Final Class Review Flashcards
How does the use of a small filament/focal spot affect the radiograph?
-sharper image
two of the three factors that influence compton scatter production:
- high kvp
- large commination area
- compression
how does collimating to a smaller area affect contrast?
- increase contrast
- decrease scatter
Name two radiosensitive cells:
- Lymphocytes
- Sperm/egg
Two factors that increase the probability that a photon will undergo a photoelectric absorption interaction.
Low KVP
High atomic number
Dosimeter reports express occupationally exposed persons doses in ____ units.
REM
Increasing OFD ____ detail sharpness.
decreases
When collimating from a 14x17 area to an 8x10 area the mAs must:
increase by 50%
Using oxidized developer ____ density and contrast.
decreases
State two condition for using a bucky grid:
Greater than 10 cm
KVP higher than 60
What is the purpose of using a bucky grid?
Reduce Compton Scatter
One of the purposes of the fixer solution:
Remove the undeveloped/unexposed silver
To harden the gelatin emulsion
Where should a radiation dosimeter be worn?
On the collar outside the lead apron
To maintain radiographic density: if 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
kVp controls this photographic property:
contrast
Name three radiation protection devices:
Lead apron Gonad shield Filter Collimator Intensifying screen
Name the crystals found in the film emulsion:
silver halide
The developer solution converts silver halide to:
black metallic silver
define linearity:
The ability to manipulate mA * time to get the same mAs
State the charge that is on the focusing cup:
negative
This type of ionizing radiation can be stopped by the out layers of the skin:
alpha particles
State the two parts that make up the cathode:
focusing cup
filaments
X-rays are produced by ____ current.
DC
what does a rectifier do?
converts AC to DC current
The anode side of the tube should be ____ when imagining an AP thoracic spine:
UP
In the x-ray tube, electrons travel from ____ to the ____
cathode to the anode
How often must lead walls be replaced?
never
Assuming patient motions may be an issue: how should all mA and time settings be set?
highest mA lowest time
The __ side of the image will exhibit the least radiographic density
anode
As mAs increase, patient exposure:
increases
How do u select the small filament on the console?
Select one of the low mA settings on our machine: pick either 25.75 or 150
Describe 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 to radiowaves:
X-ray wavelengths are shorter
How must mAs be adjusted to double radiographic density?
double mAs
You experience a tube overload, what should be done to correct it?
decrease the mAs
MAs can be rounded __ without a change in radiographic density.
30%
State the formula for REM.
RAD x QF
RAD times the quality factor or the type of radiation one is exposed to
What is the relationship between x-ray frequency and wavelength
inverse
State the heat unit formula:
kVp x mAs
Which x-ray production method is responsible for producing the majority of the x-rays in the beam?
Bremsstrahlung
Optimum kVp for extremities under 10cm is in the ____ range.
50-60
This type of rectification produces the highest energy of x-rays
high frequency
Describe the bremsstrahlung x-ray production process
Electron is decelerated by the nuclear force field and changes directions. The change 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 or full wave rectification?
full wave
Define ALARA
Exposure as low as reasonably achievable
__mRAD = 1 RAD
1,000
Why does the path of film travel matter in automotive processing?
Chemical replenishment rates
What is the only similarity between alpha, beta particles and x-ray?
They can all ionize atoms
__ Characteristic x-rays of tungsten are useful
K
State the SI unit for REM
Seivert
Where are compensating filter placed?
Between the collimator and the patient
What is the #1 enemy of detail sharpness?
motion
This classical radiation unit describes radiation energy absorbed in matter
RAD
What is the purpose of using compensating filters?
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 (around the nucleus)
When is the x-ray exposure complete
When the light goes out
