Radiology Flashcards
X rays discovered by
Roentgen, Nov 8th 1895
Rollins
developed guidelines for protection of patients; lab rats
Roentgenology
study or science of radiation as used in medicine and dentistry
Radiolucent
e- pass, so not dense, shows black
Radiopaque
e- do not pass, so dense, appears white
Direct sensor
to computer
attenuate
stop the electrons; shows up radiopaque (enamel) whereas dentin is less dense
Indirect Sensor
simple film which goes into a processor-optime; photostimulable phosphor (PSP) is used which are thin imaging plates w/ no wires and is read by a laser
How x-rays are produced
e- are produced at the tungsten filament (cathode) and propelled towards the anode at a speed dependent on the electrode potential between the anode and cathode.
bombarding a tungsten target (anode) with high V e- – go to the anode at high speeds
Thermionic emmision
term used to describe boiling off of electrons
Filament
coil of tungsten which emits electrons when heated
Focussing cup
negatively charged molybdenum
tungsten target
anode
Focal Spot
area within target where e- are directed; smaller gives sharper image
smaller focal spot
sharper image
Bermsstrahlung (braking radiation)
higher energy, e- is slowed by protons in nucleus
Characteristic radiation
e- knocks out inner shell electrons (K shell) –> unstable vacancy –> electrons fall down and emit photons
controls speed of e- from cathode to anode
kV (kilovoltage) and mA
controls quality of x ray beam
kV
controls quanity of electrons
mA and time (1 impulse = 1/60)
mA
controls numbrer of electrons and thus quanity of e-; higher = darker
higher mA
darker (b/c greater quantity of e-)
Radiographic contrast
related to quality of x-radiation; controlled by kV (high and low) related to number of shades of gray
High contrast
short scale and less shades of gray (black and white is high contrast)
low contrast
long scale (more colors), more shades of gray
how image is produced
e- emitted from cone –> tissue –> attenuated –> some e- pass and hit sensor
contrast controlled by
Kv
Examples of radiolucencies
caries, fossa, sinus, pathology, PDL space, periapical pathology
radiopaque examples
dentin, enamels, calculus, almalgam restoration (most), calculus,
Most radiopaque
almalgman restoration
DEJ visible on radiograph how
grey to white enamel
lamina dura appearance on radiograph
radiopaque covering between root and bone (white to grey)
Exposure
act of making or exposing a radiograph
Higher kV
more penetrating power because kV controls the speed and quality of the beam
Radiographic Density
degree of blackness on the radiograph, controlled by mA and time-related to quantity of x-radiation
fogged areas
e- were bent
