Abstract: A combined positron emission tomography (PET) and computed tomography (CT) detector mounted on a single support on the same gantry of a combined PET and CT scanner. The common detector includes an array of scintillator crystals or pixels with each pixel mated to a photodetector. The photodetector is connected to discrete event circuitry, which provides discrete event information to the combined PET and CT scanner. Also, the photodetector is connected to integrating circuitry, which provides integrated count rate information to the CT scanner when the discrete event information is not adequate. By using a common detector, the registration of the PET image with the CT image is improved, less components are mounted on the gantry, the overall size of the gantry is reduced, resulting in a shorter tunnel and less rotating mass, and CT performance is enhanced by providing means for selecting the energy level of the x-rays to be detected.

Abstract: A Cerium-Doped Lutetium Oxyorthosilicate scintillator boule having a graded decay time. The method for manufacturing an LSO:Ce crystal boule having a decay time gradient decreasing from the top end to the bottom end first includes the step selecting an iridium crucible. The crucible is selected based upon its diameter relative to the diameter defined by said crystal boule. The crucible is also selected based upon its volume relative to the volume of the crystal boule to be grown. A Cerium dopant (CeO2) is added to a mixture of Lutetium Oxide (Lu2O3) and Silicon Dioxide (SiO2). The composition is heated until melted to define a melt. A seed crystal is then placed in contact with the melt, is rotated, and slowly withdrawn, thereby yielding an LSO:Ce crystal boule defining a decay time gradient.

Abstract: A scintillation detector which includes a plurality of discrete scintillators composed of one or more scintillator materials. The discrete scintillators interact with incident radiation to produce a quantifiable number of photons with characteristic emission wavelength and decay time. A light guide is operatively associated with the scintillation crystals and may be either active or non-active and segmented or non-segmented depending upon the embodiment of the design. Photodetectors are provided to sense and quantify the scintillation light emissions. The process and system embodying various features of the present invention can be utilized in various applications such as SPECT, PET imaging and simultaneous PET systems.

Abstract: A coincidence transmission source serves to detect coincident activity from a radiation source. The coincidence transmission source includes a detector dedicated to collecting attenuation data. A collimated radiation source and a detector are positioned with respect to a tomography device such that only a selected strip of the imaging detector of the tomograph is illuminated such that events unrelated to the attenuation are eliminated. The coincidence transmission source includes a collimator in which is disposed a radiation source. An opening is defined by the collimator for exposing a selected portion of the imaging detectors of the tomograph device. Positioned behind the radiation source, relative to the imaging detectors, is the dedicated attenuation detector. The attenuation detector and collimator are designed to illuminate only a strip of the imaging detector, thereby eliminating events not of interest in the attenuation measurement.

Abstract: A depth of interaction detector block for improving the spatial resolution and uniformity in modern high resolution PET systems over an entire FOV. An LSO crystal layer, a GSO crystal layer, and a light guide are stacked on each other and mounted on a 2×2 PMT set, so that the corners of the phoswich are positioned over the PMT centers. The crystal phoswich is cut into a matrix of discrete crystals. The separation of the LSO and the GSO layers by pulse shape discrimination allows discrete DOI information to be obtained. The block design provides an external light guide used to share the scintillation light in four PMTs. The 4 PMT signals Si are connected to an amplifier box which offers a 4 pole semi-Gaussian shaping for each of the four PMT signals, a sample clock for triggering the ADC cards and a fast sum signal &Sgr;iSi of the four PMT signals Si for pulse shape discrimination. A CFD provides a START signal for the time to pulse height converter.

Abstract: A Cerium-Doped Lutetium Oxyorthosilicate scintillator boule having a graded decay time. The method for manufacturing an LSO:Ce crystal boule having a decay time gradient decreasing from the top end to the bottom end first includes the step selecting an iridium crucible. The crucible is selected based upon its diameter relative to the diameter defined by said crystal boule. The crucible is also selected based upon its volume relative to the volume of the crystal boule to be grown. A Cerium dopant (CeO2) is added to a mixture of Lutetium Oxide (Lu2O3) and Silicon Dioxide (SiO2). The composition is heated until melted to define a melt. A seed crystal is then placed in contact with the melt, is rotated, and slowly withdrawn, thereby yielding an LSO:Ce crystal boule defining a decay time gradient.

Abstract: A method and apparatus for producing radioactive transmission measurements to form multi-dimensional attenuation correction data with a point source of radiation, such as required in positron emission tomography applications. This involves the passing of the point source proximate the face of a selected each of the tomograph units for the formation of a 3-D image, or a selected portion of the tomograph units for a 2-D image. As such, attenuation data, transmission data, detector performance data, etc., can be obtained. This point source of radiation, in one embodiment, is rapidly circulated through a conduit that passes across each detector face under the influence of a transport fluid in, for example, an oscillatory motion to achieve a selected radiation field whereby calculation of transmission measurements within a body positioned within the tomograph scanner is achieved. When not being circulated, the radiation source is held within a shield.

Abstract: A method and apparatus for producing radioactive transmission measurements to form a 2-D or a 3-D image with a point source of radiation, such as required in positron emission tomography applications. This involves the passing of the point source proximate the face of a selected each of the tomograph units for the formation of a 3-D image, or a selected portion of the tomograph units for a 2-D image. As such, attenuation data, transmission data, detector performance data, etc., can be obtained. This point source of radiation is rapidly circulated through a conduit that passes across each detector face under the influence of a transport fluid in, for example, an oscillatory motion to achieve a selected radiation field whereby calculation of transmission measurements within a body positioned within the tomograph scanner is achieved. When not being circulated, the radiation source is held within a shield.

Abstract: A method and apparatus for producing radioactive transmission measurements to form a 3-D image with a point source of radiation, such as required in tomography applications. This involves the passing of the point source proximate the face of each detector of the tomograph units. As such, attenuation data, transmission data, detector performance data, etc., can be obtained. This point source of radiation is rapidly circulated through a conduit that passes across each detector face under the influence of a transport fluid in, for example, an oscillatory motion to achieve a selected radiation field whereby calculation of transmission measurements within a body positioned within the tomograph scanner is achieved. When not being circulated, the radiation source is held within a shield. Circulation of the transport fluid, typically a hydraulic fluid, is typically accomplished using a positive displacement pump.

Abstract: A two dimensional photon position encoder system (10) and process which includes a detector (20) for enhancing the spatial resolution of the situs of the origin of incident photons of gamma rays. A plurality of scintillator material members (22) interact with the incident photons and produce a quantifiable number of photons which exit the scintillation material members. A tuned light guide (68) having a plurality of radiation barriers (92) of predetermined lengths define slots which are operatively associated with one of the scintillator material members. Photons exiting the scintillator material members (22) enter an operatively associated slot in said slotted light guide. These slots (90) serve to enhance the predictability of the statistical distribution of photons along the length of the slotted light guide (68). A detector (20) detects the distribution of the photons at preselected locations along the length of the slotted light guide.

Abstract: A two-dimensional photon position encoder system (10) and process which includes a detector (20) for enhancing the spatial resolution of the situs of the origin of incident photons of gamma rays. A plurality of scintillator material members (22) interact with the incident photons and produce a quantifiable number of photons which exit the scintillation material members. A tuned light guide (68) having a plurality of radiation barriers (92) of predetermined lengths define slots which are operatively associated with one of the scintillator material members. These slots (90) serve to enhance the predictability of the statistical distribution of photons along the length of the slotted light guide (68). A detector (20) detects the distribution of the photons at preselected locations along the length of the slotted light guide. In one embodiment, this detector (20) comprises a photomultiplier (70) which gathers information concerning the photoelectrons which are then counted.

Abstract: A two dimensional photon position encoder system (10) and process which includes a detector (20) for enhancing the spatial resolution of the situs of the origin of incident photons of gamma rays. A plurality of scintillator material members (22) interact with the incident photons and produce a quantifiable number of photons which exit the scintillation material members. A tuned light guide (68) having a plurality of radiation barriers (92) of predetermined lengths define slots which are operatively associated with one of the scintillator material members. Photons exiting the scintillator material members (22) enter an operatively associated slot in said slotted light guide. These slots (90) serve to enhance the predictability of the statistical distribution of photons along the length of the slotted light guide (68). A detector (20) detects the distribution of the photons at preselected locations along the length of the slotted light guide.

Abstract: In the digital intervalometer disclosed herein, a vernier measurement providing a resolution finer than one clock period is obtained by charging a single capacitor both during the interval between a start signal and a subsequent clock pulse and also during the interval between a clock pulse subsequent to a stop signal and a delayed stop signal. The analog voltage to which the capacitor is charged is converted to a digital value, which digital value is then combined with a clock count accumulated between the stop and start signals to provide a combined digital measurement having a resolution substantially finer than one clock period.