Radiography/Photography - 13% 7Q Flashcards
what is the peak potential applied to the x-ray tube, which accelerates electrons from the cathode to the anode in radiography or computed tomography
kVp
What value represents the number of the electrons multiplied by the time (sec) during which x-rays are shot, which determines the density (or darkness) of a radiograph
mAs
Increasing kVp will:
( increase / decrease) penetration and
( increase / decrease) contrast
increase
decrease
increasing kVp is goof for body regions with :
many different tissue densities
if you suspect root fracture and wish to see it on a radiograph, you should ( increase / decrease ) kVp?
decrease
Increasing mA will:
( increase / decrease) number of rays produced and
( increase / decrease) contrast
increase
increase
The distance from the x-ray source to the midsaggital plane should be ___in for cephalometric images
60 in
The distance from the film to the midsaggital plane should be ___cm for cephalometric images
15cm
T/F: Time affects the penetrating power of x-rays
False
it only increases the number of photons
kVp x mA x sec/L is the equation for:
density
time and mA effect density, but not _________
contrast
changes in kVp has an effect on both _________ & ________
density and contrast
increasing kVp, mA, or time will ____________ density
increase
one way to decrease density is to ( increase / decrease)tube-to-patient distance
increase
what type of X-ray is the least reliable for evaluating condylar shape?
transcranial x-ray
what part of the TMJ is a transcranial x-ray used to visualize?
the lateral pole of the condyle
what imaging is used for diagnosis of internal derangements and anterior disc displacement?
arthogram
what diagnostic imaging is used to determine osseous components of TMJ?
tomogram
what diagnostic imaging is best for visualizing TMJ soft tissues
MRI
when taking a panorex, the patient’s Frankfort horizontal should me positioned:
parallel to the floor
During the manual cephalometric processing, development takes ___ minutes and fixation takes ___ min
5min
10min
Errors that could lead to light radiographs include:
_________-developed, __________ fixation, ________-exposure
underdeveloped
excessive fixation
underexposure
Errors that could lead to light radiographs include:
F-S distance too ______, Film packet __________
big
reversed
Errors that could lead to dark radiographs include:
Light _________, ________-developed, _________-exposed
light leakage
overdeveloped
overexposed
Errors that could lead to dark radiographs include:
__________ fixation, F-S distance too ________
inadequate fixation
distance too short
what type of image is created produced after exposure but before development
latent image
Filtration of x-ray beam with ______________ achieves preferential removal of low energy photons
aluminum
filtration of x-ray beams with with 2.5mm aluminum ____________ intensity and
______________ mean energy
decreases
increases
The purpose of using an intensifying screen made of thinner phosphor layer is that it results in increased ________________
sharpness
Case: when taking lateral cephalograms, double intensifying screens and screen films are used to reduce:
exposure time
which extra oral radiograph is specially taken to view the maxillary sinuses?
Water’s view
a submental vertex radiograph is taken
below the chin pointing straight up
a Towne’s radiograph is chosen to visualize:
occipital bone, petrous processes, condyles
A Cauldwell radiograph is chosen to visualize
frontal and ethmoid sinuses, margins of the orbit
doubling the film has what effect on the image
none
T/F: for a fat individual changing the exposure time in done to ensure that equal penetration is given
True
If we increase the film-to-patient distance by 5cm, the image:
will be slightly enlarged
What happened if post-ortho ceph shows smaller Mn?
object to film distance was changed
is a panorex useful in determining arch perimeter deficiencies or cavities?
No
the focal trough in a panorex is the :
area of dental anatomy reproduced clearly
Maximal permissible dose of radiation per week
0.01 rem/wk
= 100 milliroentgens/wk
= 0.5/50 weeks
earliest sign of excessive radiation
Erythema
Minimum total filtration required:
equivalent of 2.5mm Aluminum
Name the oral tissues most sensitive to radiation (2)
Developing tooth buds
Salivary glands
what part of the x-ray machine narrows field of exposure? It mandatory for patient protection.
Collimator
Film emulsion is done with these 2 materials:
gelatin and silver bromide
the tube target in an x-ray machine is made of:
Tungsten
to obtain optimal detail sharpness, there should be ______ focal spot area, ___________ kVp, ________ object-film distance
small
increased
short
for clinical photography, the most important aspect during selection of digital camera is
resolution
best camera for clinical photography has ___mm SLR with a fixed focal length _______ lens
35mm
macro lens
which file format of photos does not lose quality?
TIFF
which file format of photos loses the most quality?
jpeg
CBCT >/< CT :
Radiation amount: CBCT ___ CT
Faster: CBCT ___ CT
Better resolution: CBCT ___ CT
< CT
CBCT >
< CT
Digital Radiograph produces _____ shades of grey (8 bits)
256
which radiography has better resolution: traditional or digital?
Traditional
the human eye can see ___ shades of grey
16
the greatest source of error in cephalometric is:
identification of landmarks
increasing the tube distance to the patient will do what to density?
decrease it
voxel size has an effect on (2)
resolution
accuracy
T/F: voxel size has an effect on magnification
false
ABO requires that photos are ___ size, ___ bit color depth, and ___dpi jpeg with medium compression
¼
24
300
ABO requires that radiographs be ___ bit grayscale and ___dpi JPEG with medium compression
8
200
