Abstract: An imaging system includes a first silicon photomultiplier (SiPM) comprising an array of microcells. Each microcell is an avalanche photodiode (APD) operated in a Geiger mode, a first area of the first SiPM, comprising at least one of the microcells, is electrically isolated from all other microcells, and a signal from the first area, resulting from at least one photon pulse, is used to determine a gain of the first SiPM.

Abstract: An imaging system includes a first silicon photomultiplier (SiPM) comprising an array of microcells. Each microcell is an avalanche photodiode (APD) operated in a Geiger mode, a first area of the first SiPM, comprising at least one of the microcells, is electrically isolated from all other microcells, and a signal from the first area, resulting from at least one photon pulse, is used to determine a gain of the first SiPM.

Abstract: A method of correcting a timing signal that represents an arrival time of a photon at a positron emission tomography (PET) detector includes receiving a timing signal that represents an arrival time of a photon at a PET detector, receiving an energy signal indicative of an energy of the photon, calculating a timing correction using the energy signal, modifying the timing signal using the timing correction, and generating an image of an object using the modified timing signal. A system and non-transitory computer readable medium are also described herein.

Abstract: A gamma ray detector ring for a combined positron emission tomography (PET) and magnetic resonance imaging (MRI) system is integrated into a radio frequency (RF) coil assembly such that the detector ring is integrated with a RF shield. Each gamma ray detector in the detector ring includes a scintillator component that emits light when a gamma ray is detected and a photodetector component designed to be sensitive to the frequency of light produced by the scintillator. A RF shield may be integrated into a detector ring such that the RF shield is positioned between the scintillator and photodetector components of each detector, thereby saving valuable radial space within the imaging system. Multiple such detector rings may be located adjacent to one another to increase axial coverage and enable three-dimensional PET imaging techniques.

Abstract: A gamma ray detector ring for a combined positron emission tomography (PET) and magnetic resonance imaging (MRI) system is integrated into a radio frequency (RF) coil assembly such that the detector ring is integrated with a RF shield. Each gamma ray detector in the detector ring includes a scintillator component that emits light when a gamma ray is detected and a photodetector component designed to be sensitive to the frequency of light produced by the scintillator. A RF shield may be integrated into a detector ring such that the RF shield is positioned between the scintillator and photodetector components of each detector, thereby saving valuable radial space within the imaging system. Multiple such detector rings may be located adjacent to one another to increase axial coverage and enable three-dimensional PET imaging techniques.

Abstract: According to one aspect, the invention relates to a light guide which may include a first surface which receives light, a second surface which emits light, wherein the second surface is parallel to the first surface and the second surface has a smaller area than the first surface, at least one edge surface which extends between the first surface and the second surface, and a light barrier which extends between the first surface and the second surface, wherein the light barrier divides the light guide into separate regions and reduces the propagation of light between the separate regions. The light guide can be used in a positron emission tomography scanner.

Abstract: A method of calibrating detectors in a detector ring of a PET scanner, each detector including a plurality of crystals, the PET scanner having a field of view, is disclosed. The method comprises collecting timing data indicative of coincidence events occurring between each pair of crystals within the field of view. The method further comprises determining a detector adjustment value for each detector, determining a crystal adjustment value for each crystal in each detector, and discretizing the crystal adjustment value for each crystal to produce a discretized crystal adjustment value for each crystal. Lastly, the method comprises calibrating each detector by applying the discretized crystal adjustment value for each crystal in each detector to the collected timing data indicative of coincidence events.

Abstract: A method of calibrating detectors in a detector ring of a PET scanner, each detector including a plurality of crystals, the PET scanner having a field of view, is disclosed. The method comprises collecting timing data indicative of coincidence events occurring between each pair of crystals within the field of view. The method further comprises determining a detector adjustment value for each detector, determining a crystal adjustment value for each crystal in each detector, and discretizing the crystal adjustment value for each crystal to produce a discretized crystal adjustment value for each crystal. Lastly, the method comprises calibrating each detector by applying the discretized crystal adjustment value for each crystal in each detector to the collected timing data indicative of coincidence events.

Abstract: A method of calibrating detectors in a detector ring of a PET scanner, each detector including a plurality of crystals, the PET scanner having a field of view, is disclosed. The method comprises collecting timing data indicative of coincidence events occurring between each pair of crystals within the field of view. The method further comprises determining a detector adjustment value for each detector, determining a crystal adjustment value for each crystal in each detector, and discretizing the crystal adjustment value for each crystal to produce a discretized crystal adjustment value for each crystal. Lastly, the method comprises calibrating each detector by applying the discretized crystal adjustment value for each crystal in each detector to the collected timing data indicative of coincidence events.

Abstract: A radiation detector emits a signal containing pulses produced by each radiation event being detected. The pulses tend to decay and may overlap the pulse from a subsequent radiation. In order to prevent such pulse overlap a circuit is provided to clip the signal pulses. The circuit incorporates an analog delay line which produces a delayed, inverted and attenuated reflection of the original detector signal. The reflection signal is combined with the original detector signal to cancel remnants of each pulse lasting longer than the predefined delay period.

Abstract: A detector including opposed detector heads having anode signal processors which perform a sliding box car integration of each PMT anode signal, corrects for baseline shifts and pileup from the tails of previous events, vary the length of the box car based on the time between events, and use a peak detection circuit to reduce the dependence of the integrated value on timing differences between the asynchronous events and the synchronous ADC conversion is described. The outputs of anode processors are combined to provide the X and Y coordinates, and the energy E, of an event. The outputs from each head processor are then combined in a coincidence processor to provide the corrected positions and energies of coincidence events. The above described detector heads function at a high count rate with minimum dead time and pileup.

Abstract: A method for correcting the temporal relationships between event detection pulses generated by a PET scanner system, the method including, for each pulse, identifying the impact point of an associated photon on a scanner surface area and based on the impact point, selecting a compensation delay for the pulse and delaying the pulse by the compensation delay. The invention also includes an apparatus for practicing the method.

Abstract: A direct conversion nuclear particle detector including an absorption member having cathode and anode surfaces, a cathode attached to the cathode surface, a plurality of anodes attached to the anode surface and a shaping electrode also attached to the anode surface, adjacent anodes are separated by gaps, the electrode is attached to the anode surface within the gaps such that the electrode and each adjacent anode forms a space, the anodes are linked by a resistive network and at least two anodes are attached to amplifiers, the amplifiers generating signals which can be used to identify when a photon has been absorbed by the absorption member and approximately where with respect to the cathode surface the absorption occurred.

Abstract: An apparatus for use with a gamma camera to increase count rate without causing dead time or pile up, the apparatus including a first processor optimized for simplicity and minimum dead time but with moderate to poor spatial resolution for generally determining the impact point of a photon on a scintillation crystal and a second digital processor which uses the general position information from the first processor to identify a subset of PMT intensity signals for further processing to identify the precise impact point location.

Abstract: An medical imaging system includes a photodetector array which converts an X-ray image into a series of picture elements arranged in rows and columns of a two dimensional matrix. The picture elements are read from the array on a column by column basis. A spatial filter for the picture elements includes a first filter that applies one filter function to the pixels in each column of the image. The partially filtered pixels are stored in a first memory and then read therefrom row by row in a field interlaced order. The rows of picture elements are sent to a second filter that applies another filter function to each row. The fully filtered picture elements from the second filter either are stored or converted to a video signal for display.

Abstract: A PET scanner includes a ring of detector units which receive gamma rays produced by annihilation events. Each detector unit includes a 6.times.6 array of BGO scintillation crystals mounted in front of a 2.times.2 array of photomultiplier tubes. The position of a scintillation event within the crystal array is determined more accurately by selectively painting the side surfaces of the array crystals.

Abstract: The brightness of an X-ray video image during fluorography is maintained at a substantially constant level by a control circuit which varies the X-ray dose in relation to changes in the average brightness of the X-ray image. Selected picture elements of the image which lie within a defined region in the image and which have a brightness above a given level are used to derive the average X-ray image brightness. The brightness of the selected picture elements are summed and the number of such picture elements counted. The summation of the brightness and the picture element count are both scaled by a factor of 2.sup.n to reduce the size of the numbers of the complexity of the averaging circuitry. The scaled brightness summation is divided by the scaled picture element count and the result is stored as the average X-ray image brightness.

Abstract: A image detector includes an array of photodetectors arranged in n rows and m columns with at least a portion of the photodetectors in each column being selectively connected to a common column output signal line by a selector means. The image information is read out of the photodetectors by sequentially selecting groups of rows starting with a row near the middle of the array and then sequentially selecting other groups of rows on alternate sides of the array middle. As image data is read out of the photodetectors in the selected row group, groups of column outlet lines are coupled together to provide a combined output signal. This readout technique provides a reduction in the image data and reduces the likelihood of signal degradation for the central portion of the image.

Abstract: Method and apparatus for minimizing scatter in an X-ray imaging system of the type including a controllable source of X-ray radiation and means for collimating the X-ray radiation into a fan-shaped beam and effecting scanning of the X-ray beam across a target area. The improved system includes a grid assembly extending in a transverse direction across the target area and having a relatively narrow width in the beam scanning direction. A drive is coupled to the grid removing the grid in synchronism with the X-ray beam and an X-ray impervious belt is coupled to the grid and extends in a transverse direction across the target area and is movable with the grid for covering the target area outside the grid to prevent scatter radiation from impinging on X-ray film located beneath the grid. In one form, the grid includes a plurality of air interspersed septa to allow reduced beam energy.

Abstract: A scanning type radiographic imaging system is disclosed which employs novel means to produce comparable radiation intensity in the object regions being radiographed. Such result is achieved with variable radiation attenuating elements having their attenuation controlled during this scanning process with novel feedback control means. The feedback control is produced with a stationary detection unit having circuit means which generates the electrical control signals.