EXAM III Flashcards
Unit of effective dose:
Rem
High electron generating then stops:
tungsten target
Cells resistant to radiation will:
low capacity of of reproduction, more differentiation
Increase in cone length will:
increase sharpness, higher density
What image is between x-ray SOURCE and rotation center:
Ghost image
Does not cause ionization:
coherent
Objet mots distal, source moves distal:
lingual
What is the tissue modification factor?
effective dose
Factors affecting caries presentation:
angle of x-ray beam and degree of cavitation
What an intraoral radiograph sign of present of past perio disease?
alveolar bone at furcation of molar
No threshold=
cancer
What is in the cathode?
filament and focusing cup
Mesial of #30:
within physiologic limits
The narrowest portion of the focal trough is:
incisal area
Central plane of image layer:
focal trough
Predisposition to perio disease?
tilted/rotated
What is the distortion if the teeth are located outside of the central plane TOWARDS the ROTATION CENTER:
stretched wide in the horizontal direction
What effects caries diagnosis?
both vertical and horizontal angulation
A short object to receptor distance will decrease unsharpness; smaller focal spot increases usharpness
first true; second false
Hard palate superimposed on the maxillary roots:
chin up
Increasing KeV does ____ energy of photon and ____ penetration
increases; higher
What film size do you use for occlusal radiographs?
PSPP and conventional
What does DICOM stand for?
digital imaging and communications in medicine
What is the focusing cup made of?
molybdenum
What does the LOW voltage power supply heat?
filament
Who discovered the first intraoral radiograph?
Otto walkhoff
Is produced when electrons interact with atoms of the target:
bremsstrahlung radiation
Why is tungsten used as the target material?
high radiation coefficient
What the rectifier do?
changes the voltage from AC current
If the X-ray tube is set at 60 kVp, then the max voltage is:
60 kEv
What skull radiograph is used to identify growth and development?
lateral cephalometric
MPD measures threshold for:
ionizing radiation
What skull radiograph is used to evaluate facial asymmetries?
posteroanterior cephalometric
Where do you place the beam for a lateral maxillary occlusal projection?
just below the lateral cantos of the eye
What does increasing source-to-object distance do?
decreases magnification
When do you take radiographs on a pregnant woman?
ONLY in emergent situation
What is the best radiograph for interproximal caries diagnosis?
Horizontal BW with open contacts
What skull radiograph is used to identify the maxillary sinuses?
waters
How does something that is anterior to the focal trough appear?
narrower
Inverse square low: if the distance is tripled the intensity:
decreases by 9
Something in the focal trough will appear:
reasonable well-defined
Compared to CCD, CMOS is:
faster to digitize
What receptor has the LEAST radiation dose?
CCD
What is located between the SOURCE and center of rotation?
ghost image
What is true about panos?
multiple centers of rotation
What is high contrast?
short gray scale
What is true regarding panos?
unequal magnifications
If you decrease voltage from 70 kVp to 60 kVp, then you:
decrease density and increase contrast
What is the 2012 ADA recommendation for an adult new patient at a high caries risk?
Biteweings every 12-18 months
When are electrons decelerated to produce x-rays?
when hitting the tungsten target
Thermionic emission does what?
heats up and emits electrons
Which of the following interactions causes biologic effects?
compton scatter
Low contrast means:
more shades of grey
____ dose is the threshold to creat a pair of ions:
exposure
