UNIT 21: Medical Physics Application
Assignment 1: Radiation use in medical diagnosis and treatment.
Explain how the principles and production of non-ionising radiation techniques are used in
medical applications. (P1)
It is possible to diagnose and treat kidney stones using non-ionising radiation techniques, and it is
also possible to treat respiratory conditions using the method.
A kidney problem can be diagnosed with ultrasound. The common reason pregnant women use
ultrasounds is to see their foetus inside their womb. By using this technique, you can see and treat
kidney stones inside the stomach, just as you can see and treat unborn babies.
Thermography is a technique that uses infrared light to diagnose respiratory problems. As a result of
this technique, doctors are able to see the affected part of the body in a visual image by using
thermal energy that has been detected from the body. Using this technique, doctors can determine
which part of the body is abnormal so they can treat it accordingly. It is possible to diagnose a person
using the heat picked up by thermography from their body. Bronchitis, pneumonia, and influenza are
all respiratory conditions.
Despite being a non-ionizing radiation technique, ultrasounds are common among children under 16
and pregnant women who suffer from kidney disease. In addition to CT scans, ultrasound can also be
used for the diagnosis of kidney stones, but since it uses radio waves, most people prefer ultrasound
over CT scans. Patients with mental disabilities or Alzheimer's who cannot explain the source of their
pain may benefit from thermography. Using the imaging, doctors will be able to get a vague idea of
the diagnosis by seeing red on the body part that is causing pain, thus making the procedure easier
for doctors and patients.
Ultrasound
Ultrasounds are produced from transducers.
An ultrasound transducer converts electrical signals to sound waves, thereby emitting and receiving
ultrasound waves. An ultrasound transducer contains piezoelectric crystals that produce waves
whose frequency is determined by the propagation speed of the crystal, divided by the crystal's
thickness. Crystal layers typically have a thickness between 0.2mm and 2mm. Probes operate at
various frequencies, which is what a probe's bandwidth defines.
In transducers, energy and sound waves are applied in pulses, which later result in ultrasound waves
being sent or received. Ultrasound waves are pulsatile in nature, facilitating transmission and
reception.
The device can detect how powerful, direction, and when echoes are produced when incident pulses
reflect off tissues. Pulsed repetition frequency (PRF) refers to the number of pulses that are emitted
in a second, and pulsed repetition period (PRP) refers to the time between the start of two pulses. As
with period and frequency, PRF and PRP are inversely related. The greater the PRF, the shallower the
depth will be, while the higher the PRP and the longer the "listening" time will be, the deeper the
depth will be.
, In clinical ultrasound, linear arrays, phased arrays, and curvilinear arrays are commonly used, each
with a variety of configurations and frequencies. Image area and shape are determined by the
crystals and structure of the transducer face. A linear array produces a rectangular image because its
faces are flat. An array of crystals and power sequences created by phased arrays creates a sector
image that can be scanned between ribs thanks to the direction of beams from a single point. There
are a variety of curved surfaces in curvilinear arrays, which can also be used across multiple
bandwidths depending on the application. Since curvilinear transducers penetrate deeply and
provide a wide field of view, they are often used for abdominal exams. The high resolution of end
cavitary curvilinear transducers along with the small footprint make them ideal for female pelvic
examinations.
Generation of MRI and its principles:
Human bodies have a unique make-up, which makes MRI scans an effective imaging technique.
Water - mainly hydrogen ions (H2O) - is the primary component of all human cells.
As hydrogen ions (H+ ions) spin in the MRI scanner, the magnet embedded in the scanner can act on
them, similarly, causing them to spin as well. Our ability to use these magnetic fields to build layers
of detail is enabled by varying the strength and direction of their magnetic fields.
Known as precession, the process of the protons returning to their original state when the magnet is
switched off occurs as soon as the magnet is turned off. As a result of this, we are able to see and
differentiate between different types of tissues within the body because they return at different
rates.
A MR system is composed of two main types of equipment. A control center is located where the
operator sits, and it is the first thing to see. Control center computers with graphical user interfaces
house the 'host' computers.
Explain why non-ionising radiation technologies are used for diagnosis and treatment of the
human body. (P2)
Because non-ionising radiation does not cause harm to cells, it is used to treat cancer and for
radiation therapy. As ionising radiation primarily affects growing cells, this method is preferred on
children and pregnant women. As its wavelength is longer, non-ionising radiation has a low
frequency. Radiation with a longer wavelength is less harmful to the body. Radiation with ionising
particles is more dangerous than radiation without ionizing particles, thus patients and physicians
always choose non-ionised radiation when possible. Cells will lose their ability to grow, divide, and
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