Ch. 38 Principles of Rad
Discuss the pioneers of radiography.
1895 - Roentgen discovery of x-rays
Otto Walkout - first dental radiograph
1986 - Dr. Edmund Kells, first practical use of radiography in dentistry
What does the mA control?
Quantity
What are critical organs?
skin, thyroid, lens of eye, oral mucosa
What does MPD stand for?
Maximum Permissible Dose
What does ALARA stand for?
As Low As Reasonably Achievable
What is Ionization?
process by which electrons are removed from atoms, causing the harmful effects in humans
What does the kVp control?
Quality
Biological effects - explain the difference between acute vs chronic and genetic vs somatic.
Acute: short term, Chronic: long term
Genetic: affects future generations, Somatic: affects person exposed
How is radiation measured?
Roentgen, RAD, REM, SIEVERTS, GRAY AND COLOUMBS
Explain the structure of an atom.
central nucleus, composed of equal protons and neutrons
Differentiate between primary, secondary, and scatter radiation.
Primary: useful
Secondary: created when primary interacts with matter
Scatter: deflected
How much radiation can a CDA safely be exposed to per year?
0.5 REM or 0.05 Sv
In pediatric and pregnant patients, what do you consider?
Only take if necessary, less x-rays, pregnant: best in second trimester
Difference between hard x-rays and soft x-rays. Which is most useful in the dental setting?
Hard x-rays: short wavelength, high energy, good penetration -- Most useful
Soft x-rays: long wavelength, low energy, not good penetration
Explain the difference between contrast and density.
Contrast: different shades of grey, visible differences black/white
Density: overall darkness
Name 3 protective devices within the tubehead.
Collimator, Aluminum Filter 2.5, PID
What are the 6 key points to safety code 30?
Liability/Dentist responsibility, design criteria, operator recommendations, darkroom equip. specifications, patient/op. safety, radiation inspection
What is a cathode and anode and how do they relate to each other?
the cathode supplies electrons, the anode is a positive target.
When high voltage current is supplied, the electrons are attracted to the anode focal spot
List 5 ways to protect your patient during x-ray exposures.
Lead apron, thyroid collar, fast film, digital film, RINN kits
List 5 ways to protect the operator during x-ray exposures.
6 ft away, behind a barrier/wall, dosimeter/monitor badge, 90-135 degrees from primary rays, don't hold films/receptors in pt.'s mouth