Medical diagnosis system and method with multispectral imaging

• US 4,170,987 A
• Filed: 11/28/1977
• Issued: 10/16/1979
• Est. Priority Date: 11/28/1977
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: California Institute of Technology
• Inventors: Anselmo, Victor J., Reilly, Terrence H.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/855,364
• Time in Patent Office: 687 Days
• Field of Search: 128/2 A, 128/2 L, 128/2 R, 128/2.1 R, 250/226, 356/51, 356/209, 356/212, 356/222, 356/229
• US Class Current: 600/475
• CPC Class Codes: A61B 5/0064 Body surface scanning
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/445 Evaluating skin irritation or skin trauma, e.g. rash, eczema, wound, bed sore
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors

Abstract

A skin diagnosis system includes a scanning and optical arrangement whereby light reflected from each incremental area (pixel) of the skin is directed simultaneously to three separate light filters, e.g., IR, red, and green. As a result the three devices simultaneously produce three signals which are directly related to the reflectance of light of different wavelengths from the corresponding pixel. These three signals for each pixel after processing are used as inputs to one or more output devices to produce a visual color display and/or a hard copy color print, for one useable as a diagnostic aid by a physician.

Claims

1. A system for generating data for use in diagnosing the condition of surface tissue of a patient, comprising:

first means for scanning the surface tissue of a patient and for generating simultaneously n different signals from the light reflected from each incremental area of the surface tissue, each different signal being directly related to the reflectance of light of a different wavelength range from said incremental area, n being an integer not less than 2;

second means for providing a preselected number of derived signals from the n signals, associated with each incremental area, each derived signal being a function of at least two of said n signals; and

output means including at least means responsive to said derived signals for providing output data, indicative of the surface tissue condition.

2. The system as described in Claim 1 wherein n=3, said 3 signals representing the reflectance of infrared, red, and green light from each incremental area, said signals being definable as D_IR, D_R and D_G, respectively.

3. The system as described in claim 2 wherein said second means provide three ratio signals definable as D_IR/R, D_IR/G and D_R/G, where D_IR/R =D_IR/DR, D_IR/G =D_IR /D_G and D_R/G =D_R /D_G.

4. The system as described in claim 1 wherein said first means include at least first, second and third photosensitive devices, each providing an analog signal which is directly related to light received thereby and at least second and third filters, respectively positioned in the paths of light directed to said first, second and third photosensitive devices, for controlling the wavelengths of light receivable by said devices, and means for successively scanning incremental areas of the surface tissue and for simultaneously directing light to all three devices from each of said scanned incremental areas.

5. The system as described in claim 4 further including converting means, for converting the analog signals provided by each of said devices into digital numbers, and wherein said surface tissue is a patient'"'"'s skin and said first, second and third filters are an infrared filter, a red filter and a green filter respectively, said converting means provide a digital number definable as D_IR which is directly related to infrared light received to said first device, a digital number definable as D_R which is directly related to red light received by said second device and a digital number definable as D_G which is directly related to green light received by said third device.

6. The system as described in claim 5 wherein said second means include means for providing three separate derived signals which are digital ratio numbers, definable as D_IR/R, D_IR/G and D_R/G, where D_IR/R =D_IR /D_R, D_IR/G =D_IR /D_G, and D_R/G =D_R /D_G, said output means providing said color presentation as a function of D_IR/R, D_IR/G and D_R/G of each incremental area.

7. The system as described in claim 6 further including means for providing an indication of the distribution of all the numerical values of each of the D_IR, D_R and D_G digital numbers generated in response to scanning a preselected number of incremental areas.

8. The system as described in claim 7 further including means for varying selected ones of any of said D_IR, D_R and D_G numerical values as a function of their numerical value distribution.

9. The system as described in claim 1 further including means for providing an indication of the distribution of all the values of each of said n signals which are generated by said first means in response to scanning a preselected number of incremental areas of said surface tissue.

10. The system as described in claim 9 further including means for varying the values of selected ones of corresponding signals of said n signals as a function of their value distribution.

11. Apparatus for diagnosing the condition of surface tissue of a patient, comprising:

means for directing light at the tissue;

a plurality of photosensitive detectors which each generate an output dependent on the intensity of light falling thereon;

a beamsplitter for directing portions of the same light reflected from each of a multiplicity of pixels on the tissue surface, towards each of said detectors;

a plurality of filter means, each disposed between said beamsplitter and a corresponding one of said detectors, to allow a different selected wavelength range to reach the corresponding detector;

a circuit connected to said plurality of detectors for generating a derived signal corresponding to each of said pixels, wherein the signal is a function of the outputs of a plurality of said detectors resulting from the incidence of light thereon from the same pixels; and

output means responsive to said circuit for providing output data indicative of the surface tissue condition.

12. A method of generating data useful in the diagnosis of the depth of burns of burned skin of a patient, the steps comprising:

illuminating said burned skin;

scanning incremental areas of said illuminated burned skin;

simultaneously sensing light at n different wavelength ranges reflected by each incremental area, and simultaneously generating n signals related thereto;

from the n signals generated from the light reflected from each incremental area, generating a plurality of derived signals, each of said derived signals being a function of at least two of said n signals; and

utilizing the derived signals related to each incremental area to produce output data indicative of the condition of the scanned skin.

13. A method as described in claim 12 wherein three signals are simultaneously generated for each incremental area which are directly related to infrared, red and green light respectively, reflected by the incremental area, the three signals being definable as D_IR, D_R and D_G, and said step of generating derived signals includes generating signals which are each a function of at least two of said signals D_IR, D_R and D_G.

14. A method as described in claim 13 wherein said step of generating derived signals includes generating signals of the values D_IR/R =D_IR /D_R, D_IR/G =D_IR /D_G and D_R/G =D_R /D_G.

15. A method as described in claim 14 wherein said step of utilizing includes producing a color image wherein each incremental area of the image is of a color determined by the signals D_IR/R, D_IR/G and D_R/G at the same incremental skin area.