MONITORING THE BODY USING MICROWAVES

Abstract

An apparatus for determining characteristics of pulsatility of the brain (5) comprises: an ultra-wideband microwave transceiver (1) arranged to generate ultra-wideband microwave pulses (6); a transmitting means (3) arranged to transmit the ultra-wideband microwave pulses; and a receiving means (3) arranged to receive a signal corresponding to detection of the pulses. A method of determining characteristics of pulsatility of a first part of the brain comprises: transmitting ultra-wideband microwave pulses into the first part of the brain; receiving a signal corresponding to detection of the pulses; and processing the signal.

Claims

1. A method of determining characteristics of pulsatility of a first part of the brain comprising: transmitting ultra-wideband microwave pulses into the first part of the brain; receiving a signal corresponding to detection of the pulses; and processing the signal.

2. A method according to claim 1, wherein the characteristic that is determined is the frequency and/or amplitude of pulsation of the first part of the brain.

3. A method according to claim 1 or 2, comprising comparing the measured characteristics of the pulsatility of the first part of the brain to the expected characteristics of the pulsatility of the first part of the brain.

4. A method according to claim 1 or 2, comprising determining the characteristics of the pulsatility of a second part of the brain and comparing it to the characteristics of the pulsatility of the first part of the brain.

5. A method according to claim 4, wherein the first part of the brain is a portion of one of the hemispheres of the brain, and the second part of the brain is a portion in the opposed hemisphere of the brain.

6. A method according to claim 4, wherein the first part of the brain is the frontal (anterior) portion of the brain, and the second part is the posterior portion of the brain.

7. A method according to any preceding claim wherein the ultra-wideband microwave pulses have a broadband frequency of between 0.5 GHz and 10 GHz.

8. A method according any preceding claim wherein the ultra-wideband microwave pulses have a pulse repetition rate of greater than 5 Hz, more preferably greater than 10 Hz, and most preferably 20 Hz or greater, and/or wherein the ultra-wideband microwave pulses have a pulse repetition rate of less than 150 Hz, more preferably less than 100 Hz, and most preferably 50 Hz or less.

9. A method according to any preceding claim comprising processing the signal with respect to fast-time sampling within a single pulse and slow-time pulse-to-pulse variations.

10. A method according to any preceding claim, wherein the signal is processed using Principal Component Analysis.

11. A method according to any preceding claim, wherein the ultra-wideband microwave pulses are transmitted using an impulse radar transceiver.

12. An apparatus for determining characteristics of pulsatility of the brain comprising: an ultra-wideband microwave transceiver arranged to generate ultra-wideband microwave pulses; a transmitting means arranged to transmit the ultra-wideband microwave pulses; and a receiving means arranged to receive a signal corresponding to detection of the pulses.

13. An apparatus according to claim 12, comprising a processing unit operable to process the signal to determine characteristics of pulsatility of the brain.

14. An apparatus according to claim 12, comprising a communications unit for communication with a remote processing unit, preferably via a telecommunications network.

15. An apparatus according claim 13 or 14, wherein the apparatus comprises a warning indicator, and wherein the processing unit is operable to control the warning indicator to output a warning if the characteristics of pulsatility of the brain are outside of a predetermined range.

16. An apparatus according to any of claims 12 to 15, comprising a plurality of ultra-wideband microwave units, each comprising an ultra-wideband microwave transceiver, an ultra-wideband microwave transmitting antenna and an ultra-wideband microwave receiving antenna.

17. An apparatus according to any of claims 12 to 15, comprising a plurality of ultra-wideband microwave units, each comprising an ultra-wideband microwave transceiver, and an ultra-wideband microwave transmitting/receiving antenna.

18. An apparatus according to claim 16 or 17, wherein the antenna(e) is/are micro strip patch antenna(e).

19. An apparatus according to claim 16, 17, or 18 comprising a support structure to which the plurality of ultra-wideband microwave units are attached.

20. An apparatus according to claim 19 wherein the support structure includes a coupling medium to the skull.

21. An apparatus according to claim 19 or 20, wherein the support structure is a helmet, and preferably the plurality of units are arranged so as to direct microwave radiation to opposed regions of the brain.

22. An apparatus according to claim 18, 19 or 20, wherein the support structure is a hand-held device.

23. An apparatus according to any of claims 12 to 22, wherein the ultra-wideband microwave transceiver is an impulse radar transceiver.

24. An apparatus according to any of claims 12 to 23, for carrying out the method of any of claims 1 to 11.

25. An apparatus substantially as described herein, with reference to the accompanying drawings.

26. A method substantially as described herein, with reference to the accompanying drawings.

Description

[0067] Certain preferred embodiments will now be described by way of example only and with reference to the accompanying drawings, in which:

[0068] FIG. 1 shows a schematic view of an ultra-wideband microwave unit for use in an apparatus in accordance with an embodiment of the present invention;

[0069] FIG. 2 shows an apparatus in accordance with an embodiment of the present invention;

[0070] FIG. 3 shows an exemplary 2-D data matrix for one transceiving antenna of the apparatus of FIG. 1;

[0071] FIG. 4 shows an experimental test set-up; and

[0072] FIG. 5 shows power density as a function of frequency for the first to sixth components following an independent component analysis in the test set-up of FIG. 4.

[0073] FIG. 1 shows: an ultra-wideband transceiving microwave and data processor unit 1; a connection means 2 for connection to a post-processing unit (not shown); a ultra-wideband antenna 3; and a coupling medium 4. An ultra-wideband pulse 6 is transmitted into the brain 5.

[0074] The ultra-wideband transceiving microwave radar 1 is a fully integrated nano-scale impulse radar transceiver with a single-chip impulse-based radar designed for low-power (20 dBm) high-performance applications. Such a radar provides a low-cost, highly integrated and highly robust solution for a wide range of remote sensing applications and could employ 32-bit digital integration and 512 parallel samplers for maximum frame depth and sensitivity, as well as a fully programmable frame offset for an extensive detection range. Non-limiting examples of such a units are the XeThru X1 (previously NVA6100) and X2 (previously NVA6201) single-chip impulse radar transceiver integrated circuits (CMOS chips) provided by Novelda AS. The ultra-wideband microwave radiation pulse 6 is emitted with a frequency using sinusoid antennae from 3 to 6 GHz, with a pulse repetition rate of 20 Hz.

[0075] The ultra-wideband antenna 3 is a transmitting/receiving micro patch antenna.

[0076] The coupling medium 4 ensures coupling (minimal wave reflection) and prevents the beam from diverging (as it will in air) for a given aperture dimension.

[0077] FIG. 2 shows an apparatus including the unit of FIG. 1, integrated into a motorcycle helmet 10. The helmet comprises a plurality of units supported by and spaced around the helmet, so that microwave radiation can be directed from separate units to each of the two hemispheres of the brain, and to the front and back of the brain. This allows comparison of the pulsatility of the two hemispheres, and independently, comparison of the pulsatility of the front and back of the brain.

[0078] The helmet 10 includes warning indicators 11 and 12. The first indicator 11 comprises LEDs, which emit light (for example, a red flashing light) if it is determined that the brain has been damaged. The second indicator 12 comprises a speaker which can emit sound if it is determined that the brain has been damaged.

[0079] The helmet 10 also comprises a communications system (not shown) for communication via a telecommunications network to a server (not shown), which analyses data from the microwave unit to determine whether the brain is damaged. If such a determination is made, a signal is sent from the server to the helmet to activate the warning indicators 11, 12.

[0080] Post-processing of the data obtained by the microwave unit is carried out by the remote server. The signal is processed with respect to fast-time (on a time scale of the order of nanoseconds) and pulse-to-pulse variations (on a timescale of the order of milliseconds).

[0081] The experimental setup shown in FIG. 4 comprises a transceiving radar system with separate Tx and Rx inputs/outputs and a directional coupler included for monostatic antenna operation. The antenna is coupled to a layered lossy load consisting of a coupling medium (5 mm thick), a skull medium (1 mm layer) and a 28 mm muscle phantom mimicking brain tissue. Pulsatile variations are simulated by moving a target cylinder (23 mm diameter) within a square liquid-filled well of 28 mm at 26 mm depth in the phantom.

[0082] The liquid and the cylinder material were varied to obtain combinations with more or less reflection contrast for the incoming electromagnetic pulse. Longitudinal movement of the cylinder was in the range of 1-2 mm, with a periodicity of 1 second to 0.25 seconds.

[0083] The measurement for the transceiving antenna configuration is represented as a 2-D matrix X(i,j) with dimensions MN. The index T denotes fast-time (or distance into the target) on the nanosecond scale, whereas T denotes the pulse-to-pulse slow-time index (on the scale of seconds).

[0084] Such a matrix is shown in FIG. 3A. Fast-time corresponds to range along the radar beam and slow-time samples the pulse-to-pulse variations due to dynamics of the target. The shaded band corresponds to a given depth and the black dots illustrate the pulsatile variations sampled on a slow-time scale.

[0085] FIG. 3B shows a schematic of the pulsatile signal (although this is highly simplified as in the real case it will be buried in noise or other more dominant signals e.g. receiver system gain variations). The pulsatile signal is expected to be similar to a pulse train giving a spectral response with a dominant frequency and less marked, but detectable, higher harmonics. The pulsatile signal shown in FIG. 3B is extracted from the matrix using Principal Component Analysis. The M principal components of the data matrix X are given by:

Y=A.sup.TX [0086] Here, X=[x.sub.1,x.sub.2 . . . x.sub.M].sup.T, and is the zero-mean input data (MN) [0087] and Y=[y.sub.1.y.sub.2 . . . y.sub.M].sup.T, and is the output matrix of principal components.
A can be computed using the covariance matrix,

[00001]$C_X=\frac{1}{N}.Math.{\mathrm{XX}}^T$

The next step is to find the eigenvalue and eigenvector matrices of C.sub.x, and .

=diag(.sub.1, .sub.2 . . . .sub.M) where .sub.1, .sub.2 . . . .sub.M are the eigenvalues.

After arranging the eigenvalues in decreasing order, A is given by:

A=[.sub.1, .sub.2 . . . .sub.M

The principal component matrix S is given by:

S=A.sup.TX

S=[s.sub.1, s.sub.2 . . . s.sub.M].sup.T

The s vectors are principal components arranged in strength of variance.

[0088] The result of such an independent component analysis, carried out using the test-set up shown in FIG. 4, is shown in FIG. 5. Here, a signal at 1 Hz is clearly visible in the 3.sup.rd to 6.sup.th components.