Imaging methods and imaging devices

• US 5,625,192 A
• Filed: 08/22/1995
• Issued: 04/29/1997
• Est. Priority Date: 08/23/1994
• Status: Expired due to Fees

• Current Assignee: The Institute of Physical and Chemical Research
• Original Assignee: The Institute of Physical and Chemical Research
• Inventors: Oda, Minoru, Miyamoto, Shigenori, Matsutaka, Masaru, Makishima, Kazuo, Ogawara, Yoshiaki
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): Hanig, Richard
• Application Number:
  US08/518,140
• Time in Patent Office: 616 Days
• Field of Search: 250/363.1, 378/149, 378/148, 378/154
• US Class Current: 250/363.1
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

An imaging method and an imaging device are disclosed which use no image forming optical system. A grid system 25 including an objective grid array 22 with a plurality of coplanarly arranged grids having pitches different from each other and a detector grid array 23 having a similarly enlarged configuration of the objective grid array, and a detector array 24 constitute a detection system. An energy ray such as an X-ray which has been transmitted through the grid system 25 is detected by the detector array 24 while rotating an object 20 under observation placed on a rotary table 21. A signal processing means 28 subjects signals detected by the detector array 24 to inverse Fourier transform to synthesize an image of the object 20, and the image is displayed on a display 29.

Claims

1. An imaging method comprising:

providing a grid system including an objective grid array with a plurality of coplanarly arranged grid couples, and a detector grid array having a similarly enlarged configuration of the objective grid array and spaced a predetermined distance apart from the objective grid array;

the coupled grids having the same slit direction and the same pitch but having phases shifted from each other by π

/4, the grid couples having a plurality of intermittent slit directions and having different pitches in each of the slit directions,

placing an object to be observed in the vicinity of the focal point of the grid system, on which lines connecting corresponding grids in the detector grid array and the objective grid array converge,

individually detecting energy rays each of which has been emitted from the object and transmitted through the corresponding two grids in the grid system, and

subjecting each set of the detected signals corresponding to the coupled grids having the same slit direction and the same pitch but having phases shifted from each other by π

/4 as cosine and sine components in Fourier transform to an operation using linear orthogonal integral transform or a non-linear optimization method to synthesize an image of the object.

2. The imaging method according to claim 1, wherein the operation is two-dimensional inverse Fourier transform, linear orthogonal integral transform, or maximum entropy method.

3. The imaging method according to claim 1, wherein the detection is effected at predetermined time intervals to obtain signals, and images are sequentially displayed each of which is synthesized from the detected signals at each signal acquisition.

4. The imaging method according to claim 1, wherein the relative position between the focal point of the grid system and the object is changed to form a plurality of images, and based thereon, a three-dimensional image of the object is synthesized.

5. The imaging method according to claim 1 wherein the energy ray is an X-ray or gamma ray within a predetermined energy range.

6. An imaging device comprising:

a grid system including an objective grid array with a plurality of coplanarly arranged grids having pitches different from each other, and a detector grid array having a similarly enlarged configuration of the objective grid array and spaced a predetermined distance apart from the objective grid array,

a detector array including a plurality of detectors each detecting energy ray transmitted through each of the grids of the detector grid array,

a placement means on which an object is placed,

a means for relatively rotating the grid system and the placement means about the axis passing through the point on which lines connecting corresponding grids in the detector grid array and the objective grid array converge and orthogonally intersecting the plane of the grid array,

a signal processing means to which detected signals from the detector array are inputted, and

an image display means for displaying an image of the object based on the signals from the signal processing means;

said signal processing means subjecting each set of the detected signals obtained from the detector array of a plurality of rotation angles to two-dimensional inverse Fourier transform to synthesize an image of the object;

wherein the grid pitch p_k of the k-th objective grid in objective grid array is set as defined by the following formula wherein Δ

is the basic pitch set to be approximately the same as the size of the object to be observed and N is number of the grids wherein

p_k =Δ

/k and k=1, 2, . . . , N.

7. An imaging device comprising:

a grid system including an objective grid array with a plurality of coplanarly arranged grid couples, and a detector grid array having a similarly enlarged configuration of the objective grid array and spaced a predetermined distance apart from the objective grid array;

the coupled grids having the same slit direction and the same pitch but having phases shifted from each other by π

/4, the grid couples having a plurality of intermittent slit directions and having different pitches in each of the slit directions,

a detector array including a plurality of detectors each detecting energy ray transmitted through each of the grids of the detector grid array,

a signal processing means to which detected signals from the detector array are inputted, and

an image display means for displaying an image of the object based on the signals from the signal processing means;

said signal processing means subjecting each set of the detected signals corresponding to the coupled grids having the same slit direction and the same pitch but having phases shifted from each other by π

/4 as cosine and sine components in Fourier transform to two-dimensional inverse Fourier transform to synthesize an image of the object.

8. The imaging device according to claim 7, wherein the signal processing means synthesizing image through a non-linear optimization method, which is represented by maximum entropy method, instead of the two-dimensional inverse Fourier transform.

9. The imaging device according to claim 7, wherein the magnification of the similar enlargement is 3 to 10.

10. The imaging device according to claim 7, wherein the grid pitch p_k of the k-th objective grid in objective grid array is set as defined by the following formula wherein Δ

is the basic pitch set to be approximately the same as the size of the object to be observed and N is number of the grids. ##EQU5##

11. The imaging device according to claim 7, wherein the detector is an X-ray detector or gamma ray detector.

12. The imaging device according to claim 7, wherein the detector is an X-ray detector or gamma ray detector and further comprising a means for detecting only an X-ray or gamma ray within a specific energy range.