Radiation Safety & Physics Flashcards
Dr. Morris
What happens with radiation exposure?
harmful to your body
can damage DNA
What is ALARA?
As Low As Reasonably Achievable
makes every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical, consistent with the purpose for which the licensed activity is undertaken
How do we accomplish ALARA?
lead apron *
thyroid shield *
gloves *
head covering
eye wear
What type of radiation is lead PPE meant to protect us from?
scatter - not the primary beam
What are the 3 ways to accomplish ALARA?
shielding
distance
time
How does distance help with limiting exposure to radiation?
doubling distance away from the beam will reduce exposure by a factor of 4
sandbags help reduce number of people involved
What is collimation?
helps with distance; how narrow the machine is set for the primary beam
What are some examples of time regarding ALARA?
quantity (not like clock time)
how many views are necessary
how many retakes are needed
do we need to have the same technician every time?
How do we monitor radiation exposure?
dosimeter badge
What is a dosimeter badge?
used to monitor how well the occupational radiation safety program is followed
contains radiation-sensitive aluminum oxide or lithium fluoride crystals that help trap electrons energized by radiation
T/F: You can wear a dosimeter badge outside
FALSE - direct sunlight causes levels to rise and end up with false reading
What are the properties of an X-ray?
part of EM radiation
produced by electron interactions outside the nucleus
cannot be deflected by magnetic fields
penetrate ALL matter to some degree
How are x-rays made?
high speed electrons strike metal inside an x-ray tube
cathode —> anode
number of electrons produced is influenced by the amount of electric current passed through the filament
How do we adjust controls to get the best x-rays?
mAs
kVp
What is mAs?
quantity of X-rays produced
analogous to increasing the wattage of a lightbulb
What is the kVp?
tube potential - increasing this increases the voltage difference between the cathode and anode
higher energy electrons —> higher energy x-rays
increase energy AND number of X-rays produced
What is this?
a measuring caliper - allows you to measure your patient and then compare that number to a chart
How is grey scale made?
air: black
fat
water
mineral
metal
have increased or decreased opacity or radiolucency when you go through these different mediums
What is the grid?
helps to filter out scatter radiation to allow a better image to be recorded
filters out scatter radiation so only primary beam is recorded
What is the correct chain of events?
A. The anode is charged sending electrons to the cathode to produce x-rays.
B. The filament is charged sending electrodes to the positively charged anode to produce x-rays.
C. The filament is charged sending negatively charged electrons to the cathode to produce x-rays.
D. The anode is charged sending negatively charged electrons to the filament to produce x-rays.
B. The filament is charged sending electrodes to the positively charged anode to produce x-rays
