Final Flashcards
How does collimating to a smaller area effect contrast?
Contrast is increased
Name two radiosensitive cells:
Lymphocyte and Sperm cells
State two factors that increase the probability that a photon will undergo a photoelectric absorption interaction:
Low energy (kVP) High atomic #
Dosimeter reports express occupationally exposed persons doses in _____ units.
REM
Increasing OFD _______ detail shapness.
Decreases
When collimating from a 14x17 area to an 8x10 area you would ________ mAs
Increase by 50%
Using oxidized developer ______ density and contrast.
Decreases
State two condition for using a bucky grid:
- Part greater than 10 cm
- kVp greater than 60
What is the purpose of using a bucky grid?
To reduce scatter radiation
State one of the purposes of the fixer solution.
- To clear the unexposed silver halide crystals off the film.
- To harden the gelatin emulsion
Where should a radiation dosimeter be worn?
On the collar, outside the apron.
To maintain radiographic density: If the mAs is decreased by 50% the kVp should be:
Increased by 15%
This technical factor controls the quantity of x-rays in the beam;
mAs (quantity/density)
Name 3 radiation protection devices:
- Filter collimator
- Intensifying screen
- Lead shield
- Lead apron
The developer solution converts silver halide to:
Black metallic silver
Define linearity:
The ability to manipulate “mA x sec.” for the same radiographic density.
State the charge that is on the focusing cup
Negative
This type of ionizing radiation can be stopped by the outer layers of the skin:
Alpha particles
State the two parts that make up the cathode:
- Focusing cup
- Filaments (long and short)
X-rays are produced by ______ current.
Direct (DC)
What does a rectifier do?
Converts AC to DC
How often must lead walls be replace?
Never
Assuming patient motion may be an issue, how should all mA and time setting be set?
Highest mA shortest exposure time
Assuming all other factors are constant, as exposure time increases, image density ________.
Increases
The ______ side of the image will exhibit the least radiographic density.
Anode
As mAs increases, patient exposure _______.
Increases
How do you select the small filament on the console?
Select one of the low mA settings.
- O our machines = 25, 72, or 150 mA
Describe a a photon in terms of mass, charge, and velocity:
No mass
No charge
Speed of light
What photographic property does mAs control?
Density
The _______ controls the wavelength of the x-rays.
kVp
Compare the wavelengths of x-rays produced to radiowaves:
X-ray wavelengths are shorter
How must mAs be adjusted to double image density?
Double mAs
mAs can be rounded ________ without a change in radiographic density.
30%
State the formula for REM:
RAD x QF
What is the relationship between x-ray frequency and wavelengths?
Inverse
State the heat unit formula:
kVp x mAs
Which x-ray production method is responsible for producing the majorit of the x-rays in the beam?
Bremstrahlung
Optimum kVp for extremities under 10 cm is in the ______ range.
50-60 kVp
This tpe of rectification produces the highest energy x-rays:
High frequency
Describe the bremsstrahlung x-ray production process:
Electrons are decreased by the nuclear force field and changes directions. The charge in kinetic energy is converted to EM energy.
State the optimum kVp range for spine imaging:
70-90
Is optimum kVp higher for high frequency of full wave rectification?
Full wave
Define ALARA:
Exposure as low as reasonably possible
_____ mRAD = 1 RAD
1000
Why does the path of film travel matter in automatic processing?
Chemical replenishment rates
What is the only similarity between alpha particles, beta particles, and x-rays?
The can all ionize atoms
____ characteristic x0rays of tungsten are useful.
K
State the SI unit for REM
Seivert
Where are compensating filters placed?
Between the collimator and the patient
What is the #1 enemy of detail sharpness?
Motioin
What is the purpose of using compensating filter?
To produce a uniform radiographic density.
Why is the back of the cassette lined with lead?
To reduce backscatter radiation.
The x-ray tube target is made of?
Tungsten
Define radiographic density:
Blackness in the image
- Mass per unit volume of black metallic silver.
Define ionize:
The total removal of an electron from its orbit.
State the two AKA’s for SID:
TFD and FFD
What are 2 of the 3 factors that influence comptons scatter production?
- kVp (energy)
- Collimated area
- Compression
