Unit 21 Assignment A/B

RADIATION USE IN MEDICAL
DIAGNOSIS AND
TREATMENT
Unit 21 Assignment A/B




Medical Physics Application

,Contents
Non-Ionising Radiation..........................................................................................................................2
Techniques used in imaging (non-ionising)............................................................................................2
MRI....................................................................................................................................................2
MRI Principles................................................................................................................................4
Ethical justification.........................................................................................................................5
Ultrasounds.......................................................................................................................................7
How are ultrasounds generated?...................................................................................................8
Ethical justification.......................................................................................................................12
Ionising Radiation................................................................................................................................13
Techniques used in imaging (ionising).................................................................................................13
X-ray.................................................................................................................................................13
Production of X-ray photons........................................................................................................15
Using X-rays in Medical Imaging..................................................................................................18
Ethical justification.......................................................................................................................20
Gamma Cameras..............................................................................................................................21
Using a Gamma Camera for Diagnosis.........................................................................................23
Ethical justification.......................................................................................................................25
Ionising radiation VS non-ionising radiation........................................................................................26
MRI VS Ultrasounds.........................................................................................................................28
Gamma camera VS X-ray.................................................................................................................29
X-ray VS MRI....................................................................................................................................29
Bibliography.........................................................................................................................................30




1

,Non-Ionising Radiation

Non-ionising imaging includes ultrasound, magnetic resonance imaging
(MRI), and optical imaging. Among the imaging methods that healthcare
science professionals use in this discipline are ultrasound, magnetic
resonance imaging, and optical imaging. Several medical procedures,
such as laser surgery and ultraviolet therapy for skin problems, are non-
ionising imaging procedures endorsed by clinical scientists. These
medicines will be administered safely by you, contributing to their
improvement or the introduction of new therapies. Your position will
typically be in the department of radiology or medical physics at a
hospital.
In short non-ionising Radiation are any radiation that does not have the
ability to ionise atoms. Which is relatively safe to use.

Techniques used in imaging (non-ionising)

MRI


In magnetic resonance imaging (MRI), a type of scan, radio waves and
strong magnetic fields are used to provide accurate images of the inside
of the body.

MRI scanners are huge tubes with powerful magnets. In the scanning
tube, you lie on your back.

Almost any bodily part can be examined using an MRI scan, including the
following:
 bones and joints
 brain and spinal cord
 breasts
 the heart and blood arteries
 the liver, the womb, or the prostate gland, as well as internal organs
An MRI scan's findings can be used to plan treatments, diagnose illnesses,
and gauge the success of earlier therapies.[4]
Production of MRI scanners

With its sophisticated computer systems and high-tech design, the MRI
scanner is an extremely large and heavy piece of equipment.




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, A large magnet and electromagnets provide the very strong magnetic
field needed to polarize nuclei, which is why it weighs so much.

The MRI consist of:
 main magnet: Superconducting electromagnets are large,
permanent magnets. Their cost is high, but their field strength is
high, and their stability is high.
 MRI scanner coils: Signals are pinpointed with the help of a resistive
electromagnet, which produces a gradient field with different
magnetic strengths across the body. When the gradient field coils
are turned on and off during scans, a knocking sound can be heard.
 Radiofrequency coils: Nuclear magnetic resonance (NMR) signals
are produced when radion waves are applied to the nuclei. Up to 1
kW of power is required.
 Output signal receiver: Protons in resonance emit radio waves that
are picked up by these coils. Various types exist. An image type is
chosen based on the need to produce a specific image, such as a
large area or a more focused region.




Figure 1 – labelled MRI machine


A step-by-step explanation of how an MRI scan is used

1. In the MRI scanner, the patient is placed on a sliding platform.
2. Around the patient, there is a strong magnetic field.
3. As hydrogen nuclei align in the body, they line up like iron filings
when a magnet is applied.
4. Certain parts of the body are then given a short input pulse of
electromagnetic waves of a specific frequency that disturbs the
hydrogen nuclei.




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