Radiography Flashcards
What were past uses of radiation?
Shoe fitting
What type of radiation are x-rays?
Ionizing radiation
What two ways does ionizing radiation damage and what do they damage?
DNA; direct and indirect action
What is direct action?
direct damage to DNA (ie. altered base pairs and breaks bonds)
What are deterministic effects?
What is indirect action?
forms free radicals from water molecules adjacent to DNA
What are stochastic effects? Example?
no threshold of exposure below which effects won’t happen
probability of effect is proportional to dose
severity is not proportional to dose
Ex. CANCER
What is the ALARA principle and why was it created?
The ALARA principle stands for as low as reasonably achievable and it was created because stochastic effects have no threshold.
What are the 3 components of radiation safety?
Distance, Shielding, Time
X-ray beam intensity ________ as the distance from the beam ____________
decreases; increases
Explain the inverse square law
Double the distance, quarters the exposure
Triple the distance, ninths the exposure
Give examples of shield protection.
Lead protection including aprons, gloves, thyroid shields
What are the limitations of shielding?
Protects only from scatter radiation AND not allowed in the primary beam
What is the golden rule of MRI?
The magnet is ALWAYS on
Does MRI have ionizing radiation?
NO
How to minimize time and monitor length of exposure?
Staff rotation, dosimeter, periodic measurement of exposure received, wear on OUTSIDE of gown
What are the 3 components of MRI? Function of each?
Strong magnets- align hydrogen atoms
Radiofrequency pulses- excite the hydrogen atoms
Coils- receive info from the atoms returning to stable state
Explain the missile effect.
Objects go flying due to magnet
Ex. Paper clip can reach up to 40 miles per hour
Can you ever enter the magnet room?
NO
When the equine MRI is on what can you not do?
Enter corridor facing MRI
Definition of a radiograph? Two types of information given.
A 2-D representation of 3-D anatomy
Directional and opacity
How many radiographs views needed?
More than 2
