Chapter 11 Study Questions Flashcards
The International System of Units (SI) unit for measuring the absorbed dose in the patient is the:
gray-t (Gy-t)
The SI measurement of radiation exposure in air is the:
gray-a (Gy-a)
The SI unit used to report the equivalent dose, or occupational dose, to radiation workers in the United States is the.
Sievert (Sv)
According to the law of Bergonie’-Tribondeau, which of the following types of cells would be most radiosensitive?
Embryonic tissue
Short term effects of radiation are typically observed within.
3 months
Which of the following is considered an observable short-term effect of radiation exposure?
Erythema
The reduction of a limited operator’s exposure to ionizing radiation can be accomplished by.
Decreasing the time in the radiation field and increasing the distance from the radiation source
The annual effective dose limit for a whole-body dose of occupational radiation for non-pregnant workers over the age of 18 is.
50 millisieverts (mSv)
Which of the following are considered low dose techniques?
Increasing kVp, decreasing milliampere-seconds (mAs) and Using a minimum source-image receptor distance (SID) of 40 inches
Which of the following changes will decrease the patient dose?
Using high-kVp techniques
When radiation exposure occurs during pregnancy, the greatest risk of birth defects occurs when the dose to the uterus exceeds.
150 mGy-t
Limited operators can reduce radiation risk to their patients by
minimizing repeat exposures and collimating closely to the part
The radiation weighting factor for X-ray photons is.
1
In equivalent dose of 0.400 SV would be converted to____mSv
0.400 x 1000= 400
In our everyday work, the equivalent dose is used for.
radiation protection purposes
The greatest cause of unnecessary radiation exposure to patients that can be controlled by the limited operator is.
repeat exposures
Whenever the gonads are within________ of the margin of the radiation field, gonadal dose will be significantly reduced by shielding.
5 cm
A pregnant radiation worker’s monthly equivalent dose limit is.
0.5 mSv
A 33-year-old radiation worker would have a cook cumulative effective dose limit of.
33x10=330
An erythema can develop on a patient if the radiation dose to the skin reaches.
2000 mSv
When the dose to the patient is clarified by the type and energy of the radiation, it is termed the.
equivalent dose
Patient dose in ready radiography is most often calculated according to the exposure level at the.
skin
Short term effects of radiation will occur at doses greater than
500 mGy-t
In diagnostic radiology, we are most concerned about which effect of radiation exposure?
Long-term effect
The LD 50/30, or the lethal dose that would be fatal to 50% of the irradiated population within 30 days is.
3000 to 4000 mGy-t
The greatest percentage of long term effects from radiation exposure will occur
at between 10-15 years
Which of the following would be considered a long term effect of radiation exposure?
Cataracts, Life span shortening, Leukemia
When a person becomes sick very fast due to a whole body dose of radiation in a short Period of time. This is referred to as.
acute radiation syndrome (ARS)
The standard lead equivalency of the lead aprons used in the radiology department should be a minimum of 0.75.M lead.
False
Radiographers should perform lead apron and glove inspection every six months.
True
A human who receives an acute whole body exposure of 6.0 Sv will die.
True
The earliest biologic effect that will be seen in the human body after exposure to radiation is nausea and vomiting.
False
In diagnostic radiology, the absorbed dose and the equivalent dose are always the same value.
True
Younger cells are no more sensitive to radiation than adult cells.
False
Long term effects from radiation exposure are not predictable.
True
The greatest risk to a fetus is during the last three months of pregnancy.
False
Linear energy transfer (LET) is the amount of X-ray energy transfer on average per the length of passage through the tissue.
True
When there is more oxygen in the tissues, it is more sensitive to radiation compared to tissues with low oxygen.
True
