Etching a substrate: processes – Forming or treating optical article
Reexamination Certificate
2001-10-05
2004-06-15
Hasanzadeh, P. (Department: 1763)
Etching a substrate: processes
Forming or treating optical article
C250S362000, C250S370110, C250S371000
Reexamination Certificate
active
06749761
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention pertains to a method of producing a scintillator detector arrays that may be used in various applications, such as, but not limited to, a PET detector module or nuclear physics applications. More specifically, it relates to a method of producing a high resolution detector array that can be coupled to photodetectors. In certain applications, the photodetector provides an accurate timing pulse and initial energy discrimination, identification of the crystal interaction, which may include the depth of interaction (DOI).
2. Description of the Related Art
When constructing scintillator arrays, it is known to use block scintillator arrays with sawcut grooves packed with reflector powder. However, this method is not feasible for producing arrays of individual crystals. It is also known to use reflector molds made of a white compound. However, it is often desired to produce light output with a greater depth dependence than these type of reflectors are capable of producing.
Finally, it is also known to hand wrap “plumbers” Teflon® tape around individual detectors as a standard reflector choice for research PET cameras. However, plumbers Teflon® tape is not a realistic choice for large cameras and/or cameras that use very small crystals. Further, hand wrapping individual crystals is both time consuming and difficult to do consistently. Hand wrapping with Teflon® tape also limits the reduction of crystal size for future cameras. In addition, plumbers Teflon® tape, or thicker 8 mil Teflon® tape, is not an ideal reflector. It stretches and creeps, so it can be difficult to accurately cover only the surface of each crystal not coupled to a photodetector. The Teflon® tape also becomes transparent when squeezed, which occurs when making a compact scintillator crystal array, and when glue wicks through it. Moreover, it is difficult to wrap the individual crystals tightly with thicker 8 mil Teflon® tape resulting in inaccurate measures of depth dependence.
What is missing from the art is a method of disposing a reflector between each individual crystal of a high resolution detector array which can efficiently, consistently and accurately cover the desired surfaces of an individual crystal. Accordingly, it is an object of the present invention to provide a method of producing a high resolution detector array having a reflector disposed between individual crystals of the array.
It is a further object of the present invention is to provide a method for producing a high resolution detector array efficiently, consistently and accurately covers the desired surfaces of an individual crystal.
Yet another the object of the present invention is to provide a method for producing a high resolution detector array which will provide very high packing fraction i.e. the distance between scintillator elements will be minimized so the detector efficiency will be higher than is currently achievable.
Still another object of the present invention is to provide a method for producing a high resolution detector array which eliminates the need to hand wrap individual crystals.
BRIEF SUMMARY OF THE INVENTION
In one embodiment of the present invention, the fabrication methodology is enhanced by handling LSO bars rather than single crystals when gluing on the Lumirror® as well as etching the LSO. Namely, an LSO boule is cut into bars of a selected dimension, for example 30 mm wide, which are then acid etched. A selected number, N, of these LSO bars can then be glued together with Lumirror® sheets between each bar (coating the LSO bars and Lumirror® sheets with Epotek 301-2). The glued bar block is then cut again into bars in a perpendicular direction, and these new LSO-Lumirror® bars are etched. Finally, a selected number, M, of these LSO-Lumirror® bars are glued together with Lumirror® sheets between each bar; thus creating an etched N×M LSO-Lumirror® array without having to handle individual LSO crystals or small Lumirror® pieces It will be appreciated by those skilled in the art that while M may be equal to N, M can also be greater than or less than N.
REFERENCES:
patent: 4750972 (1988-06-01), Casey et al.
patent: 4879465 (1989-11-01), Persyk et al.
patent: 5378894 (1995-01-01), Akai
patent: 6245184 (2001-06-01), Riedner et al.
S. R. Cherry et al., “MicroPET: A High Resolution PET Scanner for Imaging Small Animals,” IEEE Transactions on Nuclear Science, vol. 44, No. 3, 1161-1166, Jun. 1997.
C. L. Melcher et al., “Cerium-doped Lutetium Oxyorthosilicate: A Fast, Efficient New Scintillator,” IEEE Transactions on Nuclear Science, vol. 39, No. 4, 502-505, 1992.
J.S. Huber et al., “Characterization of a 64 Channel PET Detector Using Photodiodes for Crystal Identification,” IEEE Transactions on Nuclear Science NS-44, 1197-1201, 1997.
M. Pedrali-Noy et al., “PETRIC—A Positron Emission Tomography Readout Integrated Circuit,” IEEE Transactions on Nuclear Science, vol. 48, No. 3, 479-484, Jun. 2001.
W. W. Moses et al., “The Electronics System for the LBNL Positron Emission Mammography (PEM) Camera,” IEEE Transactions on Nuclear Science, vol. 48, No. 3, 632-636, Jun. 2001.
W. W. Moses et al., “PET Camera Designs for Imaging Breast Cancer and Axillary Nodeinvolvement,” J. Nucl. Med., vol. 36, 69P, 1995.
K. Kurashige et al., “Surface Polishing of GSO Scintillator Using Chemical Process,” IEEE Transactions on Nuclear Science, vol. 45, No. 3 522-524, 1998.
J. S. Huber et al., “Geometry and Surface Treatment dependence of the Light Collection from LSO Crystals,” Nuclear Instruments and Methods in Physics Research A 437, 374-380, 1999.
W. W. Moses et al., “A “Winner-Take-All” IC for Determining the Crystal of Interactions in PET Detectors,” IEEE Transactions on Nuclear Science, vol. 43, No. 3, 1615-1618, Jun. 1996.
Andreaco Mark S.
Moyers J. Clifton
Valgneur Keith
Williams Charles W.
CTI PET Systems, Inc.
Culbert Roberts
Hasanzadeh P.
Pitts & Brittian PC
LandOfFree
Method for producing a high resolution detector array does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing a high resolution detector array, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing a high resolution detector array will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3351085