Depth-resolved fluorescence instrument

• US 6,825,928 B2
• Filed: 12/18/2002
• Issued: 11/30/2004
• Est. Priority Date: 12/19/2001
• Status: Expired due to Term

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Ramanujam, Nirmala, Zhu, Changfang, Liu, Quan
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US10/322,907
• Publication Number:
  US 20030220549A1
• Time in Patent Office: 713 Days
• Field of Search: 356/317, 356/318, 356/417, 250/458.1, 250/459.1, 250/461.1, 250/461.2, 600/317
• US Class Current: 356/317
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence

Abstract

A fluorescence instrument illuminates the surface of tissue with light of a selected wavelength and light emanating from the tissue due to fluorescence is collected. The size of the effective illumination/collection aperture is varied to probe at various depths beneath the surface of the tissue for a fluorescence layer. Three embodiments of the instrument are described.

Claims

1. A fluorescence instrument which comprises:

a light source for producing light;

illumination optical fiber for conveying the light to the surface of a subject to be examined and having an end disposed to direct light at a first location on said surface;

a collection optical fiber for collecting light emanating from the surface of the subject which is produced by fluorescence within the subject and beneath the surface, the optical fiber having an end disposed to receive light from a second location on said surface; and

;

means for changing the effective aperture of the fluorescence instrument to enable fluorescence measurements of the subject to be made at different depths beneath the surface; and

in which the means for changing includes means for changing the second location by moving the collection optical fiber to different positions relative to the illumination optical fiber.

2. A fluorescence instrument which comprises:

a light source for producing light;

illumination optical fiber for conveying the light to the surface of a subject to be examined and having an end disposed to direct light at a first location on said surface;

a collection optical fiber for collecting light emanating from the surface of the subject which is produced by fluorescence within the subject and beneath the surface, the optical fiber having an end disposed to receive light from a second location on said surface; and

;

means for changing the effective aperture of the fluorescence instrument to enable fluorescence measurements of the subject to be made at different depths beneath the surface; and

in which the collection means includes a plurality of said collection optical fibers, each having an end disposed to receive light from a corresponding different second location on said surface; and

in which the means for changing includes means for separately connecting each of said collection optical fibers to a detector.

3. A fluorescence instrument which comprises:

a light source for producing light;

illumination optical fiber for conveying the light to the surface of a subject to be examined and having an end disposed to direct light at a first location on said surface;

a collection optical fiber for collecting light emanating from the surface of the subject which is produced by fluorescence within the subject and beneath the surface, the optical fiber having an end disposed to receive light from a second location on said surface; and

;

means for changing the effective aperture of the fluorescence instrument to enable fluorescence measurements of the subject to be made at different depths beneath the surface; and

in which the illumination optical fiber is oriented at an angle such that the light is directed at the surface of the subject at an angle θ

from a direction perpendicular to the surface.

4. The fluorescence instrument as recited in claim 3 in which the subject is tissue and the angle θ

is substantially 45°

.

5. A fluorescence instrument which comprises:

a light source for producing light;

illumination optical fiber for conveying the light to the surface of a subject to be examined and having an end disposed to direct light at a first location on said surface;

a collection optical fiber for collecting light emanating from the surface of the subject which is produced by fluorescence within the subject and beneath the surface, the optical fiber having an end disposed to receive light from a second location on said surface; and

;

means for changing the effective aperture of the fluorescence instrument to enable fluorescence measurements of the subject to be made at different deaths beneath the surface; and

in which the means for changing the effective aperture includes means for moving the collection means relative to the illuminating means to change the distance between the illuminated surface of the subject and the surface of the subject from which light is collected.

6. A fluorescence instrument which comprises:

a light source for producing light;

illumination means for conveying the light to the surface of a subject to be examined;

collection means for collecting light emanating from the surface of the subject which is produced by fluorescence within the subject and beneath the surface;

a detector for measuring the collected light;

means for changing the effective aperture of the fluorescence instrument to enable a series of fluorescence measurements of the subject to be made at different depths beneath the surface; and

in which the illuminating means and the collection means includes an optical fiber having an end positioned to direct light onto the surface of the subject and receive light emanating from the same surface; and

the means for changing the effective aperture of the fluorescence instrument includes means for moving the end of the optical fiber to locations at different distances from the surface of the subject.

7. A method for probing beneath the surface of a target media at a selected location for a fluorescence layer, the steps comprising:

a) acquiring a depth-resolved reference fluorescence profile using a fluorescence instrument to probe at a series of different depths beneath the surface of the target media at a location of known characteristics;

b) acquiring a depth-resolved fluorescence profile using the fluorescence instrument to probe at the series of depths beneath the surface of the target media at the selected location;

c) calculate a fluorescence ratio profile using the reference fluorescence profile and the fluorescence profile; and

d) examining the fluorescence ratio profile to detect the presence of the fluorescence layer.

8. The method as recited in claim 7 in which step d) includes determining the peak fluorescence response in the fluorescence ratio profile.

9. The method as recited in claim 8 which includes producing an indication of the depth of the fluorescence layer using information related to the peak fluorescence response.

10. The method as recited in claim 9 in which the target media is tissue and the fluorescence layer is squamous cell carcinoma in the tissue.

11. The method as recited in claim 7 in which step c) includes calculating the ratio of values at different depths in the reference fluorescence profile to values at corresponding depths in the fluorescence profile.