Describes production, techniques uses and benefits of ionising and non-ionising techniques. Describes MRI, X-rays, Ultrasound, Gamma Rays, Health and Safety and Justification for such techniques (Distinction Task).
UNIT 21: A & B: Explore the principles, production, uses and benefits of non-ionising
instrumentation techniques in medical applications
What is radiation?
Radiation is the process where energy particles or waves pass through a medium.
What is ionizing radiation?
Ionising radiation is the act of removing electrons from atoms and molecules such as air, water
and tissue. The radiation is from electromagnetic waves that contain enough sufficient energy to
to break chemical bonds which produce charged ions in materials that they pass through. The
emitted photon or electron is radiation. The radiation will continue to ionise matter until there is
no more energy left to expel.
Two examples of where ionising radiation techniques are used in medicine are Gamma ray
imaging and X-rays. Other examples include alpha emission and beta emission.
The production of X-rays
X-Rays are produced when an negatively charged electrode is heated by electricity which is
produced by high-speed electrons. The electrons will collide with a metal plate or an anode
(which is kept cool by using a circulation of oil or water) and produce an x-ray image. This is
because the electrons are accelerating at a high speed, therefore the kinetic energy increases
and a small amount of that energy is transformed into an x-ray. The rest is transferred into
thermal energy. The x-ray will then pass through a small window in the lead shielding.
Principles of X-Rays
All types of X-rays function on the same basic principle; an X-ray beam is passed through the
body where a fraction of the x-rays are either absorbed into internal structures and the rest of
the x-ray patterns will be absorbed by a computer or detector. The quality, wavelength and
intensity of the x-ray will affect the penetration. For example, bones are dense and this will be
more apparent on an x-ray image. However, tissue is not as dense as bones and therefore will
not absorb the x-rays as well and this will cause no image or a fainter image to show. All types
of X-rays function on the same basic principle; an X-ray beam is passed through the body
where a fraction of the x-rays are either absorbed into internal structures and the rest of the x-
ray patterns will be absorbed by a computer or detector. The quality, wavelength and intensity
of the x-ray will affect the penetration. For example, bones are dense and this will be more
apparent on an x-ray image. However, tissue is not as dense as bones and therefore will not
absorb the x-rays as well and this will cause no image or a fainter image to show.
X-rays are part of the electromagnetic spectrum, which means that the particles spread out as
they travel. The further the distance in which the x-ray travels, the less intense the x-ray will be.
So for example, if the distance in which the x-ray has to travel is doubled, the intensity of the x-
ray will fall by one quarter. This is known as inverse square law.
, X-Rays in medicine
x-rays beams are an invisible energy that pass through the body to show an image of tissue,
bones, teeth or organs. The radiation passes through the body and onto electric detectors that
are linked up to a computer. In general, denser objects will such as calcium, will absorb more
radiation. This reduces the amount of radiation that passes through the body, causing images to
show up on the detector. Bones and teeth tend to show up lighter than tissue and organs due to
the density of the bones and teeth. After the X-ray is completed, Radiologists will be able to
examine these images to diagnose medical conditions or injuries. X-rays are commonly used in
CAT scans (Computer Axial Tomography) which are machines that produce a two dimensional
image of the body. The patient is placed in a large chamber lying down, where a rotating x-ray
beam will spin around them, producing an image on the detector. X-rays are not only used in
medicine. They are also used in other ways such as in airport security, industry and engineering,
architecture and astronomy.
The benefits and limitations of X-Rays
Limitations
- X-Rays don’t have a high resolution imagery like MRI or CAT scans. MRI or CAT scans give
detailed imagery of the body, meanwhile X-ray don’t give enough data to see tissue or organs
as they are only able to see bones.
- Radiation is exposure is very real when It comes to X-rays and this can cause serious
damage to healthy cells. MRI does not cause damage to cells due to images being produced by
utilizing magnetic energy against hydrogen, a element that is very prevalent in the body. T
Benefits
- They are much cheaper than something like MRI or CAT scans. They require less health
insurance, and are a lot more cost effective in hospitals.
- They are easier to use than MRI or CT scans, MRI scans require appointments to be
booked, whilst X-ray are easy and quick to set up and use
The production of Gamma rays
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