PHOTOACOUSTIC APPARATUS

• US 20150099973A1
• Filed: 09/30/2014
• Published: 04/09/2015
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Abe, Hiroshi
• Granted Patent: US 10,143,382 B2
• Time in Patent Office: Days
• US Class Current: 600/440
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: G01N 2021/1706 in solids
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids

Abstract

A photoacoustic apparatus disclosed in the present specification includes: a light source configured to emit light; an acoustic wave transmission unit configured to transmit an acoustic wave to a specific area; a photoacoustic wave reception unit configured to receive a photoacoustic wave generated by a subject due to emission of the light, which is emitted from the light source, to the subject and configured to output a time-series photoacoustic signal; an echo reception unit configured to receive an echo generated due to reflection, in the subject, of the acoustic wave transmitted from the acoustic wave transmission unit and configured to output a time-series echo signal; and a processing unit configured to acquire, based on the time-series photoacoustic signal and the time-series echo signal, optical property information in which information a component corresponding to a reflected wave of the photoacoustic wave generated in the specific area is reduced.

Claims

1. A photoacoustic apparatus comprising:

a light source configured to emit light;

an acoustic wave transmission unit configured to transmit an acoustic wave to a specific area;

a photoacoustic wave reception unit configured to receive a photoacoustic wave generated by emission of the light, which is emitted from the light source, to an area including the specific area and configured to output a time-series photoacoustic signal;

an echo reception unit configured to receive an echo generated due to reflection of the acoustic wave transmitted from the acoustic wave transmission unit and configured to output a time-series echo signal; and

a processing unit configured to acquire, based on the time-series photoacoustic signal and the time-series echo signal, optical property information in which a component corresponding to a reflected wave of the photoacoustic wave generated in the specific area is reduced.

2. The photoacoustic apparatus according to claim 1, wherein the processing unit acquires a time-series difference signal between the time-series photoacoustic signal and the time-series echo signal and acquires the optical property information by using the time-series difference signal.

3. The photoacoustic apparatus according to claim 2, wherein the processing unit acquires the time-series difference signal after performing weighting, with a weighting coefficient, on at least one of the time-series photoacoustic signal and the time-series echo signal.

4. The photoacoustic apparatus according to claim 3, wherein the processing unit acquires a correlation between the time-series photoacoustic signal and the time-series echo signal and sets the weighting coefficient with which a difference between amplitude of the photoacoustic signal and that of the echo signal, which signals have a high correlation with each other, becomes small.

5. The photoacoustic apparatus according to claim 3, wherein the processing unit acquires the time-series difference signal after performing weighting, with the weighting coefficient, only on the time-series echo signal.

6. The photoacoustic apparatus according to claim 4, wherein the processing unit acquires the time-series difference signal after performing weighting, with the weighting coefficient, only on the time-series echo signal.

7. The photoacoustic apparatus according to claim 1, wherein the processing unit acquires a difference signal after correcting at least one of the time-series photoacoustic signal and the time-series echo signal in such a manner that a difference between reception time of a photoacoustic signal corresponding to a reflected wave generated due to reflection of the photoacoustic wave by a specific reflector and reception time of an echo signal corresponding to an echo generated due to reflection of the transmitted acoustic wave by the specific reflector becomes small.

8. The photoacoustic apparatus according to claim 1, wherein the processing unit acquires a correlation between the time-series photoacoustic signal and the time-series echo signal and acquires a difference signal after correcting at least one of the time-series photoacoustic signal and the time-series echo signal in such a manner that a difference between reception time of the photoacoustic signal and that of the echo signal, which signals have a high correlation with each other, becomes small.

9. The photoacoustic apparatus according to claim 1, wherein the processing unit deletes, from the time-series echo signal, an echo signal acquired in a period of time in which the acoustic wave is propagated from the acoustic wave transmission unit to the certain area.

10. The photoacoustic apparatus according to claim 1, wherein the processing unit starts acquiring an echo signal at a time point at which the acoustic wave is propagated from the acoustic wave transmission unit to the specific area.

11. The photoacoustic apparatus according to claim 1, wherein the processing unit acquires initial sound pressure distribution based on the time-series photoacoustic signal, acquires echo sound pressure distribution based on the time-series echo signal, and acquires difference distribution between the initial sound pressure distribution and the echo sound pressure distribution.

12. The photoacoustic apparatus according to claim 11, wherein the processing unit acquires the difference distribution after performing weighting, with a weighting coefficient, on at least one of the initial sound pressure distribution and the echo sound pressure distribution.

13. The photoacoustic apparatus according to claim 12, wherein the processing unit sets the weighting coefficient with which a difference between an initial sound pressure value and an echo sound pressure value in an arbitrary area becomes small.

14. The photoacoustic apparatus according to claim 13, further comprising an input unit with which a user can specify the arbitrary area from the initial sound pressure distribution or the echo sound pressure distribution displayed on a display unit.

15. The photoacoustic apparatus according to claim 12, wherein the processing unit acquires the difference distribution after performing weighting, with the weighting coefficient, only on the echo sound pressure distribution.

16. The photoacoustic apparatus according to claim 11, wherein the photoacoustic wave reception unit and the echo reception unit respectively receive the time-series photoacoustic signal and the time-series echo signal at the same reception sampling time, and

the processing unit acquires the initial sound pressure distribution and the echo sound pressure distribution in a minimum unit larger than a product of the reception sampling time and a speed of sound.

17. The photoacoustic apparatus according to claim 11, wherein the photoacoustic wave reception unit and the echo reception unit respectively acquire the time-series photoacoustic signal and the time-series echo signal at different reception sampling time, and

the processing unit acquires the initial sound pressure distribution and the echo sound pressure distribution in a minimum unit larger than a product of longer reception sampling time in the different reception sampling time and a speed of sound.

18. A photoacoustic apparatus comprising:

a light source configured to emit light;

an acoustic wave transmission unit configured to transmit an acoustic wave;

a photoacoustic wave reception unit configured to receive a photoacoustic wave generated by emission of the light, which is emitted from the light source, to a subject and configured to output a time-series photoacoustic signal;

an echo reception unit configured to receive an echo generated due to reflection of the acoustic wave transmitted from the acoustic wave transmission unit and configured to output a time-series echo signal; and

a processing unit configured to acquire a time-series difference signal between the time-series photoacoustic signal and the time-series echo signal and to acquire optical property information by using the time-series difference signal.

19. A photoacoustic apparatus comprising:

a light source configured to emit light;

an acoustic wave transmission unit configured to transmit an acoustic wave;

a photoacoustic wave reception unit configured to receive a photoacoustic wave generated by emission of the light, which is emitted from the light source, to a subject and configured to output a time-series photoacoustic signal;

an echo reception unit configured to receive an echo generated due to reflection of the acoustic wave transmitted from the acoustic wave transmission unit and configured to output a time-series echo signal; and

a processing unit configured to acquire initial sound pressure distribution based on the time-series photoacoustic signal, acquire echo sound pressure distribution based on the time-series echo signal, and acquire difference distribution between the initial sound pressure distribution and the echo sound pressure distribution.