55 results about "Depth of interaction" patented technology

A depth of interaction detector with uniform pulse-height comprises a multi-layer scintillator obtained by coupling at least two scintillator cells on a plane and then stacking the planar coupled scintillator cells, in layers, up to at least two stages and a light-receiving element connected to the bottom face of each scintillator cell of this multi-layer scintillator, wherein the detector is provided with a means for discriminating the position of a scintillator cell, which receives radiant rays and emits light rays and a means for making, uniform, the quantity of the light emitted from each scintillator cell and received by the light-receiving element. The detector can provide precise detection information even when radiation is absorbed by and emitted from a scintillator layer positioned above the scintillator layer optically coupled to the light-receiving element, permits the production of a depth of interaction detector having a three-dimensional depth of interaction-detecting function and can provide the same total output signal, which is independent of the position or a specific scintillator cell practically emitting light if the radiation energy is identical.

A modular radiation detector (10) with scintillators (13) and semi-conductor photodiodes (12) and integrated readout (15) can be used in positron emission tomography (PET) for functional imaging of humans and animals. Spatial resolution is improved by measuring the depth-of-interaction and modules using photodiodes and integrated readout circuits according to the invention instead of photo-multipliers give rise to lighter and less bulky tomographic instruments. The invention uses very large scale integrated (VLSI) electronic readout circuits for measuring signals from photo-diodes. The electronic readout circuits (15) are located on the module and allow data to be measured and processed at very high rates on the module level rather than on the system level. The use of photodiodes promises greater stability during operation and improved reliability over photo-multipliers. The invention can be used in magnetic fields and therefore allows PET and MRI/NMR imaging techniques to be combined.

A phoswich device for determining depth of interaction (DOI) includes a wavelength shifting layer between first and second scintillators of different scintillation materials and having different decay time characteristics. The wavelength shifting layer allows a true phoswich device to be constructed where the emission wavelength of one scintillator is in the peak excitation band of the other scintillator, by shifting the scintillation light outside of this excitation band to prevent scintillation light of one scintillator from exciting a response in the other scintillator, thus enabling unique identification of the location of a gamma photon scintillation event. The phoswich device is particularly applicable to positron emission tomography (PET) applications.

A radiation detector (20, 20') includes scintillator pixels (30) that each have a radiation-receiving end, a light-output end, and reflective sides extending therebetween. The reflective sides have a reflection characteristic (40, 40', 42, 44) varying between the radiation-receiving end and the light-output end such that a lateral spread of light emanating from the light-output ends of the scintillator pixels responsive to a scintillation event generated in one of the scintillator pixels depends upon a depth of the scintillation event in the scintillator pixel. A plurality of light detectors (46) optically communicate with the light-output ends of the scintillator pixels to receive light produced by scintillation events.

The preferred embodiments of the present invention include a device for measuring an ionizing event in a radiation sensor. The device can include a charge amplifier and a timing shaper. The charge amplifier receives a cathode signal and is configured to output an amplified cathode signal. The timing shaper is operatively connected to the charge amplifier to receive the amplified cathode signal. The timing shaper is configured to generate a first pulse in response to a beginning of the ionizing event and a second pulse in response to an end of the ionizing event. The first and second pulses are associated with a depth of interaction of the ionizing event and are generated in response to a slope of the amplified cathode signal changing.

A detector is provided for nuclear medicine imaging. Scintillator pixels form an axial array and a transaxial array. A first photosensor is positioned along the axial array; and a second photosensor is positioned along the transaxial array, wherein the first photosensor and the second photosensor provide dual event localization for nuclear medicine imaging.

The invention provides a grid mould, a detector including the grid mould and emission imaging equipment. The grid mould comprises a plurality of transverse walls, a plurality of longitudinal walls and light reflecting layers. The transverse walls and the longitudinal walls extend transversely and longitudinally respectively to form a plurality of grid troughs which are arranged in a m*n matrix mode and used for containing scintillation crystal of the detector, m and n are positive integers, and light-transmitting windows with light capable of penetrating side walls are formed in the side walls of the grid troughs. The light reflecting layers are arranged on the areas, except for the light-transmitting windows, of the side walls. The grid mould obtains the information of the depth of interaction (DOI) of the scintillation crystal, and the space resolution ratio and the system detection sensitivity of the emission imaging equipment can be improved.

The invention is directed to several crystal arrangements for time-of-flight (ToF) positron emission tomography (PET) with depth of interaction (DOI) encoding for high spatial, energy and timing resolution. Additionally, several implementations of the ToF-DOI PET detector arrays are proposed with related measurements which all show that no timing degradation is visible in the used setup for first photon trigger for digital silicon photo multipliers (dSiPMs).

A radiation detector is disclosed that includes a scintillation crystal and a plurality of photodetectors positioned to detect low-energy scintillation photons generated within the scintillation crystal. The scintillation crystals are processed using subsurface laser engraving to generate point-like defects within the crystal to alter the path of the scintillation photons. In one embodiment, the defects define a plurality of boundaries within a monolithic crystal to delineate individual detector elements. In another embodiment, the defects define a depth-of-interaction boundary that varies longitudinally to vary the amount of light shared by neighboring portions of the crystal. In another embodiment the defects are evenly distributed to reduce the lateral spread of light from a scintillation event. Two or more of these different aspects may be combined in a single scintillation crystal. Additionally, or alternatively, similar SSLE defects may be produced in other light-guiding elements of the radiation detector.

The present invention is directed to a system and method for efficiently and cost effectively determining an accurate depth of interaction for a crystal that may be used for correcting parallax error and repositioning LORs for more clear and accurate imaging. The present invention is directed to a detector assembly having a thin sensor (e.g., APD) deployed in front of the detector (the side where the radioactive source is located and the photon is arriving to hit the detector) and a second sensor (APD or photomultiplier) on the opposite side of the detector. The light captured by the two interior and exterior sensors which is proportional to the energy of the incident photon and to the distance where the photon was absorbed by the detector with respect to the location of the two sensors, is converted into an electrical signal and interpolated for finding the distance from the two sensors which is proportional to the location where the photon hit the detector.

A scintillation detector according to an embodiment of the invention features a monolithic scintillation crystal and a plurality of optical fibers coupled to the scintillation crystal. The optical fibers are arranged to convey scintillation light to an optical sensor that is located exterior to the scintillation crystal. Because the optical fibers are extremely small in diameter, a multiplicity of them can be coupled to the scintillation crystal to provide the extremely high resolution of a pixelated scintillation crystal while the comparative manufacturing simplicity of a monolithic scintillation crystal is maintained. In preferred embodiments, the optical fibers are further arranged so that depth of interaction information can be obtained.

A three-dimensional PET detector of a type having a scintillation crystal and first and second photosensitive detectors arranged one at each opposite end face of the crystal for detecting scintillation interactions within the crystal is calibrated to determine a depth-of-interaction (DOI) function thereof by irradiating the crystal to cause a predetermined distribution of interactions along a depth axis of the crystal, and applying probability theory to signal data collected by the two photosensitive detectors. The method provides a DOI function that indicates DOI position as a function of a signal ratio R obtained from the signal data.

The invention discloses a method of improving PET (positron emission tomography) image reconstruction quality by constructing a virtual DOI (depth of interaction) and a corresponding system matrix. The method comprises the following steps: 1) virtual DOIs are divided: a scintillation crystal in a PET detector ring is divided into a plurality of regions which correspond to different DOIs; 2) the detection probability of a virtual DOI is calculated: the virtually-divided DOI regions are paired, and the probability of each pair being detected at a different signal source position is calculated; 3) a virtual LOR (Line of response) event in the virtual DOI is divided: one LOR event in one original pair of crystals is divided to multiple sub events in the virtual DOI; 4) a conventional system matrix is optimized: multiple factors that affect the image reconstruction quality are considered; 5) image reconstruction is carried out: a statistical iterative algorithm is used to reconstruct an image; and 6) a GPU platform is used for distributed operation, and the data processing time can be greatly reduced. Through the method disclosed in the invention, the resolution of PET-class equipment after image reconstruction can be greatly improved, the location of a tumor can be positioned accurately, and important clinical value and significance are achieved.