Enrico M' Staderini, MD, PhD

1
Medical applications of UWB radars

• Enrico M. Staderini, MD, PhD
• School of Medicine - Medical Physics
• Tor Vergata University of Rome
• ITALY
• staderini_at_med.uniroma2.it

Tip this document has hyperlinks to related
documentation on the web, use them for further
information.
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This is the physicians view on(and a review
about)UWB radars in medicine
3
The medical radar history halted 20 years ago...

• 1971 A contactless apnoea detector based on
  radar presented (Lancet 1971 Oct
  302(7731)959-61) .
• 1976 Radar respiration monitor for infants
  described (Med. Biol. Eng. 1976
  May14(3)306-318) .
• 1980 Respiratory patterns in infants detected
  using radar (Arch. Dis. Child 1980
  Aug55(8)595-603) .

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The possible reasons for a failure

• Microwave radiation safety concerns.
• Cumbersome, bulky apparatuses.
• Power supply concerns.
• Cost/benefit concerns.
• Pneumology limited applications.
• Not a strong rationale for using.

• Rejection.

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The medical radarhistory restarted with UWB
technology in 1994
Image from LLNL MIR website, Livermore,
USA http//lasers.llnl.gov/lasers/idp/mir/cardio.h
tml
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The medical UWB radar history

• Aug. 9, 1994 first US Patent application filed
  for a medical UWB radar.
• Mar. 23, 1995 MIT educational project for the
  Radar Stethoscope.

Image from MIT website, Cambridge,
USA http//me.mit.edu/courses/2.744/s95/prj2/Sketc
hModels.html
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The medical UWB radar history

• Jan. 1996 The biomedical use of UWB radars is
  better described with photo and sample tracings
  (Science and Technology Review,
  UCRL-52000-96-1/2, Jan. 1996).
• Nov. 12, 1996 US Patent (no. 5,573,012) awarded.

Image from US Patent 5,573,012
8
The medical UWB radar history

• Nov. 12, 1996 second US Patent application
  filed.
• 1998 UWB radar application in medicine first
  described on a paper in a scientific journal (J.
  Acoust. Soc. Am. 103 (1), January 1998).
• Jun. 16, 1998 US Patent (no. 5,766,208 )
  awarded.
• 1999 Works in progress for UWB radar
  applications in cardiology, obstetrics, breath
  pathways and arteries.

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The medical UWB radar history

• UWB radar applications in medicine are being
  studied here (list may be incomplete)
• Lawrence Livermore National Laboratory
• (heart, breath, speech)
• University of California Davis
• (breath, speech)
• University of California Berkeley
• (speech)
• University of Iowa
• (speech)
• Tor Vergata University of Rome
• (heart)

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Could misunderstanding destroy a promising
technology ?

• As early as March 1995 a project was assigned to
  the students of the Mechanical Engineering
  Department of MIT. The purpose was the Design of
  a product concept the Radar Stethoscope .
• It was the very first attempt to test the
  feasibility of a real product for the biomedical
  market using UWB radar technology. Follow the
  link above.

Woody C. Flowers - Pappalardo Professor of
Mechanical Engineering, MIT David R. Wallace -
Assistant Professor of Mechanical Engineering, MIT
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Could misunderstanding destroy a promising
technology ?

• Unfortunately, the project was too much prone to
  the stethoscope concept and it appears to be a
  misunderstanding of the real strength of the
  technology and an opportunity lost.
• The radar stethoscope is NOT a stethoscope, so a
  different name (and claims!) should have had to
  be devised.

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Could misunderstanding destroy a promising
technology ?

• Most of the students developed clever prototypes
  just too much resembling a conventional
  electronic stethoscope.

Images from MIT website, Cambridge,
USA http//me.mit.edu/courses/2.744/s95/prj2/Rhond
aMassie.html
13
Could misunderstanding destroy a promising
technology ?

• A few of them quite attractive, indeed!

Images from MIT website, Cambridge,
USA http//me.mit.edu/courses/2.744/s95/prj2/Franc
isPahng.html
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Could misunderstanding destroy a promising
technology ?

• The bioengineering approach was probably wrong
• the sounds obtained with a radar stethoscope
  are too much different from conventional acoustic
  sounds.
• The new device appeared not just a new way to
  explore what is already known
• indeed it is a new, and unknown, modality of
  probing the human body.

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Could misunderstanding destroy a promising
technology ?

• The project is not known having reached the
  market
• (a first batch of 1000 was initially considered).
• 5 years after the filing of the first patent,
  commercial medical applications are still
  missing.
• Many new technologies has to fight against
  conservative approaches.

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A suitable model for UWB radar interaction with
the human body is missing
When you can measure what you are speaking
about, and express it in numbers, you know
something about it but when you cannot measure
it, when you cannot express it in numbers, your
knowledge is of a meager and unsatisfactory kind
it may be the beginning of knowledge, but you
have scarcely, in your thoughts, advanced to the
stage of science. William Thomson, Lord Kelvin
(1824-1907)
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?

• Is UWB really a golden egg tech in medicine

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Key questions

• What can be reasonably devised?
• What kind of medical problems really deserve UWB
  radar technology for their solution?
• Is UWB radar technology able to address yet
  unresolved medical problems?
• What should have to be the role of medical and
  bioengineering research?

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Most wanted technical features for any
electrical medical instrumentation

• Non invasiveness.
• Low power.
• Non contact remote operation.
• Biocompatibility.
• Biological friendliness.
• Environmental friendliness.
• Intrinsic electrical transducer.

UWB radar features them all!
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Most wanted clinical features for any electrical
medical instrumentation

• User friendliness.
• Imaging properties.
• Technical understandability by the users.
• Hardly to get physiological measurements.
• High sensitivity.
• High specificity.

UWB radar needs more research!
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Useful tips for any medical device
inventor/designer

• Look for a solid rationale before
  reinventing/modifying the wheel.
• Dont fall in love with technology.
• Aim to credible, clear, understandable
  objectives.
• Consider medical specificity.

UWB radar needs more research!
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The magic of seeingliving internal organs
But John Castorps attention was drawn by
something sack-shaped, a sort of formless animal,
dark and visible almost in the middle of the
thorax, and mostly on the right side as seen by
an observer, - it was contracting and relaxing
with a regular alternation between the two, like
a swimming jellyfish. Can you see his heart ?
My God! It was the heart, Johns aspiring
heart I am seeing your heart ! he said
with repressed voice. Thomas Mann - The
enchanted mountain Nobel Laureate German writer
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Cardiology

• Applications for heart monitoring were the first
  devised for UWB radar technology.
• Heart related research has a high impact on the
  general public.
• Unfortunately UWBtech had no visibility in the
  medical research area, although the situation is
  about to change.

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Cardiology

• The first Mc Ewans patent on the radar
  stethoscope

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Cardiology

• heart echoes

Images from US Patent 5,573,012
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Cardiology
The Visible Human Project http//www.dhpc.adelaide
.edu.au/projects/vishuman2/

• cardiology

• What we are looking at ?

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Cardiology

• EKG vs. UWB

Image from US Patent 5,573,012
UWB vs. US
Research needed!
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Cardiology

• Intensive Care Unit monitoring (avoiding a few
  more wires)

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Cardiovascular research
Image from US Patent 5,573,012

• Bio-mechanics of circulation

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Cardiology

• Advantages over current instrumentation
• Non-contact.
• No need for cleaning.
• No need for disposables.
• Remote and continuous operation.
• Lower cost.
• Lower maintenance.
• Easier use.

New
New
New
New
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Cardiology

• Summary of cardio applications
• Heart rate monitoring.
• Heart movements recording.
• Ambulatory cardiac output monitoring.
• Blood vessel movements recording.
• Blood pulse pressure celerity measurement.
• Shock diagnosis in emergency patients.

New
New
New
New
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Pneumology

• Respiratory patterns monitor.
• Apnea monitor in infants.
• Obstructive sleep apnea monitor.
• Polysomnography (sleep studies).
• Dynamic chest diameters measurement.
• Allergy and asthma crisis monitoring.
• Chest imaging (?).

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Obstetrics

• Great concern regarding RF safety for the newborn
  (but, why is ultrasound generally considered
  safe?).
• Very useful and common use devices might be
  produced (even for large scale sales).

Italian 16th century pregnancy ring
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Obstetrics
An ultrasound fetal monitor is a device designed
to transmit and receive ultrasonic energy into
and from the pregnant woman, usually by means of
continuous wave (doppler) echoscopy. The device
is used to represent some physiological condition
or characteristic in a measured value over a
period of time (e.g. perinatal monitoring during
labor) or in an immediately perceptible form
(e.g. use of the ultrasonic stethoscope).

• Conventional (octopus) ultrasound-based fetal
  monitor.

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Obstetrics
Unfortunately, emissions from the device make
this a fear generating situation!

• A comprehensive obstetrical UWB radar-based
  monitor.

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Obstetrics

• Advantages over current instrumentation
• Non-contact.
• Unimpaired mother and child care.
• Remote operation.
• Lower cost.
• Lower maintenance.
• No cleaning.
• Easier use.

New
New
New
New
New
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Ear-Nose-Throat

• Medical applications of the throat microphone
• In principle the throat microphone is a device
  able to monitor vocal chords movements by means
  of UWB radar.

Image from LLNL MIR website, Livermore,
USA http//lasers.llnl.gov/lasers/idp/mir/throatmi
c.html
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ENT

• medical uses may not be concerned with voice at
  all, as in
• vocal chords diseases
• inflammations
• allergies
• cancer
• for medical purposes, a vocal chords movements
  monitor is much more valuable than a simple
  throat microphone.

New
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ENT

• The University of Iowas National Center for
  Voice and Speech and the UC Davis
  Voice/Speech/Swallowing Center are actively
  working on speech sensors using UWB radar
  technology.
• Correlations were found between UWB radar
  signature and other conventional tracings while
  recording the movements of lips, tongue, glottis
  and tracheal wall.

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Rehabilitation medicine

• Biofeedback-based rehabilitation protocols
• respiratory rehabilitation
• cardiovascular rehabilitation
• occupational therapy
• Artificial prosthesis control and actuation
• wheelchair driving systems
• smart-home systems

New
New
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Other medical areas of application

• Underwater medicine measurements.
• Space medicine measurements.
• Sport medicine measurements.
• Military medicine.
• Emergency medicine
• Rubble Rescue Radar

New
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The optical UWB radar
Fast pulse IR laser
Target
Fast PIN photodiode

• IR pulse and echo

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Neurology

• Brain studies.
• Biochemical studies.
• IR spectral imaging.
• Brain hemoglobin O2 sat

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Research directions
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Research directions
UNDERSTAND WHAT WE GET

• To validate UWB radar as a viable technology to
  be used in medicine we need to better know the
  genesis of the UWB radar signal, so to correlate
  it with already known electro/mechano biological
  phenomena.

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Research directions
A MODEL OF UWB PULSE INTERACTION WITH THE LIVING
TISSUES IS REQUIRED

• UWB echos coming from the structures inside the
  human body are mainly explained in the framework
  of the time domain reflectometry (TDR) theory
  (see McEwans patents on body movements
  monitoring).

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Research directions

• According to McEwans model
• (as presented in US Patent 5,573,012)

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Research directions

• A more appropriate model for the echoes from the
  frontal heart wall

Picture from the Visible Human Project
right lung
echo generating surfaces
UWB radar device
left ventricle
impedance attenuation wave speed
thickness
left lung
beam path
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Research directions

• Electromagnetic data obtained from
• Camelia Gabriel, PhD., Sami Gabriel, MSc.
• Compilation of the Dielectric Properties of Body
  Tissues at RF and Microwave Frequencies

Physics Department King's College London London
WC2R 2LS, UK. Armstrong Laboratory (AFMC)
Occupational and Environmental Health Directorate
- Radiofrequency Radiation Division 2503 D Drive
Brooks Air Force Base TX, 78235-5102 Report
AL/OE-TR-1996-0037
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Research directions

• The pulse propagation model

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Research directions

• The echo propagation model

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The results from the model

• Time delay pulse-echo flight time 1.74 ns

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The results from the model

• Echo decay pulse-echo decay -35.6 dB

Power losses balance echoes from non-target
surfaces -10 dB attenuation from layers in the
pulse-echo path -10 dB useful echo from target
surface -15 dB
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Limitations of the model

• Although more accurate, the new model of
  pulse-echo behavior in the thorax is all but
  correct. As the dielectric properties used were
  those measured on actual living tissues using a
  continuous wave at 1500 MHz, the model remains
  intrinsically wrong.
• Indeed, for an effective model to be developed,
  we need ultra wide-band dielectric properties,
  not narrow band ones (although in the microwave
  region). This means that a convolution method, or
  a Finite Differences Time Domain technique, like
  that already employed in UWB antenna
  calculations, should be used.

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Limitations of the model

• Also, both the real part and the imaginary one of
  the reflection coefficients at the boundaries
  should be considered, as the UWB receiving
  correlator, working in the time domain, is by
  design strongly sensitive to phase errors.
• Another point to be addressed is that of the
  receiving correlator itself to assess what amount
  is actually its phase sensitivity.

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Research directions

• In a nutshell we know that a heart-related
  signal is obtained out of a UWB radar device
  aimed at the thorax, but what are we actually
  measuring? To what extent do correlator
  performances, pulse shape and tissues properties
  affect the intensity and morphology of the
  recovered signal?
• These problems ask for some clear answers to
  reach an adequate physical understanding of
  medical UWB radar and subsequent clinical
  viability and acceptability of the technique.
  Accurate modeling of the phenomena with correct
  and extended electromagnetic measures should help
  advancement of science in this field.

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Research directions

• The SARA prototype (1997)

Just an amateur prototype, it was initially built
for fun. It actually detects heart beats from a
distance of 1/2 inch to the thorax using a simple
dipole antenna.
Tor Vergata University of Rome,
1997 http//www.uniroma2.it/fismed/UWBradar
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Research directions

• The CASTORP prototype (1999)

• Improvements over SARA
• µP controlled range gating using dual channel
  VCDG (Voltage Controlled Delay Generator with
  Dtmax 35 ns).
• higher pulse power (Peak power 2W Mean power
  2mW).
• higher CMRR in the UWB receiver.
• ADC conversion and direct RS-232 connection to
  host PC.
• software elaboration of UWB heart signature
  using FWT (fast wavelet transform).

Tor Vergata University of Rome, 1999
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Research directions

• What next ?

• Studies in the medical domain to correlate UWB
  heart signature signals with
• ultrasound heart M-Mode tracings.
• external phonocardiogram and apexcardiogram
  tracings.
• external ballistocardiogram tracings.
• invasive pressure pulse recordings.
• electrocardiogram recordings.
• better understanding and modeling of RF pulse
  propagation in the living tissues

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My card