CORE Flashcards
memorized
which of the following statements are correct regarding the link between radiation dose and genetic effects?
- the link has been demonstrated in human studies
- The link has been demonstrated in animal studies
- increased risk to humans cannot be predicted with respect to an individual
2 and 3 only
The link has been demonstrated in human studies
and
increased risk to humans cannot be predicted with respect to an individual
which of the following changes in kilovoltage (KvP) will result in the greatest reduction of patient dose, when milliampere seconds (mAs) is adjusted to compensate for the change?
Increased kvp by 30%
which radiographic imaging systems uses storage phosphors to temporarily store energy representing the image signal?
Computed radiography
what is the primary purpose of using gonad shields during radiography ?
Reduce the likelihood of genetics effects
which of the following are types of gonad shields?
1. Aperture
2. contact
3. shadow
contact and shadow
when should gonad shielding be used ?
when the gonads are within 5 cm of the radiation field
the greatest cause of unnecessary radiation to patients that can be controlled by the limited operator is
repeat exposures
the limited operator can reduce repeat exposures by
clearly instructing patients
how does x-ray beam restriction minimize patient exposure
it limits the radiation field to the area of interest
what is the device that allows the limited operator to vary the size of the radiation field ?
collimator
how does filtration reduce patient exposure
removes longer-wavelength photons
what is the national council on radiation protection and measurements (NCRP) recommendation for the amount of total filtration?
2.5 MM AI equiv
what are the three principal methods used to protect limited operators from unnecessary radiation exposure?
Time , distance, and shielding
which of the following is not a type of personnel radiation shielding ?
shadow
personnel shielding must be worn on the rare occasion during which the limited operator may need to remain in the radiographic room during an exposure to assist the patient in maintaining the proper position. what is the source of the greatest radiation hazard under this circumstance?
scattered radiation from the patient
what is the term for radiation that escapes from the x-ray tube housing ?
Leakage radiation
why are limited operators prohibited from activities that result in direct exposure to the primary x-ray beam ?
They are considered occupationally exposed individuals
distance as a method used to limit operator exposure means that :
The operator should maximize the distance from the source during an exposure .
Shielding worn for personnel protection is designed to attenuate what source of exposure
scatter radiation
which of the following is an acronym for a common type of personnel dosimeter?
TLD
what is the recommended placement for a personnel dosimeter on the body of the limited operator ?
the badge should be worn in the region of the collar on the anterior surface of the body and outside the lead aprons, if worn.
what is the NCRP recommended annual effective dose limit for occupational exposure ?
5.0 rem (50 mSv)
what is the NCRP recommended monthly effective (or equivalent ) dose limit to the fetus for a pregnant worker?
0.05 rem (0.5 mSv)
radiation monitoring of personnel is required when what percentage of the annual occupational effective dose limit is likely to be received ?
10 percent
what is the SI radiation unit express radiation intensity in air?
colomb / kilogram (c/kg)
the SI unit used to report occupational doses to radiation workers is the
MSV
what is the SI radiation unit of absorbed dose?
GRAY
according to the bergonie - tribondeau law ,which of the following types of cells are most radiosensitive ?
Embryonic tissue cells
which type of x-ray photon interaction with the body is PRIMARLY responsible for the radiation dose absorbed by the patient ?
photoelectric
what is the NCRP (report #102) recommendation for lead equivalency of aprons used for personnel protection
0.5 mm
what is erythema, as it relates to radiation exposure
Redding of the skin caused by a high radiation dose
what is the guiding philosophy of radiation protection?
ALARA - as low as reasonably achievable
which of the following statements reflects current scientific opinion regarding the effects of diagnostic levels of ionizing radiation?
There is an increased risk of cancer,leukemia, birth defects and cataracts.
which of the following changes will decrease patient dose?
- increasing the kvp sing the 15 % rule while decreasing the mAS to compensate.
- decreasing the grid ratio to a 6:1 ratio while decreasing the mAs to compensate .
when radiation exposure occurs during pregnancy the greatest risk of birth defects occurs when exposure
- exceeds 5 rad to the uterus
- occurs within the first trimester of pregnancy.
what is the principal source of scatter radiation in radiography?
The patient
at what kvp levels do Compton interactions occur
they occur throughout the diagnostic radiology kvp range.
the greatest portion of the x-ray beam is made up of : Bremsstrahlung radiation
bremsstrahlung radiation
what are the four essential elements required for x-ray production
A target , a vacuum an electron source and a high potential difference
the penetrating power of the x-ray beam is controlled by varying the
kilovoltage (kvp)
which of the following function involve the autotransformer ?
Kvp selection
what is the IR that is used for computed radiography
photostimulable phosphor (PSP plate)
nearly all new x-ray machines manufactured today use
high frequency generators
what is the standard control limit for the field light to radiation field alignment test?
+-2% of SID