Chapter 5: Radiation Protection Flashcards
What is the first step in limiting the amount of x-radiation received by a dental patient?
Proper prescribing, or ordering of dental images
What does x-radiation cause
biologic changes in living cells and can adversely effect all living tissues
situations in which radiographs may be indicated
previous periodontal or endodontic treatment
history of pain and trauma
history of family dental anomalies
evidence of periodontal disease
What appropriate thigs should the dental xray tubehead have
aluminum filter
lead collimator
PID
What are the two types of filtration ?
- Inherent filtration
2. added filtration
what is inherent filtration?
when primary beam passes through glass window of xray tube insulating oil and tubehead seal
What is added filtration ?
placement of aluminum disks in path of xray beam between collimator and tubehead seal
what is the purpose of an aluminum disk ?
filters out longer wavelengths with low energy which is harmful is not useful in diagnostic imaging
What is total filtration?
Inherent + added filtration
xray machines operating below 70 kV require a minum total of ____ mm aluminum filtration
1
what is collimation
restricts size and shape of xray beam to reduce patient exposure
what is a collimator
Lead plate with hole in the middle that fits over the opening of the machine housing
what shapes do the collimator have
rectangle and circular
which collimator is better? rectangle or circular’?
rectangle bcause it restricts 60% less
federal regulations require than xray beams are not to be more than ____ mm
2.75
what is the purpose of the Position Indicating Device (PID)
directs xray beam
what are the two shapes of a PID
rectangular(16in) round (8 in)
which PID shape produces less divergence of the xray beam ?
rectangular
purpose of the thyroid collar
flexible lead shield that protects thyroid gland
reccomended for intra oral
Purpose of lead apron
flexible shield placed on chest and lap of patients to protect reproductive organs and blood forming tissues.
Most effective film in reducing patients exposure to x-radiation
f speed film
What do beam alignment devices do ?
helps stabilize the receptor in the mouth and reduces chances of movement.
recommended for periapical and bitewings
what is the optimal kV and mA setting to limit patient exposure
60-80 kV and and mA setting of 6-8 mA
at the shortest time possible.
How must the dental radiographer avoid the primary beam ?
by positioning himself perpendicular to the primary beam or 90-135 degree angle to beam
what must the dental radiographer never do
hold the receptor in place for the patient
hold or stabilize the xray tubehead.
what is leakage radiation
any xray leakage except for the primary beam that is emitted from the dental tubehead.
what is Maximum Permissable Dose (MPD)
a maximum dose equivalent that a body is permitted to receive within a specific period.
MPD of those who work with radiation
50 mSv / year
MPD of those who work in radiation and are pregnant
0.5 mSv during months of pregnancy
MPD of the general public
1 msV/ year
