Exam 2 Flashcards
What is the definition of radiation in dental radiography?
A form of energy carried by waves or a stream of particles.
Who discovered the X-ray?
Willhelm Conrad Roentgen, on November 8, 1895.
What is the main function of a radiograph?
To produce a two-dimensional image of a three-dimensional object using ionizing radiation.
What is the role of a dental radiographer?
To position, expose, and process dental x-ray image receptors.
What is an image receptor in dental radiography?
A recording medium such as x-ray film, phosphor plate, or digital sensor.
Who is credited with the first practical use of radiographs in dentistry?
C. Edmund Kells.
What particle has a positive charge within an atom?
Proton.
Which force maintains electrons in their orbits around the nucleus?
Electrostatic force.
Define ionization in atomic structure.
The process by which ions are formed by the gain or loss of an electron.
What is primary radiation?
The penetrating x-ray beam produced at the anode target in the tubehead.
What is the function of the lead collimator in an x-ray tubehead?
To restrict the size of the x-ray beam.
What process occurs when tungsten filaments are heated, releasing electrons?
Thermionic emission.
Which radiation effect involves a dose threshold and increases in severity with dose?
Nonstochastic (deterministic) effects.
What describes a linear, nonthreshold dose-response curve?
Tissue response is directly proportional to the dose, with no threshold for damage.
Which cells are the most radiosensitive?
Small lymphocytes.
How is “absorbed dose” measured in traditional units?
Rad (radiation absorbed dose).
What SI unit is equivalent to the rem for dose equivalent?
Sievert (Sv).
What is the ALARA principle in radiation safety?
Keep radiation exposure as low as reasonably achievable.
Who is credited with creating the first dental radiograph and in what year?
Otto Walkhoff, in 1895.
What is Bremsstrahlung, or “braking radiation”?
Electromagnetic radiation produced when charged particles are slowed or deflected by atomic nuclei.
What is the maximum permissible dose (MPD) for occupationally exposed dental radiographers per year?
50 mSv/year (0.05 Sv/year or 5.0 rem/year).
What part of the tubehead absorbs heat created during x-ray production?
Insulating oil.
What is the purpose of the thyroid collar in patient protection?
To protect the thyroid gland from scatter radiation.
Which cells are classified as radioresistant?
Nerve cells and mature bone cells.
What term describes the elapsed time between radiation exposure and the appearance of clinical signs?
Latent period.
What is Acute Radiation Syndrome (ARS)?
A short-term effect of radiation exposure that causes nausea, vomiting, diarrhea, and hair loss.
What unit is used to measure ionization in air for x-rays?
Roentgen (R).
Who developed the first hot-cathode x-ray tube?
William D. Coolidge in 1913.
What is inherent filtration in x-ray equipment?
The aluminum disc covering in the x-ray tube that filters out non-useful, longer-wavelength x-rays.
What theory explains radiation injury from the formation of toxins within a cell?
Indirect theory.
Which type of radiation interaction creates an image by passing through the patient without interaction?
No interaction.
What is the function of a collimator in dental radiography equipment?
To restrict the size and shape of the x-ray beam, reducing patient exposure.
What federal act standardizes x-ray equipment performance?
The Radiation Control for Health and Safety Act of 1968.
What is the role of a film badge for personnel monitoring?
To measure radiation exposure over time, usually worn for a month and sent for analysis.
What is the difference in exposure between an 8-inch and a 16-inch PID?
The 16-inch PID reduces exposure by creating a more focused beam.
What technique did C. Edmund Kells invent, and how did it contribute to dental radiography?
William H. Rollins, for developing the first dental x-ray unit and advocating for radiation safety.
