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9.3 Medical technology - Bionics 5. Non-invasive medical techniques
Extract from Senior Science Stage 6 Syllabus (Amended October 2002).
© Board of Studies, NSW.
Prior learning: Preliminary modules 8.4 (subsections 1, 2, 3, 4, 5 and 6)
Science Stages 4-5 syllabus: Outcomes 4.8 (content 4.8.1 a, b, c, d; 4.8.4 b, c, d and
4.8.5 a, b), Outcome 5.8 (content 5.8.1 a), Outcome 5.12 (content 5.12 d, f, g)
Background: Before the development of aseptic techniques by Joseph Lister
(1827-1912) surgery hardly seemed worthwhile. At least one-third of the patients
died and most of the surviving patients suffered horrible complications through
infections such as septicaemia, tetanus and gangrene. As surgery moves into
the 21st century, new minimally invasive and non-invasive techniques are gaining
popularity. These techniques are designed to minimise both the risks of infection
and the recovery time of the patient.
sources, gather, process,
analyse and present information to discuss
the advantages and disadvantages of non-invasive and minimally invasive medical
- Decide what data you need to gather and in what form you will gather it so that
it can be efficiently processed. It might be useful to work with a group to collect
information into a table. You will need to decide on the structure and components of the
table and the language to be used by each team member. The following is one possible
||Examples or evidence
||Examples or evidence
- Medical journals and the Internet should be good data sources for gathering
information about these medical techniques. Use a search engine and type in some of the
words like X-rays, ultrasound, thermography, magnetic resonance imaging. Other
terms for minimally invasive techniques could be keyhole surgery, endoscopy and microsurgery.
- Process the information by firstly checking its consistency, and thus its
reliability. Secondly, organise it into Non-invasive techniques and Minimally
invasive techniques. Then sort the techniques by Advantages and Disadvantages
to see if any patterns develop.
- From your reorganised table, analyse the information to identify the arguments
for and against the techniques, making sure you can provide supporting examples and
evidence. You might then consider the general recommendation you could provide, based on
your specific findings.
- Present your findings as a discussion. A scaffold and some language features of a
||Scaffold for a discussion
||Use generalised ideas and terms.
||Focus on specific arguments and related evidence.
Use words like: furthermore, thus, therefore, if ... then...,
alternatively, on the other hand.
||Provide your general conclusions based on the arguments and related evidence.
discuss the terms
non-invasive and minimally invasive in relation to medical techniques
- Non-invasive surgery refers to the performing of a surgical technique without
making an incision in the skin at all. The removal of gallstones using laser treatment is
an example of a non-invasive technique currently in use.
- Non-invasive diagnostic techniques include ultrasound, x-rays, thermography and
magnetic resonance imaging.
- Minimally invasive refers to techniques that are performed by making the smallest
practical incision in the skin.
- Keyhole surgery is a recently developed form of minimally invasive surgery. A small
incision is made in the skin, and specially designed surgical tools are inserted through
the incision to perform the required tasks. A small camera is also inserted into the hole
so the surgeon can see what to do.
Keyhole bypass surgery , Department of Cardiothoracic Surgery, Keck
School of Medicine of the University of Southern California, Los Angeles, USA
non-invasive diagnostic techniques including X-rays, ultrasound, thermography, and
magnetic resonance imaging (MRI) and discuss their importance in diagnostic medicine
- The discovery of X-rays in 1896 revolutionised medicine, as it meant it was possible to
see inside the body without cutting it open.
- X-rays are used mostly for producing images of bones and joints, but they
may be used for other things, such as detecting tuberculosis (TB) and breast
- X-rays are important in diagnostic medicine as they reduce the need for invasive
surgery. However, because X-ray images are two-dimensional, it is often necessary to take
multiple images from different angles. It is necessary to minimise patient exposure as
X-rays can cause cancer to cells of the body.
- Ultrasound is a technique in which high-pitched (ultra) sound waves are
projected onto tissues under examination. The waves are reflected, captured
and registered electronically as an image we can see.
- Ultrasound is commonly used in obstetrics, to determine the position and
maturity of the developing foetus. It can also be used for the treatment of
hypothermia and in non-invasive surgery. In these applications, the duration
and intensity of the signal are carefully controlled.
- A new development is three-dimensional ultrasound imaging. This technique
allows for greater resolution of internal organs and has been important in
the early diagnosis of the presence of growths, such as fibroids and polyps.
- Echocardiography uses ultrasound waves that emit from a probe placed on
the chest of the patient and travel through the body. The sound waves are
harmless. The echocardiogram machine receives and interprets these sound waves
and makes a representing picture of the inside structures based upon the received
sound waves. Furthermore, since the probe constantly emits ultrasound waves,
it will receive a constant feedback of the heart structures as it changes
during its contraction. This enables the visualisation of heart muscles, valves
and blood vessels in motion.
- Thermography, or digital infra-red thermal imaging (DITI), is a diagnostic technique
which allows the examiner to map and quantify changes in skin surface temperature.
- DITI has been shown to be useful as a diagnostic tool in the diagnosis of
neuromusculoskeletal injuries and their prognosis for return to participation in sport.
Digital Infrared Thermal Imaging in Sports Medicine and Musculoskeletal Disorders
Meditherm Clinic, North Carolina, USA
Magnetic resonance imaging (MRI)
- Magnetic resonance imaging is a technique of scanning the body. It is based
on the fact that living tissues give off their own special electromagnetic
signals, depending on the water content of the tissue.
- If the tissue is subjected to a large external magnetic field, the small
electromagnetic signals may be detected and built up to form a 3D image.
- MRI is a popular diagnostic technique, as it ignores bones (as they contain
little water), concentrating on soft tissue. In this respect, MRI is the opposite
of x-rays, which tend to concentrate mainly on the bones.
How Magnetic Resonance
Imaging (MRI) Works Howstuffworks, Inc., USA
advantages of using minimally invasive surgery techniques such as keyhole surgery
- Minimally invasive medical techniques, such as keyhole surgery, have several advantages
over standard surgical techniques (i.e. those techniques requiring larger incisions). They
- smaller incisions
- less post-operative pain
- fewer complications from healing wounds
- minimal scarring
- quicker recovery time
- shorter hospital stays and so they are considerably cheaper.
gather, process and analyse
information and use
available evidence to discuss
how technological developments have impacted on the understanding of how the
- Gather information for your discussion from books and journals and from the
Internet (some useful sites are given below).
ultrasounds and CT scans Orthosports, Sydney, NSW
pregnancy The website of Dr. Joseph S.K. Woo, MBBS, FRCOG (Eng), FHKAM
(O&G), Hong Kong.
- Process your information, making sure you assess its reliability by comparing
information from various sources.
- Analyse your information by using discussion points like the following to
identify trends, patterns and relationships, as well as contradictions, in the information
you have gathered. Possible discussion points include:
- How the discovery of X-rays led to the understanding of bones and bone movement.
- How the discovery of ultrasound led to the understanding of blood flow in the body.
- How antibiotic developments were important in understanding how the bodys immune
- How computer simulation of biomechanical movements has helped in the understanding of
the biophysics of the body, leading to the development of implantable aids or external
- Use the available evidence to propose ideas that demonstrate coherence and
logical progression and include the correct use of scientific principles and ideas.