Final lecture questions Flashcards
Which of the following is/are considered low-LET radiation(s)? X-rays 2. Alpha particles 3. Gamma rays
1 & 3 - xrays and gamma rays
Which of the following curves illustrates the radiation sensitivity of a particular type of cell? cell specialization curve cell extrapolation curve dose-response curve cell survival curve
cell survival curve
Which of the following groups of cells is least radiosensitive? adult nerve cells nerve cells in an embryo-fetus lymphocytes immature spermatogonia
adult nerve cells
When LET increases, the chance of producing a significant biologic response in the radiosensitive DNA macromolecule____
grows
If a person receives radiation exposure sufficient to cause the gastrointestinal syndrome, fatality occurs primarily because of
catastrophic damage to the epithelial cells that line the gastrointestinal tract, resulting in the death of the exposed person within 3 to 5 days from a combination of infection, fluid loss, and elect
The term LD 50/30 signifies the whole-body dose of radiation that can be lethal to
50% of the exposed population in 30 days
Atrophy refers to
shrinkage of organs and tissues after a high radiation dose is received
Which of the following are classified as early tissue reactions of ionizing radiation
Nausea, epilation, and intestinal disorders
Radiation-induced cataracts in humans follow a ____ dose-response relationship
threshold, nonlinear
What of the following late effects caused by exposure to ionizing radiation is considered to be most important?
cataract formation
embryologic or birth defets
cancer
none; all are considered to be of equal importance
cancer
in general, laboratory experiments with mice prove that cataracts may be induced with doses of ionizing radiation as low as
0.1 Gyt
Existing data on radiation-induced genetic effects in humans
are both contradictory and inconclusive
Which of the following terms involves a random effect of ionizing radiation? early tissue reactions change in white blood cell count reddening of the skin stochastic event
stochastic event
Determine the cumulative effective dose (CumEfD) limit to the whole body of an occupationally exposed person who is 46 years old
460 mSv (ch. 10 table)
The effective dose (EfD) limiting system supersedes
the maximum permissible dose (MPD) system
The ALARA concept adopts an extremely conservative model with respect to the relationship between
ionizing radiation and potential risk
Which of the following is not an x-ray beam limitation device?
filter
the protective tube housing services as a shield against ______ entering the x-ray tube, thereby preventing electric shock while also facilitating cooling of the x-ray tube
the high voltage
If the luminance of the collimator light source is adequate, the localizing light beam will satisfactorily outline the margins of the radiographic beam on the area of clinical interest on
all patients
When using digital fluoroscopy systems, making use of the last image hold feature can
be an effective dose reduction technique
Which of the following x-ray procedures increases the radiographer’s risk of exposure to ionizing radiation compared to radiography?
- Mobile C-arm fluoroscopy
- interventional procedures that use high level control fluoro
- mobile rad
1, 2, & 3
Whenever scattered radiation decreases, the radiographer’s exposure
decreases
which of the following adjustments in technical exposure factors decreases the production of scattered radiation during routine radiographic procedures?
increases kVp and decreases mAs in compensation
A protective curtain, or sliding panel, with a minimum of 0.25-mm lead equivalent, should normally be positioned between the fluoroscopist and the patient to intercept which of the following types of radiation?
scattered radiation above the tabletop
