Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
1998-11-23
2002-06-11
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S366000
Reexamination Certificate
active
06403964
ABSTRACT:
FIELD OF INVENTION
The invention relates to imaging apparatus having a modular structure. In particular the invention relates to imaging apparatus comprising a plurality of imaging devices.
BACKGROUND TO INVENTION
The invention finds application to imaging apparatus for large area imaging using semiconductor imaging devices and is particularly suitable for high energy radiation imaging (i.e. radiation having energies in excess of 1 keV, such as X-rays).
Traditional arrangements for X-ray imaging, including cassette film, other modalities such as wire chambers, scintillating crystals or screens, (e.g. Sodium Iodide NaI), BGO (Bismuth Germanium Oxide) and CR plates (Computed Radiography), have been utilized over the past forty years.
More recently, semiconductor imaging devices have been employed, including CCD-based devices, both in stand-alone implementations and coupled to scintillating screens, silicon microstrip detectors and semiconductor pixel detectors.
Semiconductor pixel detectors, such as have been described in the Applicant's International patent application WO95/33332 incorporated herein by reference, based on ASIC (Application Specific Integrated Circuit) CMOS processing, can provide high spatial resolution, direct detection, compactness, high absorption efficiency and real-time imaging. However, limitations on ASIC CMOS technology (e.g. yield) limit the maximal size of monolithic detectors to a few square centimeters. Various methods of combining individual monolithic detectors have been, therefore, proposed. The major challenge is the formation of a large continuous imaging area without any blind regions.
One method of eliminating such inactive regions in the final image has been the use of software interpolation. However, this method does not recover lost information but only provides an approximation.
Other methods for combining monolithic detectors in large imaging areas without the presence of inactive regions have been proposed.
In the Applicant's International patent application WO 95/33332 mentioned above, a tiling approach is proposed where individual detectors are staggered on a mosaic in a manner that one third of the total desired area is imaged in a single exposure. Three different exposures, at different positions of the mosaic, are required. This approach is cost efficient as it reduces the total number of required detectors and allows for replacement of defective detectors. Nevertheless, this solution requires a moving device, translating the imaging area in two subsequent positions. A total of three snapshots are taken in order to provide substantially continuous coverage.
In European patent application EP-A-421 869, an approach to the joining of individual image detectors is described. The detectors are glued to a stepped support with a detector on a step extending beyond the edge of the step to partially overly a detector on the next lower step. Although this approach allows for large area continuous imaging, it provides a rigid device whose thickness increases with imaging area. Furthermore, as individual detectors are rigidly glued on the apparatus defective component replacement is not addressed.
Another approach to large area imaging is described in European patent application EP-A-577 487. This approach provides an imaging apparatus comprising several individual detector substrates arranged adjacent to each other and rigidly connected to each other by means of support substrates which overlap adjacent detector substrates. The detector substrates are rigidly connected to the support substrates by means of indium bumps. Although the total thickness of the apparatus is independent of the imaging area, the overall structure is, once again, rigid and does not allow for simple individual detector replacement. Furthermore, EP-A-577 487 is silent about possible practical difficulties in fabricating a large structure comprising an array of elements rigidly bump-bonded each together.
The Applicant's UK patent application GB-A-2,305,096 describes an approach to the mounting of imaging devices, for example of the type described in WO95/33332, on a support plane, in which imaging device is secured to a mount to form an imaging device tile, and then the tile is removably mounted on a support plane by means of screws, vacuum, or other fastening arrangements permitting non-destructive removable mounting of the imaging device tiles. However, individual mounting of the individual tiles is required, which can be a time consuming and difficult task for large arrays. Also, providing large numbers of electrical connections to the individual tiles for a large array can require the development of expensive support planes.
Accordingly, there remain problems to be solved regarding the large area imaging, such as facilitating the accurate relative positioning of large numbers of individual tiles on the support plane. Also, there is a need for structures which provide the basis for simplifying the arrangement of and connections to electronic components external to the tiles for enabling readout from the tiles.
The present invention seeks to facilitate the accurate mounting of individual tiles with respect to one another and to the master support plane.
Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from dependent claims may be combined with those of the independent claims in any appropriate manner and not merely in the specific combinations enumerated in the claims.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, there is provided apparatus for imaging radiation, said apparatus comprising:
a plurality of tiles, each tile comprising an imaging device having an array of radiation detector cells;
a number of modules, each module supporting a plurality of said tiles; and
a module support structure, said support structure supporting said module(s).
Thus, according to the invention, an imaging module can be provided for mounting a plurality of imaging devices for forming an imaging array, wherein the imaging module is configured to be mountable on a master support structure and configured to support at least one imaging device tile in a predetermined location. One or a plurality of modules can then mounted on a common module support structure, as required for a particular application.
This enables a modular arrangement of a plurality of tiles such that the tiles can be readily arranged with respect to one another and whereby the modules may be assembled with respect to one another to provide a large area imaging apparatus. The imaging apparatus according to the invention also provides a basis for simplifying the connection to and arrangement of circuit components external to the imaging devices as will be explained below with respect to preferred developments of the invention.
In a preferred embodiment, tiles are mounted on a module and then the modules are mounted on the support structure, for example for forming an imaging cassette. The modules provide a plurality of tile mounting locations in one or more rows whereby the tiles may be accurately mounted with respect the modules and to each other prior to being mounted on the master support structure.
Preferably, the tiles are mounted on the modules in a removable manner to facilitate the replacement of faulty tiles when required and/or the replacement of tiles having different resolutions and/or specifications for different imaging applications. Preferably, the modules are also mounted on the support structure in a removable manner permitting easy replacement of a complete module when required and/or the replacement of modules carrying tiles having different resolutions and/or specifications for different imaging applications.
In one embodiment, an imaging device has a two-dimensional array of radiation detector cells and a module supports a two-dimensional array of tiles.
In a preferred embodiment, a module comprises a board comprising, on a first surface thereof, an array of tile mounting locations, eac
Gagliardi Albert
Hannaher Constantine
Simage Oy
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