Radiation Safety Flashcards
What are the hazards of ionizing radiation
Harmful to immature and rapidly dividing cells
What is a millisievert
Unit for measuring amounts of low-level radiation received
What is the acceptable exposure limit of radiation per year
50 mSv’s per year
What is the exposure limit for five years of radiation
100 mSv
What is the limit of radiation for a declared pregnant worker
4 millisievert’s
Which patients are at risk for x-rays
Breeding animal
What are three sources of exposure to radiation for personnel
Primary beam, scatter radiation, x-ray tube hosting
Do lead gloves protect from the primary beam
No just from scatter radiation
How do you expose large animals to the primary beam
Use a cassette holder instead of holding the cassette with your hands
What is scatter radiation
It is produced when x-rays from the primary beam change direction after colliding with objects in their path. Large portion travels in an upward path towards chest and head of restrainer.
What is a personal radiation monitoring device called
Dosimeter
What does a dosimeter do
Registers amount of radiation received
What are the two dosimeter types
Film badge dosimeter, thermoluminescent dosimeter
How often is the dosimeter sent to the lab for analysis
Every three months or every two weeks during pregnancy
How do you shield yourself from radiation
Using protective apparel, a portable lead wall, collimation.
What are four examples of protective apparel for radiation
Aprons, thyroid shield, gloves, lead-based glasses
How do you clean lead apparel
With a soapy water and a soft brush
What is a portable led wall used for
Preventing radiation.
What does an aluminum filter do
Absorbs soft x-rays
What does collimation do
Reduces exposure to primary beam and scatter radiation
What is fluoroscopy
Special imaging modality that uses x-rays to produce a real time moving image. Used for evaluation of dynamic processes and to facilitate surgical treatment
What is digital radiography
Uses digital sensors instead of traditional film
What are the two types of digital radiography
Computer radiography
Digital radiography
What is computer radiography
Image receptor screen is phosphor crystals that become energized during exposition. Latent image is read by a laser and sent to the computer
What is digital radiography
The image sent directly to the computer
What are the advantages to digital radiography
Reduced need for retakes, time efficiency, easier storage, can be sent to specialists
What is a cat scan
X-ray generating tube that makes a continuous circular movement around the patient. X-rays are picked up by a row of detectors and table moves in sync with x-ray tube. A computer is used to mathematically reconstruct a cross-sectional images of a body area
Why do we do CAT scans
Visualize internal organs, bones, soft tissue, blood vessels
What is an MRI
Does not use ionizing radiation. Uses strong magnetic field and radio waves to form images of the body. Provides better imaging then CAT scan for soft tissues
What is an ultrasound
Does not use ionizing radiation. Uses soundwaves with a higher frequency than the upper limit of the human hearing range. Gives a dynamic image. Allows for better soft tissue differentiation then x Rays
What is ionizing radiation
Radiation composed of particles that carry enough Kinetic Energy to liberate an electron from an atom.
What is radiation
Energy that comes from a source and travels through media or space.
What are the two forms of radiation use the medical imagery
Corpuscular an electromagnetic
What are x-rays considered
A form of electromagnetic radiation
Describe electromagnetic radiation
Has no Mass, no charge, can travel in a vacuum, constant speed, travels in a straight line, its wavelength is inversely proportional to its energy
What is wavelength
Distance between two consecutive corresponding points. Measured in nanometers
What is frequency
The number of cycles per second. Inversely proportional to the wavelength
What is energy
Proportional to the frequency and inversely proportional to the wavelength
Describe a shorter wavelength
High frequency and high energy
Describe a long wavelength
Low-frequency and low energy
What are four basic properties of x-rays
Can penetrate through materials that absorb or reflect visible light.
Can make certain substances fluoresce.
Can produce Latent images on film. Can cause biological changes in living tissue
Describe x-ray production
Produced in an x-ray tube that is a glass tube with a vacuum
What is the Cathode
Produces the electrons
What is the anode
Attracts electrons and creates X-rays
What are the two components of the cathode
Coiled wire filaments and focusing cups
What is the cathode controlled by
The mA
What are the two components of the anode
The tungsten target and copper casing
What are the two types of anodes
Stationary and rotating
Where is a stationary anode usually found
In dental or small portable x-ray units
Where is the rotating anode generally found
And large x-ray units
Describe the logic behind the focal spot
The smaller the focal spot the more heat at the spot and the clear the image
Describe the angle of the anode target
Smaller angle makes a smaller focal point and better detail
What is a penumbra
The loss of detail
What happens if the focal spot is bigger than the pinpoint
Causes a penumbra
On which side is the primary X-ray beams intensity stronger
On the cathode side
What is a transformer necessary for
Necessary to multiply the incoming voltage to the necessary kilovolt a
What are step down transformers used for
Provides electricity to heat the filament and creates mA
What do step up transformers do
Creates the KVP
Which type of current is necessary to generate X-rays
Direct current
What does monophasic direct current needs to be changed to
Triphasic
What is the KVP
The difference between the cathode on the anode. Determines the speed and energy of electrons. Causes a high penetrating power
What is the MA
Determines the quality of x-rays in the beam
What is MAS
Total quantity of x-rays produced in a certain amount of time
What do x-rays due to the film
Make the radiographic film go black
How do you reduce scatter radiation
Collimate and use an anti-diffusion grid
What is the collimator used for
Nerves the atomic region to x-ray. Decreases scatter radiation. Increases quality of image
What is the anti-diffusion grid
Thin vertical lead strips that absorb x-rays which travel at abnormal angles
What does the potter Bucky diaphragm do
Prevents the outline of the grid from appearing on the film by moving the grade during the exposure
Describe the cassette
Lightproof, rigid, has two intensifying screens, contains foam padding. Lead blocker for patient ID
Describe the back of the Cassette
Lead lined to absorb back scatter radiation
What crystals are located in the intensifying screen
Phosphor crystals that expose the film an account for more than 95% of film exposure
Describe a slow screen
High definition when exposure time is not critical
Describe a medium speed
Good resolution with relatively low exposure time
Describe a fast speed
Reduce exposure time and lower MAS needed
What are five factors that affect screen speed
Phosphor type, crystal size, layer thickness of phosphors, reflective later efficiency, dyes in phosphor layer
Describe the emulsion layer of the x-ray film
Has silver halid crystals
What are the four steps to manual developing
Developer five minutes. Fix or 10 minutes. Final wash 30 minutes. Drying
