Quiz3 Wed Flashcards
(29 cards)
Spin top test (half wave)
•time x 60= # of dots
Spin top test
- disk with hole exposure is made while top is spinning
* used to test timer
Spin top test (full wave)
Time x 120= # of dots
Spin top (three phase)
- can’t be used
* must use synchronized timer
Wire mesh tool
•used to check for screen film contact
Does the temperature of the developer effect density?
- yes
- to hot= too dense “overexposed”
- to cold= less dense “underexposed”
Processing artifact which looks like lightning or trees?
•static- static discharge from low humidity
Field size increases as
•SID increases
If distance is halved then mAs is
•1/4 the original
Geometric unsharpness is due to
- focal spot
- SID
- OID
Subject unsharpness is due to
- patient thickness
- tissue density
- object shape
Xray & light field congruence
- must be within 2% of SID
* test tool or coin is used if off adjust mirror
If SID is outside the grid radius what is the result
•grid cutoff
Reproducibility
•Output radiation intensity should be constant from
One exposure to the next
•should not vary more than 5%
Linearity
- same mAs settings with different mA & time should be same output
- should not exceed 10%
If u can’t get part close to the imaging plate what can u do to decrease blur & magnification
- increase SID
* use small focal spot
How do u determine resolution in digital
- Matrix size
* the more pixels the more resolution
What has larger latitude/linear, film or digital
•digital
Quantum mottle (digital)
- not enough radiation hitting the IR
* underexposed
Exposure index
- amount of radiation reaching the receptor
- determines over or under exposure
- median 200 higher number is underexposed.
Conventional tomography is based on the theory of
•controlled blurring
Conventional tomography tube and film move in
•opposite directions
Fulcrum point
- Point of motion
* pivot point
What determines thickness of tomo cut
- angle of arch
- sm. angle thick cut
- lrg. angle thin cut
