Exam III Flashcards
Unit of effective dose:
REM
High electron generating then stops:
tungsten target
Cells more resistant to radiation will:
low capacity of reproduction; more differentiation
Increase in cone length will:
increased sharpness, higher density
What image is between X-RAY SOURCE and ROTATION CENTER:
Ghost image
Does not cause ionization:
coherent radiation
Object moves distal, source moves distal:
lingnual
What is the tissue modification factor?
Effective dose
Factors affecting caries presentation:
angle of X-ray beam & degree of cavitation
What is an intraoral radiograph sign of present or past periodontal disease?
alveolar bone loss at furcation of molar
No threshold=
cancer
What is in the cathode?
filament & focusing cup
Mesial of #30:
within physiological limits
The narrowest portion of the focal trough is in:
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 place TOWARDS the ROTATION CENTER:
stretched wide in a horizontal direction
what affects caries diagnosis?
both vertical & horizontal angulation
A short object to receptor distance will decrease unsharpness; smaller focal spot increases unsharpness
First true; second false
Hard palate is superimposed on maxillary roots:
chin up
Increasing KeV does ______ energy of photon and ____ penetration
increases; higher penetration
What film size do you use for occlusal radiographs?
PSPP and conventional
What ford DICOM stand for?
digital imagine 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 does a rectifier do?
changes the voltage for the AC current
If the X-ray tube is set at 60 kVp, then the maximum 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 sis used to evaluate facial asymmetries?
Posteroanterior cephalometric
Where do you place the beam for a lateral maxillary occlusal projection?
Just below lateral canthus of the eye
What does increases source-to-object distance do?
decreases magnification
When do you take radiographs on a pregnant women?
only in emergent situation
What is the best radiograph for interporximal caries diagnosis?
Horizontal bitewing with open contacts
What skull radiograph is used to identify the maxillary sinuses?
Waters
How does some thing that is anterior to the focal trough appear?
narrower
Inverse square law, if the distance is tripled intensity:
decreases by 9
Something in the focal trough will appear:
reasonably 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 grey scale
What is true regarding panos?
unequal magnification
if you decrease voltage form 70 to 60 kVp, then you:
decrease density, increase contrast
What is the 2012 ADA recommendation for an adult new patient at a high caries risk?
bitewings 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 scattering
Low contrast means:
more shades of gray
