Claims:We claim:
1. A digital radiation detector (200) using back illumination camera sensor array (204), the digital radiation detector (200) comprising:
a) an energy conversion component (201) to convert high radiation impinging on a surface of the energy conversion component to a low energy radiation to be detectable by a plurality of cameras;
b) a high energy blocking component (202) located between an energy conversion component (201) and a refraction component (203) to prevent high energy radiation from reaching a back-illumination camera sensor array (204), wherein the refraction component (203) concentrates the converted low energy radiation with appropriate focal length to the back-illumination camera sensor array (204);
c) the back-illumination camera sensor array (204) comprises one or more back-illumination cameras, wherein each back-illumination camera (204) comprises:
o a lens at a front end, a metal wiring to conduct the signal at a back end and a photo diode located between the lens and the metal wiring to provide better light profile at the edge of the lens;
o an analog-to-digital converter (205) connected to each of the back-illumination camera (204) to convert the images captured by the back-illumination camera (204) from analog to digital signals;
o one or more slave controllers (206) connected to the analog-to-digital converter (205) to receive digital signals from the analog-to-digital converter (205);
o a master controller (207) to receive digital signals from the slave controllers (206) and to send the acquired images to a processing and storage system, wherein the processing and storage system stitches one or more images from multiple overlapping images obtained by the master controller (207) into a single image with improved image quality along the edges of the image.

2. The digital radiation detector (200) as claimed in claim 1, wherein each of the back-illumination cameras(204) are arranged such that the field of view of each of the back-illumination cameras (204) partially overlaps with the field of view of the adjacent back-illumination camera (204) to form multiple overlap regions to form a single image.

3. The digital radiation detector (200) as claimed in claim 1, wherein the back-illumination camera sensor array (204) comprises a single back-illumination camera.

4. The digital radiation detector (200) as claimed in claim 1, wherein the digital radiation detector (200) further comprises a light sensitive detector (208) to transmit control signals to a master controller (207) to activate one or more back-illumination cameras (204) at identical timings to capture images.

5. The digital radiation detector (200) as claimed in claim 1, wherein the digital radiation detector (200) is used in intra oral x-ray detector, extra oral x-ray detector, general radiography, cone beam computed tomography scan, fan beam computed tomography scan, bone mineral density scan, gamma camera and single photon emission computed tomography to provide improved image quality along the edges of the image.

6. The digital radiation detector (200) as claimed in claim 1, wherein the digital radiation detector (200) used in bone mineral density scan (DEXA) is moved at constant speed to capture images of the target (902) in a line scan mode.
, Description:PREAMBLE TO THE DESCRIPTION:
[0001] The following specification particularly describes the invention and the manner in which it is to be performed:
DESCRIPTION OF THE INVENTION:
Technical Field of the Invention
[0002] The present invention relates to a digital x-ray and gamma ray detector using back illumination camera sensor array.
Background of the Invention
[0003] Digital x-ray detector is commonly employed to measure the flux, spatial distribution, spectrum, and other properties of x-rays. Further, the most important parameter in any digital x-ray detector is that equal x-ray sensitivity in the entire detector area to avoid poor image contrast along the edges. The present digital x-ray detector uses multiple front illuminated camera for digital x-ray. However, the light reaching along the edges of the front illuminated camera is less when compared to the light reaching the center of the camera. The traditional front illuminated camera has a lens (101,as exemplarily illustrated in Fig. 1) at a front end, a photo diode (102) at a back end and a metal wiring (103) to conduct the signal (as exemplarily illustrated in Fig. 1). The metal wiring (103) blocks some of the light thereby resulting in less light reaching the edge of the lens. Further, if the clarity of the image in the edges is less then stitching of images becomes difficult.

[0004] Since, digital x-ray detector captures multiple images and the captured image must be stitched together to resemble as a single image. The clarity of the images across the edges is very important. As exemplarily illustrated in Fig 1A, clarity of blending of images takes place at the edges(104) is less in traditional front illuminated camera, as the clarity of the images at the edges is less.

[0005] For example, US Patent document US8872116B2 titled “Method and apparatus for multi-camera x-ray flat panel detector” discloses an apparatus for providing signal indicative of radiation impinging on the camera. The apparatus comprises multiple cameras arranged in an array such that each of the camera produces a signal indicative of radiation impinging on the respective camera. The cameras are arranged such that the field of view of each of the cameras partially overlaps the field of view of one adjacent camera to form multiple overlap regions to form an image.

[0006] Thus, there exists a need for a digital x-ray detector that improves image quality along the edges of the image.

Summary of the Invention
[0007] The present invention overcomes the drawbacks in the prior art and provides a digital x-ray and gamma ray detector using back illumination camera sensor array to improve image quality along the edges of the image. The detector comprises an energy conversion component to convert high radiation impinging on a surface of the energy conversion component to a low energy radiation to be detectable by a plurality of cameras. A high energy blocking component located between an energy conversion component and a refraction component to prevent high energy radiation from reaching a back-illumination camera sensor array. A refraction component to concentrate the converted low energy radiation with appropriate focal length to the back-illumination camera sensor array.

[0008] In an embodiment, the back-illumination camera sensor array comprises one or more back-illumination cameras. Each back-illumination camera comprises a lens at a front end, a metal wiring to conduct the signal at a back end and a photo diode located between the lens and the metal wiring. The metal wiring located at the back end provides better light profile at the edge of the lens. An analog-to-digital converter connected to each of the back-illumination camera to convert the images captured by the back-illumination camera from analog to digital signals. One or more slave controllers connected to the analog-to-digital converter to receive digital signals from the analog-to-digital converter. A master controller to receive digital signals from the slave controllers and to send the acquired images to a processing and storage system. The processing and storage system stitches one or more images from multiple overlapping images obtained by the master controller into a single image with improved image quality along the edges of the image.

[0009] Thus, the back-illumination camera comprises a lens at a front end, a metal wiring to conduct the signal at a back end and the photo diode located between the lens and the metal wiring. The metal wiring located at the back end provides better light profile at the edge of the lens.

Brief Description of Drawings
[0010] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0011] Fig1 illustrates a traditional front illuminated camera, according to one embodiment of the present invention.

[0012] Fig 1a illustrates blending of images using the traditional front illuminated camera, according to one embodiment of the present invention.

[0013] Fig 2 illustrates a digital x-ray detector using back illumination camera sensor array, according to one embodiment of the present invention.

[0014] Fig 3illustrates a top view of a digital x-ray detector with a light sensitive detector.

[0015] Fig 3a illustrates a light collecting efficiency of front illuminated camera against the light collecting efficiency of back illuminated camera, according to one embodiment of the present invention.

[0016] Fig 3b illustrates blending of images using the back illumination camera sensor array, according to one embodiment of the present invention.

[0017] Fig 4 illustrates a top view of a digital x-ray detector, according to one embodiment of the present invention.

[0018] Fig 5 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in general radiography, according to one embodiment of the present invention.

[0019] Fig 6 and Fig 6a illustrates implementation of a single slice digital x-ray detector using back illumination camera sensor array in a fan beam CT scan detector, according to one embodiment of the present invention.

[0020] Fig 7a and Fig 7b illustrates implementation of a digital x-ray detector using back illumination camera sensor array in intra oral and extra oral x-ray detection, according to one embodiment of the present invention.

[0021] Fig 8 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in cone beam CT scan, according to one embodiment of the present invention.

[0022] Fig 9 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in Dual-energy X-ray absorptiometry (DEXA), according to one embodiment of the present invention.

[0023] Fig 10 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in a single photon emission computed tomography, according to one embodiment of the present invention.

Detailed Description of the Invention
[0024] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0025] Fig 2 illustrates a block diagram of a digital x-ray detector (200) using back illumination camera sensor array (204), according to one embodiment of the present invention.

[0026] As exemplarily illustrated in Fig 2, the digital x-ray detector (200) using back illumination camera sensor array (204) comprises an energy conversion component (201) to convert high radiation impinging on a surface of the energy conversion component to a low energy radiation. Here, the converted low energy radiation is detectable by multiple cameras. The digital x-ray detector also comprises a high energy blocking component (202) located between an energy conversion component (201) and a refraction component (203) to prevent high energy radiation from reaching a back-illumination camera sensor array (204). In an embodiment, a phosphor screen is used as the energy conversion component (201). The refraction component (203) concentrates the converted low energy radiation with appropriate focal length to the back-illumination camera sensor array (204). In an embodiment, a lens is used as a refraction component (204) to concentrate the converted low energy radiation with appropriate focal length to the back-illumination camera sensor array (204).

[0027] In an embodiment, the back-illumination camera sensor array (204) includes one or more back-illumination cameras. The back-illumination camera (204) comprises a lens at a front end, a metal wiring to conduct the signal at a back end and a photo diode located between the lens and the metal wiring to provide better light profile at the edge of the lens. An analog-to-digital converter (205) is connected to each of the back-illumination camera (204) to convert the images captured by the back-illumination camera (204) from analog to digital signals. The digital x-ray detector (200) also comprises multiple slave controllers (206) connected to the analog-to-digital converter (205) to receive digital signals from the analog-to-digital converter (205). The digital x-ray detector (200) also comprises a master controller (207) to receive digital signals from the slave controllers (206). The master controller (207) is configured to send the acquired images to a processing and storage system. The processing and storage system stitches one or more images from multiple overlapping images obtained by the master controller into a single image with improved image quality along the edges (305, as exemplarily illustrated in Fig 3b) of the image.

[0028] In an embodiment, the processing and storage system stitches one or more images from multiple overlapping image using any of the stitching technique, for example, key feature extraction. In key feature extraction technique, the key features are obtained by identifying the edges. The edges are then mapped to similar edge features in next image to stitch the images.

[0029] In an embodiment, the back-illumination cameras(204) are arranged such that the field of view of each of the back-illumination cameras partially overlaps with the field of view of the adjacent back-illumination camera (204) to form multiple overlap regions to form a single image.

[0030] Fig 3 illustrates a top view of a digital x-ray detector using back illumination camera sensor array with a light sensitive detector, according to one embodiment of the present invention.

[0031] As exemplarily illustrated in Fig 3, the digital x-ray detector (200) further comprises a light sensitive detector (208) to transmit control signals to a master controller (207) to activate multiple back-illumination cameras (204) at identical timings to capture images.

[0032] Fig 3a illustrates a light collecting efficiency of front illuminated camera against the light collecting efficiency of back illuminated camera, according to one embodiment of the present invention.

[0033] As exemplarily illustrated in Fig 3a, the light collecting efficiency of back illuminated camera (204) is more at an incident angle of 10degree, 15 degree and 20 degree when compared to front illuminated camera.

[0034] Fig 4 illustrates a top view of a digital x-ray detector, according to one embodiment of the present invention.

[0035] As exemplarily illustrated in Fig 4, the digital x-ray detector (200) comprises the energy conversion component (201) to convert high radiation impinging on a surface of the energy conversion component to a low energy radiation. The high energy blocking component (202) is located between the energy conversion component (201) and the refraction component (203) to prevent high energy radiation from reaching a back-illumination camera sensor array (204). The refraction component (203) concentrates the converted low energy radiation with appropriate focal length to the back-illumination camera sensor array (204). The back-illumination camera (204) comprises a lens at a front end, a metal wiring to conduct the signal at a back end and a photo diode located between the lens and the metal wiring to provide better light profile at the edge of the lens. The light sensitive detector (208) transmits control signals to a master controller (207) to activate multiple back-illumination cameras (204) at identical timings to capture images.

[0036] Fig 5 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in general radiography, according to one embodiment of the present invention.

[0037] As exemplarily illustrated in Fig 5, the digital x-ray detector (200) detects the extent of x-ray attenuation caused by the object exposed to the x-ray radiation. An x-ray tube (501) is used to expose the object to x-ray radiation. The back-illumination camera (204) of the digital x-ray detector (200) comprises a photo diode located between the lens and the metal wiring to provide better light profile at the edge of the lens. Further, the field of view of each of the back-illumination cameras (204) partially overlaps with the field of view of the adjacent back-illumination camera (204) to form multiple overlap regions with improved image stitching, less geometry distortion and better contrast in overlapping regions of captured x-ray images.

[0038] Fig 6and Fig 6a illustrates implementation of a single slice CT-Scan with digital x-ray detector using back illumination camera sensor array in a fan beam configuration, according to one embodiment of the present invention.

[0039] As exemplarily illustrated in Fig 6, the single slice digital x-ray detector (200) using back illumination camera sensor array (204) to detect extent of x-ray attenuation caused by the object (602) exposed in cone beam configuration. Here, the cone beam configuration consists of multiple rows of back-illumination camera.

[0040] A fan beam CT X-Ray generator (601) is used to produce cone beam x-rays. Further, the field of view of each of the back-illumination cameras (204) partially overlaps with each other to form multiple overlap regions with improved image stitching, less geometry distortion and better contrast in overlapping regions.

[0041] Fig 7a and Fig 7b illustrates implementation of a digital x-ray detector using back illumination camera sensor array in intra oral and extra oral x-ray detection, according to one embodiment of the present invention.

[0042] As exemplarily illustrated in Fig 7a, the digital x-ray detector (200) using back illumination camera sensor array (204) flexibly fits within a patient’s mouth to capture image of an intra-oral region (702) such as patients teeth/gum exposed to x-rays (701). The intra-oral region (702) captured using the digital x-ray detector (with back illumination camera sensor array) (200) has improved image quality along the edges of the image.

[0043] As exemplarily illustrated in Fig 7b, the digital x-ray detector (200) using back illumination camera sensor array (204) captures image of an extra-oral region (704) such as patients gum region exposed to x-rays (703). The extra-oral region (704) captured using the digital x-ray detector (200) (with back illumination camera sensor array) has improved image quality along the edges of the image. Further, the field of view of each of the back-illumination cameras (204) partially overlaps with the field of view of the adjacent back-illumination camera (204) to form multiple overlap regions of the captured intra-oral/extra-oral images with improved image stitching and less geometry distortion.

[0044] Fig 8 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in cone beam CT scan, according to one embodiment of the present invention.

[0045] As exemplarily illustrated in Fig 8, the digital x-ray detector (200) using back illumination camera sensor array (204) captures image of an extra-oral region (802) such as patients gum region exposed to cone shaped x-rays (generated using a source 801). The target image captured using the digital x-ray detector (200) (with back illumination camera sensor array) has improved image quality along the edges of the image. Further, the field of view of each of the back-illumination cameras (204) partially overlaps with the field of view of the adjacent back-illumination camera (204) to form multiple overlap regions of the captured intra-oral/extra-oral images with improved image stitching and less geometry distortion.

[0046] Fig 9 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in (Dual-energy X-ray absorptiometry) DEXA, according to one embodiment of the present invention.

[0047] As exemplarily illustrated in Fig 9, the x-ray source (901) uses a very small dose of ionizing radiation to produce images of the target (902), for example, the lower-spine and hips to measure bone loss. The digital x-ray detector (200) using back illumination camera sensor array(204) captures images of target (902) with improved image quality along the edges of the image. Further, the field of view of each of the back-illumination cameras (204) partially overlaps with each other to form multiple overlap regions of the captured target (902) with improved image stitching, and less geometry distortion. In an embodiment, the digital x-ray detector (200) is moved at constant speed to capture images of the target (902) in a line scan mode at very high image resolutions. In line scan mode the digital x-ray detector (200) captures information line by line to build up an image.

[0048] Fig 10 illustrates implementation of a digital x-ray detector using back illumination camera sensor array in a single photon emission computed tomography, according to one embodiment of the present invention.

[0049] As exemplarily illustrated in Fig 10, the digital x-ray detector (200) using back illumination camera sensor array (204) is configured to detect extent of gamma attenuation caused by the object (904) injected with a radioactive tracer (903).

[0050] The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.