Radiation safety Flashcards
Radiation safety in workplace
Radiation doses to worker and patients within the veterinary facility must be reduced to a level AS LOW AS REASONABLY ACHIEVABLE
It is vital over the course of a career to protect staff and patients from excess amounts of radiation
Be your own advocate!
If a setup or situation makes you feel uncomfortable/unsafe speak up
You are allowed to refuse to work in a setting deemed unsafe
Cell biology and radiation
Animals stay alive by dividing and subdividing of their cells
Mitosis – most cells
Meiosis – genetic cells (involved in procreation)
Energy contained in radiation will disturb natural sequencing of these processes
Various effects depending on which cells involved and which stage of division they are in
Radiation dose is cumulative IMPT
Primary effect on cells is due to interaction between fluid in body and radiation
Stochastic effects
Stochastic Effects: occur by chance and may occur without a threshold level dose
Late-term effects appear many years after initial exposure or appear as genetic effect that causes mutation in offspring
Most common effect – Cancer
Others include cataracts, hyper and hypothyroidism, and sterility
Radiation effets on DNA
Four effects may occur when DNA affected:
Radiation may pass through the cell and not affect critical points. Mitosis may be suspended, but cell not damaged
Cell may display no immediate effects but internal damage may have occurred that will affect individual later when mitosis occurs – cell division may not occur successfully and the cell dies
Obvious cell damage occurs, portions of DNA compromised
Cell death occurs, severely damages molecule
Radioactivity
Atoms that exist in abnormally excited state with unstable nucleus
Radiographic decay or disintegration
Very important in the nuclear medicine
What is LET
Linear energy transfer (LET): describes the amount of energy imparted to the target
In radiography – LET is measure of rate at which energy is transferred from ionizing radiation into the tissue of patient
Dosimeters are
Any person required to work with or around radiation required to wear personal radiation dosimeter
Capture radiation dose from x-ray, beta and gamma radiation and maintain until read by dosimetry service
Dosimeters replaced at specific time intervals so can be read
Control dosimeters should be kept in container received in mail and stored away from possible radiation exposure
Rules of use apply to all dosimeters
Radiation personnel required to give personal information to dosimetry service to allow calculation of total exposure annually
Dosimeters guidlines
Must not be taken home
Must be stored in location where not likely to be exposed to radiation
Must not be stored where exposed to heat or sunlight
Must be worn only at site to which it is registered
Worn on body between waist and shoulders
Must never be shared
Must not be worn on jacket/lab coat that may be removed and hung in radiation area
During fluoroscopic examinations, second dosimeter should be worn on thyroid collar – these cannot be exchanged and should be clearly marked
Visitors/new staff must be provided with dosimeters
Facilities responsible for posting results of readings
Radiation exposure
Occupational Health and Safety Acts specify it is employer’s responsibility to ensure worker is protected against any excessive radiation exposure
Maximum permisible dose
The maximum dose of radiation that a person may receive in a given period
Denotes the amount of radiation that does not involve a significantly greater risk so as to affect future generations or the technologist themselves
Helps to determine if procedures and equipment are adequate to provide the degree of protection necessary to stay within safe limits
Note – your MPD monitored by your dosimeter only applies to exposures you receive on the job. It does not include radiation from other sources (dentist, medical diagnostics etc.)
Radiation units
Absorbed dose – Radiation Absorbed Dose (RAD) measures amount radiation absorbed per unit mass of matter
Concerns biological effects
Dose equivalent – Radiation Equivalent Man/Mammal (REM) is unit measured by dosimeters worn by personnel
Measured radiation – (Roentgen) dose output of x-ray unit. Is the dose measured by service personnel calibrating unit
Section 3.4 of safety code 28
All students, operators-in-training and personnel not experienced in the use of X-ray equipment must work only under the DIRECT supervision of a qualified operator.
Section 6.2 of safety code 28
Minimum requirement: apron, gloves, thyroid collars
Must provide attenuation equivalent to at least 0.5 mm lead at X-ray tube voltages of up to 150 kVp
“Protection must be provided throughout the glove, including fingers and wrist”
Section 7.1 of safety code 28
All personnel must fully use all protective devices available.
The X-ray tube housing must never be held by hand or supported by any part of the body during operation.
Personnel must keep as far away from the X-ray beam as is practicable at all times. Exposure of personnel to the X-ray beam must never be allowed.
If necessary, the animal should be sedated or holding devices used during radiography.
However, if this is not possible and a person must restrain the animal, protective aprons, collars, and gloves must be worn, and irradiation by the X-ray beam must be avoided.
Principles of radiation protection
Three cardinal rules:
Time
Reduce time of exposure
Distance
Increase distance between source of radiation and subject
Shielding
Place shield or barrier between operator and source
Particular attention to male or female with ability to reproduce
