First log submissions have now been graded.
Those achieving full marks included:
Logs within the word limit or less than 10% above.
Overview of their understanding of the topics discussed and their own opinions – just simply what
Clear evidence of having read material in addition to the slides – references etc.
Clear evidence of having undertaken the practicals.
Many also include a reflection / self learning / background reading section.
Assignment progress section from now on.
Tips:- include logs in a single word doc or better still use word press and publish online – be sure to
reference sources to avoid copyright issues.
WEEK 4 PRACTICAL
If possible, bring along a pair of headphones.
Practical focuses on editing sound files using a
program called Goldwave.
MEDICAL IMAGING AND BIOSIGNAL
Healthcare Technologies encompass all IT
solutions in healthcare ranging from software
systems which support patient management to
devices which support diagnosis and management
Today, we want to focus on those devices which are
used for obtaining measurements from the human
body to assist with detection or absence of disease.
HEALTHCARE TECHNOLOGY CATEGORIES
Human beings are very complex, consisting of muscle,
bone, organs and transport vessels.
Healthcare technologies have emerged as a direct need
for examining the human body to provide diagnosis and
prognosis for a variety of different complex ailments.
Healthcare technologies can be used to examine the:
CURRENT HEALTHCARE TECHNOLOGIES
What can we measure from the
Electrical Properties and Behaviors
Note. We often want to look at things
that are obvious on the outside of
the body, like temperature. We look
only at more invasive applications
These are alterations
observed in the physical
structure of the body.
E.g. A broken bone or abnormal
growth such as a tumor.
ELECTRICAL PROPERTIES AND BEHAVIORS
Many of the body’s organs are
controlled by OR generate
E.g. The brain and muscles, including
Changes observed in the typically
produced signals often indicate
changes to the physical /
mechanical structure of the organs.
When organs become damaged or experience
shock or trauma they release chemicals into the
body’s blood stream.
E.g. During a myocardial infarction (heart attack) the
chemical troponin is released into the blood stream.
The presence of such chemicals or elevated
concentrations of such chemicals can indicate
potential problems with the body’s organs.
The sounds generated by the body’s organs can be
Auscultation is the technical term given to listening
to the internal sounds of the body, usually using a
Typically performed for examining the circulatory or
i.e. heart or lungs.
Many devices and techniques exist to measure the physical make up of
Large portion of these devices are grouped under ‘medical imaging’.
Main purpose of these devices is to non-invasively produce images
of internal aspects of the body:
Clinical rationale: examination, diagnosis, and prognosis.
Medical science: assist with the study and understanding of the
Different Medical Imaging devices include:
Magnetic Resonance Imaging (MRI)
Computed Axial Tomography (CAT) better known as CT
Phrase coined in 1895 by a German Physicist.
Widely used approach which is based on the usage of
In diagnostic applications the X-rays are passed through
the body and detected on a photographic plate or film.
More dense parts of the body absorb the x-rays while
less dense parts of the body allow the x-rays to pass
This produces a shadow like image of the internal part
of the body which has been x-rayed.
This approach can show up solid
items such as bones or tumours.
Very cheap, fast and relatively safe.
Applications: Dentist, Broken bones,
Organs / blood vessels can also be
examined using contrast media to
more effectively absorb the x-ray
Injected or swallowed. SOURCE http://www.davidlnelson.md/Xrays_normal_hand_PA.htm
X-RAY VIDEO DESCRIPTION
ARE X-RAYS SAFE?
X-rays can be harmful if exposed to for long periods.
Radiation sickness can occur
X-rays are a form of ionizing radiation. When normal
light hits an atom, it can't change the atom in any
significant way. But when an X-ray hits an atom, it can
knock electrons off the atom to create an ion
Free electrons then collide with other atoms to create more
An ion's electrical charge can lead to unnatural chemical
reactions inside cells, such as the breaking of DNA chains,
leading to mutations such as cancer.
Nevertheless, X-ray still safer than invasive surgery and
therefore regarded as one of the most useful medical devices
of all time.
COMPUTED (AXIAL) TOMOGRAPHY
A major drawback of X-Ray is that it can only represent the
internal system on one axis at a time .
CAT scan or CT scan overcomes this drawback by capturing a
series of 2D X-ray images which are processed to provide 3D
CT used to separate anatomical structures at different depths.
The computer varies the intensity of the X-rays in order to scan each
type of tissue with the optimum power.
Especially good for scanning bone structure!
Contrast materials are used to allow the viewing of some
structures like vessels.
Images are typically rendered on a computer.
CT uses x-rays but instead of passing the x-
rays through the body from one angle the x-
rays are passed into the body from
numerous locations and angles.
With the aid of a special computer the
resulting patterns can be captured and
pieced together to form a cross-sectional
image of inside the body.
This technique can also produce 3d images.
Excessive exposure to x-rays does produce
a risk to the patient’s health.
This applies to both conventional x-ray
machines and CT scans.
CT SCAN – OVERCOMING THE 2D
CT SCAN VIDEO DESCRIPTION
MAGNETIC RESONANCE IMAGING (MRI)
MRI works in a different way from X-ray.
This technique relies on a strong magnetic field (effectively a large magnet) and
No metals allowed in an MRI room.
Small metal object such as paperclips or pens can be lethal!
Magnetic coding on Credit cards wiped!
Orthopaedics are typically ok
These waves can pass through the body and produce an image which represents
a 2d slice of the body.
MRI can generate cross-sectional images in any plane.
These 2d slices can then be put together to produce a 3d image of what ever
organ is under investigation.
MRI VIDEO DESCRIPTION
Useful in the diagnosis of neurological, musculoskeletal,
cardiovascular, and oncological (tumors) diseases.
An advantage of MRI over X-ray is that there is no reliance
between soft and hard tissue so non-solid parts of the body
can be imaged
E.g. the brain
Unlike CT, the entire scanner does not need to be rotated.
A further advantage is that MRI is deemed not to be as
Pregnant women not scanned.
Because MRI scanners consist of a large magnet, this
approach is not always suitable to people who have some sort
of metal inside their body.
For example, a pace maker
MRI can cause claustrophobia.
MRI machines are VERY noisy.
Similar dbs to a jet engine.
Ear plugs and headphones usually worn.
Patient must remain VERY still during the examination.
20 – 90 minutes in duration.
Any movement requires the section to be rescanned.
Orthopedic implants can cause artifact if present in the area
MRI machines are very expensive, therefore examination is
MRI VS X-RAY VS CT SCAN
Xray more clearly shows the difference between soft and hard tissue.
MRI more clearly shows a better contrast between different types of soft
MRI contains no radiation (no known biological harm)
Noisy though and patients have to remain very still.
Patients with pacemakers cant be scanned using MRI.
Very obese people cannot be scanned in an MRI machine.
X-ray contains a minimal amount of radiation.
CT scan contains a considerable amount of radiation. Requires injection
prior to SCANS.
Ultrasound imaging is a process
where sound waves are sent into
the body and the reflection of these
sound waves is measured.
The technique relies on the
principle that tissues of varying
density will reflect sound waves in
a different way.
In most cases a hand held device
(transducer) is placed against the
skin to transmit and measure the
A gel is used to ensure that this
device makes a good mechanical
contact with the skin.
It is very effective for imaging soft tissues.
The patterns of reflection of the sound from within the
body can be converted into images and be displayed on
Although ultrasound relies on measuring acoustics
these are not sounds that are actively generated by the
body (i.e. they are merely passed through the body from
an external source – a transducer).
Very safe procedure
ULTRASOUND (3) – DIFFERENT TYPES
The ultrasound that we have described so far
presents a 2d image, or "slice," of a 2d object (fetus,
Two other types of ultrasound are currently in use
3D ultrasound imaging
In 3D Ultrasound, series of 2D images are
acquired by moving the probes across the body
surface or rotating inserted probes.
The two-dimensional scans are then processed
digitally to produce 3D models
3-D imaging provides enhanced view of organs.
Particularly beneficial for early detection of
cancerous and benign tumors, and for
visualizing a fetus to assess its development.
ULTRASOUND (4) – DIFFERENT TYPES
Based on Doppler effect
Visualizing blood flow in various organs or a fetus
Moving objects reflect ultrasound waves at different
Higher frequency if object moving towards the
probes and lower freq. if object moving away from
Variance in frequency is proportional to speed of
Doppler ultrasound most used to measure rate of
blood flow through the heart and blood vessels.
As stated various organs and systems within the body can
produce or rely on electrical impulses and electrical activity.
There are many such systems within the body. Here we focus
on some of the most commonly measured.
The ECG is the result of measuring
the electrical activity of the heart as
projected from inside the body onto
the body’s surface.
The heart is essentially a collection of
muscles which rely on an electrical
signal to make them contract and
push blood out.
These electrical signals are generated
and travel to the surface of the body
each time the heart beats.
The ECG is measured by placing
electrodes in contact with the skin.
Several recording configurations exist
but the most common is the 12 lead
This approach records 12 signals and
a clinician will view these and look for
changes in the waveforms which
might signal abnormality.
ECGs can be recorded when the
patient is at rest or when the patient
is exercising to assess different
effects of physical activity on the
The EEG is a measurement of the brain’s electrical activity.
Brain cells communicate by producing small electrical impulses.
Similar to the heart, the brain produces electrical patterns which can be
measured on the scalp.
The measurement process involves putting numerous (16 – 25)
electrodes on the scalp
these can be part of a cap like structure.
Like in the ECG the resulting signals can be analysed to look for
abnormal patterns in brain activity.
It should be noted that the signal produced and the origin of the signal is
very different between the EEG and the ECG.
In deep sleep the EEG pattern produces large slow
When relaxing the waves being faster.
When active the EEG is described as being very
dense with a low voltage and a high frequency
which produce a fast wave
The auditory brainstem response is the
recording of signals from the brain in
response to a form of external audible
Temporal representation of
the ABR signals show clear
differences between the
waveforms with and without
EEG is commonly used to detect:
Presence and type of seizures (epilepsy, convulsions)
Cause of confusion
Effects of head injury
Brain activity in coma
Brain activity during sleep (narcolepsy)
As with the ECG the recording of EEG is VERY
BRAIN COMPUTER INTERFACES (BCI)
In recent years EEG has been used to acquire brain activity for
the purposes of controlling machines.
Every time we move, think, feel or remember our brain fires
By placing electrodes on the surface of the scalp it is possible to capture
some of this electrical activity.
Some of the electrical activity is distorted as it passes through the brain
tissue and bone of the skull.
Implantable electrodes in also an option.
Sensory OUTPUT BCI can be used to control some external device or
An MRI can help with profiling the activity.
Sensory INPUT BCI can be used to ‘feed’ signals INTO the brain
(implant) to bypass some damaged section of it.
Allowing a blind person to see!
BCI (2) - APPLICATIONS
Controlling external device with you mind.
Controlling an onscreen mouse via mental commands to
assist with communication.
Severely disabled persons.
Controlling an artificial limb.
Often requires training – ‘imagine’ closing your fist or moving
BCI – APPLICATIONS (2)
Sensory input from
cameras to allow sight
for blind people.
To date, only limited
sights can be restored.
represented as a
series of dots.
ELECTROMYOGRAPHY (EMG) (1)
EMG is the discipline that deals with the detection,
analysis, and use of the electrical signals that emanates
from the muscles. In the words of De Luca (1997)
“…it provides easy access to physiological processes that
cause the muscle to generate force, produce movement and
accomplish functions which allow us to interact with the world
The origin of these signals is similar in principle to that
of the ECG as the heart is in effect a muscle.
Nerves cells (Motor neurons) connect to our muscles from the
ELECTROMYOGRAPHY (EMG) (2)
The technique can be used to study muscle function and
The EMG can be recorded by placing needle electrodes
in the muscle or by placing (gel) electrodes on the
surface of the skin.
The former provides a more specific measurement
whilst the latter provides a more general picture of the
operation of the muscles in the area under interrogation.
EMG - APPLICATION
Figure 2.2 Amplitude and Frequency spectrum of
the EMG signal
Figure 5.5 Screen shot of Animation Program
Figure 5.4 Screen shot of Analysis Program
EOG is a technique for measuring the resting
potentials of the retina.
Electrode pairs are placed either above and below
the eye or to the left and right of it.
ACOUSTIC MEASUREMENTS (1)
Sounds emanating from various organs
can be measured.
The two organs which are most
commonly interrogated in this way are
the lungs and the heart.
Sounds from these organs are typically
measured using a stethoscope.
The classical stethoscope consists of a
chestpiece which is placed against the
ACOUSTIC MEASUREMENTS (2)
Vibrations are picked up by this chestpiece and
transmitted along a hollow tube to a set of ear buds.
When auscultating (listening to) the heart, doctors listen for
heart murmurs, gallops and heart rate.
When examining the lungs, doctors listen for wheezes or
More recently electronic stethoscopes have been
invented which use a sensor inside the chest piece (in
some cases a microphone).
Information from this sensor can be processed and
enhanced before being transmitted to a headset.
Noise reduction / filtering and signal enhancement.
Digitized sounds can be stored and shared.
Changes in the conditions of various organs and body
systems can also be reflected in chemical changes.
For example if muscles are damaged i.e. if muscle tissue dies,
enzymes can be released into the blood.
A particular case where this is used as a diagnostic test is in
the case of cardiac patients.
The heart can be considered as a muscular organ, and when
someone has a heart attack, this muscle releases various
chemicals into the blood.
One such chemical is troponin-t (a protein). This is often used
to diagnose if someone has had a a heart attack.
Takes time to conduct test thus why ECG is so important.
o We have studied (briefly) how various signals / images
can be measured from the body.
o Changes in these signals allow a specialist to make a
o We have thought exclusively about diagnostic
o There also the reverse of this where we push signals
into the body:
o Therapeutic radiography
o Implantable devices
o Cardiac pacemakers, defibrillators, vascular pumps
Lectures – running!
Tutorial and Practical Sessions
Use this time wisely to work on your assignment!
This is a really good opportunity to produce a draft of your
Visit the library, do a literature review etc…
This should ensure that everyone is able to submit a good
piece of work in week 7.