CORE- Safety Flashcards
The contrast in the radiographic image is controlled by
kVp
Which of the following can the limited operator do to keep radiation exposure to patients as low as reasonably achievable? 1. Use a small radiation field 2. Use the highest kVp possible 3. Never use an SID below 40 inch
1, 2, and 3
A smaller effective focal spot produces
greater image sharpness
Higher kVp settings produce images with
long-scale contrast
What term is applied to the distance from one crest to the next in a sine wave?
wavelength
When a body part appears on a radiograph as longer than it actually is, the term used is
elongation
Contrast is directly influenced by 1. SID, 2. fog, 3. collimation
- fog and 3. collimation
The factors that affect x-ray quality are 1. kilovoltage, 2. filtration, 3. mAs
- kilovoltage and 2. filtration
The unit commonly used to report the effective dose to occupational workers in the US is
mSv
The federal regulation for the lead-equivalency of protective aprons that are worn in the radiographic room is __ mm
0.5mm
What is the guiding philosophy of radiation protection?
ALARA (as low as reasonably achievable)
Which of the following is an accurate statement regarding the characteristics of x-rays? They can:
penetrate matter
The lead-equivalent thickness of a gonadal shield should be __mm
0.5mm
Which of the following minimizes shape distortion? 1. Position plane of subject parallel to plane of IR, 2. Position plane of subject perpendicular to plane of IR, 3. Position the CR perpendicular to IR and subject
- Position plane of subject parallel to plane of IR and 3. Position the CR perpendicular to IR and subject
Which of the following occurs when the mA is doubled? 1. The number of x-ray photons decreases by 50%, 2. Radiographic density increases, 3. There are twice as many photons in the x-ray beam
- Radiographic density increases and 3. There are twice as many photons in the x-ray beam
The primary controlling factor of penetration of x-rays is
kVp
The frequency of a sine wave is measured by the:
number of times per second that the crest passes a given point
The precise area on the target where the x-rays strike is called the:
focal spot
All electromagnetic energy moves through space at the same
velocity
When an image demonstrates many densities, and there is little difference between the densities, the image is described as having
long-scale contrast
Scatter radiation fog will 1. increase density, 2. decrease contrast, 3. reduce the visibility of detail
1, 2, and 3
When an image demonstrates great differences between the densities, the image is described as
high contrast
The SI unit for measuring absorbed dose is
Gray (Gy-t)
During the photoelectric effect, an incoming photon interacts with the atom in the patient’s body. What happens to the photon with this effect?
it is totally absorbed by the atom
The annual effective dose limit for an occupational worker is
50 mSv
The primary controlling factor of contrast is
kilovoltage (kVp)
The inverse square law states that the intensity of x-ray beam ___ to the square of the distance?
inversely proportional
The geometric factors that affect the formation of the image are 1. SID, 2. OID, 3. focal spot
1, 2 and 3
What type of radiation is produced when an incoming electron interacts with the K-shell electron in the tungsten atom?
characteristic radiation
The NCRP recommended monthly equivalent dose limit for pregnancy worker is __ mSv
0.5
What is required to move the electron stream rapidly across the x-ray tube?
high potential difference
What is the SI unit of exposure that measures radiation in the air?
Air kerma (Gy-a)
Which quality factor is a key to visibility of detail?
contrast
As kVp is increased, compton interactions will
increase
Which of the following changes decrease the dose to the limited operator? 1. minimize the time spent in the radiation area, 2. increase the distance between the operator and the source of radiation, 3. use shielding-control booth and lead apparel
1, 2, and 3
Patient doses in radiography are usually calculated as the
entrance skin exposure (ESE)
What are the four primary aspects that directly affect how the x-ray image looks?
density, contrast, distortion, and spatial resolution
A change from the small focal spot to the large focal spot results in
decreased resolution
The degree of angulation of the x-ray target will determine the
effective focal spot
What are the four essential elements required for x-ray production?
a target, vacuum, electron source, and a high potential difference
Which of the following are the prime factors of exposure in radiography?
mA, exposure time, kV, and SID
Which of the following transformers would have more windings on the primary side?
step-down transformer
How does scatter radiation fog reduce the visibility of detail in a radiographic image?
by decreasing contrast
Which of the following reduces the amount of scatter radiation fog on a radiograph? 1. decrease in kVp, 2. decrease in field size, 3. decrease in grid ratio
- decrease in kVp and 2. decrease in field size
If the mAs doubles, the quantity of exposure will
double
Short term effects of radiation would occur within how long?
3 months
The unit of potential difference is the:
volt
The photoelectric effect occurs when an incoming photon from the primary beam interacts with which part of the atom in the patient’s body?
inner shell electron
Compton scatter occurs when an x-ray photon interacts with which part of the atom in the patient’s body?
outer orbital electron
Which of the following would be considered characteristics of x-rays? 1. travel in straight lines, 2. can cause a biological effect in tissue, 3. cannot be seen, felt, or heard
1, 2, and 3
