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Summary Unit 11 - Physiology of Human Body Systems
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Summary of 9 pages for the course Unit 11 - Physiology of Human Body Systems at PEARSON (its a document)
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Getting startedThe techniques used in medical physics for diagnosis and treatment are
now widely used and accepted by both the medical profession and the
public. They are now regarded as essential tools to combat the onset and
spread of life-threatening illnesses. Your knowledge of science will enable
you to explore and grasp both the principles of the complex technologies
used and the precautions needed because of the potentially dangerous
high energies used. Conduct a short survey of learners and staff in your
school or college to determine the percentage of individuals or their
family members who have received diagnosis or treatment from one of the
methods outlined in this unit.
Analytical chemistry is an exact branch of chemistry which is performed
using an extensive range of laboratory equipment including; glassware,
digital and mechanical devices. Using a prepared worksheet and examples
of the equipment used and provided by your tutor, attempt to memorise the
names of the apparatus. Test your answers with a partner.
Explore the principles, production, use and
A benefits of non-ionising instrumentation
techniques in medical applications
Not all diagnostic methods use dangerous ionising radiation. ▸▸ Main magnet – a large, permanent superconducting
In this section you will explore four non-ionising techniques: electromagnet. (A coil carrying a steady electric
magnetic resonance imaging, lasers, infrared thermography current generates a magnetic field running through its
and ultrasound. For each, you will learn about how they centre. Superconducting magnets are not technically
work, their main uses and their benefits and limitations. ‘permanent’, though they are long-lasting. They perform
You will also cover the detail of the instrumentation and the role previously filled by large permanent magnets. If
the benefits of each method to be able to form your own there is an emergency they can be suddenly quenched
opinion as to their uses and convey this to others. by blowing off the liquid helium coolant into the
outside atmosphere.) They are costly but produce a
Magnetic resonance imaging (MRI) high field strength of high stability.
The human body contains a vast number of hydrogen ▸▸ MRI scanner coils – resistive electromagnets that
atoms and different tissues contain different amounts. The produces a gradient field where different magnetic
Copyright © 2017. Pearson Education, Limited. All rights reserved.
nucleus of a hydrogen atom consists of a single proton strengths over the body help to pinpoint the signals.
that acts like a small magnet and can be easily affected by When scans are being carried out, a knocking sound
a large magnetic field. can be heard when the gradient field coils are switched
on and off.
Key term
▸▸ Radiofrequency coils – produce the input radio
Proton – the positively charged particle in the nucleus waves that excite the nuclei and result in the nuclear
of atoms. magnetic resonance (NMR) signal. They need to
sustain a power output of up to 1 kW.
Instrumentation/production ▸▸ Output signal receiver – these are essentially tuning
The MRI scanner (see Figure 21.1) is a large and heavy piece coils that pick up the output radio waves from the
of equipment that uses the most up-to-date technologies protons in resonance. There are many types. The type
and complex computer systems. Most of its weight comes selected is based on the need to produce a specific
from the large magnet and electromagnets that provide image, such as large volume areas or more focused
the very strong magnetic fields needed to polarise nuclei. tissues. The receiver is linked to a powerful computer
These can weigh up to 100 tonnes. The MRI consists of: that processes the information.
Annets, F., Hartley, J., Hocking, S., Llewellyn, R., & Meunier, C. (2017). Btec level 3 nationals applied science student book 2. Pearson Education, Limited.
Created from cityuk-ebooks on 2022-03-04 19:19:05.
232 Medical Physics Applications
M21 BTEC National Applied Science Student B2 XXXXX.indd Page 232 09/05/17 8:14 PM f-0314 /122/PE02858/BTEC_Applied_Science/NA/SE/Applied_Science/G1/XXXXXXXXXX/Layout
, Learning aim A UNIT 2
liquid He Key terms
cryostat
superconducting Polarise – producing charged poles in an object (e.g.
primary coil radiofrequency coil molecule) that limit its vibrations to a single direction.
Field coil – a resistive electromagnet that produces
central patient a gradient field over the body helping to locate the
gradient coil access bore radiofrequency signals.
thermal
insulation
Nuclear magnetic resonance (NMR) – the absorption
of specific electromagnetic frequencies by atomic
nuclei which resonate and, after a short delay, re-emit a
▸▸ Figure 21.1 Plan view of MRI scanner
radiofrequency.
Electron – a sub-atomic particle in all atoms that has a
Particles such as protons, electrons and neutrons have a negative electrical charge.
property called spin, which makes them behave like tiny Spin – a property of nature that causes particles to
magnets when they are placed in a magnetic field and behave like small magnets in a uniform magnetic field.
rotate with a wobble motion. They show a north and south
pole that will line up with the poles of the magnetic field.
Step-by-step: MRI scan 7 Steps
1 The patient is placed on a sliding platform into the MRI scanner.
2 A large magnetic field is created around the patient.
3 The alignment of hydrogen nuclei in the body changes, causing them to line up, similar to the effect of a
magnet on iron filings.
4 The hydrogen nuclei are then disturbed by a short input pulse of electromagnetic waves of a particular
frequency given to certain parts of the body.
5 The hydrogen nuclei flip out of their alignment when the wave gives them extra energy at the right
frequency.
6 When the input radiofrequency wave is switched off, one by one the hydrogen nuclei flip back into
Copyright © 2017. Pearson Education, Limited. All rights reserved.
alignment giving out the same radiiofrequency wave energy that they had absorbed earlier. This ‘relaxation’ can
take several milliseconds.
7 A receiver detects the radiofrequency output and the information is analysed by a well-trained radiologist.
the protons can be detected in their exact locations
Key term
in the body. The process can also provide information
Radiologist – a medically qualified specialist responsible about the type of tissue that the protons are in because
for diagnosing and treating conditions requiring ionising they re-align at different speeds in different tissues,
and non-ionising radiological techniques. sending a signal that is particular to the tissue type. The
resulting images produced by a powerful computer are
very detailed. The photograph shows an MRI scanner
MRI principles in action.
Nuclear magnetic resonance (NMR), the process used in
MRI, produces a very detailed picture of tissues because
Annets, F., Hartley, J., Hocking, S., Llewellyn, R., & Meunier, C. (2017). Btec level 3 nationals applied science student book 2. Pearson Education, Limited.
Created from cityuk-ebooks on 2022-03-04 19:19:05.
23
M21 BTEC National Applied Science Student B2 XXXXX.indd Page 233 09/05/17 8:14 PM f-0314 /122/PE02858/BTEC_Applied_Science/NA/SE/Applied_Science/G1/XXXXXXXXXX/Layout
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