Diagnostic tomographic laser imaging apparatus

• US 6,195,580 B1
• Filed: 07/31/1998
• Issued: 02/27/2001
• Est. Priority Date: 07/10/1995
• Status: Expired due to Fees

• Current Assignee: Richard J. Grable
• Original Assignee: Richard J. Grable
• Inventors: Grable, Richard J.
• Primary Examiner(s): Casler, Brian L.
• Application Number:
  US08/952,821
• Time in Patent Office: 942 Days
• Field of Search: 600/407, 600/473, 600/476, 600/310, 250/358.1, 250/330, 250/332, 250/334, 356/338, 356/300, 356/446, 378/37, 359/216, 359/217, 359/218, 359/223, 359/226
• US Class Current: 600/473
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence

Abstract

A laser imaging apparatus comprises (R) a platform (16) for supporting a female patient in frontdown, prone position, including an opening (20) permitting a breast of the patient to be vertically pendant below the surface of the platform; scanning mechanism including a multi-faceted mirror (38) adjacent the underside of the platform, the mirror being rotated about its own axis and orbited around the pendant breast; a source of coherent near infrared narrow light pulses operably directed to the multi-faceted mirror; optical reflectors directing the light pulses onto the facets of the mirror from a point spaced from the platform for reflection in a series of horizontal fan shaped beams through a breast pendant below the platform; photodetectors (40) operably disposed to detect the light pulses after passing through the breast; circuit for deriving voltages proportional to the intensity of the received pulses; and computer (10) programmed for storing and displaying images of tissue in the breast derived from the voltages.

Claims

1. A laser imaging apparatus, comprising:

a) a non-vertically movable and non-tiltable platform including a top surface to support a female patient in front-down, prone position;

b) said platform including an opening adapted to permit a breast of the patient to be vertically pendant below said surface;

c) a scanning chamber disposed below said opening to receive therein the breast;

d) said scanning chamber including a source of laser beam for passing through the breast and at least one photodetector adapted to respond to the laser beam exiting the breast, said at least one photodetector having a response curve with a leading edge component;

e) a time-gate switch circuit for sampling said leading edge component of said response curve for said at least one photodetector; and

f) a computer programmed to generate an image of the scanned breast from the sampled leading edge component of said response curve.

2. A laser imaging apparatus as in claim 1, and further comprising:

a) a current-to-voltage conversion circuit connected to said at least one photodetector for converting the sampled leading edge component of said response curve to a voltage.

3. A laser imaging apparatus as in claim 1, and further comprising:

a) said current-to-voltage conversion circuit includes an operational amplifier.

4. A laser imaging apparatus as in claim 1, wherein:

a) said current-to-voltage conversion circuit includes an integrator.

5. A laser imaging apparatus as in claim 1, and further comprising:

a) a clamp circuit adapted to protect said current-to-voltage conversion circuit from over-voltage.

6. A laser imaging apparatus as in claim 1, wherein:

a) said at least one photodetector includes an avalanche photodiode.

7. A laser imaging apparatus as in claim 1, wherein:

a) said source of laser beam includes near infrared laser pulses.

8. A laser imaging apparatus as in claim 1, and further comprising:

a) a rotating mirror adapted to direct said source of laser beam into a fan-shaped beam through the tissue.

9. A laser imaging apparatus as in claim 1, wherein:

a) said time-gate switch includes a Schottkey diode operably connected to said at least one photodetector.

10. A laser imaging apparatus, comprising:

a) a non-vertically movable and non-tiltable horizontal surface to support a female patient in a front-down, prone position, said surface including an opening adapted to permit a breast of the patient to be vertically pendent through said opening;

b) a source of narrow coherent near infrared light pulses directed through the breast in a horizontal pattern from a plurality of positions completely surrounding the breast;

c) a mechanism to vertically move said source in increments to image the breast at several horizontal planes to allow the entire breast to be scanned;

d) photodetectors disposed around said opening to detect the light pulses after passage through the breast; and

e) a computer programmed to derive images of the breast from the detected light pulses by computed tomography reconstruction.

11. A laser imaging apparatus as in claim 10, wherein:

a) said source of light pulses is orbited around the breast.

12. A laser imaging apparatus as in claim 10, wherein:

a) said source of light pulses is distributed in a fan pattern at each of said plurality of positions.

13. A laser imaging apparatus as in claim 10, wherein:

a) said source of light pulses is distributed in a fan pattern at each of said plurality of positions with a rotating multifaceted mirror.

14. A laser imaging apparatus as in claim 10, wherein:

a) said photodetectors include avalanche photodiodes.

15. A laser imaging apparatus as in claim 10, wherein:

a) said photodetectors include a response curve with a leading edge component; and

b) a time-gate switch to sample the leading edge component of the response curve.

16. A laser imaging apparatus as in claim 10, wherein:

a) said mechanism includes a scanning chamber disposed below said surface and said opening;

b) said scanning chamber includes a frame and a rotatable plate supported on said frame, said plate including another opening to permit the breast to be suspended in the another opening; and

c) said source of light pulses is carried by said plate such that said source of laser beam makes a complete orbit around said opening when said plate is rotated.

17. A laser imaging apparatus as in claim 16, wherein:

a) said photodetectors are disposed on said plate.

18. A laser imaging apparatus as in claim 16, wherein:

a) said photodetectors are disposed on said frame.

19. A laser imaging apparatus as in claim 16, and further comprising:

a) bearing assembly adapted to rotatably support said plate from said frame, said bearing assembly including an outer race secured to an opening on said frame, and an inner race secured to said plate.

20. A laser imaging apparatus as in claim 16, and further comprising:

a) drive screws operably associated with said frame such that rotation of said drive screws are effective to lower or raise said frame.

21. A laser imaging apparatus as in claim 10, wherein:

a) said photodetectors are disposed in an arc around said opening.

22. A laser imaging apparatus as in claim 10, wherein:

a) said photodetectors are disposed in a circle around said opening.

23. A laser imaging apparatus as in claim 10, wherein:

a) said light pulses are on the order of 100 femtoseconds in width and a wavelength on the order of 850 nanometers.

24. A laser imaging apparatus as in claim 10, wherein:

a) said source of light pulses include a titanium sapphire laser and an argon ion laser adapted to pump said titanium sapphire laser.

25. A laser imaging apparatus as in claim 10, wherein:

a) said photodetectors includes avalanche photodiodes.

26. A laser imaging apparatus, comprising:

a) a non-vertically movable and non-tiltable horizontal surface to support a female patient in a front-down, prone position, said surface including an opening adapted to permit a breast of the patient to be vertically pendent through said opening;

b) a scanning chamber adjacent the underside of said surface, said scanning chamber including a frame;

c) a rotatable plate supported on said frame, said plate including another opening to permit the breast to be disposed in said another opening;

d) a source of narrow coherent light pulses directed through the breast in a horizontal pattern from a plurality of positions completely surrounding the breast;

e) photodetectors disposed on said plate adapted to detect said source of light pulses after passage through the breast;

f) a mechanism to vertically move said scanning chamber in increments to image the breast at several horizontal planes to allow the entire breast to be scanned; and

g) a computer programmed to derive images of the breast from the detected light pulses by computed tomography reconstruction.