test 1 - intro Flashcards
radiation when an electron is removed from its orbital
ionization
is produced with e (-) and atom (+)
ion pair
what are seven different types of non-ionizing radiation
microwaves
radio waves
ultraviolet
radar
cellular
infrared
ultrasound
____ frequency wavelength exhibits greater energy versus ___ freqency wavelength exhibits lesser energy
short - greater
long - lesser
types of radiation from short to long wavelengths
short: gamma ray, x-ray, ultraviolet
middle: visible light
middle to long: infrared, microwave, radio
what is the greatest source of radiation in the US
radon (54%)
what date did x rays become discovered and by whom
Nov 8, 1895
wilhelm roentgen
what the the 6 different x-ray properties
- no charge
- invisibility
- penetrability of most matters dependent on Z (atomic number)*
- ionization and biologic effect*
- making compounds fluoresce and emit light*
- travel at speed of light
what three components make up the imaging system
x-ray tube
operating console
high voltage generator
what specifc aspect in the x-ray tube forms the x-ray
anode
x rays are emitted _____ or in all directions
isotropically
x ray tube:
negative (-) end of the tube
cathode
what is the x-ray tube made up of
heat resistant filament made of thoriated tungsten
initially low electrical current “heats” the filament slowly analogous to a house-hold toaster or an incanadescent light bulb
filament current
when the filament temperature is sufficiently high the outer shell electrons become unstable and after a jolt and a small rise in the filament current the electrons will “boil off” and to be ejected from the filament
thermionic emission
electron cloud maintains a very strong negative charge and repel any additional electrons to be emitted from the filament
space charge effect
T/F: all electrons accelerated from the cathode to anode are (-) charged
T
T/F: focusing cup is (-) charged
T
what is the focal spot
where the electrostatically confines accelerated electrons beam towards their anode’s target or a small area of the anode
there are 2 focal spots on the anode corresponding to the large or small filament of the cathode called
dual focus
(+) charged end of the tube
anode
what are the three main functions of the anode
target for x-ray photons production
rotates and dissipates heat
electrical conductor which conducts electrons through the connecting cables back to the tube
is the small focal spot able to dissipate heat
no
rotating ____ have significantly reduced potential heat damage to the tube
anodes
in order to maintain uniform tissue exposure the _____ side must always face the thinner body part
anode
off focus radiation creates
extrafocal or off focus radiation
electrons bounce off and land outside the focal spot
T/F: grid will not reduce extrafocal radiation
T
it is not considered scatter radiation
modifies incoming voltage and current to provide an x-ray tube with the power needed to produce an x-ray beam of the desired peak kilovoltage
x ray generator
modifies the voltage of incoming alternating current (AC) electrical signals to increase or decrease the voltage in a circuit
transformer
convert alternating current (AC) into direct current (DC) required by the x-ray tube. restricts current flow in an x-ray tube to one direction from cathode to anode only, preventing damage to the x-ray tube filament
rectifiers
voltage rectification
versus
high frequency power generator
voltage recitification: converts AC to DC to ensure sustained flow of e- to minimize ripple effect
high frequency power generator: provides nearly constant potential voltage waveform
a beam restrictive lead line device, prime use is to reduce the patients dose by restricting xray beam to the desired anatomy
collimator
