Coded aperture masks for radiation-based medical imaging
View Patent ↗This invention relates to a coded aperture mask for use in diagnostic nuclear medicine imaging. The coded aperture mask consists of a sheet of radiation opaque mask material having a series of apertures extending therethrough. The thickness of mask material has an attenuation percentage of less than 75% and, in a preferred embodiment, about equal to 29%. The coded aperture mask also, in a preferred embodiment, has a lead attenuation tube and has a projection of the smallest hole occupying the same area as a single pixel of a detector. The invention extends to a diagnostic nuclear medicine imaging system which uses a 16 bit gamma camera as a radiation detector.
1. A coded aperture mask for use in radiation-based medical imaging comprising a sheet of radiation opaque mask material having a series of apertures extending therethrough, the thickness of mask material having an attenuation percentage of less than 50%.
2. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 1 in which the mask material has an attenuation percentage of less than 30%.
3. A coded aperture mask for use in radiation-based medical imaging as claimed in any one of claims 2 and 1 in which the coded aperture mask is used for imaging gamma-rays.
4. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 3 in which the sheet of radiation opaque mask material is a sheet of metal selected from the group consisting of tungsten, gold, lead and platinum.
5. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 4 in which, when the metal is tungsten, it has a thickness of 100 μm (which is largely transparent) for imaging Technetium-99 m (which has an energy of 140 keV).
6. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 4 in which, when the metal is gold, it has a thickness of 90 μm (which is largely transparent) for imaging Technetium-99 m (which has an energy of 140 keV).
7. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 4 in which, when the metal is lead, it has a thickness of 130 μm (which is largely transparent) for imaging Technetium-99 m (which has an energy of 140 keV).
8. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 4 in which, when the metal is platinum, it has a thickness of 80 μm (which is largely transparent) for imaging Technetium-99 m (which has an energy of 140 keV).
9. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 1 in which the coded aperture has a projection of the smallest hole occupying the same area as a single pixel of a detector.
10. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 1 in which multiple coded apertures are arranged in an array which is from a 3 by 3 to a 5 by 5 array.
11. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 10 in which a radiation attenuating tube extends about each coded aperture mask in the direction of the axes of the apertures therein.
12. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 11 in which each tube extends from either side of the respective masks.
13. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 12 in which each tube has parallel sides.
14. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 11 in which the masks are carried on one sheet of material.
15. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 11 in which the coded aperture masks are made of tungsten and the radiation attenuating tubes are made of lead.
16. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 15 in which the tungsten has a thickness of 100 μm.
17. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 15 in which the lead has a thickness of 1 to 2 mm.
18. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 17 in which each tube extends up to 50 cm on either side of the array.
19. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 17 in which each tube extends up to at least 10 cm on either side of the array.
20. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 1 in which the masks are configured for gamma rays.
21. A coded aperture mask for use in radiation-based medical imaging as claimed in claim 20 in which the gamma rays have an energy of 140 keV.
22. A radiation-based medical imaging system comprising a radiation source, a coded aperture mask as claimed in claim 1 and a radiation detector.
23. A radiation-based medical imaging system as claimed in claim 22 in which the radiation source is a gamma-ray radiation source.
24. A radiation-based medical imaging system as claimed in claim 22 in which the radiation detector is a gamma camera.
25. A radiation-based medical imaging system as claimed in claim 24 in which, the gamma camera is a 16 bit gamma camera.
26. A coded aperture mask for use in radiation-based medical imaging comprising a sheet of radiation opaque mask material having a series of apertures extending therethrough, the thickness of mask material having an attenuation percentage of less than 75% and the coded aperture having a projection of the smallest hole occupying the same area as a single pixel of a detector.