Shielding an imaging array from x-ray noise

Abstract

An electronic imaging sensor, which has an improved immunity to noise caused by unwanted x-rays, images an object by collecting charge carriers produced in the sensor when the object is exposed to x-rays. One or more shielding areas are formed proximate the sensor to capture or sweep away any undesirable charge carriers generated by the unwanted x-rays. The shielding areas extend deeper beneath the surface of the sensor than the depth at which the desired charge carriers corresponding to the object being imaged is collected. The shielding areas capture charge carriers formed by the unwanted x-rays, which penetrate into the sensor to a greater depth than the depth at which the desired charge carriers are collected. In this way, the undesirable charge carriers are captured near the region where they are generated and before they migrate towards the surface where they can be collected and manifest as noise in the resulting image of the object.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to the field of radiation-sensitive imaging devices, and more specifically to radiation-sensitive imaging devices that have improved immunity to x-ray noise.[0003]2. Related Background Art[0004]Increasingly, electronic imaging sensors have been replacing film-based sensors in commercial, industrial, and medical imaging applications. Examples of such electronic sensors include charge-coupled device (CCD) sensors and complementary metallic-oxide-semiconductor (CMOS) sensors, to name a few. CMOS sensors, in particular, have emerged as a preferred candidate due to advantages in manufacturing cost, integration of components, charge efficiency, and low power consumption. An excellent example of a detector system suitable for medical imaging applications that uses a CMOS active pixel sensor (APS) array is provided in U.S. Pat. No. 5,912,942 to David B. Schick et al., assigned to the assi...

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