5. Radiology Flashcards
T/F Radiographic screening for the purpose of detecting disease before clinical examination should be performed.
False, should NOT be performed
T/F Dental radiation had deterministic effects
False, dental radiation has stochastic effects
What are deterministic effects from radiation?
killing of cells
What are stochastic effects from radiation?
probability to cause cancer, severity not dose dependent
Younger people are more or less susceptible to developing cancers from radiation?
more
The younger the individual and the faster the tissue grows, the higher the potential risk to develop fatal cancer from being exposed to ionizing radiation
What is the distance an operator should be from the radiation?
at least 6 feet from tube head or behind a barrier
What principle should be used when taking radiographs?
ALARA
A PA radiograph should include what structures?
tooth crown and at least 2 mm bone below apex
What are the most radiosensitive head and neck structures?
thyroid
salivary glands
marrow
brain
What is the recall radiation frequency of a HIGH risk caries patient
primary/mixed: 6-12 mo
permanent: 6-18 mo
What is the recall radiation frequency of a LOW risk caries patient
primary/mixed: 12-14 mo
mixed/adolescent: 18-26 mo
adult: 24-36 mo
Dental radiograph exposure (excluding CBCT) contribute to what % of total lifetime health care x-ray dose?
2.5%
For a recall pt with clinical caries/increased risk of caries, what is the recommended frequency of radiographs?
6 to 12 months
After eruption of third molars: 6-18 months
For a recall pt with no clinical caries and low risk, what is the recommended frequency of radiographs?
Primary/Transitional dentition: 12 to 24 months
Adult dentition: 18 to 36 months
After eruption of third molars: 24-36 months
What is the justification principle?
exposure only justified if there is no other way to obtain information and only after review of patient’s dental and medical history and clinical examination, if available aways try to obtain previously taken radiographs.
What is the optimization principle?
always try to obtain best quality images
What does rectangular collimation do?
Reduces scatter thus improving image quality.
Reduces absorbed radiation dose by approx 50% and can omit use of protective apron.
A thyroid shield is more effective if exposure is direct or indirect?
direct (i.e. Ceph)
For analog films, what speed receptors are recommended
E or F (fast, similar to digital)
Are there special recommendations for dental radiographs for those undergoing head and neck radiation therapy?
No
How should field of view be positioned
As close to the area of interest as possible
How do x-rays move from their source?
Divergent waves and beams become less intense as they move farther away from the source
Are there special recommendations pregnant employees and radiographs?
No, use standard precautions
For pts who cannot tolerate pano or intramural radiographs what is another alternative type of radiograph
lateral oblique
What type of films are rare earth screens used for
Pano and Ceph
What are the three type of digital receptors?
charged coupled devices (CCD)
complementary metal oxide semiconductors (CMOS)
phosphor storage plates (PSP)
Exposure time ranking of digital and analog receptors
E/F = PSP > CCD = CMOS
longer) > (shorter/faster
Cons of PSP
scratches and bite marks
Cons of CCD and CMOS
bulky and connecting cable
What should be the kVp of wall mounted machines
60-70 kVp
Hand held x-ray machines have (longer/shorter) exposure time
Longer exposure time due to 60 kVp and lower mA
Indications for a CBCT
impacted or supernumerary tooth
pathology and/or craniofacial anomaly
orthognathics
TMD
Increasing mA or exposure time does what to the radiation dose
increases dose equally
Methods to take radiographs on a severe gagger
distraction
topical lidocaine
nitrous oxide
when should baseline anterior PA/occlusal be taken in the primary dentition
proximal surfaces cannot be visualized
hx of trauma
clinical pathology or anomaly
what should be documented regarding radiographs
consent to obtain
# of exposures
diagnosis/analysis
