UNIT 6
Introduction to Radiation
Protection
Goal of Radiation
Protection:
To minimize exposure to
the patient and the
operator ALARA Concept
What is radiation?
Radiation is a form of energy;
“Electromagnetic radiation”.
More specifically, it is a form of
radiant energy.
Ionizing radiation (IR) has the
ability to cause chemical and
biological changes through
ionization.
Electromagnetic Spectrum
These are the different types of electromagnetic
radiation. Cosmic radiation has the most energy on the
spectrum; Infrared has the least energy. The more
energy the radiation has, the more its ability to penetrate
matter.
Types of Radiation
Type
Charge
Symbol
Alpha (particulate)+2 charge
Beta (particulate) -1 charge
Gamma (e-m)
no charge
X-Ray (e-m)
no charge
X
Characteristics of
X-Rays
Invisible
Highly penetrating
Ability to ionize matter
Travel in straight lines
Travel at the speed of light in a vacuum
Cause chemical and biological changes
(due to ionization)
Produce scattered/secondary radiation
Sources of Radiation
Natural
Background
Radiation
Manmade
Radiation
3 Types of Natural Background
Radiation
Cosmic
Terrestrial
elements
Internal
radiation from the sun & stars
radiation from radioactive
in the earth
radiation from inside the body
Manmade Radiation from...
Medical and Dental
X-Rays
Nuclear Reactors
Radioactive Fallout
Percent exposure to various types of
ionizing radiation
Most radiosensitive organs
Lens of the eyes
Bone marrow
Gonads
Thyroid
Main Principles of Protection
Time
Distance
Shielding
Devices/Methods to Reduce
Operator Exposure
Reduce time of exposure
Don’t hold patients during exposure
Get it right the first time! Reduce
repeats!
Operator Protection
Utilize Shielding
Available
Lead Aprons,
Gloves, Thyroid
Shields, Pb Goggles
Stand behind Pb
Control Booth
during exposures
Operator Protection
Distance yourself from the source of Radiation
(ie. The tube or the patient)
Distance yourself from the patient during exposures.
Patient is the greatest source of scatter(Fluoroscopy and Mobile)
Distance yourself from the X-Ray Tube
(source of x-rays)
Wear personnel monitoring device correctly to
develop and awareness of exposure you receive.
(at the collar level & outside the Pb apron when one is
worn)
Devices/Methods to Reduce Patient
Exposure
Use of Beam
Limitation - Cones,
Collimators,
Diaphragms, PBL
(Positive Beam
Limitation)
This reduces patient
exposure and
scattered radiation
Devices/Methods to Reduce Patient
Exposure
Use of Filtration Al (Aluminum)
filters protect
patient skin
exposure
2.5 mm Al filtration
is required for
equipment using
70 kVp or higher
Devices/Methods to Reduce
Patient Exposure
High KvP / Low mAs
exposures are best for
the patient.
mAs is directly
proportional to the
amount of exposure the
patient receives.
Use of higher kVp
increases penetration
thus reduces absorption.
Patient Protection
For conventional systems, use of high
speed film/screen systems reduce the
amount of exposure required.
Reduce repeats ie: use short exposure
times which eliminate motion (blurry
pictures), Use immobilization devices to
prevent patient movement.
Use gonad shielding (when indicated) to
reduce patient gonad dose.
Measurement of Radiation
Exposure
in Air
Absorbed
Dose
Dose
Equivalent
Traditional SI Unit
Definition
Unit
Roentgen
1.08X109 ion
Coulombs/kG pairs/cc
“R”
(C/kG)
Radiation
100 ergs/gm
Gray
(Gy)
Absorbed Dose
“Rad”
Radiation
Equivalent Man
“Rem”
Radioactivity Curie
(Ci)
Sievert (Sv)
Rad x QF
Becquerel
(Bq)
3.7X1010dps
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