摘要:
A photodetector for X-ray applications is disclosed incorporating a photodiode design with reduced leakage at each pixel location. The photodiode is of a reduced surface area and has a peripheral edge of reduced length. The length may be minimized by making the photodiode round. The diode is surrounded by a reflective layer that may act as a contact for the diode. Photons are reflected by the reflective layer back towards the reduced area diode to maintain good sensitivity. The reflective/contact layer may form a capacitor with another contact layer by disposing a dielectric layer therebetween, thereby increasing the effective capacitance of the photodiode.
摘要:
A photodetector for X-ray applications includes a photodiode at each pixel location that is gated to reduce leakage of charge from the photodiode. A gate layer may be disposed around the entire peripheral edge of the detector, and maintained at a common potential with a contact layer, or at a different potential. A passivation or dielectric layer separates the gate layer from the photodiode. Leakage around the edge of the diode that can result from extended exposure to radiation is reduced by the gate layer.
摘要:
A motion correction system and method for motion correction for an x-ray tube is presented. One embodiment of the motion correction system includes a sensing unit coupled to an x-ray tube to determine a distance with which an impingement location of an electron beam generated by the x-ray tube deviates from a determined location due to motion of the x-ray tube. The motion correction system further includes a control unit coupled to the sensing unit to generate a control signal corresponding to the distance with which the impingement location of the electron beam deviates. Also, the motion correction system includes a deflection unit coupled to the control unit to steer the electron beam to the determined location based on the generated control signal.
摘要:
A detector for identification and localization of radioisotopes, comprising a position sensitive detector configured to observe the location of emitted high energy radiation, wherein the position sensitive detector comprises a surface comprised of a first radiation sensitive material; and an active mask disposed in front of the position sensitive detector positioned such that the emitted high energy radiation is detected by the position sensitive detector after passage through the mask, wherein the mask comprises a second radiation sensitive material.
摘要:
A detector assembly including a radiation conversion layer directly coupled to a pixel array is provided. The radiation conversion layer is adapted to receive radiation passing through an object. The pixel array is adapted for receiving one of a plurality of signals representative of the radiation passing through the object or the corresponding optical signals from an optional intermediate light production layer and further configured for generating a corresponding image of the object.
摘要:
A coded aperture includes a position sensitive detector configured to observe the location of emitted high energy radiation, and a mask disposed in front of the position sensitive detector, wherein the mask has a non-linear shape configured to define a perimeter around position sensitive detector, wherein the mask comprises a plurality of attenuating and transparent elements of a predetermined configuration, positioned such that the emitted radiation is detected by the position sensitive detector after passage through the mask.
摘要:
An imaging system includes a platform having mounted thereon a coded-aperture imaging device and positioned to receive radiation over a baseline. The imaging system includes a computer configured to acquire a plurality of far-field datasets over the baseline, the plurality of far-field datasets comprising data received via the coded-aperture imaging device. The computer is also configured to form a preliminary image based on the acquired plurality of far-field datasets, and apply an expectation maximization (EM) algorithm to the preliminary image; wherein the EM algorithm includes an ordered subset algorithm.
摘要:
Dual modality detection devices and methods are provided for detecting nuclear material, the devices include a neutron detector including multiple neutron detection modules; and a gamma detector including multiple gamma detection modules, where the multiple neutron detection modules and the multiple gamma detection modules are integrated together in a single unit to detect simultaneously both gamma rays and neutrons.
摘要:
An imaging system includes a platform having mounted thereon a coded-aperture imaging device and positioned to receive radiation over a baseline, and a computer configured to acquire a plurality of far-field datasets over the baseline, the plurality of far-field datasets comprising data received via the coded-aperture imaging device, form a first image from the plurality of far-field datasets, and form a second image if the first image indicates presence of a source, the second image formed from the plurality of far-field datasets using an estimated source location from the first image and thereby having a higher contrast than the first image.
摘要:
A solid-state photomultiplier (SSPM) includes an optical isolation structure therein. The SSPM includes a substrate and an epitaxial diode layer positioned on the substrate. A plurality of avalanche photodiodes (APDs) are fabricated on the epitaxial diode layer and the optical isolation structure is positioned about the plurality of APDs to separate each of the plurality of APDs from adjacent APDs. The optical isolation structure contains at least one of a light absorbing material and a light reflecting material deposited therein to reduce optical crosstalk and dark count rate in the SSPM.