Abstract: An apparatus for reducing photodiode thermal gain coefficient includes a bulk semiconductor material having a light-illumination side. The bulk semiconductor material includes a minority charge carrier diffusion length property configured to substantially match a predetermined hole diffusion length value and a thickness configured to substantially match a predetermined photodiode layer thickness. The apparatus also includes a dead layer coupled to the light-illumination side of the bulk semiconductor material, the dead layer having a thickness configured to substantially match a predetermined thickness value and wherein an absolute value of a thermal coefficient of gain due to the minority carrier diffusion length property of the bulk semiconductor material is configured to substantially match an absolute value of a thermal coefficient of gain due to the thickness of the dead layer.

Abstract: An apparatus for reducing photodiode thermal gain coefficient includes a bulk semiconductor material having a light-illumination side. The bulk semiconductor material includes a minority charge carrier diffusion length property configured to substantially match a predetermined hole diffusion length value and a thickness configured to substantially match a predetermined photodiode layer thickness. The apparatus also includes a dead layer coupled to the light-illumination side of the bulk semiconductor material, the dead layer having a thickness configured to substantially match a predetermined thickness value and wherein an absolute value of a thermal coefficient of gain due to the minority carrier diffusion length property of the bulk semiconductor material is configured to substantially match an absolute value of a thermal coefficient of gain due to the thickness of the dead layer.

Abstract: An imaging system includes a gantry having a bore therethrough designed to receive a patient being translated through the bore an x-ray source disposed in the gantry and configured to emit x-rays toward the patient, and a detector module disposed in the gantry to receive x-rays attenuated by the patient. The detector module includes a scintillator configured to absorb the x-rays and to convert the x-rays into optical photons, a device configured to receive the optical photons and to convert the optical photons to electrical signals, and an adaptive data acquisition system (DAS) configured to switch an operating mode of the device from a charge integrating mode to a photon counting mode, and vice versa.

Abstract: An imaging system includes a gantry having a bore therethrough designed to receive a patient being translated through the bore an x-ray source disposed in the gantry and configured to emit x-rays toward the patient, and a detector module disposed in the gantry to receive x-rays attenuated by the patient. The detector module includes a scintillator configured to absorb the x-rays and to convert the x-rays into optical photons, a device configured to receive the optical photons and to convert the optical photons to electrical signals, and an adaptive data acquisition system (DAS) configured to switch an operating mode of the device from a charge integrating mode to a photon counting mode, and vice versa.

Abstract: A detector module for a CT imaging system includes a scintillator to convert x-rays to optical photons. The scintillator is optically coupled to a solid-state photomultiplier with internal gain to receive the optical photons and convert them into a corresponding electrical signal output.

Abstract: A CT detector includes a pixel having a single photodiode and multiple charge storage devices that are alternately stored and read out. The photodiode is a frontlit diode with a pair of capacitors that alternately store charge generated during data acquisition. Multiple pixels are connected to a single readout amplifier. Charge is continuously acquired from each photodiode and stored on the charge storage devices, but such readout is from a single charge storage device at a time. As such, each charge storage device is read out independently, but the charge storage devices are connected to a common readout channel or port.

Abstract: A CT detector includes a pixel having a single photodiode and multiple charge storage devices that are alternately stored and read out. The photodiode is a frontlit diode with a pair of capacitors that alternately store charge generated during data acquisition. Multiple pixels are connected to a single readout amplifier. Charge is continuously acquired from each photodiode and stored on the charge storage devices, but such readout is from a single charge storage device at a time. As such, each charge storage device is read out independently, but the charge storage devices are connected to a common readout channel or port.

Abstract: An optical mask layer for a CT detector is disclosed and is disposed between the photodiode array and scintillator array of a CT detector. The optical mask layer, which may extend along the x-axis, z-axis, or both, is designed to absorb and/or reflect light emitted the scintillators of the scintillator array. Through this absorption and/or reflection, transference of light photons from a scintillator to the photodiode corresponding to a neighboring scintillator is reduced. This reduction in cross-talk reduces artifacts in a reconstructed image and therefore improves the diagnostic value of the image.

Abstract: A method is provided for identifying detector elements in a solid state X-ray detector susceptible to causing line artifacts due to faulty detector elements that leak charge. A portion of the X-ray detector is covered by a radiation occluding material and the detector is exposed to a level of radiation sufficient to reach a predetermined threshold in the exposed portion of the detector. An image representative of the radiation is acquired and further analyzed to determine whether line artifacts exist. Data lines found to exhibit line artifacts are stored in the image processor.

Abstract: A method is provided for identifying detector elements in a solid state X-ray detector susceptible to causing line artifacts due to faulty detector elements that leak charge. A portion of the X-ray detector is covered by a radiation occluding material and the detector is exposed to a level of radiation sufficient to reach a predetermined threshold in the exposed portion of the detector. An image representative of the radiation is acquired and further analyzed to determine whether line artifacts exist. Data lines found to exhibit line artifacts are stored in the image processor.

Abstract: A large area solid state x-ray detector employs a number of photodiodes that are charged electrically then discharged by exposure to x-ray. Ghost images resulting from release of charge trapped in photodiodes during prior exposures are eliminated by adjusting the biasing during a reset portion of the imaging cycle. Biasing may be increased to decrease the recharge time or reversed in polarity to evenly discharge the diodes or decreased to preserve the offset so that it may be removed from subsequent images by image processing.

Abstract: A solid state array device includes a plurality of pixels with associated respective TFT switching transistors; a plurality of first address lines disposed in a first layer of the array device; a plurality of second conductive address lines disposed in a second layer of the array device, respective ones of said first and second address lines being disposed substantially perpendicular to one another in a matrix arrangement such that respective ones of the second address lines overlie respective ones of the first address lines at respective crossover regions; a TFT gate dielectric layer disposed in a channel region of each of the pixel TFTs and further being disposed over the first address lines; and a crossover region supplemental dielectric layer disposed in respective ones of the crossover regions between the first and second address lines, but disposed so as to not extend over the TFT channel regions.

Abstract: A method of repairing an open circuit defect in a damaged address line in a thin film electronic imager device includes the steps of forming a repair area on the device so as to expose the open-circuit defect in the damaged address line and then depositing a conductive material to form a second conductive component and to coincidentally form a repair shunt in the repair area so as to electrically bridge the defect. The step of forming the repair area includes the steps of ablating dielectric material disposed over the first conductive component in the repair area, and etching the repair area so as to remove dielectric material disposed over the defect in the address line in the repair area such that the surface of the address line conductive material is exposed but is not contaminated by the removal of the overlying dielectric material.

Abstract: A flat panel radiation imaging device that exhibits reduced capacitive coupling between pixel photodiodes and readout data lines, and thus in operation has reduced phantom images and image artifacts, includes a ground plane electrode that is disposed between the substrate and the plurality of pixels arranged in an imaging array pattern. The ground plane electrode is a conductive material layer that is disposed in a continuous sheet underlying the imaging array pattern; alternatively, the ground plane is a patterned sheet of conductive material having data line cutout areas disposed so that no ground plane conductive material underlies or is closer than a lateral set off distance from data lines in the imaging array pattern. A patterned ground plane further may include pixel electrode cutout sections disposed such that ground plane conductive material underlies pixel electrodes in the imaging array pattern only by a selected overlap distance around the boundaries of the pixel electrode.

Abstract: A solid state radiation imager that exhibits reduced capacitive coupling between pixel photodiodes and readout data lines, and thus further has reduced phantom images or image artifacts, includes a plurality of shield lines disposed at the same level of the device as the scan lines and associated gate electrodes for the switching transistors. The shield lines include respective pixel shielding spurs oriented along the same axis as the data lines and disposed between portions of the pixel photodiode and adjacent portions of the data lines. The shield lines are typically coupled to a shield voltage source such that the shield lines are maintained at a common potential.

Abstract: A low noise fluoroscopic radiation imager includes a large area photosensor array having a plurality of photosensors arranged in a pattern so as to have a predetermined pitch, and a low noise addressable thin film transistor (TFT) array electrically coupled to the photosensors. The TFT array includes a plurality of low charge retention TFTs, each of which have a switched silicon region that has an area in microns not greater than the value of the pitch of the imager array expressed in microns. The portion of the switched silicon region underlying the source and drain electrodes of the TFT is not greater than about 150% of the portion of the switched silicon region in the channel area of the TFT. The ratio of the TFT channel width to channel length (the distance between the source and drain electrodes across the channel) is less than 20:1, and commonly less than 10:1, with the channel length in the range of between about 1 .mu.m and 4 .mu.m.

Abstract: In the fabrication of thin-film field-effect transistors, a dielectric island is first formed over a gate and between locations where source and drain contacts are to be deposited. A dielectric cap with an overhanging brim is formed on the island. A layer of SD metal which will form the source-drain contacts is next deposited. Because of the overhang, the SD metal does not coat the entire cap, but leaves part of the cap remaining exposed and attackable by an etchant. Application of an etchant etches away the island and the cap, thereby lifting off the SD metal coated on the cap, leaving the fully-formed source and drain contacts in place, separated by the extent of the island.

Abstract: A thin-film field-effect transistor is fabricated by forming an electrically insulative island between the source and the drain. A cap is formed on the island with a brim that overhangs the island. A layer of source-drain metal, which will subsequently constitute the source and drain contacts, is then deposited upon the source, the drain, and the cap, but the overhang creates an exposed region which can be attacked by an etchant. When the etchant is applied, it etches away the cap, thereby lifting off the source-drain metal which coated the cap, leaving the fully formed source and drain contacts separated by the island.

Abstract: A computed tomography (CT) imager includes a scintillator and a photosensor array optically coupled to the scintillator through an optical coupling layer. The photosensor array includes a plurality of photosensitive devices disposed in a block so as to receive incident light from the scintillator through a first surface of the block; each photosensitive device forms a pixel in the array, and each pixel further has a fully photoactive region in which the quantum efficiency of the photosensor is greater than about 65%. The optical coupling layer further includes a pixel boundary light barrier that is made of light absorptive material disposed in the optical coupling layer overlying the areas on the photosensor array first surface between respective fully photoactive regions of the photosensitive devices.

Abstract: A method of fabricating a self-aligned thin film transistor (TFT) with a lift-off technique includes the steps of forming a multi-tier island on a semiconductive layer such that the island structure is disposed in a desired alignment over the gate electrode. The island structure includes a base layer portion, an intermediate body portion, and an upper cap portion, which overhangs the intermediate body portion by an amount between about 0.5 .mu.m and 1.5 .mu.m. Source and drain electrodes are formed such that the source/drain material is disposed over the semiconductive material up to the sidewalls of the base portion of the island structure, which base portion is patterned such that the source and drain electrodes are self-aligned with and extend a selected overlap distance over the gate to provide desired TFT performance characteristics. The upper cap layer is removed in a lift-off technique and the intermediate body portion of the island is removed to complete fabrication oft the TFT.