US3786270A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Proportional counter radiation camera
Assignee: United States Atomic Energy Commission
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Filing: 1973-02-01
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Granted: 1974-01-15
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Expires: 1993-02-01
Abstract
Abstract A gas-filled proportional counter camera that images photon emitting sources has been provided. A two-dimensional, positionsensitive proportional multiwire counter is provided as the detector. The counter consists of a high voltage anode screen sandwiched between orthogonally disposed planar arrays of multiple parallel strung, resistively coupled cathode wires. Two terminals from each of the cathode arrays are connected to separate timing circuitry to obtain separate X and Y coordinate signal values from pulse shape measurements to define the position of an event within the counter arrays which may be recorded by various means for data display. The counter is further provided with a linear drift field which effectively enlarges the active gas volume of the counter and constrains the recoil electrons produced from ionizing radiation entering the counter to drift perpendicularly toward the planar detection arrays. A collimator is interposed between a subject to be imaged and the counter to transmit only the radiation from the subject which has a perpendicular trajectory with respect to the planar cathode arrays of the detector.
Inventors
- 👤 C Borkowski
- 👤 M Kopp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:51
CPC Classifications
H; H01; H01J; H01J47/00; H01J47/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
340 words
An ionizing radiation camera for imaging radiation sources, comprising: a gas-filled proportional counter envelope having a radiation pervious window therein for receiving radiation from said source; first, second, and third closely stacked planar detection electrodes disposed within said counter envelope in spaced parallel planes, at least two of said planar electrodes comprising multiple resistively coupled parallel strung wires so as to form first and second pairs of output terminals, each pair of said output terminals taken at opposite sides of said resistively coupled multiple wire electrodes so that the shape of output pulses from the respective terminal pairs is indicative of the location of a radiation event across the corresponding multiple wire electrode, and said multiple wire electrodes being disposed orthogonally with respect to each other; means for providing an electrostatic drift field region in the path of radiation from said source between said window and said electrodes so that electrons generated by radiation interacting with the counter gas are forced to drift along the same trajectory as the entering radiation; a positive high voltage source connected to the central one of said stacked detection electrodes forming an anode so as to provide an electrostatic field in the area of said electrodes; a first pulse detector means connected to said first pair of output terminals and responsive to the rise times of output pulses from said first pair of output terminals for producing an output pulse having an amplitude proportional to the position of a detected event across the corresponding multiple wire electrode connected to said first pair of terminals; a second pulse detector means connected to said second pair of output terminals and responsive to the rise of output pulses from said second pair of output terminals for producing an output pulse having an amplitude proportional to the position of said event acrOss the corresponding multiple wire electrode connected to said second pair of terminals; and two dimensional recording means connected to the outputs of said first and second detector means for recording the radiation image of said source.
Claim 2
Dependent Claim
340 words
An ionizing radiation camera for imaging radiation sources, comprising: a gas-filled proportional counter envelope having a radiation pervious window therein for receiving radiation from said source; first, second, and third closely stacked planar detection electrodes disposed within said counter envelope in spaced parallel planes, at least two of said planar electrodes comprising multiple resistively coupled parallel strung wires so as to form first and second pairs of output terminals, each pair of said output terminals taken at opposite sides of said resistively coupled multiple wire electrodes so that the shape of output pulses from the respective terminal pairs is indicative of the location of a radiation event across the corresponding multiple wire electrode, and said multiple wire electrodes being disposed orthogonally with respect to each other; means for providing an electrostatic drift field region in the path of radiation from said source between said window and said electrodes so that electrons generated by radiation interacting with the counter gas are forced to drift along the same trajectory as the entering radiation; a positive high voltage source connected to the central one of said stacked detection electrodes forming an anode so as to provide an electrostatic field in the area of said electrodes; a first pulse detector means connected to said first pair of output terminals and responsive to the rise times of output pulses from said first pair of output terminals for producing an output pulse having an amplitude proportional to the position of a detected event across the corresponding multiple wire electrode connected to said first pair of terminals; a second pulse detector means connected to said second pair of output terminals and responsive to the rise of output pulses from said second pair of output terminals for producing an output pulse having an amplitude proportional to the position of said event acrOss the corresponding multiple wire electrode connected to said second pair of terminals; and two dimensional recording means connected to the outputs of said first and second detector means for recording the radiation image of said source.
Claim 3
Dependent Claim
24 words
The radiation camera as set forth in claim 1 further including a channel collimator disposed between said source and the window of said counter.
Claim 4
Dependent Claim
59 words
The radiation camera as set forth in claim 2 wherein said means for providing an electrostatic drift field region includes a plurality of parallel stacked electrodes and a source of negative high potential connected to said electrodes forming said drift field so as to provide a linear drift field region through an extended active gas region of said counter.
Claim 5
Dependent Claim
112 words
The radiation camera as set forth in claim 3 wherein said drift field electrodes are formed by a plurality of parallel insulatably spaced apart conductive plates each having a central aligned rectangular opening defining the sensitive detection area of said counter, a first one of said plates disposed adjacent said window having an electrically conductive radiation pervious material disposed in the rectangular opening thereof so as to limit the drift field region, said first plate being connected to said negative high voltage supply and a plurality of equal value resistors connected respectively between adjacent ones of said plates and the last one of said plates adjacent said detection electrodes and ground potential.
Claim 6
Dependent Claim
40 words
The radiation camera as set forth in claim 4 wherein said at least two of said multiple wire detection electrodes are formed of series connected equal resistance wires disposed on either side of said central one of said stacked electrodes.
Claim 7
Dependent Claim
138 words
The radiation camera as set forth in claim 1 wherein said window is of a size to form a pinhole image of said radiation source on said detection electrodes and wherein said means for providing said drift field region includes a plurality of insulatably spaced apart electrodes each having a central aligned different size opening forming a frustoconical shaped aperture projecting therethrough, a first one of said electrodes disposed adjacent said window and whose opening forms the top of said frustoconical shaped aperture, and means for applying a negative high voltage to said electrodes so as to provide a generally spherical drift field in said region, said voltages applied to said electrodes decreasing from the top to the base of said region by a factor of 1/R, where R is the distance of a plate from said window.
Claim 8
Dependent Claim
49 words
The radiation camera as set forth in claim 6 further including a spherical segment shaped grid forming one of said electrodes disposed adjacent said detection electrodes at the base of said frustoconical shaped aperture, said spherical segment grid having a radius equal to its distance from said pinhole window.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |