homework review Flashcards
Cosmic radiation occurs in which two forms?
solar and galactic
Diagnostic efficacy includes….
- determining if an imaging procedure is justified.
- producing optimal quality images with the least radiation exposure to the patient.
- adhering to radiation safety guidelines.
- revealing the presence or absence of disease in a patient.
Of the two sources of ionizing radiation listed below, which source remains fairly constant from year to year?
Natural, human-made
natural
terrestrial radiation includes long-lived radioactive elements such as ______________ that are present in variable quantities in the _____ of the Earth
uranium-238, radium-226, and thorium-232, crust
The term as low as reasonable achievable (ALARA) is synonymous with the term
optimization for radiation protection (ORP)
What is the most common unit of measure of equivalent dose?
millisievert
Which of the following are forms of electromagnetic radiation?
1. Microwaves
2. Visible light
3. X-rays
4. Gamma rays
5. Ultraviolet radiation
all of the options
Which of the following is a method of explaining radiation to the public?
a. BERT
b. ALARA
c. NEXT
d. ORP
BERT
ALARA is important because radiation-induced cancer (does/does not) appear to have a fixed threshold, that is, a dose level below which a person would have no chance of developing this disease.
does not
true/false: after TMI-2, many excess cancer deaths have been predicted to occur in the 2 million people living within 50 miles of the plant at the time of the accident.
false
Compton scattering is synonymous with
incoherent scattering
If two anatomic structures have the same density and atomic number but one is twice as thick as the other, the thicker structure will absorb _____________
twice as many x-ray photons
In photoelectric absorption to dislodge an inner-shell electron from its atomic orbit, the incoming x-ray photon must be able to transfer a quantity of energy
as large as or larger than the amount of energy that holds the electron in its orbit
Particles associated with electromagnetic radiation that have neither mass nor electric charge and travel at the speed of light are
x-ray pohtons
The probability of occurrence of photoelectric absorption _________ as the energy of the incident photon decreases and the atomic number of the irradiated atoms _________.
increases markedly, increases
What are the by-products of photoelectric absorption?
photoelectron, characteristic photon
What particle is considered to be a form of antimatter?
positron
What results in all-directional scatter?
compton interactions
The x-ray photon energy required to initiate pair production is
1.022 MeV
Which of the following is not a type of interaction between x-radiation and biologic matter?
a. Photoelectric absorption
b. Bremsstrahlung
c. Compton scattering
d. Pair production
Bremsstrahlung
An ionization chamber connected to an electrometer is a device that can measure
tiny electric currents with high precision and accuracy.