A. To increaase the average percent of useful x-rays
What is inherent filtration? What is it's Al eq?
A. Filtration built within the collimator box. 0.5- 1.0 al/eq
What is the standard filtering material?
C. Aluminum
What is added filtration? What is it's al eq?
A. Located outside the tube. Average 1.0 mm
What is a compound filter ( k-edge fitler)?
A. 2+ materials that complement in absorbing abilities
What does a compensating filter do?
A. Evens out unequal density like the wedge and the boomerang.
What is total filtration?
A. Equal to the sum of inherent and added filtration
When filtration is increased, what must be done to technical fascgors to maintain the same density?
A. Increase technical factors to keep the same density.
What is the recommended filtration levels for eqiopment operating below 50 kVp?
C. .5 mm
What is the recommended filtration levls for equipment operating between 50-70 kvp?
C. 1.5 mm
What is recommended filtration levels for equipment operating above 70 kvp?
A. 2.5 mm
What is x-ray quantity?
A. Measurement of the #of x-ray photons in the useful beam
What is x-ray quality?
A. Measurement of the penetratng ability of the x-ray beam as well as the distasnce between an x-ray photon travels in matter.
What is mAs? What does it control?
A. #of electrons crossing the tube per second. Controls density.
How do changes in mAs affect density?
A. Gets darker making it more dense
What is the law of reciprocity?
D. Two answers: density is proportional to intensity and duration as well as the density being the same long as mAs is constant
What is kvp? What does it control?
A. Kvp is the speed and energy of electrons going across the tube. It controls quantity and quality of x-ray beam.
How do changes in kvp affect density?
A. A visible change can be detected with a 4-5 percent change in lower rnages, 8-9 percent in mid range, 10-12 percent in higher ranges.
What is the inverse square law (x-ray intensity and distance)?
C. I1/I2 x (D2)^2/(D1)^2
What is the density maintenance formula?
A.
What type of contrast does kvp provide?
C. Higher kvp, low contrast. Low kvp, high contrast.
What is another name for high contrast?
A. Long scale
B. Short scale
C. None of the above
Define attentuation:
A. Amount of the beam is absorbed as it goes through matter.
Explaain the photoelectric interaction between x-ray and matter
C. Results when an x-ray photon interacts with inner shell electron
What are the by products of a PE interaction?
B. Ionized taom beause of an ejected electron which aka photoelectron
What are the 3 basic rules that govern the possibility of a PE? ( pick three )
A. Incident x-ray photon energy must be greater than the binding energy of the innershell
B. A photoelectric interaction is more likely to occur wen the x-ray photon energy and the electron binding energy are nearer to one another
C. A photoelectri interaction is morel ikely ot occur with an electron that is more tightly bound in its orbit
D. Incident x-ray photon energy must be less than the binding energy of the inner shell.
E. A photo electric interaction is more likely to occur when the x-ray photon energy and the electron binding energy are farther to one another.
- Incident x-ray photon energy mustb e greater than teh binding energy of the innershell
- A photoelectric interaction is more likely to occur when the x-ray photon energ and the electron binding energy are nearer to one another
- A photoelectric interaction is more likely to occur with an electron that is more tightly bound in its orbit.
Explain compton scattering interaction between x-rays and matter.
A. Occurs when an incident x-ray photon interacts with a loosely bound outer-shell electron removes the electron from its shell and then proceeds in a different direction as a scatter photon.
Explain coherent scattering inteation between x-rays and matter
A. An inteaction that occurs between very low energy x-ray photons and matter.
What are the by products of compton interaction?
A. Dislodged elctron known as a compton or recoil
B. Photon that exits the atom in a different direction called a compton scattered photon
C. Asingle electorn inteaction calle thompson.
D. Involves more than one electron known as rayleigh.
Two answers:a dislodged electron known as compton/recoil and a photon that exits the atom in a different direction called a compton scattered photon.
What is the predominant interaction in the diagnostic x-ray range?
B. Compton scattering
As kvp increases what inteaction increases in percentage?
D. Compton scatter increases
As kvp decreases what interaction increases in percentage?
A. Photoelectric absorption
When Photoelectric interactions are more prevalent, the radiograph will have ________ contrast.
A. Radiographic image with high contrast ( short scale )
What are the two principle factors that affect the amount of scatter produced
A. Kvp and patient thickness
How does beam restriction affect scatter production?
A. Decrease in field size decreses scatter.
How does beam restriction affect patient dose?
A. Decreases patient dose.
How does beam restriction affect beam density?
D. Less density because of less scatter.
How does beam restriction affect film contrast?
A. Scale of contrast shortens.
What is penumbra?
A. Area of geometric unshortness that increases off-focus radiation.
What type of beam restriction is the most effective at reducing penumbra an off-focus radiation?
D. Cylider cone
The upper fixed lead shutters in a collimator serves to...
A. Control off-focus radiation
The mirror in the collimator is mounted at what angle?
A. 45 degrees
What type of filtration does a collimiator provide?
B. Added filtration
How does atomic number affect attentuation?
A. Higher atomic number mens more attentuation
How does tissue density affect attenuation?
A. Less density = less attenuation
What is the purpose of the grid?
A. Improve radiograpic contrast by absorbing scatter
What is a grid composed of?
B. Lead nickel or aluminum
What is grid ratio?
A. Hieght of lead strips divided by distance between strips
