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What is radiation protection?
The physical, technical and procedural factors involved in protecting both patients and personnel from unjustified radiation exposure
Absorbed dose
Amount of energy absorbed per unit mass
______ ________ is responsible for biologic damage
Absorbed dose
How is absorbed dose expressed?
Grays (GY): Quantified amount of radiant energy transferred to an object
Previously RAD (radiation absorbed dose)
What is needed for safe operation of x-ray equipment?
Technique charts
Positioning aids
Protective clothing
Personnel dosimetry
Quality control
All living cells can be damaged by ________ radiation
Ionizing
Biologic damage can be _______ or _________
somatic, genetic
What is the threshold relationship of biologic effects?
Point where a response to increasing stimulus first occurs
Biologic effects observed only when threshold is reached
What is the non-threshold relationship of biologic effects?
Any radiation dose has potential to produce a biologic effect
No radiation is believed to be safe
Deterministic (non-stochastic) effects
Biologic somatic effects of ionizing radiation that can be directly related to the dose received
Have a threshold
Examples of deterministic effects
Erythema (skin burn)
Sterility
Cataracts
Stochastic (probabilistic) effects
Probability of occurrence increases with dose
Regarded as main health risk from low dose radiation from diagnostic exposures
Example of Stochastic effects
Chance of radiation induced leukemia considerably greater after exposure to a dose at 100 than 1 rad, but no difference in severity of disease
What are the fundamental principles of radiation protection
Net Benefit
ALARA
Dose limits
Net benefit
Benefit vs. risk: Justify radiation exposure
Medical exposure to radiation should be of some benefit to the individual
ALARA
As Low As Reasonably Achievable
What are dose limits?
Quantity or amount of radiation exposure that must not be exceeded
Pertains to doses received by individual on a yearly basis or accumulated over a working lifetime
______ ________ are intended to reduce the probability of biological effects
Dose limits
How are dose limits expressed?
Sieverts (SV)
Cardinal Principles of Radiation Protection
Minimize time
Maximize distance
Maximize shielding
Exposure = ________ ________ x _________ _________
exposure rate, exposure time
As ________ _______ increases, so does ________ _______ received
exposure time, radiation dose
What is the benefit of reducing exposure time on the image quality?
Reduces motion blur
What is the benefit of maximizing distance from the image generator?
Most effective means of protection from ionizing radiation
Inverse square law
Radiation intensity is inversely related to the square of the distance from the source
What substances are used to shield from radiation?
Lead
Concrete
Primary protective barrier
Struck by primary or direct radiation
Secondary protective barrier
Provides shielding from scatter radiation and leakage radiation
What type of shielding must exist when producing x-ray images?
Gonadal shielding
Personnel shielding
Room shielding
X-ray tube shielding
Filtration (Personnel protection techniques)
Reduces the amount of low energy photons that reach patient
Reduces scatter
Technical factors (Personnel protection techniques)
As energy of the beam increases, radiation scatter moving in in foreword direction increases
Amount of scatter radiation is decreased
High-Speed image receptors (Personnel protection techniques)
Less mAs required
Fewer photons available to produce scatter
Correct positioning (Personnel protection techniques)
Reduces repeat exposures
Reduces chance for personnel exposure