Final chapter questions Flashcards
In a DNA macromolecule, the sequence of _____ determines the characteristics of every living thing
Nitrogenous organic bases
How many base pairs are there in the human genome?
2.9 x 10^9
Radiation-induced chromosome damage may be evaluated during which of the following processes?
Metaphase
If exposure to ionizing radiation damages the components involved in molecular synthesis beyond repair, cells do which of the following?
Function abnormally or die
Which of the following produces antibodies?
lymphocytes
Water comprises approximately _____ of the weight of the human body
80-85%
Which of the following must the human body provide to ensure efficient cell operation?
1, 2, & 3.
1) Food as a source of raw material for the release of energy
2) Oxygen to help break down food
3) Water to transport inorganic substances into and out of the cell
Which human cell component controls cell division and multiplication as well as biochemical reactions that occur within the cell?
nucleus
What term is used to describe chemical secretions that are manufactured by various endocrine glands and carried by the bloodstream to influence the activities of other parts of the body?
hormones
somatic cells divide through the process of
Mitosis
For radiation protection, high-LET radiation is of greatest concern when internal contamination is possible, that is, when a radionuclide has been implanted, ingested, injected, or inhaled because:
Then the potential exists for irreparable damage because multiple-strand breaks in DNA are possible.
Free radicals behave as an extremely reactive single entity as a result of the presence of:
unpaired valence electrons
Which of the following are classified as high-LET radiation?
Alpha particles
Gamma rays
X-rays
Alpha particles
a biologic reaction is produced by 3 Gyt of a test radiation. it takes 12 Gyt of 250-kVp x-radiation to produce the same biologic reaction. What is the relative biologic effectiveness (RBE) of the test radiation?
4
Which action of ionizing radiation is most harmful to the human body?
indirect action
Which molecules in the human body are most commonly directly acted on by ionizing radiation to produce molecular damage through an indirect action?
water
When does ionizing radiation cause complete chromosome breakage?
When two direct hits occur in the same rung of the DNA macromolecule
When significant numbers of lymphocytes are damaged by exposure from ionizing radiation, the body:
1) loses its natural ability to combat infection
2) becomes more susceptible to bacteria
3) becomes more susceptible to viral antigens
1, 2, and 3.
1) loses its natural ability to combat infection
2) becomes more susceptible to bacteria
3) becomes more susceptible to viral antigens
With respect to the law of Bergonie and Tribondeau, which of the following would best complete this statements? “the most pronounced radiation effects occur in cells with the ______”
Greatest reproductive activity, longest mitotic phases, and least maturity and specialization or differentiation.
What do basal cells of the skin, intestinal crypt cells, and reproductive cells have in common?
All cells are radiosensitive
The total radiation dose given to a somatic or genetic cell and the period of time in which that dose was delivered determine the rate of production of
chromosome aberrations
Acute radiation syndrome presents in four major response stages. In what order do these stages occur?
prodromal, latent period, manifest illness, recovery or death
Which of the following systems is the most radiosensitive vital organ system in human beings?
hematopoietic
When cells are exposed to sublethal doses of ionizing radiation, approximately ____ of radiation-induced damage may be repaired over time and about ____ is irreparable.
90%, 10%
As radiation dose increases, the severity of early tissue reactions:
increases sharply and then gradually decreases
Prolonged exposure to x-rays in the diagnostic energy range results in high radiation dose to the skin while underlying tissues receive?
A substantially less dose
In 1898 after personally developing burns attributed to radiation exposure, this Boston dentist began investigating the hazards of radiation exposure and became the first advocate of radiation protection. Who is this person?
William Herbert Rollins
In the female, the ovarian stem cells:
Multiply to millions of cells only during fetal development, before birth, and then steadily decline in number throughout life
Which of the following types of cells develop from single precursor cell, the pluripotential stem cells?
1) lymphocytes and granulocytes
2) thrombocytes and erythrocytes
3) platelets
1,2, and 3
1) lymphocytes and granulocytes
2) thrombocytes and erythrocytes
3) platelets
With regard to radiation exposure, which part of the gastrointestinal tract is most severely affected?
small intestine
cancer and genetic defects are examples of
Stochastic effects
Some examples of measurable late biologic damage are:
1) cataracts
2) leukemia
3) nausea and vomiting
4) genetic mutations
1,2, and 4.
1) cataracts
2) leukemia
4) genetic mutations
which of the following provide the foundation for the sigmoid, or S-shaped, threshold curve of radiation dose response?
1) data from human populations observed after acute high doses of radiation
2) data from human populations observed after chronic low doses of radiation
3) laboratory experiments on animals
1) data from human populations observed after acute high doses of radiation
The linear nonthreshold curve implies that biologic response is
directly proportional to the dose
Reevaluation of the quantity and type of radiation that was released in the atomic bombing of the cities of Hiroshima and Nagasaki has led to revised atomic bomb data in which radiation-induced leukemia and solid tumors may now be attributes predominantly to
gamma radiation exposure
The radiation dose-response relationship is demonstrated graphically through the use of a curve that maps the observed effects of radiation exposure in relation to the dose of radiation received. Which of the following curves expresses a linear-quadratic nonthreshold dose response?
concave curve down (image on pg. 180, answer C)
During the 10 years immediately after the 1986 Chernobyl nuclear power station accident, which of the following was the most pronounced health effect observed?
Dramatic increase in thyroid cancer in children living in the regions where the heaviest radioactive contamination occurred
The early demise of experimental animals exposed to nonlethal doses of ionizing radiation actually resulted from
induction of cancer
According to data from studies performed on US radiologic technologists, individuals who began working before 1950 had a somewhat higher risk of dying of ____ when compared with technologists who started working in 1950 and later.
leukemia
most diagnostic procedures result in equivalent doses
less than 0.1 Sv
Which of the following agencies is responsible for enforcing radiation safety standards?
NRC
Determine the cumulative effective dose (CumEfD) to the whole body of an occupationally exposed person who is 27 years old.
270 mSv
Biologic effects such as cataracts that result from exposure to ionizing radiation appear to have which of the following?
Sigmoid threshold dose-response curve
for radiation workers, such as medical imaging personnel, occupational risk may be equated with occupational risk in which of the following?
other industries that are generally considered reasonably safe
Revised estimates derived from the more recent reevaluations of dosimetric studies on the atomic bomb survivors of Hiroshima and Nagasaki indicates which of the following?
An increase in the number of solid tumors in the survivor population.
When exposed to radiation as part of their educational experience, 18-year-old students should not exceed an effective dose limit of ______ annually.
1 mSv
Which of the following groups has provided sufficient evidence of the induction of stochastic effect in humans resulting from high radiation absorbed doses?
Japanese atomic bomb survivors
Responsibilities of a medical facility’s radiation safety officer (RSO) include which of the following?
1) developing an appropriate radiation safety program
2) maintaining radiation-monitoring records for all personnel
3) repairing all broken or defective imaging equipment
1 & 2
1) developing an appropriate radiation safety program
2) maintaining radiation-monitoring records for all personnel
To reduce exposure for pregnant imaging professionals and to control the exposure of the unborn during potentially sensitive periods of gestation, the NCRP now recommends a monthly equivalent dose limit not exceeding ____ per month to the embryo-fetus and a limit during the entire pregnancy not to exceed ____ after declaration of a pregnancy.
0.5 mSv. 5.0 mSv
Which of the following is the annual occupational effective dose that applies to radiographers during routine operations?
50 mSv
The radiographic beam should be collimated so that it is which of the following?
no larger than the image receptor
Both alignment and length and width dimensions of the radiographic and light beams must correspond to within:
1% of the SID
What is the function of a filter in diagnostic radiology?
to decrease the x-radiation dose to the patient’s skin and superficial tissue
HVL may be defined as the thickness of a designated absorber required to do which of the following?
decrease the intensity of the primary beam by 50% of its initial value
the photostimulable phosphor in the computed radiography imaging plate is more sensitive to scatter radiation before and after it is sensitized through exposure to a radiographic beam. Because of this increased sensitivity, which of the following is true?
A radiographic grid may be used more frequently during CR imaging.
To minimize skin exposure to electrons produced by photon interaction with the collimator, how far below the collimator should the patient’s skin surface be?
At least 15 cm below
which of the following aluminum equivalents for total permanent filtration meets the minimum requirement for mobile diagnostic and fluoroscopic equipment?
2.5 mm aluminum equivalent
the trough, or bilateral wedge, filter, which is used in some dedicated chest radiographic units, is an example of which of the following?
compensating filter
To decrease patient exposure during fluoroscopic procedures, the fluoroscopist can:
1 & 2
1) Limit the size of the fluoroscopic field to include only the area of anatomy that is of clinical interest
2) employ the practice of pulsed fluoroscopy to reduce the overall length of exposure
A diagnostic-type protective tube housing must be constructed so that leakage radiation measured at a distance of 1 m from the x-ray source does not exceed ____ when the tube is operated at its highest voltage at the highest current that allows continuous operation.
1 Gya/hr
As a consequence of their anatomic location, the female reproductive organs receive about _____ exposure during a given radiographic procedure involving the pelvic region than do the male reproductive organs.
three times more
In fluoroscopy, how if the amount of radiation that a patient receives usually estimated?
by measuring the radiation exposure rate at tabletop and multiplying this by the fluoroscopy time
As part of the Image Gently Campaign, radiographers and imaging facilities can pledge to:
image gently
in which of the following projections will a young female patient receive a significantly lower dose to her breast tissue during a chest x-ray study?
PA
A woman who is 3 months pregnant has been in a motor vehicle accident. The emergency room physician suspects there is injury to her cervical spine and thus feels justified in ordering an x-ray examination to aid in determining the extent of the patient’s injury. Because the patient is pregnant, the radiographer should:
1,2, and 3.
1) select the smallest technical exposure factors that will produce a diagnostically useful image
2) adequately and precisely collimate the radiographic beam to include only the anatomic area of interest
3) shield the patient’s lower abdomen and pelvic region with a suitable protective contact shield
pediatric patients require special consideration and appropriate radiation protection procedures because they are much more vulnerable to which of the following
both the late somatic effect and the genetic effects of radiation
The use of the PA projection during a juvenile scoliosis radiographic examination results in which of the following?
Lower entrance exposure dose to the anterior body surface, thereby significantly reducing the dose to the breast
For protection of the ovaries of a female patient, the shield should be placed approximately:
2.5 cm (1 in) medial to each palpable anterior superior iliac spine.
Which of the following examinations are considered unnecessary radiologic procedures?
1 & 3.
1) chest x-ray study as part of a preemployment physical
3) whole-body multislice spiral CT screening
If a maximum of 500 people inhabited an island and each person were to receive an equivalent dose (EqD) of 0.005 Sv gonadal radiation, the gross genetic effect would be _____ the effect occurring if 50 individual inhabitants were each to receive 0.05 Sv of gonadal radiation and no equivalent dose were received by other inhabitants.
identical to
When performing a mobile radiographic examination, if the protection factors of distance and shielding are equal, the radiographer should stand at a ____ to the scattering object (the patient) line.
90-degree angle
diagnostic imaging personnel may receive an annual occupational effective dose of ____ for whole body exposure during routine operations
50 mSv
at a 90-degree angle to the primary x-ray beam, at a distance of 1 m, the scattered radiation is what fraction of the intensity of the primary beam?
1/1000
if a radiographer stands 6 m away from an x-ray tube and receives an exposure rate dose of 4.0 mGya/hr, what will the exposure rate dose be if the same radiographer moves to stand at a position located 12 m from the x-ray tube?
1 mGya/hr
Which of the following are methods that can be used by a C-arm operator to reduce occupational exposure for himself or herself and other personnel?
1 &2
1) collimate the x-ray beam to include only the anatomy of interest.
2) use the foot pedal or the handheld exposure switch with their cables extended away from the machine as far as possible whenever making an exposure.
If the Bucky slot shield and protective curtain or sliding panel were not in the correct position during a routine fluoroscopic examination, what exposure dose rate would the fluoroscopist experience?
exceed 1 mGya/hr at a distance of 0.6 m from the side of the x-ray table
units of either mAx/wk or mA-min/wk are used to determine the ____ for a specific x-ray room.
workload
a Bucky slot shielding device of at least ______ must automatically cover the Bucky slot opening in the side of the x-ray table during a fluoroscopic examination when the Bucky tray is positioned at the foot end of the table.
0.25-mm lead equivalent
For mobile radiographic units, which are not equipped with remote control exposure devices, the cord leading to the exposure switch must be long enough to permit the radiographer to stand at least ____ from the patient, the x-ray tube, and the useful beam to reduce occupational exposure.
2 m
Of the following factors, which are specifically considered when determining thickness requirements for protective barriers?
occupancy factor (T) Workload (W) and Use factor (U)
