Gamma-ray imaging with sub-pixel resolution

Claim 2

A gamma-ray imaging system for producing high resolution images, comprising: (a) a collimator plate having multiple holes for collimating gamma photons emitted from an object to be imaged; (b) a gamma detector pixel array located in an imaging plane, comprising a plurality of pixels having predetermined pitch between pixels, each pixel operative to convert the gamma photons directly into electrical signals which comprise the image data, said multiple holes in the collimator plate being smaller in diameter than half the pitch between the pixels, and being arranged in a spatial periodic structure such that the pitch between the pixel contains two or more periods of the holes in the spatial periodic structure; (c) an actuator for producing relative movement between the object to be imaged and the gamma detector pixel array in the imaging plane to successive predetermined imaging positions, the distance between each successive predetermined imaging position being equal to the pitch of the spatial periodic structure of the holes in the collimator plate, (d) an electronic controller for controlling the relative movement between the object to be imaged and the gamma detector pixel array according to a predetermined program, said multiple holes and said successive predetermined imaging positions being arranged so that the photons emerging from each hole at each imaging position produce discrete multiple irradiated regions on the pixels outside dead areas at the edges of the pixels; (e) an electronic signal measurer for measuring at each successive predetermined imaging position the electrical signals produced by the pixels of the gamma detector pixel array, and (f) an electronic processing unit for processing the electrical signals produced by the pixels of the gamma detector pixel array at each successive predetermined imaging position by constructing a set of independent equations equal to the number of said irradiated regions, accurately solving the set of independent equations to derive a data value of the electrical signals corresponding to each of the irradiated regions, and using the data values to compose and display an image of the object.

Claim 3

A system according to claim 1 wherein the electronic signal measurer measures the electrical signals produced by the pixels by means of single photon counting corresponding to a predetermined energy range.

Claim 4

A system according to claim 2 wherein the collimator plate has borders without holes.

Claim 5

A system according to claim 3 wherein the object is a human body after treatment with a gamma emitting tracer material.

Claim 6

A system according to claim 4 wherein the imaging plane comprises arrays of modular detectors assemblies.

Claim 7

A system according to claim 5 wherein each modular detector includes a "chip on board" package comprising at least one ASIC.

Claim 8

A system according to claim 1 wherein the material of the detector pixel array is CdTe.

Claim 9

A system according to claim 1 wherein the material of the detector pixel array is CdTe.

Claim 10

A system according to claim 1 wherein the actuator for producing relative movement comprises a motor.

Claim 11

A system according to claim 6 wherein said actuator for producing relative movement does so when the collimator plate is attached to the gamma ray imaging system so that it moves together with the imaging plane.

Claim 12

A system according to claim 10 wherein the actuator for producing relative movement does so when said object is in a static position.

Claim 13

A system according to claim 10 wherein said actuator for producing relative movement does so when said imaging plane is in a static position.

Claim 14

A system according to claim 10 wherein said actuator for producing relative movement does so when said imaging plane and said object are both moving.

Claim 15

A system according to claim 6 wherein said actuator for producing relative movement does so when the collimator plate is kept in a static position.

Claim 16

A system according to claim 14 wherein the actuator for producing relative movement does so when said object is in a static position.

Claim 17

A system according to claim 14 wherein said actuator for producing relative movement does so when said imaging plane is in a static position.

Claim 18

A system according to claim 14 wherein said actuator for producing relative movement does so when said imaging plane and said object are both moving.

Claim 19

A system according to claim 1 wherein the relative movement is controlled by a closed loop electronic control system.

Claim 20

A system according to claim 18 wherein the closed loop electronic control system includes a position reader that feeds a controller for controlling the actuator for producing relative movement.

Claim 21

A system according to claim 1 wherein the actuator for producing the relative movement includes a moveable platform.

Claim 22

A system according to claim 20 wherein the platform is arranged to carry a human body.

Claim 23

A system according to claim 1 wherein said relative movement is produced by means of discrete step motion between said successive predetermined imaging positions.

Claim 24

A system according to claim 1 wherein said relative movement is produced by means of continuous motion between said successive predetermined imaging positions.

Claim 25

A system according to claim 1 wherein the path of the relative movement between the object to be imaged and the gamma detector pixel array is repeated periodically and the resultant images integrated in order to improve signal to noise ratio, and to average out time-independent phenomena.

Claim 26

A system according to claim 1 wherein the set of independent equations is solved numerically.

Claim 27

A system according to claim 25 wherein the numerical solution is performed by a microprocessor.

Claim 28

A system according to claim 25 wherein the numerical solution is performed by a computer.

Claim 29

A system according to claim 1 wherein a region of interest is defined on the object.

Claim 30

A system according to claim 28 wherein the region of interest is defined by the window of a frame placed between the object and the collimator plate in the vicinity of the object.

Claim 31

A system according to claim 29 wherein the frame is made of lead.

Claim 32

A system according to claim 1 wherein the signals of the irradiated regions are corrected in the processing unit to compensate for the time that they are screened by the borders of the collimator-plate.

Claim 33

A gamma-ray imaging system for producing high resolution images, comprising: (a) a collimator plate having multiple holes for collimating gamma photons emitted from an object to be imaged; (b) a gamma detector pixel array located in an imaging plane, comprising a plurality of pixels having predetermined pitch between pixels, each pixel operative to convert the gamma photons directly into electrical signals which comprise the image data, said multiple holes in the collimator plate being smaller in diameter than half the pitch between the pixels, and being arranged in a spatial periodic structure such that the pitch between the pixels contains two or more periods of the holes in the spatial periodic structure; (c) an actuator for producing relative movement between the object to be imaged and the gamma detector pixel array in the imaging plane to successive predetermined imaging positions, the distance between each successive predetermined imaging position being equal to an integral number times the spatial period of the pixels; (d) an electronic controller for controlling the relative movement between the object to be imaged and the gamma detector pixel array according to a predetermined program, said multiple holes and said successive predetermined imaging positions being arranged so that the photons emerging from each hole at each imaging position produce discrete multiple irradiated regions on the pixels outside dead areas at the edges of the pixels; (e) an electronic signal measurer for measuring at each successive predetermined imaging position the electrical signals produced by the pixels of the gamma detector pixel array, and (f) an electronic processing unit for processing the electrical signals produced by the pixels of the gamma detector pixel array at each successive predetermined imaging position by constructing a set of independent equations equal to the number of said irradiated regions, accurately solving the set of independent equations to derive a data value of the electrical signals corresponding to each of the irradiated regions, and using the data valves to compose and display an image of the object, images acquired at each successive predetermined position being summed and averaged after being referred back electronically to an initial reference positions.

Claim 34

A gamma-ray imaging system for producing high resolution images, comprising: (a) a collimator plate having multiple holes for collimating gamma photons emitted from an object to be imaged; (b) a gamma detector pixel array located in an imaging plane, comprising a plurality of pixels having predetermined pitch between pixels, each pixel operative to convert the gamma photons directly into electrical signals which comprise the image data, said multiple holes in the collimator plate being smaller in diameter than half the pitch between the pixels, and being arranged in a spatial periodic structure such that the pitch between the pixels contains two or more periods of the holes in the spatial periodic structure; (c) an actuator for producing relative movement between the object to be imaged and the gamma detector pixel array in the imaging plane to successive predetermined imaging positions, the distance between each successive predetermined imaging position being equal to an integral number times the spatial period of the pixels; (d) an electronic controller for controlling the relative movement between the object to be imaged and the gamma detector pixel array according to a predetermined program, said multiple holes and said successive predetermined imaging positions being arranged so that the photons emerging from each hole at each imaging position produce discrete multiple irradiated regions on the pixels outside dead areas at the edges of the pixels; (e) an electronic signal measurer for measuring at each successive predetermined imaging position the electrical signals produced by the pixels of the gamma detector pixel array, and (f) an electronic processing unit for processing the electrical signals produced by the pixels of the gamma detector pixel array at each successive predetermined imaging position by constructing a set of independent equations equal to the number of said irradiated regions, accurately solving the set of independent equations to derive a data value of the electrical signals corresponding to each of the irradiated regions, and using the data valves to compose and display an image of the object, images acquired at each successive predetermined position being summed and averaged after being referred back electronically to an initial reference positions.

Claim 35

A gamma-ray imaging system for producing high resolution images, comprising: (a) a collimator plate having multiple holes for collimating gamma photons emitted from an object to be imaged; (b) a gamma detector pixel array located in an imaging plane, comprising a plurality of pixels having predetermined pitch between pixels, each pixel operative to convert the gamma photons directly into electrical signals which comprise the image data, said multiple holes in the collimator plate being smaller in diameter than half the pitch between the pixels, and being arranged in a spatial periodic structure such that the pitch between the pixel contains two or more periods of the holes in the spatial periodic structure; (c) an actuator for producing relative movement between the object to be imaged and the gamma detector pixel array in the imaging plane to successive predetermined imaging positions, the distance between each successive predetermined imaging positions being equal to the pitch of the spatial periodic structure of the holes in the collimator plate; (d) an electronic controller for controlling the relative movement between the object to be imaged and the gamma detector pixel array according to a predetermined program, said multiple holes and said successive predetermined imaging positions being arranged so that the photons emerging from each hole at each imaging position produce discrete multiple irradiated regions on the pixels outside dead areas at the edges of the pixels; (e) an electronic signal measurer for measuring at each successive predetermined imaging position the electrical signals produced by the pixels of the gamma detector pixel array; (f) an electronic processing unit for processing the electrical signals produced by the pixels of the gamma detector pixel array at each successive predetermined imaging position by constructing a set of independent equations equal to the number of said irradiated regions, accurately solving the set of independent equations to derive a data value of the electrical signals corresponding to each of the irradiated regions, and using the data values to compose and display an image of the object, and (g) a rotator for rotating the gamma detector pixel array about an axis through its center operative to acquire images at positions rotationally shifted relative to each other by 90 degrees, the images being summed and averaged after being referred back electronically to an initial reference position.

Claim 36

A gamma-ray imaging system for producing high resolution images, comprising: (a) a collimator plate having multiple holes for collimating gamma photons emitted from an object to be imaged; (b) a gamma detector pixel array located in an imaging plane, comprising a plurality of pixels having predetermined pitch between pixels, each pixel operative to convert the gamma photons directly into electrical signals which comprise the image data, said multiple holes in the collimator plate being smaller in diameter than half the pitch between the pixels, and being arranged in a spatial periodic structure such that the pitch between the pixel contains two or more periods of the holes in the spatial periodic structure; (c) an actuator for producing relative movement between the object to be imaged and the gamma detector pixel array in the imaging plane to successive predetermined imaging positions, the distance between each successive predetermined imaging positions being equal to the pitch of the spatial periodic structure of the holes in the collimator plate; (d) an electronic controller for controlling the relative movement between the object to be imaged and the gamma detector pixel array according to a predetermined program, said multiple holes and said successive predetermined imaging positions being arranged so that the photons emerging from each hole at each imaging position produce discrete multiple irradiated regions on the pixels outside dead areas at the edges of the pixels; (e) an electronic signal measurer for measuring at each successive predetermined imaging position the electrical signals produced by the pixels of the gamma detector pixel array; (f) an electronic processing unit for processing the electrical signals produced by the pixels of the gamma detector pixel array at each successive predetermined imaging position by constructing a set of independent equations equal to the number of said irradiated regions, accurately solving the set of independent equations to derive a data value of the electrical signals corresponding to each of the irradiated regions, and using the data values to compose and display an image of the object, and (g) a rotator for rotating the gamma detector pixel array about an axis through its center operative to acquire images at positions rotationally shifted relative to each other by 90 degrees, the images being summed and averaged after being referred back electronically to an initial reference position.