Skin Evaluation Method and Skin Evaluation Device

• US 20150105635A1
• Filed: 12/16/2014
• Published: 04/16/2015
• Est. Priority Date: 06/18/2012
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: YOSHIDA, Naoko, Kuroiwa, Karin
• Granted Patent: US 10,383,567 B2
• Time in Patent Office: Days
• US Class Current: 600/306
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• CPC Class Codes: A61B 5/1075 for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer A61B8/0858 takes precedence
• CPC Class Codes: A61B 5/1077 Measuring of profiles
• CPC Class Codes: A61B 5/1079 using optical or photographic means
• CPC Class Codes: A61B 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

A profile of optical reflectance relative to a depth within a depth range from an epidermis to an upper layer of a dermis is created based on a coherence signal obtained by optical coherence tomography, an evaluation index is determined by calculating a difference between reflectance at a local minimum point and reflectance at a second local maximum point from the created profile, and skin conditions are evaluated based on the evaluation index.

Claims

1. A skin evaluation method, comprising the steps of:

detecting coherent light by optical coherence tomography by multiplexing measurement light with which skin is irradiated and which is sequentially reflected from inside of the skin and reference light which moves along an optical path length corresponding to a depth position in the skin at which the measurement light is reflected;

creating a profile of optical reflectance relative to a depth within a depth range from an epidermis to an upper layer of a dermis based on a coherence signal obtained by detecting the coherent light; and

evaluating skin conditions based on an evaluation index determined according to the profile as created.

2. The skin evaluation method according to claim 1,

wherein the profile has, as the depth of the skin increases, a first local maximum point that appears at a position corresponding to a point in the uppermost layer of the epidermis, a local minimum point that appears after the first local maximum point and a second local maximum point that appears after the local minimum point.

3. The skin evaluation method according to claim 2,

wherein the evaluation index is a difference or a ratio between any two out of reflectance at the first local maximum point, reflectance at the local minimum point and reflectance at the second local maximum point.

4. The skin evaluation method according to claim 2,

wherein the evaluation index is a ratio between a profile area on a shallower side of a certain depth position and a profile area on a deeper side thereof within a range from a lower layer of the epidermis to the upper layer of the dermis.

5. The skin evaluation method according to claim 4,

wherein the certain depth position is a depth position associated with the second local maximum point.

6. The skin evaluation method according to claim 4,

wherein the certain depth position is a depth position associated with the local minimum point.

7. The skin evaluation method according to claim 4,

wherein the certain depth position is a predetermined depth position set in advance.

8. The skin evaluation method according to claim 2,

wherein the evaluation index is a thickness of the epidermis as determined according to the profile.

9. The skin evaluation method according to claim 8,

wherein the thickness of the epidermis is determined by a thickness from a surface of the epidermis to the depth position associated with the second local maximum point.

10. The skin evaluation method according to claim 2,

wherein the evaluation index is a degree of internal scattering in the epidermis as determined according to the profile.

11. The skin evaluation method according to claim 10,

wherein the degree of internal scattering in the epidermis is calculated from an average of optical reflectance within a depth range from the surface of the epidermis to the depth position associated with the second local maximum point.

12. The skin evaluation method according to claim 2,

wherein the evaluation index is a comprehensive index created by combining at least two out of a reflectance difference or a reflectance ratio between any two selected from among the first local maximum point, the local minimum point and the second local maximum point, a ratio between a profile area on a shallower side of a certain depth position and a profile area on a deeper side thereof within a range from a lower layer of the epidermis to the upper layer of the dermis, a thickness of the epidermis as determined according to the profile, and a degree of internal scattering in the epidermis as determined according to the profile.

13. The skin evaluation method according to claim 12,

wherein the comprehensive index is created by combining a reflectance difference between the local minimum point and the second local maximum point, the thickness of the epidermis as determined according to the profile and the degree of internal scattering in the epidermis as determined according to the profile.

14. The skin evaluation method according to claim 1,

wherein the measurement light with which the skin is irradiated is near infrared light.

15. The skin evaluation method according to claim 1,

wherein the measurement light with which the skin is irradiated is visible light.

16. A skin evaluation device, comprising:

a light source configured to emit emission light;

a probe configured to irradiate skin with measurement light and receive reflected light sequentially reflected from inside of the skin which has been irradiated with the measurement light;

an optical path length adjusting unit configured to adjust an optical path length of reference light such that the optical path length is substantially identical to an optical path length of the reflected light received by the probe;

a dividing and multiplexing unit optically connected to the light source, the probe and the optical path length adjusting unit, the dividing and multiplexing unit configured to divide the emission light emitted from the light source into measurement light and reference light to supply the measurement light and the reference light to the probe and the optical path length adjusting unit, respectively, and generate coherent light by multiplexing the reflected light received by the probe and the reference light whose optical path length has been adjusted by the optical path length adjusting unit;

a coherent light detecting unit configured to detect the coherent light generated by the dividing and multiplexing unit;

a signal processing unit configured to create a profile of optical reflectance relative to a depth within a depth range from an epidermis to an upper layer of a dermis based on a coherence signal obtained as a result of detection of the coherent light by the coherent light detecting unit; and

a skin condition evaluating unit configured to evaluate conditions of the skin based on an evaluation index determined according to the profile created by the signal processing unit.

17. The skin evaluation device according to claim 16,

wherein the signal processing unit and the skin condition evaluating unit are constituted by a CPU.

18. The skin evaluation device according to claim 16, further comprising:

a storage unit configured to store evaluation results of the skin conditions obtained by the skin condition evaluating unit; and

a display unit configured to display the evaluation results of the skin conditions stored in the storage unit.