LOW-COST DEVICE FOR C-SCAN PHOTOACOUSTIC IMAGING

• US 20100016717A1
• Filed: 07/17/2009
• Published: 01/21/2010
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: Rochester Institute of Technology
• Original Assignee: University of Rochester
• Inventors: DOGRA, Vikram S., RAO, Navalgund A.H.K.
• Granted Patent: US 8,353,833 B2
• Time in Patent Office: Days
• US Class Current: 600/437
• 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
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/415 the glands, e.g. tonsils, adenoids or thymus
• CPC Class Codes: A61B 5/418 lymph vessels, ducts or nodes
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: A61B 5/4337 of the vagina
• CPC Class Codes: A61B 5/4381 Prostate evaluation or disorder diagnosis
• CPC Class Codes: A61B 5/4571 Evaluating the hip
• CPC Class Codes: A61B 8/4416 related to combined acquisition of different diagnostic modalities, e.g. combination of ultrasound and X-ray acquisitions
• CPC Class Codes: G01S 7/52061 Plan position indication (PPI display); C-scan display

Abstract

The prostate gland or other region of interest is stimulated with laser light, resulting in ultrasound waves (photoacoustic effect) which are focused by an acoustic lens and captured by a specific 1- or 2D sensor array and subsequently displayed as a C-scan on a computer screen. The amplitude of the ultrasound waves generated by laser stimulation is proportional to the optical absorption of the tissue element at that spatial location. Variability in tissue absorption results in C-scan image contrast. The photoacoustic imaging is combined with an ultrasound C-scan image produced with a plane ultrasound wave applied to the region of interest.

Claims

1. A method for imaging a region of interest, the method comprising:

(a) stimulating the region of interest with light from a light source to produce a first set of ultrasound waves through a photoacoustic effect;

(b) stimulating the region of interest with ultrasound radiation from an ultrasound source to produce a second set of ultrasound waves reflected from the region of interest;

(c) focusing the first and second sets of waves through an acoustic lens to produce focused waves;

(d) detecting the focused waves in a transducer while applying a time gate to produce time-gated photoacoustic signals, the time-gated photoacoustic signals providing at least one photoacoustic C-scan at any given period of time, step (d) being repeated multiple times to provide real-time imaging;

(e) detecting the focused waves in a transducer while applying a time gate to produce time-gated ultrasound signals, the time-gated ultrasound signals providing at least one ultrasound C-scan at any given period of time, step (e) being repeated multiple times to provide said real-time imaging; and

(f) imaging the region of interest from the at least one photoacoustic C-scan and the at least one ultrasound C-scan provided in steps (d) and (e).

2. The method of claim 1, wherein, in step (a), the light comprises laser light from a laser light source.

3. The method of claim 2, wherein the laser light is generated by a photodiode.

4. The method of claim 2, wherein the light source comprises an optical fiber in communication with the laser light source.

5. The method of claim 1, wherein, during steps (a)-(c), the light source and the transducer are scanned relative to the region of interest.

6. The method of claim 5, wherein the light source and the transducer are provided in a rigid assembly, and wherein the rigid assembly is scanned during steps (a)-(c).

7. The method of claim 5, wherein the light source and the transducer are scanned in two dimensions.

8. The method of claim 5, wherein the light source and the transducer are scanned in three dimensions.

9. The method of claim 1, wherein the transducer comprises a transducer array.

10. The method of claim 9, wherein the transducer array is a two-dimensional array.

11. The method of claim 1, wherein an optical fiber is used to deliver the light from the light source to the region of interest.

12. The method of claim 1, wherein the region of interest is located in a living body.

13. The method of claim 12, wherein the region of interest is located at least partially in a prostate.

14. The method of claim 12, wherein the region of interest is located at least partially in a breast.

15. The method of claim 12, wherein the region of interest is located at least partially in a pelvic region.

16. The method of claim 15, wherein, during steps (a) and (b), the light source and the transducer are inserted into a vagina.

17. The method of claim 1, wherein the region of interest is located in an in vitro environment.

18. The method of claim 1, wherein step (b) is performed using a single or compound acoustic lens.

19. The method of claim 18, wherein the acoustic lens comprises a biconcave lens.

20. The method of claim 1, wherein step (b) is performed with a non defracting ultrasound source.

21. The method of claim 20, wherein the non-defracting ultrasound source comprises a plane wave generator of an acoustic wave.

22. A probe for imaging a region of interest, the probe comprising:

a light source for stimulating the region of interest with light to produce a first set of ultrasound waves through a photoacoustic effect;

an ultrasound source for stimulating the region of interest with ultrasound radiation to produce a second set of ultrasound waves reflected from the region of interest;

an acoustic lens for focusing the first and second sets of waves through an acoustic lens to produce focused waves;

a transducer for detecting the focused first set of waves while applying a time gate to produce time-gated photoacoustic signals, the time-gated photoacoustic signals providing at least one photoacoustic C-scan at any given period of time, said at least one photoacoustic C-scan being repeated multiple times to provide real-time imaging, and for detecting the focused second set of waves while applying a time gate to produce time-gated ultrasound signals, the time-gated ultrasound signals providing at least one ultrasound C-scan at any given period of time, said at least one ultrasound C-scan being repeated multiple times to provide said real-time imaging.

23. The probe of claim 22, further comprising a rigid assembly in which the light source and the transducer are provided.

24. The probe of claim 22, wherein the transducer comprises a transducer array.

25. The probe of claim 24, wherein the transducer array is a two-dimensional array.

26. The probe of claim 22, wherein the light source comprises a laser source.

27. The probe of claim 26, wherein the laser source comprises a photodiode.

28. The probe of claim 26, wherein the light source further comprises an optical fiber an optical fiber.

29. The probe of claim 22, wherein the acoustic lens comprises a single or compound acoustic lens.

30. The probe of claim 29, wherein the acoustic lens comprises a biconcave lens.

31. The probe of claim 22, wherein the non-defracting ultrasound source comprises a plane wave generator of an acoustic wave.

32. A method for imaging a region of interest, the method comprising:

(a) receiving acoustic waves from the region of interest;

(b) focusing the acoustic waves onto a two-dimensional detector array to detect the acoustic waves; and

(c) imaging the region of interest in accordance with the acoustic waves detected by the array.

33. The method of claim 32, wherein step (c) comprises time-gating the detected acoustic waves such that a C-scan image is produced.

34. A system for imaging a region of interest, the system comprising:

a two-dimensional detector array;

an acoustic lens for receiving acoustic waves from the region of interest and for focusing the acoustic waves onto the two-dimensional detector array to detect the acoustic waves; and

a processor, in communication with the array, for imaging the region of interest in accordance with the acoustic waves detected by the array.

35. The system of claim 34, wherein the processor time-gates the detected acoustic waves such that a C-scan image is produced.

36. A method for imaging a region of interest, the method comprising:

(a) receiving acoustic waves from the region of interest;

(b) focusing the acoustic waves onto a detector to detect the acoustic waves;

(c) time-gating the acoustic waves to produce time-gated acoustic waves; and

(d) performing a C-scan of the region of interest in accordance with the time-gated acoustic waves.

37. The method of claim 36, wherein the acoustic waves comprise photoacoustic waves.

38. The method of claim 36, wherein the acoustic waves comprise ultrasound waves.

40. The method of claim 36, wherein the detector comprises a 1D or 2D array.

39. The method of clam 38, wherein the acoustic waves further comprise photoacoustic waves.

41. A system for imaging a region of interest, the system comprising:

a detector;

an acoustic lens for receiving acoustic waves from the region of interest and for focusing the acoustic waves onto the detector to detect the acoustic waves; and

a processor for time-gating the acoustic waves to produce time-gated acoustic waves and performing a C-scan of the region of interest in accordance with the time-gated acoustic waves.

42. The system of claim 41, wherein the detector comprises a 1D or 2D array.