Attenuator for providing a test image from a radiation source
First Claim
1. A nuclear radiation attenuator for providing a test image from a flood source of radiation for testing a scintillation camera comprising:
- a plurality of stackable plates formed of radiation attenuating material and selected so that a plate provides a background region of substantially uniform background radiation passed therethrough from said flood sources, each of said plates having a generally uniform thickness;
said plates each including a plurality of apertures which form discrete target regions located in the background region of the plate, each target region enabling the transmittal of radiation from said flood source with an intensity that differs from the radiation passed through said background region to provide for each target region a desired target to background intensity contrast ratio between it and said background region, said apertures being regularly distributed over a plate to enable examination of the linearity of said camera, and with the size of said apertures being selected to provide an indication of the spatial resolution of said camera and wherein wherein the apertures in the plates are so located that when said plates are stacked, first target regions each have a material thickness that is different from the combined plates background region thickness and wherein second target regions have a material thickness that is different from the thickness of said first target regions and said combined plates background region.
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Abstract
A nuclear radiation attenuator for providing a test image from a source of radiation is disclosed. The attenuator provides a test image including a plurality of discrete target images located in a background image. Each target image has an intensity that differs from the intensity background image to provide a target to background contrast ratio for each target image. A plurality of the target images each have a different contrast ratio so that the contrast ratios of the target simulate contrast ratios found in clinical testing. The attenuator provides a standardized test image that enables the performance of a scintillation camera to be tested routinely.
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Citations
14 Claims
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1. A nuclear radiation attenuator for providing a test image from a flood source of radiation for testing a scintillation camera comprising:
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a plurality of stackable plates formed of radiation attenuating material and selected so that a plate provides a background region of substantially uniform background radiation passed therethrough from said flood sources, each of said plates having a generally uniform thickness; said plates each including a plurality of apertures which form discrete target regions located in the background region of the plate, each target region enabling the transmittal of radiation from said flood source with an intensity that differs from the radiation passed through said background region to provide for each target region a desired target to background intensity contrast ratio between it and said background region, said apertures being regularly distributed over a plate to enable examination of the linearity of said camera, and with the size of said apertures being selected to provide an indication of the spatial resolution of said camera and wherein wherein the apertures in the plates are so located that when said plates are stacked, first target regions each have a material thickness that is different from the combined plates background region thickness and wherein second target regions have a material thickness that is different from the thickness of said first target regions and said combined plates background region. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A nuclear radiation attenuator for providing a test image from a radiation source comprising:
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a body formed of a plurality of stacked plates having apertures, with apertures of different plates being aligned with each other to form discrete target regions, with the portion of the body lying between the plates providing a background region with a radiation attenuation that is substantially constant throughout the background region so as to transmit radiation from said source as a uniform background image; said apertures being of substantially equal area and regularly distributed over the body with each target passing radiation with an intensity that differs from radiation passed through said background region to provide a target to background intensity contrast ratio, with the number of plates in said body being selected to provide a target to background ratio that lies in the range between 1.1 to 1 and 2.5 to 1 wherein the apertures in the respective plates are so distributed that selected ones of apertures in different plates align while other apertures in plates align with a background region of a plate so that said body provides a plurality of regularly distributed target regions with different target to background ratios. - View Dependent Claims (9, 10)
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11. A nuclear radiation attenuator for providing a test image from a radiation source comprising:
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a body of stacked generally flat plates, each of which comprises radiation attenuating material, said body including a background region having a substantially uniform material thickness; said body including a plurality of target regions located in said background region and having a thickness that is smaller than the thickness of said background region, each said target region having a material thickness differing from said background region thickness, each said target region transmitting from said source a target image having an intensity that differs from said background image intensity to provide for each target image an intensity contrast ratio between it and said background image, a first said target region differing in material thickness from a second target region to provide target images having different contrast ratios, said body further comprising at least first and second plates aligned in parallel relation to each other, said first plate including a first aperture corresponding in location to said first target region, said second plate including first and second apertures corresponding in location respectively to said first and second target regions, said first aperture of said second plate having an area substantially identical to and being aligned with said first aperture of said first plate so that radiation is attenuated by both said plates in the background region, so that radiation is attenuated by said first plate in said second target region and radiation is attenuated by neither plate in said first target region said first and second apertures of said second plate being substantially equal in area to each other, said second plate including a third aperture differing in area from said first and second apertures of said second plate and corresponding in location to a third target region, said first plate including a second aperture differing in area from said first aperture of said first plate and corresponding in location to said third target region, said second aperture of said first plate being substantially identical in area to and aligned with said third aperture of said second plate, whereby radiation is attenuated by neither plate in said third region thereby providing a target image substantially identical in intensity and differing in area to said first target image, said first and second target images being substantially identical in area and differing in intensity. - View Dependent Claims (12, 13, 14)
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Specification