IMAGING SYSTEM UTILIZING SPATIAL CODING

• US 3,748,470 A
• Filed: 10/02/1970
• Issued: 07/24/1973
• Est. Priority Date: 10/02/1970
• Status: Expired due to Term

• Current Assignee: Harrison H. Barrett
• Original Assignee: Harrison H. Barrett
• Inventors: Barrett, Harrison H.
• Primary Examiner(s): Borchelt, Archie R.
• Application Number:
  US05/077,459
• Time in Patent Office: 1,026 Days
• Field of Search: 250/71.5S,105
• US Class Current: 378/2
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G01T 1/1641 Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
• CPC Class Codes: G01T 1/1642 using a scintillation crystal and position sensing photodetector arrays, e.g. ANGER cameras
• CPC Class Codes: G01T 1/1645 using electron optical imaging means, e.g. image intensifier tubes, coordinate photomultiplier tubes, image converter
• CPC Class Codes: G01T 1/295 using coded aperture devices, e.g. Fresnel zone plates handling of radiation of particles, e.g. using diaphragms, collimators, diffraction G21K1/00
• CPC Class Codes: G01T 1/2978 Hybrid imaging systems, e.g. using a position sensitive detector (camera) to determine the distribution in one direction and using mechanical movement of the detector or the subject in the other direction or using a camera to determine the distribution in two dimensions and using movement of the camera or the subject to increase the field of view G01T1/2985 takes precedence
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

An imaging system suitable for use with high energy nuclear particles or photons such as gamma radiation and X-radiation. The system provides means for illuminating an object with radiation as well as spatially coding the illuminating radiation or emitted radiation if the object is self-luminous, to provide a composite image representing the summation of the shadows from all points of the source of illumination. Spatial modulation is accomplished by a mask having a coded pattern of transparent and opaque regions linearly scanned in time. The resulting signal has the characteristics of a chirp waveform typical of pulse compression radars. The composite image is readily decoded by a delay line having a phase or delay characteristic complementary to that of the spatial modulation pattern.

Claims

1. In combination:

means for spatially distributing sequentially occurring quanta of radiant energy in a coded format, said distribution having a succession of first regions and a succession of second regions, the transmissivity of said second regions to said raDiant energy being less than the transmissivity of said first regions to said radiant energy, said first regions being interspersed among said second regions and being arranged in accordance with said format;

means responsive to said quanta of radiant energy for providing signals having information relative to the locations of said quanta of radiant energy, said signal providing means including means for converting radiant energy into energy carried by electronic charges;

said signal providing means being spaced apart from said distributing means such that quanta of radiant energy emanating from loci which are spaced apart and equidistant from siad said distributing means can impinge upon a single point of said signal providing means; and

means having information relative to said format for decoding said signals to extract therefrom information relative to locations of points of emanation of said quanta of radiant energy.

2. The device as defined by claim 1 wherein said decoding means provides an image and comprises:

means for scanning the information of said signals, said scanning means providing a time modulated signal in response to the locations of said quanta; and

means for filtering said time modulated signal to provide a point of said image.

3. The device as defined by claim 2 further comprising:

means responsive to said filtering means for displaying said point of said image; and

means for coordinating said display means with said scanning for positioning said point within said image.

4. In combination:

means responsive to quanta of radiant energy emitted sequentially from a source of such radiant energy, said means inhibiting the passage of such ones of said quanta being emitted in any one of a plurality of predetermined directions, said means permitting the passage of at least some of said quanta of radiant energy emitted from said source in other predetermined directions, said means being further structured for providing a sequence of regions of inhibited passage and a sequence of regions of permitted passage of quanta of radiant energy, said regions of inhibited passage and permitted passage varying in size in accordance with a predetermined spatial code;

means including scintillation means for detecting the presence of such ones of said quanta of radiant energy which have passed through said impeding means, said detecting means providing signals having information relative to the locations of such quanta;

said detecting means and said inhibiting means being positioned relative to each other and relative to said source such that quanta of radiant energy emitted from separate points of said source and passing through separate ones of said regions of permitted passage can impinge upon a single point of said detecting means; and

means responsive to said signals of said detector means for decoding said information to provide an image of said source of radiation.

5. In combination:

means for illuminating an object with quanta of radiant energy, said means having regions of emission of said radiant energy interspersed among regions of non-emission, said regions of emission being arranged in a spatially coded pattern, said means being positioned relative to said object to permit quanta of radiant energy from different ones of said emissive regions to impinge upon a single point of said object;

means responsive to the transmissivity of said object to said radiant energy for detecting radiant energy transmitted through said object, said detecting means providing information relative to the locations of such ones of said quanta of radiant energy arriving at said detecting means within a predetermined interval of time; and

means responsive to said information of said detecting means for decoding said spatially coded pattern to provide an image of said object.

6. In combination:

means responsive to rays of radiation emitted from an object having sources of such radiation for moduLating said radiation while retaining the directions of said rays, said means comprising an array of radiation transmissive regions interspersed among relatively opaque regions, said transmissive regions being arranged in accordance with a predetermined format;

means for detecting said modulated radiation, said detecting means being positioned relative to said modulating means such that one of said rays of radiation transmitted via one of said transmissive regions and a second of said rays of radiation transmitted via a second of said transmission regions can impinge upon a single point of said detecting means, said detecting means providing a signal having information relative to said format and to the locations of such ones of said rays of radiation which pass through said transmissive regions; and

means for correlating said first signal with the arrangement of said transmissive regions in said predetermined format to provide an image of said object, said correlating means including means for scanning said detector signal and means for filtering the output of said scanning means, said filtering means being frequency dispersive.

7. The device defined by claim 6 wherein said correlating means further comprises:

means for generating a second signal which is modulated with said information relative to said format and further modulated with said information relative to said rays of radiation; and

second means for providing a filtering function and filtering said detector signal, said second filtering means having a temporal weighting function complementary to the arrangement of said transmissive regions in said format for providing an image of said object.

8. In combination:

means responsive to the energy of particles moving along substantially linear paths for modulating the intensity of said particles, said modulating means comprising an array of barrier elements having predetermined sizes and being arranged in a predetermined format;

means for detecting selected ones of said particles which pass between said barrier elements to provide a signal having information relating to the locations of said selected particles, said detecting means being spaced from said modulating means to permit particles moving along a pair of said paths disposed on opposite sides of a barrier element to impinge on a single point of said detector means; and

means for comparing said signal with said format to extract said information for forming an image.

9. An imaging system responsive to radiation emitted from an object, said imaging system comprising:

means for spatially modulating said radiation while retaining the direction of rays of said radiation, said moduating means comprising an array of radiation transmissive regions having differing sizes and arranged in a predetermined configuration;

means responsive to said spatially modulated radiation for forming a first image having information relative to said object and relative to said predetermined configuration, said first image forming means being positioned relative to said modulating means such that one of said rays passing through one of said transmissive regions and a second of said rays passing through a second of said transmissive regions can impinge upon a single point of said first imaging forming means;

a delay medium; and

means for transmitting portions of said first image through said delay medium, said delay medium imparting to each of said portions a differential delay complementary to a corresponding portion of said predetermined configuration for providing said information relative to said object.

10. The system as defined by claim 9 further comprising means responsive to said transmission means for displaying an image of said object.

11. The system as defined by claim 10 wherein said transmission means comprises:

means for scanning said first image to provide a time modulated signal containing information relative to said predetermined configuration; and

Wherein said delay medium comprises means for generating surface waves.

12. The system as defined by claim 11 wherein said modulating means further comprises means for impeding radiation having an energy lower than a preset magnitude.

13. An imaging system comprising:

a source emitting radiation for illuminating an object, said source being adapted to provide said radiation with a spatially modulated pattern, said source having a series of spaced apart luminous regions each of which is positioned for illuminating a common point on said object;

means responsive to said spatially modulated radiation for forming a first image having information relative to said object and relative to said pattern;

a delay medium; and

means for transmitting portions of said first image through said delay medium, said delay medium imparting to each of said portions a differential delay inverse to a corresponding portion of said pattern for providng said information relative to said object.

14. The system as defined by claim 13 further comprising means responsive to said transmission means for displaying an image of said object.

15. The system as defined by claim 14 wherein said transmission means comprises:

means for scanning said first image to provide a time modulated signal containing information relative to said pattern; and

wherein said delay medium comprises means for generating surface waves.

16. An array of regions each of which comprises a radiation emissive material and has a predetermined size, each of said regions being spaced apart such that each of said sizes and each of said spacings have preselected magnitudes for providing a predetermined spatial frequency characteristic, and means for positioning each of said regions in said array, a plurality of regions of said array of regions being arranged in a sequence according to the magnitudes of their sizes and their spacings ordered by monotonically increasing magnitudes to provide said spacial frequency characteristic with a characteristic of a chirp wave form.

17. In combination:

means responsive to rays of radiation emitted from an object having sources of such radiation for modulating said radiation with a spatial pattern while retaining the directions of said rays, said means comprising an array of radiation transmissive regions illuminated by said radiation and interspersed among relatively opaque regions, said transmissive regions being configured and arranged in accordance with a predetermined format such that said spatial pattern contains information relative to said format; and

means responsive to the locations of said modulated rays of radiation for correlating said modulated rays with said format to derive an image of said object, said correlating means being positioned relative to said modulating means such that one of said rays passing through one of said transmissive regions and a second of said rays passing through a second of said transmissive regions can impinge upon a single point of said correlating means.

18. The device as defined by claim 17 wherein said correlating means comprises means for varying said responsivity in accordance with the spacing between said object and said modulating means whereby said device is focused.

19. In combination:

means responsive to rays of radiation emitted from a source of radiation for modulating said radiation, said means comprising an array of radiation transmissive regions interpersed among relatively opaque regions, said transmissive regions being arranged in accordance with a predetermined format;

means including scintillation means for detecting said modulated radiation for providing a signal having information relative to said format and to the locations of such ones of said rays of radiation which pass through said transmissive regions;

said detecting means being spaced apart from said modulating means to permit rays of radiation passing through noncontiguous ones of said transmissivE regions to impinge upon a common point of said detecting means; and

means for correlating said signal with said predetermined format to provide the direction of said source.

20. In combination:

means responsive to the energy of particles emanating from a source of such particles and moving along substantially linear paths for modulating the energy of said particles, said modulating means comprising an array of barrier elements having predetermined sizes and being arranged in a predetermined format;

means for detecting selected ones of said particles which pass between said barrier elements to provide a signal having information relating to the locations of said selected particles, said barrier elements being spaced from said detecting means to permit particles traveling on opposite sides of one of said barrier elements to impinge upon a common point of said detecting means; and

means for comparing said signal with said format to extract said information to provide the direction of said source.

21. In combination:

means for modulating the spatial distribution of quanta of radiant energy illuminating an object, said spatial modulation having a predetermined format;

means responsive to the locations of quanta of radiant energy for receiving said quanta of radiant energy, said receiving means preserving information relative to said locations; and

means for filtering said received radiant energy concurrently with the reception of quanta of radiant energy by said receiving means, the impulse response function of said filtering means having a format complementary to said spatial modulation format for providing information relative to said object.

22. A scanning system comprising:

means for modulating the distribution of radiant energy emanating from an object, said modulating means having a succession of radiation transmissive regions of differing sizes, said radiation transmissive regions being arranged in a sequence of monotonically increasing sizes in a first direction and in a second direction;

means for detecting said quanta of radiant energy, said detecting means providing an electrical impulse in response to the reception of a quanta of said radiant energy, said detecting means being spaced apart from said modulating means to permit radiant energy passing through different ones of said transmissive regions to impinge upon a common point of said detecting means;

means for storing said impulses, said storage means preserving data relative to the locations of the received quanta of radiant energy;

means for filtering the data in said storage means, said filtering means having a phase characteristic which is the inverse of the spatial modulation format of one of said sequences of transmissive regions;

second storage means for receiving data from the filtering means;

second filtering means for filtering the data in said second storage means, said second filtering means having a phase charactertistic which is inverse to that sequence of said transmissive regions in a second direction; and

means responsive to the data filter by said first filtering means and the data filtered by said second filtering means for providing image points of said object in a first direction and in a second direction.

23. The scanning system of claim 22 wherein said first filtering means includes means for scanning said first storage means in accordance with a predetermined format.

24. The scanning system in accordance with claim 23 wherein said filtering means comprises a surface wave delay line.

25. The scanning system in accordance with claim 24 wherein said first storage means comprises a storage tube display.

26. The scanning system in accordance with claim 25 wherein said scanning of said first storage means provides a chirped frequency signal to said first filtering means.

27. A scanning system comprising:

means for placing a source of radiant energy in an object to be scanned;

means for detectIng said radiant energy;

means interposed between said object and said detecting means for casting a shadow of said radiant energy upon said detecting means, said shadow comprising a plurality of shaded regions varying in size and position in accordance with a predetermined format;

said shadow casting means being spaced from said detecting means such that a second source of radiant energy located alongside the aforesaid source of radiant energy casts a second shadow comprising a plurality of shaded regions which overlap the shaded regions of the aforesaid shadow;

means coupled to said detecting means for storing data relative to the configuration of said shadow; and

means for processing said stored data while said radiant energy is incident upon said detecting means, said processing means providing data relative to the form of said object.

28. In combination:

an array of sources of radiant energy positioned to illuminate an object, said sources having differing sizes and being arranged in a predetermined format;

means for detecting quanta of said radiant energy, said detecting means being positioned relative to said object such that radiant energy from a plurality of said sources can impinge upon a common point of said object and in passing by said object is incident upon said detecting means, said detecting means providing data relative to the spatial positions of such ones of said quanta of radiant energy which are incident upon said detecting means; and

means for filtering the data provided by said detecting means, said filtering means having a phase characteristic functionally dependent upon said format to provide data relative to the form of said object.

29. In combination:

means for altering the spatial distribution of gamma rays, said gamma rays being utilized for illuminating an object, said altering means comprising a succession of radiation transmissive regions dispersed among regions of relative opacity to gamma rays, said transmissive regions being arranged in a predetermined format, said transmissive regions having a depth smaller than the width of such regions;

means for detecting such ones of said gamma rays that pass through said altering means, said detecting means providing data relative to the locations of said gamma rays; and

means for correlating said data with said format to provide information about said object.

30. A nuclear imaging system comprising:

means for altering the spatial distribution of radiation utilized for illuminating an object, said altering means comprising a succession of radiation transmissive regions interspersed among regions of relative opacity to said radiation, said transmissive regions being arranged in a predetermined format in the form of a chirp pattern in at least one dimension such that the transmissive regions are arranged according to size in a monotonically decreasing array;

means for detecting rays of said radiation that pass through said altering means, said detecting means including means for providing data relative to the locations upon said detecting means where individual rays of said radiation impinge; and

means for correlating said data with said format to provide information about said object.

31. The nuclear imaging system in accordance with claim 30 wherein the format of said altering means includes a chirp pattern in a second dimension providing an array of radiation transmissive regions arranged according to size in a monotonically decreasing array.

32. The nuclear imaging system in accordance with claim 31 wherein:

the detecting means further comprises means for storing said data, said data being stored in the form of an array of points each of which represents the location of a point of impingement of a ray of radiation upon the detecting means; and

wherein said correlating means comprises means for scanning the array of data points of said detecting means to provide a scan signal, said correlating means further coMprising means for filtering said scan signal, the frequency bandwidth of said scan signal being related to the spacing between locations of said points of impingement of rays of radiation upon said detecting means, said filtering means enabling a focussing of said nuclear imaging system when the bandwidth of said scan signal approximates the bandwidth of said filtering means.

33. The imaging system in accordance with claim 32 further comprising means for varying said focus.

34. The imaging system according to claim 33 wherein said variable focus means comprises means for varying the scanning rate of said scanning means of said correlating means.

35. A nuclear imaging system comprising:

means for illuminating an object with radiation, said illuminating means comprising a succession of radiation emissive regions interspersed among regions of non-emission, said emissive regions being arranged in a predetermined format in the form of a chirp pattern in at least one dimension such that the emissive regions are arranged according to size in a monotonically decreasing array;

means for detecting rays of said radiation that pass from said illuminating means, said detecting means including means for providing data relative to the locations upon said detecting means where individual rays of said radiation impinge; and

means for correlating said data with said format to provide information about said object.

36. The nuclear imaging system in accordance with claim 35 wherein the format of said illuminating means includes a chirp pattern in a second dimension providing an array of radiation emissive regions arranged according to size in a monotonically decreasing array.

37. The nuclear imaging system in accordance with claim 36 wherein:

the detecting means further comprises means for storing said data, said data being stored in the form of an array of points, each of which represents the location of a point of impingement of a ray of said radiation upon the detecting means; and

wherein said correlating means comprises means for scanning the array of data points of said detecting means to provide a scan signal, said correlating means further comprising means for filtering said scan signal, the frequency bandwidth of said scan signal being related to the spacing between locations of said points of impingement of rays of said radiation upon said detecting means, said filtering means enabling a focussing of said nuclear imaging system when the bandwidth of said scan signal approximates the bandwidth of said filtering means; and

wherein said nuclear imaging system further comprises means for varying said focus, said variable focus means comprising means for varying the scanning rate of said scanning means of said correlating means.

38. In combination:

means for spatially distributing quanta of radiant energy in a coded format, said distribution having a succession of regions of differing dimensions, said regions having differing amounts of said quanta; and

means responsive to said quanta of radiant energy for providing signals having data relative to the locations of said quanta of radiant energy, said signal providing means including means for converting radiant energy into energy carried by electronic charges, and said signal providing means being spaced from said distributing means to permit quanta of radiant energy emanating from points disposed at differnt angular orientations to said signal providing means to impinge upon a common point of said signal providing means.

39. The combination according to claim 38 further comprising means coupled to said signal providing means for storing said signals, and means for focussing said signal providing means.

40. The combination according to claim 39 further comprising means for extracting data from said storage means, said extracting means including means for filtering said data, said filtering means having a filter characteristic complementary to said spatial distribution.

41. IN combination:

means responsive to a spatial distribution of quanta of radiant energy for providing a transform domain representation of an image, said means providing signals having data relative to the locations of said quanta radiant energy and including means for converting radiant energy into energy carried by electronic charges suitable for electronic amplification; and

means responsive to said signals for decoding said spatial distribution to extract data from said signals, said data being suitable for forming an image.

42. The combination according to claim 41 further comprising means for storing said signals.

43. The combination according to claim 42 further comprising means for extracting data from said storage means, said extracting means including means for filtering said data, said filtering means having a filter characteristic complementary to said spatial distribution, and means for scanning said signal providing means.