X-scan Imaging Corporation

Shizu Li

Hsin-Fu Tseng

Chinlee Wang

Linbo Yang

Lin-Bo Yang

Nguyen Phuoc Luu

A dual/multi-energy x-ray image sensor with stacked two-dimensional pixel arrays. Each pixel in one pixel array has a corresponding 'overlaid' pixel in the other pixel array. The pixel arrays are stacked parallel and aligned so that they are nominally normal to the x-ray path, and so that a straight path taken by an x-ray photon from the x-ray source to a pixel in one pixel array will also nominally intersect the corresponding pixel in the other pixel array(s). The energy image sensor provides an x-ray scanning detector system, which has increased signal levels and signal-to-noise ratios over dual- or multi-energy detectors using linear diode arrays, specifically when the pixel arrays are TDI pixel arrays that offer higher sensitivities in high-speed line-scan applications. Signal processing circuitry is placed on a periphery of the pixel arrays and shielded. Dual-to-multiple energy applications can be accomplished by increasing the number of stacked pixel arrays.

Dual/multiple-energy x-ray sensor with separation between pixels and active circuitry

A radiation damage resistant linear X-ray detector array system based on a unique buttable monolithic image sensor design and precision chip-on-board assembly technology includes at least one of the detector chips. Multiple chips of the image sensor may be butted end-to-end on a common printed circuit board to accommodate larger detection systems. A layer of scintillating material, such as GdOS:Tb (GOS), CsI(Tl), or CdWO, is placed on the image sensor to convert the impinging X-ray energies into visible light which can be detected efficiently by the image sensor array. A protective metal shield is fastened to the substrate to protect the sensitive circuits of the image sensor from X-ray radiation damage. A proper separation of sensitive circuits from the photodiode array on the sensor chip, coupled with precision registration of the sensor chips on the substrate, allows easy installation of the protective metal shield.

Linear X-ray detector with monolithic detector chip including both photodiode array and peripheral circuits spaced apart

A CMOS TDI image sensor consists of M pixels where each pixel is formed by a column of N TDI stages. Each TDI stage contains a photodiode that collects photo-charge and a pre-amplifier that proportionally converts the photo-charge to a voltage. Each TDI stage also has a set of capacitors, amplifiers, and switches for storage of the integrated signal voltages, where Correlated Double Sampling (CDS) technique (true or pseudo) maintains both photo-signal and reset voltages simultaneously. The CDS signal voltages can be passed from one TDI stage to the next TDI stage along a column for summing. The CDS signal voltages of the last TDI stages of M pixels are read out with a differential amplifier. This CMOS TDI structure is especially advantageous for implementing X-ray scanning detector systems requiring large pixel sizes and signal processing circuitry that is physically separated from the photodiode array for X-ray shielding.

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San Jose, CA, United States of America

Shizu Li