xray production Flashcards
x rays are a form of —
radiation
what is radiation
energy in transit
forms of radiation
- particulate (corpuscular) radiation
2. electromagnetic radiation–x rays
particulate radiation
- subatomic particles that carry energy in the form of kinetic energy of mass in motion
ex: alpha particles, electrons, beta particles, protons, and neutrons
alpha particles=
2 protons + 2 neutrons
tritium
naturally occurring radioactive form of hydrogen
found in groundwater
electromagnetic radiation
energy carried by oscillating electric and magnetic fields traveling through space at the speed of light
x rays are carried by oscillating electric and magnetic fields but the trajectory of x rays is _____
straight
examples of electromagnetic radiation
x rays gamma rays UV light visible light radio and microwaves
properties of x rays
- invisible, no charge, no mass
- straight lines
- diverge over distance like a beam of light
- travel at speed of light
- wide range of wavelengths (0.01-0.05 nm)
- bc of short wavelengths and higher energy, can penetrate materials that absorb light
greater the energy, the more readily xrays —
penetrate matter
x ray absorption depends on ?
atomic structure and density of the matter and energy of xrays
frequency
number of waves passing a particular point in a unit time
low energy xray
longer wavelength
lower frequency
high energy xray
shorter wavelength
higher frequency
wavelength and frequency are —-
inversely proportional
max speed of electromagnetic radiation
speed of light
in some situations, electromag radiation behaves like—- while in others it behaves like —-
waves or units of energy (photons)
number of orbital electrons
2(n)^2
binding energy
amount of energy required to remove an electron from its shell
-greatest in inner most shell and in atoms with higher atomic numbers
binding energy is a —- energy
negative
atomic number
number of protons in the nucleus
mass number
total number of protons and neutrons in the nucleus
ionization
formation of positive and negative ions by the removal of an electron from an electronically neutral atom
-elicits chemical changes in matter
components of x ray tube
- cathode – negatively charged; tungsten and metal focusing cup
- anode– positively charged; tungsten target insert and surrounding copper block
how are xrays produced?
when high speed electrons are suddenly decelerated or brought to a stop
-some of their kinetic energy is converted into electromagnetic radiation
conditions necessary to make an x ray
- generation of electrons
- production of high speed electrons
- focusing of electrons on tungsten target
- sudden stop of high speed electrons
what is the source of electrons?
filament from the cathode (heat)
what is the filament made of?
tungsten
thermionic emission
filament current (low voltage) heats tungsten filament to incandescent with resultant separation of electrons
the _____ setting heats the filament
milliampere (mA) and controls the quantity of electrons produced
the ____ setting creates the voltage across the x-ray tube and therefore controls the speed of electrons
kV (kilovoltage)
production of high speed electrons
- potential difference made bw the cathode and anode by kV
- electrons that surround the filament are accelerated toward the anode at 1/2 speed of light
focal spot
where the electron beam is focused on the anode target and is the source of x rays
focusing cup
small metal thing that helps focus the beam on the focal spot
what happens when the electrons strike the tungsten target?
- electron stream is stopped
- kinetic energy is converted to 99% heat and 1% rays
bremsstrahlung radiation
- interaction with nuclei of target atoms
- makes up most of x ray beam
- closer electron gets to nucleus the higher energy of radiation
- kinetic energy turned into x ray energy
characteristic radiation
- interaction with electrons of target atoms
- energy is the difference between 2 shells
most x rays are of — origin
bremsstrahlung
current x ray exposure time
0.32 sec
