representation is reconstructed using the radiation emitted by the subject and corrected in accordance with the transmitted radiation data.

Scanning line source for gamma camera

A gamma camera system includes two or more radiation detector heads and which are mounted opposite each other to a gantry for rotation about a subject. A transmission radiation source assembly is mounted to the front face of at least one of the detectors and can be moved across the face of the detector. The source assembly includes a radiation attenuating housing, a leaded bronze source holder, and a radionuclide source. The radionuclide source is retained in a longitudinal groove disposed in the source holder. The source holder may be rotated into open, closed, and access positions. The transmission radiation emitted by the source assembly is directed across the examination region, attenuated by the subject, and detected by the opposed detector. The gamma camera system also includes a filter which selectively attenuates the transmission radiation based on the attenuation profile of the object so as to prevent saturation of the opposed detector. An image representation is reconstructed using the radiation emitted by the subject and corrected in accordance with the transmitted radiation data.

A SPECT system includes two or more radiation detector heads (32) and (34) which are mounted opposite each other to a gantry (30) for rotation about a subject. Each detector head has a collimator (38) mounted in front of the detector head. The collimator (38) is separated into a top portion (40) and a bottom portion (42). The top portion (40) and bottom portion (42) are spaced from each other to provide a gap (44) within the collimator (38). The gap (44) receives one or more devices to provide additional functionality during a scan. The insertable devices include a transmission radiation source (52), a calibration source, a radiation filter, and others.

Gamma camera split collimator collimation method and apparatus

A method of scatter correction for use with gamma cameras includes the steps of detecting and producing a first count value indicative of gamma radiation falling within a first energy range generally associated with a radionuclide photopeak. Gamma radiation falling within second and third energy ranges is also detected and a corresponding count produced. The second and third ranges are above and below the photopeak, respectively. The location of the second and third energy ranges is determined based on the energy resolution of the gamma camera such that a predetermined percentage of the radiation falling within the second and third ranges results from primary radiation. The second and third energy ranges may be located such that they are non-contiguous with the first energy range. Based on the count of radiation falling within the second and third ranges, the scatter radiation falling within the first energy range can be estimated, and the first count value corrected. The method is suitable for use with radionuclides having multiple closely spaced photopeaks as well as with multiple widely spaced photopeaks.

Split window scatter correction

A rotatable gantry portion (16) is rotatably mounted on the stationary gantry portion (18) of a SPECT camera. A plurality of radiation detector heads (10a, 10b, 10c) are mounted to the rotating gantry. A transmission radiation source holder and collimator assembly (40, 42) is mounted to the rotatable gantry portion opposite one of the detector heads. A transmission radiation source (60) is mounted in a lead shield (62) with an opening (64) pointing toward an examination region (12). A shutter (66) is rotatable between a closed position in which a lead arc segment (70) blocks the opening (64), a calibration orientation in which tin (72) covers opening (64), and an open position in which an opening (74) is aligned with the opening (64). A safety interlock means (80) locks the shutter in the closed position and against rotation when the radiation source holder is removed from the rotatable gantry portion. A collimator (42) has lead side walls (200) and tin or tin alloy septa (202). When radiation from the radiation source strikes the lead side walls, they emit characteristic lead x-rays of about 88 keV whereas the tin radiates x-rays of only about 30 keV. A filter (210) includes an inner layer (212) of tin for attenuating any remaining 88 keV lead x-rays coming from the transmission line source assembly and converting them to about 30 keV radiation. The filter has an outer layer (214) for attenuating the radiation around 30 keV.

Transmission line source assembly for spect cameras

A SPECT system includes three gamma camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. Transmission radiation from a transmission radiation source (30) is truncated to pass through a central portion of the subject but not peripheral portions and is received by one of the camera heads (22a) concurrently with the emission data. As the heads and radiation source rotate, the transmitted radiation passes through different parts or none of the peripheral portions at different angular orientations. An ultrasonic range arranger (152) measures an actual periphery of the subject. Attenuation properties of the subject are determined by reconstructing (90') the transmission data using an iterative approximation technique and the measured actual subject periphery. The actual periphery is used in the reconstruction process to reduce artifacts attributable to radiation truncation and the associated incomplete sampling of the peripheral portions. An emission reconstruction processor (112) reconstructs the emission projection data and attenuation properties into an attenuation corrected distribution of emission radiation sources in the subject.

Simultaneous transmission and emission converging tomography

A SPECT system includes three gamma camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. A reconstruction processor (112) reconstructs the emission projection data into a distribution of emission radiation sources in the subject. Transmission radiation from a radiation source (30) passes through the subject and is received by one of the camera heads (22a) concurrently with the emission radiation. The transmission radiation data is reconstructed into a three-dimensional CT type image representation of radiation attenuation characteristics of each pixel of the subject. An attenuation correction processor (118) corrects the emission projection data to compensate for attenuation along the path or ray that it traversed. In this manner, an attenuation corrected distribution of emission sources is generated.

Radiation passing through a cone-beam collimator is received by a radiation detector, such as a gamma camera head, as the gamma camera head is moved in a circular orbit and in a line orbit. Data collected during the circular orbit is stored (42c), transformed (50c) into the frequency domain and redundant data removed (52c, 52c), and transformed (56c) back to the spatial domain. The data collected during the line orbit is stored (42l). The line orbit data is transformed to the frequency domain and repeatedly filtered with a family of filter functions (52l, 54) to remove redundant data. Each filter function corresponds to a different row through the examination region. The filtered frequency domain slice data sets (62.sub.1, 62.sub.2, . . . , 62.sub.n) are transformed (56l) back to the spatial domain and transferred to a central portion of a spatial domain memory (58l). Empty memory cells of the memory (58l) are filled with zeros. The spatial domain data from memories (58c b, 58l) are filtered (72c, 72l), backprojected (74c, 74l), and summed (76) into a three-dimensional image representation that is stored in an image memory (78).

Cone beam reconstruction using combined circle and line orbits

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. Digital data values representing characteristics of different film-screen combination are stored in a second storage means. A processor develops a kV ramp reference signal base on one of the kV reference curves and data values. Scaling factor equations and values representative of system variable are also stored in the first and second storage means. The processor includes means for developing scaling factor which compensate the reference signal for the effect of system variables on film density.

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Highland Heights, OH, United States of America

Hugh T Morgan