System for quantitative radiographic imaging

• US 7,330,531 B1
• Filed: 05/11/1995
• Issued: 02/12/2008
• Est. Priority Date: 12/05/1989
• Status: Expired due to Fees

• Current Assignee: University Of Massachusetts
• Original Assignee: University Of Massachusetts
• Inventors: Karellas, Andrew
• Primary Examiner(s): THOMAS, COURTNEY D
• Application Number:
  US08/438,800
• Time in Patent Office: 4,660 Days
• Field of Search: 378/98.8, 378 54- 56, 378/5, 378/19, 378/62, 250/370.08, 250/370.09, 250/370.11
• US Class Current: 378/98.8
• CPC Class Codes: A61B 6/4042 K-edge filters
• CPC Class Codes: A61B 6/4241 using energy resolving detectors, e.g. photon counting
• CPC Class Codes: A61B 6/4258 for detecting non x-ray radiation, e.g. gamma radiation A61B6/037 takes precedence
• CPC Class Codes: A61B 6/4488 Means for cooling A61B6/045 takes precedence
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: A61B 6/508 for non-human patients
• CPC Class Codes: H04N 23/30 for generating image signals from X-rays
• CPC Class Codes: H04N 23/54 Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A system for spectroscopic imaging of bodily tissue in which a scintillation screen and a charged coupled device (CCD) are used to accurately image selected tissue. Applications include the imaging of radionuclide distributions within the human body or the use of a dual energy source to provide a dual photon bone densitometry apparatus that uses stationary or scanning acquisition techniques. An x-ray source generates x-rays which pass through a region of a subject'"'"'s body, forming an x-ray image which reaches the scintillation screen. The scintillation screen reradiates a spatial intensity pattern corresponding to the image, the pattern being detected by a CCD sensor. The image is digitized by the sensor and processed by a controller before being stored as an electronic image. A dual energy x-ray source that delivers two different energy levels provides quantitative information regarding the object being imaged using dual photon absorptiometry techniques. Dual scintillation screens can be used to simultaneously generate images of low-energy and high-energy x-ray patterns. Each image is directed onto an associated respective CCD or amorphous silicon detector to generate individual electronic representations of the separate images.

Claims

1. A method of measuring bone density and imaging a patient'"'"'s spine comprising:

positioning a patient on a support surface;

providing an x-ray tube radiation source such that radiation emitted by the source at a first energy and a second energy is transmitted through a region of the patient'"'"'s spine to be imaged during a first exposure interval at the first energy and during a second exposure interval at the second energy;

providing a single charged coupled device (CCD) sensor that detects light generated by a scintillator in response to x-ray radiation from the source during each exposure interval that is transmitted through the region at the first and second energies, the single CCD sensor being aligned with the source by a C-arm;

providing a (CCD) controller that is electrically connected to the sensor such that the controller performs readout of charge collected by the CCD after each exposure interval;

scanning the spine with the C-arm, source, scintillator and CCD sensor, the C-arm being scanned along a longitudinal axis of the spine of the patient;

generating an electronic representation of a spatial intensity pattern from the light received by the CCD sensor at the first energy level and at the second energy level during the scanning of the spine;

determining the density of bone within the region of the spine from the electronic representation; and

forming an image of the spine from the electronic representation.

2. The method of claim 1 wherein the charged coupled device comprises a binnable CCD sensor.

3. The method of claim 1 further comprising providing a data processor electrically connected to the CCD sensor, the data processor having a memory in which the electronic representation is stored and a processing circuit that filters the electronic representation to provide a filtered image of bodily tissue.

4. The method of claim 1 further comprising performing pulse height analysis on the discrete electronic representation.

5. The method of claim 1 further comprising selecting a reference intensity and performing pulse height analysis to remove components of the representation.

6. The method of claim 1 further comprising providing a fiber optic coupler between the scintillator and the CCD sensor, the coupler being a fiber optic plate or a fiber optic reducer or a fiber optic bundle.

7. The method of claim 4 wherein the step of performing pulse height analysis comprises applying a filter to the discrete electronic representation, the filter having one or more selectable parameters.

8. The method of claim 7 wherein a selectable parameter comprises an energy range.

9. The method of claim 1 further comprising providing a mirror between the region of the spine and the CCD sensor, the mirror reflecting radiation from a first optical path directed through the region of the spine onto a second optical path such that the CCD sensor receives radiation reflected along the second optical path.

10. The method of claim 9 further comprising providing a lens between the mirror and the CCD sensor.

11. The method of claim 1 further comprising providing a collimator between the regions of the spine and the scintillator.

12. The method of claim 1 further comprising rotating the x-ray source and CCD sensor relative to the region of the spine to a second angle and providing further image of the region of the spine.

13. The method of claim 1 further comprising providing a CCD sensor having an array of at least 512 by 512 pixels or larger.

14. A method of performing quantitative x-ray densitometry comprising:

providing an x-ray tube radiation source such that radiation emitted by the source is transmitted through a patient'"'"'s spine onto a scintillator at a first energy and a second energy;

providing a single charged coupled device (CCD) sensor that detects light received from the scintillator that is emitted by the scintillator in response to radiation from the x-ray source at both the first energy and the second energy;

providing a CCD controller that is electrically connected to the single CCD sensor, the controller performing readout of charge collected by the sensor;

directing x-ray radiation through a region of the patient'"'"'s spine at the first and second energies during a first exposure interval and a second exposure interval onto the scintillator which emits a spatial intensity pattern that is detected by the CCD sensor, the x-ray radiation source, the scintillator, and the CCD sensor being stationary relative to the region of the patient'"'"'s spine while detecting light at the first energy and at the second energy;

generating an electronic representation of a spatial intensity pattern from the light received by the CCD at each of the two energies;

forming an image of a body from the representation; and

determining a density of bone within the spine of the patient from the detected radiation.

15. The method of claim 14 further comprising providing a shutter to control exposure time of the region of the spine to the radiation source.

16. The method of claim 14 further comprising detecting x-ray radiation at a first energy level with the CCD sensor and detecting x-ray radiation at a second energy level with the CCD sensor.

17. The method of claim 14 further comprising positioning a fiber optic plate between the region of the spine and the CCS sensor.

18. The method of claim 14 further comprising providing a data processor to analyze the electronic representation and a memory in which the store the electronic representation.

19. A method of x-ray imaging a patient'"'"'s spine comprising:

providing an x-ray tube radiation source such that radiation emitted by the source is transmitted through a body to be imaged;

providing a scintillator that receives radiation transmitted through the body;

providing a single charged coupled device (CCD) sensor and a controller connected to the CCD such that the CCD receives light from the scintillator in response to radiation emitted by the source and transmitted through the body;

providing a C-arm that positions the x-ray source relative to the CCD sensor;

directing x-ray radiation from the source through the spine at two different energies onto the scintillator;

generating an electronic representation of a spatial intensity pattern from the light received by the single CCD sensor from the scintillator at the two energies;

forming an image of the spine from the representation; and

determining a density of bone in a region of the patient'"'"'s spine from the electronic representation.

20. The method of claim 19 further comprising the step of determining the density of bone within spine.

21. The method of claim 19 further comprising direction x-ray radiation through the spine with energy in the range of 20-200 KeV.

22. The method of claim 19 further comprising the step of scanning the C-arm along the spine.

23. The method of claim 19 further comprising optically coupling the scintillator to the CCD sensor with a fiberoptic coupler.

24. The method of claim 23 further comprising providing a curved fiberoptic coupler.

25. The method of claim 19 further comprising filtering radiation with a filter between the x-ray source and CCD sensor to selectively control an energy level of radiation received by the CCD sensor.

26. The method of claim 19 wherein the step of directing x-ray radiation through the spine comprises directing energy having a first energy range through the spine and thereafter directing energy of a second energy range through the spine.

27. The method of claim 19 further comprising rotating the source and detector relative to the spine to obtain an image at a different angle.

28. The method of claim 19 further comprising optically coupling the scintillator tot the CCD sensor with a fiberoptic plate.

29. The method of claim 19 further comprising moving the C-arm relative to the patient and generating a second image.

30. A method of performing quantitative x-ray densitometry comprising:

providing an x-ray radiation source such that radiation emitted by the source is transmitted through a patient'"'"'s bone onto a scintillator;

providing an amorphous silicon sensor to detect light from the scintillator that is emitted in response to radiation from the x-ray source, the sensor having flat array of at least 512×

512 pixels, each pixel of the amorphous silicon sensor storing charge during a first x-ray exposure interval and a second x-ray exposure interval such that a representation can be generated during each of the first x-ray exposure and second x-ray exposure intervals, the silicon sensor having a two-dimensional array of pixels;

providing a controller connected to the sensor that controls readout from the sensor;

directing x-ray radiation including two energies through a region of the patient'"'"'s bone onto the scintillator which emits a spatial light intensity pattern that is detected by the sensor;

generating an electronic representation of a spatial light intensity pattern from the radiation received by the sensor from the scintillator at each of the two energies;

forming an image of a body from the electronic representation; and

determining a density of bone within the patient from the detected radiation.

31. The method of claim 30 wherein the step of providing a pixellated silicon sensor comprises providing a binnable sensor.

32. The method of claim 30 further comprising providing a data processor connected to the sensor, the data processor having a memory for storing the discrete electronic representation.

33. The method of claim 30 further comprising performing pulse height analysis on the discrete electronic representation.

34. The method of claim 30 further comprising providing a fiber optic coupler between the scintillator and the sensor.

35. The method of claim 30 wherein the step of providing a pixellated sensor array further comprises providing cooled sensor array.

36. The method of claim 30 further comprising switching between a low energy and a high energy to obtain a low energy representation and a high energy representation with the sensor.

37. The method of claim 30 wherein the pixellated silicon sensor comprises an integrated circuit having an array of MOS diodes.