Safety, testing and artifacts Flashcards
How often are leaded products tests
annually
How do you test the integrity of the leaded products
Spreading product over the cassette that is on the table top and taking an image. The image will show cracks, tears, imperfections.
Poor screen contact causes what?
areas of fuzziness and less detail on the radiograph image
What are some common artifacts and how do they appear
Dirt- small dark area that may move
Screen wear - lighter areas on the film
Grid deterioration- indistinct pattern of vertical lines
extra focal radiation- imprints image beyond collimation
What are the 2 main types of radiation effects
Stochastic effects - occur by chance and may occur within the threshold level of dose (genetic effects)
Deterministic effects - noticeable in the short term. (cataracts and skin reddening)
Linear energy transfer (LET)
measure of the rate at which energy is transferred from ionizing radiation to soft tissue
(soft tissue penetration and transfer of energy)
The higher the value the greater the amount of energy being transferred
Secondary/scatter radiation
High LET with low penetrability
X-ray/Gamma rays
Low LET with high penetrability
Bones
absorb radiation = white appearance
Fat/air
radiolucent = black or dark areas
ALARA
As Low As Reasonably Achievable
The higher the kV (kilovoltage)
The higher the scattered and secondary radiation
Who should use protection
an individual male or female who has the ability to reproduce
ICRP
international commission on radiological protection
Effective dose of radiation
20 mSv per year, averaged over 5 years, with no single year exceeding 50 mSv or 5 REM
After a worker declares pregnancy the effective dose
should not exceed about 1 mSv during the remainder of pregnancy
What act specifies that it is the employer’s responsibility to ensure that the health care worker is protected against excessive radiation exposure
Occupational Health and Safety Act (OSHA)
Absorbed dose is measured in
RAD (US) or Gray (Gy- international)
Dose equivalent is measured in
REM ( US) Sv ( international)
This is what dosimeters are read in
3 Principles of radiation protection
Time
Distance
Shielding
Exposure
Exposure rate X Exposure time
Inverse square law
Accounts for the fact that the intensity of radiation becomes weaker as it spreads out from the source
Thermoluminescent dosimeter (TLD)
Demonstrate radiation exposure by measuring the intensity of light emitted from a crystal within the detector when the crystal is heated
Optically stimulated luminescence ( OSL)
contains elements that absorb radiation and store some of the energy in the form of excited electrons. Read by stimulating the elements which releases some of the stored energy as light.
Rules of dosimeter use
-not taken home
-stored in a place where it will not be exposed to radiation, heat, or sunlight
-must be worn to the site it is registered
-worn attached to the thyroid collar outside of the apron
-not shared
-not worn on a jacket/lab coat that may be taken off and hung in radiation room
radiation protective devices
-leaded aprons (usually effective at 125kV)
-leaded gloves
-leaded goggles
-movable barriers
