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LEARNING AIM A: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF NON-IONISING INSTRUMENTATION TECHNIQUES IN MEDICAL APPLICATIONS. LEARNING AIM B: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF IONISING INSTRUMENTATION TECHNIQUES IN M$27.28
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LEARNING AIM A: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF NON-IONISING INSTRUMENTATION TECHNIQUES IN MEDICAL APPLICATIONS. LEARNING AIM B: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF IONISING INSTRUMENTATION TECHNIQUES IN M
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Course
Unit 21 - Medical Physics Applications
Institution
PEARSON (PEARSON)
Medical physics is the application of physics to medicine or healthcare, using the physic concepts, theories, and methods to help screen, diagnoses, or treatment. Radiation is used in medical application, which is an energy that transfers from one place to another in the form of a wave or particle....
BTEC LEVEL 3 APPLIED SCIENCE
UNIT 21: MEDICAL PHYSICS
HAJRAH ALI – 40157986
RADIATION USE IN DIAGNOSIS AND
TREATMENT
JENNIFER HOLLANDS
UXBRDIGE COLLEGE
Medical physics is the application of physics to medicine or healthcare, using the physic concepts, theories, and methods
to help screen, diagnoses, or treatment. Radiation is used in medical application, which is an energy that transfers from
one place to another in the form of a wave or particle. There are two types of radiation, ionising and non-ionisng.
1. Ionising: Uses high frequency radiation which can knock electrons out of a substance as the radiation passes through
it. This can damage or kill the cells and can cause mutations and cancerous growth. e.g., Electromagnetic Waves in
Gamma and X-ray Region.
2. Non-ionisng: Uses low frequency radiation which does not damage or kill cells. e.g., high frequency sound waves and
transverse waves in ultrasound and the use of Nuclear Magnetic Resonance in MRI.
This report will explain the principles, production, and uses of the two radiation techniques used in medical physics.
LEARNING AIM A: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF NON-IONISING
INSTRUMENTATION TECHNIQUES IN MEDICAL APPLICATIONS.
LEARNING AIM B: EXPLORE THE PRINCIPLES, PRODUCTION, USES AND BENEFITS OF IONISING INSTRUMENTATION
TECHNIQUES IN MEDICAL APPLICATIONS.
EXPLAIN HOW THE PRINCIPLES AND PRODUCTION OF NON-IONISING TECHNOLOGIES ARE USED IN MEDICAL
APPLICATIONS.
EXPLAIN WHY NON-IONISING RADIATION TECHNOLOGIES ARE USED IN MEDICAL APPLICATIONS.
MAGNETIC RESONANCE IMAGING (MRI)
, HAJRAH ALI – 40157986
Magnetic Resonance Imaging (MRI) is a non-ionising instrumentation technique in medical applications which helps
diagnose problems occurring in the body internally. It uses Nuclear Magnetic Resonance (NMR) to produce detailed 3-
dimensioanl images.
PRINCIPLES
60% of the human body consists of water. Water molecules contain two hydrogen atoms. An MRI can produce detailed
images of the internal body and tissues due to the protons (in the nucleus of the hydrogen atoms) which are detected in
their exact location because of the protons not being an even amount of the neutrons being even.
The hydrogen nuclei consist of a proton which has a ‘magnetic moment’ which allows the proton to
interact with an external magnetic field. The magnetic moment means protons behave like bar
magnets. When a strong field externally is applied, the hydrogen atoms can orient their magnetic
moment so that they are either parallel or anti-parallel to the field. The axis of the proton spins can
all be aligned in one direction; protons can align in one or two way, parallel or anti-parallel. In an
external magnetic field, the protons become aligned, so their magnetic axis rotate around the
direction of the field and line up parallel or anti-parallel. The parallel alignment is lower in energy.
LARMOR FREQUENCY:
The Larmor frequency is the corresponding frequency to the energy difference between the two states (parallel or anti-
parallel). The energy spacing between the two states, make a resonant system. The Larmor frequency can be altered by
changing the external magnetic field strength as opposed to incoming electromagnetic wave packets called photons; its
frequency of the photon is a certain value, so they must match the energy difference between the ‘two
states’. External
magnetic
Nuclear Magnetic Resonance (NMR) is the Field.
process used in MRI allowing it to produce fine
detailed images. This is because it can detect
protons in their exact location in the body, due
to the use of an external magnetic field and the
hydrogen protons in the atoms. The ratio of
hydrogen atoms to neutrons in the body are not
even. NMR can help detect the type of tissue the
protons are in as they send a signal and re-align
at different speeds, depending on their location
(relaxation times [time taken to come back to its original state]). This then produces an image, in the computer, which is
taken to be analysed and examined by specialists.
Protons in an antiparallel state have a higher energy than those in a parallel state. Radio Frequency (RF) excitation
pulses make aligned protons flip into transverse plane (becoming horizontal). The RF pulses ends, and net magnetization
begins to relax and returns to horizontal plane, causing protons to emit an RF photon.
Exited protons give off signals when they de-excite, they give off certain amount of energy to the Larmor frequency.
Fatty tissues have large molecules consisting of protons, which de-
In an MRI image the colour’s represent:
excite quickly. The water molecules de-excite slowly. By looking at
the relaxation time we can detect tissues at specific location. This White: dense areas (fat, bone, protein
allows an image to be produced for that cross-section slither. rich)
Grey: soft tissues/soft part of spine
Black areas – Air, some bones
PRODUCTION
, HAJRAH ALI – 40157986
PLANE VIEW OF MRI SCANNER.
The basic design of an MRI scanner is the same in all models. The key components include:
COMPONEN IMPORTANCE AND WHY IT IS USED.
T
MAIN This is a horizontal tube which runs through the magnet-bore. Magnetic field strength ranges
MAGNET between O.2-2 tesla. The magnetic field is produced by passing current through multiple coils in the
magnet. Resulting in a state of superconductivity (ability of certain materials to conduct electric
current with zero resistance) (WhatIs.com, n.d.) [10] which produces a lot of energy by reducing
resistance in wires to 0.
GRADIENT These are in the main magnet and consist of three different gradient coils. Each producing a different
COILS magnetic field strength, all of which are weaker than the main magnet. The gradient coils create a
variable field which can be increased or decreased to allow specific different parts of the body to be
scanned by altering and adjusting the main magnet. The gradient coils superimpose small, non-
uniform fields on the main field. Every point has a different field strength in the section or slither
being imaged. This locates the point of origin of each signal, different frequencies correspond to
different points in the patient.
RF COILS Transmit RF waves into the body. Different coils located inside MRI scanner to transmit RF signal into
different body parts. When focusing on a specific area all Rf coils usually become focused on that area
which improves the quality of the scan and image produced, they can also detect RF pulses emitted by
protons when they relax.
PATIENT This is a table where patients are told to lay. This then slides into an MRI machine. Patients can be
TABLE positioned according to the area that is being scanned. When the body part under examination is at
/PLATFORM the centre of the magnetic field (isocentre), the scanning process is started.
COMPUTER Is a system which receives, records, and analyses the images of the patient’s body that have been
SYSTEM scanned.
THE BASIC PRINCIPLES OF A MAGNETIC RESONANCE (MR) SCANNER USED
MRI IN MEDICAL APPLICATIONS:
Doctors will judge patients on the signs and symptoms they are showing to decide whether an MRI scan is necessary.
functional Magnetic Resonance Imaging (fMRI):
Functional Magnetic Resonance Imaging (fMRI) is used to observe the structure of the brain and to find out which areas
of the brain consume more oxygen in in different cognitive tasks. fMRI relies on oxygen which is delivered by
hemoglobin in the red blood cells, deoxyhemoglobin absorbs RF pulses, but oxyhemoglobin does not. This is used as it
can provide new ways of understanding neurological status and neurosurgical risk.
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