Radiograph with many light and dark areas, but FEW shades of grey is said to have....
High contrast
few shades of gray with high contrast is prooduced with------kVp
low kvp
increasing mA alone results in a film with
increased density
film produced using 90 kVp and 0.25 seconds. what exposure time is needed to produce the same at 75 kVp ?
0.50 seconds
The total energy contained in the xray beam in a specific area at a given time is termed....
intensity
Increasing these will increase the intensity of the x-ray beam?
kVp, mA, and exposure time
The HVL is the amount of..
Aluminum needed to reduce the x-ray beam intensity by half.
The kVp range for most dental x-rays is
65-100 kV
A higher kVp produces x-rays with
more penetrating ability
Radiation produced with high kVp results in
short wavelengths
increasing mA results in an increase in
Temp of filament and number of x-rays produced
the mA range for dental radiography is
7 to 15 mA
Thermionic emission occurs in the
negative cathode
which radiation accounts for 70% of all the x-ray energy produced at the anode?
General radiation
Which radiation occurs only at 70 kVp or higher ad accounts for a very small part of dental x-rays produced?
Characteristic radiation
Primary radiation best described as
radiation exists the tubehead
Which type of scatter happens most often with dental x-rays?
Compton
why is an increased target film distance required in the paralleling technique?
to avoid image magnification
Thin transparent coating that is placed over the emulsion.
protective layer
flexible piece of plastic that withstands heat, moisture and chemical heat
film base
Chemical compounds that change when exposed to radiation or light are termed
halides crystals
invisible pattern of stored energy on the exposed film is termed?
latent image
Purpose of a lead foil sheet in the film packet is:
to protect film from back scattered radiation
The -----the crystals, the -------- the film speed
The larger the crystals , the faster the film speed
What regulates the flow of electrical current to the filament of the x-ray tube?
low -voltage circuit
What is used to increase the voltage in the high -voltage circuit?
step-up transformer
Process by which unstable atoms undergo a spontaneous disintegration in an effort to attain a more balance nuclear state?(undergo decay trying
to become more balanced )
Radioactivity
Who introduced paralleling tech. and exposed first dental radiograph in the US using a live person?
C. Edmund Kells 1896
Introduced bisecting technique?
Weston Price 1904
Introduced Bite-Wing tech?
Howard Raper 1925
Four components of a film packaging?
x-ray film
paper film wrapper
Lead foil sheet
Outer packaging
The higher the speed of the film....
the faster the film exposure and the less radiation to patient
ALARA
Four basic Components of x-ray film??
Film base
Adhesive layer
Film Emulsion
Protective layer
Developer
Softens emulsion, reduces exposed crystals to black metallic silver
Fixer
Hardens emulsions, cleans away unexposed crystals ( silver halide)
Chemical components that change when exposed to radiation or light are termed?
silver halide crystals- reduced to black metallic silver
Five Rules for Paralleling tech
Film Placement- most cover teeth to be examined
Film Position- parallel to the long axis
Vertical Angulation- CR directed perpend to film
Horizontal Angulation - CR directed thru contact-open
Film Exposure- center x-ray beam to espose film
Molecule
2 or more atoms joined by chemical bonds
Ionization
losing or gaining an electron
Radiation
Emission or propagation of energy though space or matter, waves or particles
Ionizing Radiation
Radiation that is capable of producing ions by removing or adding electrons to an atom.
Velocity
Wave speed= speed of light
Wavelength
distance b/t crests- energy and penetrating power
Frequency
# of wavelenths that pass a given point in a certain amount of time.
Low freq./ Long wavelength = decreased energy
High freq/ short wavelength= increase energy
X- radiation
type of High energy, ionizing electromagnetic radiation
Amperage (mA)
# of electrons moving through the cathode filament
Voltage ( kV)
meaurment of electrical force that causes electrons to move from (-) to (+) pole
kVp
Controls the current passing from the cathode to the anode
Speed of light
186,000 miles/sec
Produced when radiation strikes matter, reduces penetrating power
Secondary Radiation
When radiation is deflected off matter
Scatter Radiation
Compton Scatter
62%
x-ray photon is deflected form path during passage through matter
IONIZATION occurs
Coherent Scatter
8%
x-ray photon that has its path altered by matter
No change in atom occurs, NO ionization