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Radiation Protection and Radiobiology Questions and Answers 100% Solved
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Radiation Protection and Radiobiology
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Radiation Protection and RadiobiologyIonizing radiation - answer produces diagnostic image
radiation risks - answer Exposure to radiation - involves risk of biologic changes
Use sound judgment - minimize quantity of radiation
Protect all persons from unnecessary exposure
Group includes self, patient and anyone else
Sources of Ionizing Radiation - answer Natural (background) - cosmic radiation from the
sun & planetary bodies, uranium and radium inhaled or ingested through food, water or
air
Human-made - nuclear industry, radionuclides, and medical/dental exposures.
Nuclear industry - fallout from above-ground weapons testing, accidents in nuclear
power stations, and disposal of by-products from these plants
Radionuclide exposure includes products like smoke detectors that contain radioactive
elements and radiopharmaceuticals used in diagnosing and treating disease.
Medical/dental exposures - greatest source
Human-made radiation (x-rays) - answerform of electromagnetic radiation that travels at
the speed of light.
Unlike particulate radiation (a liberated portion of the atom capable of traveling for short
distances and reacting with matter.)
Bundles of energy moving as waves in space, depositing energy at random
Source of electrons, force to move them rapidly and something to stop the movement
must all be present - provided by the x-ray tube and its electrical supply.
particulate radiation - answer(a liberated portion of the atom capable of traveling for
short distances and reacting with matter.)
all must be present - answerSource of electrons, a force to move them rapidly and
something to stop the movement - provided by the x-ray tube and its electrical supply.
Tube - answercathode (negative terminal) and anode (positive terminal) in glass
envelope to maintain the vacuum needed for optimal x-ray production
, Cathode's filament - answerthoriated tungsten which provides the source of electrons.
Kilovoltage - answerapplied to the filament accelerates the stream of electrons toward
the anode end. X-rays are produced when the electrons strike the anode (energy
conversion) and produces x-rays and heat. Heterogeneous (has many energies) -
measure in kiloelectron volts (keV). This is the primary beam and it is directed toward
the patient through a window in the tube.
Three possibilities when x-rays strike matter: - answerCan be absorbed
Can transfer some energy and then scatter
Can pass through unaffected
Interactions with matter - answerClassic coherent scattering
Photoelectric interactions
Compton scattering (the Compton effect)
Pair production
Photodisintegration
Basis for all patient exposure and reason behind need for protection -
answerphotoelectric interactions and Compton scattering
Classic coherent scattering - answeroccur within the diagnostic range of x-ray energies.
- (Thomson scattering) - occurs when incoming x-ray photon strikes an atom and is
absorbed, exciting the atom so it releases excess energy in the form of another x-ray
photon that proceeds in a different direction (scattering). The scattered photons travel in
a forward direction, stopping when they hit anything in their path. Results in no energy
transfer to the patient.
Photoelectric interactions - answeroccur within the diagnostic range of x-ray energies.
Directly influence patient and radiographer's exposure (transfer their energy to living
tissue). Occurs when incoming x-ray photon strikes an inner shell electron and ejects it
from its orbit around the nucleus of the atom - creates an ion pair. Atom becomes
positively charged and the released electron is the photoelectron. It continues to travel
until combining with other matter. All energy is completely consumed. Energy is
"absorbed by the atom". Since complete energy absorption takes place, this is the
greatest hazard to patients.
Compton scattering (the Compton effect) - answeroccur within the diagnostic range of x-
ray energies. Directly influence patient and radiographer's exposure (transfer their
energy to living tissue). Incoming x-ray photons strike a target atom and uses a portion
of its energy to eject an outer shell electron. The remainder of the energy proceeds in a
different direction than the incoming photon and results in a Compton or recoil electron
that travels until combining with matter and a photon carrying less energy that can react
with the patient through further Compton or photoelectric interation and may exit the
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