INVESTIGATION OF PHYSICAL PROPERTIES OF AN OBJECT

• US 20110237956A1
• Filed: 10/12/2009
• Published: 09/29/2011
• Est. Priority Date: 10/13/2008
• Status: Active Grant

• Current Assignee: Oxford University Innovation Limited (University of Oxford)
• Original Assignee: Isis Innovation Limited
• Inventors: Edwards, David John, Stevens, Christopher John
• Granted Patent: US 9,164,033 B2
• Time in Patent Office: Days
• US Class Current: 600/473
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61B 5/0051 by applying vibrations
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/0825 for diagnosis of the breast, e.g. mammography
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01N 2021/1706 in solids
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01S 15/899 Combination of imaging systems with ancillary equipment

Abstract

An imaging system for an object such as human or animal tissue uses scattering of an illuminating electromagnetic wave by acoustic vibrations to generate a scattered electromagnetic wave including Doppler components shifted from the frequency of the illuminating electromagnetic wave by frequencies of the acoustic vibration and multiples thereof. An acoustic transducer apparatus applies acoustic vibrations localised in two or three dimensions in a plurality of regions. A transmitter simultaneously illuminates the object with an illuminating electromagnetic wave that has a frequency in the range from 100 MHz to 100 GHz, the vibration direction of the acoustic vibration having a component parallel to the propagation direction of the illuminating electro-magnetic wave. A receiver receives the scattered electromagnetic wave. A signal processing apparatus derives characteristics of the Doppler components, and stores image data representing the derived characteristic.

Claims

1. A method of investigating physical properties of an object, comprising:

Applying to the object acoustic vibration localised in two or three dimensions in a region in the object;

simultaneously illuminating the object with an illuminating electromagnetic wave that has a frequency in a range extending down from 30 THz, the vibration direction of the acoustic vibration having a component parallel to the propagation direction of the illuminating electromagnetic wave so that the acoustic vibration of the object in the region generates a scattered electromagnetic wave including Doppler components shifted from the frequency of the illuminating electromagnetic wave by frequencies of the acoustic vibration and multiples thereof; and

receiving the scattered electromagnetic wave generated in the region, and

deriving from the received, scattered electromagnetic wave data representing at least one characteristic of the Doppler components.

2. A method according to claim 1, wherein the object is human or animal tissue.

3. A method according to claim 1, wherein said range of the frequency of the illuminating electromagnetic wave extends down from 100 GHz.

4. A method according to claim 1, wherein said range of the frequency of the illuminating electromagnetic wave extends down to 100 MHz.

5. A method according to claim 1, wherein the acoustic vibration has a frequency in the range from 10 MHz to 1 GHz.

6. A method according to claim 1, wherein the vibration direction of the acoustic vibration and the propagation direction of the illuminating electromagnetic wave are parallel.

7. A method according to claim 1, wherein the scattered electromagnetic wave is received along a line parallel or antiparallel to the propagation direction of the illuminating electromagnetic wave.

8. A method according to claim 1, wherein the method is performed with acoustic vibrations of different frequencies and/or with an illuminating electromagnetic wave of different frequencies to derive data representing said at least one characteristic of the Doppler components in respect of the different frequencies of the acoustic vibrations and/or the illuminating electromagnetic wave.

9. A method according to claim 1, wherein at least one characteristic of the Doppler components includes at least one of an amplitude or a phase of one or more of the Doppler components.

10. A method according to claim 1, wherein the step of deriving at least one characteristic of the Doppler components comprises frequency-modulation demodulating the Doppler components from the component of the scattered electromagnetic wave of the same frequency as the illuminating electromagnetic wave.

12. A method according to claim 1, being a method of imaging the object wherein:

the step of applying acoustic vibration comprises applying the acoustic vibration localised in a plurality of regions sequentially, or simultaneously but with different frequencies in each region;

the step of receiving the scattered electromagnetic wave comprises receiving the scattered electromagnetic wave generated in each of the plurality of regions;

the step of deriving data comprises deriving data representing at least one characteristic of the Doppler components in respect of each region;

the method further comprises storing the derived data in respect of each region as image data.

14. A method according to claim 12, wherein the acoustic vibration applied to the object is localised in three dimensions in a region in the object, being applied as a pulse localised in space in a first and second dimension and localised in a third dimension in different regions at different times as it propagates.

22. A method according to claim 12, wherein the acoustic vibration applied to the object is localised in three dimensions in a region in the object, being applied as a plurality of simultaneous propagating beams of different frequencies localised in space in a first and second dimension in different regions and localised in a third dimension in different regions at different times as the beams propagate.

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29. A system for investigating physical properties of an object, the system comprising:

an acoustic transducer apparatus arranged to apply to the object acoustic vibration localised in two or three dimensions in a region in the object;

a transmitter arrangement arranged to illuminate the object with an illuminating electromagnetic wave having a frequency in a range extending down from 30 THz simultaneously with the application of acoustic vibration, the vibration direction of the acoustic vibration having a component parallel to the propagation direction of the illuminating electromagnetic wave so that the acoustic vibration of the object in the region generates a scattered electromagnetic wave including Doppler components shifted from the frequency of the illuminating electromagnetic wave by frequencies of the acoustic vibration and multiples thereof;

a receiver arrangement arranged to receive the scattered electromagnetic wave generated in the region; and

a signal processing apparatus arranged to derive, from the received scattered electromagnetic wave generated in the region, data representing at least one characteristic of the Doppler components.

31. A system according to claim 29, wherein said range of the frequency of the illuminating electromagnetic wave extends down from 100 GHz.

32. A system according to claim 29, wherein said range of the frequency of the illuminating electromagnetic wave extends down to 100 MHz.

33. A system according to claim 29, wherein the acoustic vibration has a frequency in the range from 10 MHz to 1 GHz.

34. A system according to claim 29, wherein the vibration direction of the acoustic vibration and the propagation direction of the illuminating electromagnetic wave are parallel.

35. A system according to claim 29, wherein the receiver arrangement is arranged to receive the scattered electromagnetic wave along a line parallel or antiparallel to the propagation directions of the illuminating electromagnetic wave.

36. A system according to claim 29, wherein the acoustic transducer apparatus is arranged to apply acoustic vibrations of different frequencies and/or with an illuminating electromagnetic wave of different frequencies, and the signal processing apparatus is arranged to derive data representing at least one characteristic of the Doppler components in respect of the different frequencies of the acoustic vibrations and/or the illuminating electromagnetic wave.

37. A system according to claim 29, wherein at least one characteristic of the Doppler components includes at least one of the amplitude and phase of one or more of the Doppler components.

38. A system according to claim 29, wherein the original signal processing apparatus includes a frequency-modulation demodulator arranged to demodulate the Doppler components from the component of the scattered electromagnetic wave of the same frequency as the illuminating electromagnetic wave.

40. A system according to claim 29, being an imaging system wherein

the acoustic transducer is arranged to apply acoustic vibration localised in a plurality of regions sequentially, or simultaneously but with different frequencies in each region;

the receiver is arranged to receive the scattered electromagnetic wave generated in each of the plurality of regions; and

the signal processing apparatus is arranged to derive data representing at least one characteristic of the Doppler components in respect of each region, and to store the derived data in respect of each region as image data.

43. A system according to claim 40, wherein the acoustic transducer apparatus is arranged to apply the acoustic vibration localised in three dimensions in a region in the object, being arranged to apply the acoustic vibration as a pulse localised in space in a first and second dimension and localised in a third dimension in different regions at different times as it propagates.

47. A system according to claim 40, wherein the acoustic transducer apparatus is arranged to apply the acoustic vibration localised in three dimensions in a region in the object, the acoustic transducer apparatus being arranged to apply the acoustic vibration localised in three dimensions in a region in the object, being arranged to apply the apply the acoustic vibration as a plurality of propagating beams of different frequencies localised in space in a first and second dimension in different regions and localised in a third dimension in different regions at different times as the beams propagate.

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