General Consideration of all Radiology (imaging) Modalities

General Consideration of all
Imaging Modalities
Muhammad Arif Afridi
Lecturer in Medical Imaging
Medical Imaging Technologist (MIT) - Radiology
Master in Public Health (MPH)
Email: RFafridi@hotmail.com
Lecturer in Medical Imaging | RFafridi@hotmail.com
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Definitions:Definitions:
Radiology: The science dealing with X-rays and other high-energy
radiation, especially the use of such radiation for the diagnosis and
treatment of disease.
X-rays: X-rays are a form of electromagnetic radiation that can pass
through objects, including the body.
 X-rays penetrate different objects more or less according to their
density.
 In medicine, X-rays are used to view images of the bones and other
structures in the body.
Radiation: Energy emitted and transferred through matter.
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IntroductionIntroduction
 Radiology is the science dealing with X-rays and other high-energy
radiation, especially the use of such radiation for the diagnosis and
treatment of disease.
 General Radiography, commonly referred to as X-ray.
 X-ray is an important diagnostic tool and was the first established
modality of Diagnostic Imaging.
 X-rays are used to create images of the body's internal structures.
 These images are used to detect abnormalities in bones, lungs and
other internal organs
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RadiationRadiation
• Energy emitted and transferred through
space is called radiation.
• Radiation is the transfer of energy.
• Ionizing radiation is a special type of
radiation that includes x-rays. Ionizing
radiation is any type of radiation that is
capable of removing an orbital electron
from the atom with which it interacts.
• interaction between radiation and matter
is called ionization.
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Sources of Ionizing RadiationSources of Ionizing Radiation
• divided into two main categories:
• natural environmental radiation
• man-made radiation
• Natural environmental radiation results in an annual dose of
approximately 3 millisieverts (mSv).
• Man-made radiation results in 3.2 mSv annually.
• An mSv is the unit of effective dose.
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Units of Radiation
In 1948, an international system of units based on the metric system was
developed.
These units are called SI units or Systems International.
Radiography utilizes the units of radiation to determine the amount of exposure
that reached the patient,
how much radiation was deposited in tissue?
how much damage occurred?
The four fundamental units of radiation used in radiology are:
• 1. Exposure
• 2. Absorbed Dose
• 3. Effective dose
• 4. Activity
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Exposure
Exposure is defined as the amount of ionization produced by
radiation in a unit mass of air. We could count the number of x-rays,
but it is easier to measure the amount of ionization produced by the
x-rays.
Exposure is measured in the SI system by coulombs per kilogram
(C/kg) or in the conventional system using roentgens (R).
The roentgen is a fairly large unit so a smaller unit, the milliroentgen
(mR), is more commonly used.
One mR is 1,000 times smaller than a roentgen.
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Effective Dose
• The effective dose relates the risk from irradiating a part of the body
to the risk of total body irradiation.
• In other words, the tissues of the body are not equally affected by
ionizing radiation.
• Some tissues are more sensitive to the effects of ionizing radiation.
• A dose of 6 sievert (Sv) to the entire body is fatal. However, a dose of
6 Sv to a patient’s hand or foot is not fatal.
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Effective Dose
• The harm from a radiation dose depends on both the amount of
radiation or dose and the part of the body irradiated.
• The combination of the dose and the body parts irradiated is
measured by the effective dose.
• The effective dose has units of Sv in the SI system or rem (radiation
equivalent man) in the conventional system.
• One sievert is equal to 100 rem. Because the units are so large, the
millisievert (mSv) and the millirem (mrem) are often used.
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Special Quantities of Radiologic Science andSpecial Quantities of Radiologic Science and
Their Associated Special UnitsTheir Associated Special Units
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Discovery Of XDiscovery Of X--raysrays
• Wilhelm Roentgen, a German professor of
physics, was the first person to discover
electromagnetic radiation in a wavelength
range commonly known as X-rays today.
• For his remarkable achievement he was
honored with the first Nobel Prize in Physics
in 1901.
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First RadiographFirst Radiograph
• The hand shown in this
radiograph belongs to Mrs.
Roentgen.
• This first indication of the
possible medical applications of
x-rays was made within a few
days of the discovery.
• (Courtesy Deutsches Roentgen Museum.)
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EnergyEnergy
• Energy emitted and transferred through space is called radiation.
• When a piano string vibrates, it is said to radiate sound; the sound is a
form of radiation.
• Ripples or waves radiate from the point where a pebble is dropped
into a still pond.
• Visible light, a form of electromagnetic energy, is radiated by the sun
and is electromagnetic radiation.
• Electromagnetic energy is usually referred to as electromagnetic
radiation or, simply, radiation.
• Radiation is the transfer of energy.
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Basic Radiation ProtectionBasic Radiation Protection
 Always practice ALARA: Keep radiation exposures as low as
reasonably achievable.
 Filtration
 Collimation
 Protective Apparel
 Gonadal Shielding
 Protective Barriers
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Radiologic UnitsRadiologic Units
1. Air kerma (Gya) is the unit of
radiation exposure
2. The gray (Gyt) is the unit of
radiation absorbed dose (rad).
3. The sievert (Sv) is the unit of
occupational radiation
exposure and effective dose.
4. The becquerel (Bq) is the unit
of radioactivity.
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Five Basic Radiographic DensitiesFive Basic Radiographic Densities
1. Metal (Bright White)
2. Mineral (White)
3. Fluid/Soft tissue (Gray)
4. Fat (Dark Gray)
5. Air (Black)
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Radiologic TechnologistRadiologic Technologist
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A radiologic technologist can specialize in many
types of imaging modalities.

Radiology ModalitiesRadiology Modalities
1. Radiography (X-ray)
2. Fluoroscopy
3. Computed Tomography (CT)
4. Magnetic Resonance Imaging (MRI)
5. Ultrasound
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Radiography (XRadiography (X--ray)ray)
• X-ray machine provide a static image
on radiograph.
• X-ray or radiography uses a very
small dose of ionizing radiation to
produce pictures of the body's
internal structures.
• X-rays are the oldest and most
frequently used form of medical
imaging.
• They are often used to help
diagnosed fractured bones, look for
injury or infection and to locate
foreign objects in soft tissue.
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FluoroscopyFluoroscopy
• Fluoroscopy is based on x-rays.
• X-ray tube is installed
• The radiation dose is higher than Radiography.
• Provide both static and dynamic images.
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Computerized Tomography (CT) scanComputerized Tomography (CT) scan
• A computerized tomography (CT) scan
combines a series of X-ray images
taken from different angles and
• uses computer processing to create
cross-sectional images, or slices, of the
bones, blood vessels and soft tissues
inside your body.
• CT scan images provide more detailed
information than plain X-rays do.
• CT scan can be used to visualize nearly
all parts of the body and is used to
diagnose disease or injury as well as to
plan medical, surgical or radiation
treatment.
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Magnetic resonance imaging (MRI)Magnetic resonance imaging (MRI)
• Magnetic resonance
imaging (MRI) is a type of
scan that uses strong
magnetic fields and radio
waves to produce detailed
images of the inside of the
body.
• An MRI scanner is a large
tube that contains powerful
magnets. You lie inside the
tube during the scan.
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UltrasoundUltrasound
• Ultrasound is a type of imaging.
• It uses high-frequency sound
waves to look at organs and
structures inside the body.
• Health care professionals use it
to view the heart, blood
vessels, kidneys, liver, and other
organs.
23

Thank you
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General Consideration of all Radiology (imaging) Modalities

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