Lecture 4 (Chapter 1-2) History and Properties of the X-rays Flashcards
Fluorescence
An emission of light by a substance exposed to various kinds of stimuli
Photographic Effect
We can produce the latent image into a visible image
Penetrating and Invisible
Can penetrate matter and cannot be seen
Ionizing
Ability to alter atoms of matter by removing an electron from an atom. Can have biological effects (cell damage or death)
Electrically Neutral
Not affected by magnetic or electric fields
Who created the first x-ray in 1895?
Dr. Wilhelm Conrad Roentgen
Atoms
smallest particle of an element that retains the properties of the element.
The nucleus of the atom contains _____ and ____ subatomic particles
protons, neutrons
Radiation
Process by which energy wavelengths in the form of heat, light or rays are sent out of atoms and molecules as they undero internal change
X-rays are produced…?
produced when fast moving electrons experience sudden change in direction and/or speed
Begin at Cathode»_space; Anode»_space;
Anode
A metal target
_____% of energy created is lost in the form of heat.
99
Cathode
Negative electrode that has a filament coil of tungsten wire and mounted in a focusing cup made of molybdenum.
Thermionic emission
The boiling off of electrons (then ‘hang out’ in a cloud around the filament)
Label tubehead (p15)
Cathode=purple C-shape
Anode= green made of tungsten (embedded with copper)
Which metals used in conjunction with the anode?
made up tungsten and embedded in copper
When x-rays come from anode and leave and exit the tubehead, they pass through _____.
Aluminum disks
X-rays with _______ wavelengths are best to get a good image. They will have a higher _______.
shorter; frequency
Frequency
Refers to the # of wavelengths that pass a given point in a certain amount of time.
Wavelength
Defined as the distance between the crest of one wave and the crest of the next.
Filter
Controls the % of x-rays escaping through tubehead; Aluminum disks .5mm thick placed at the opening for x-ray escape; filters low energy, less penetrating, longer wavelength x-rays.
By law, >70 kVp eed a minimum of ____ of aluminum filter
2.5mm
By law, <70 kVp need a minimum of ____ of aluminum filter
1.5mm
Tube Head Housing
Glass envelope surrounding a vacuum; outer housing is metal (decrease leakage)
Oil
Between glass envelope and metal; helps absorb heat from x-ray production
Collimator
Helps limit patient exposure; Restricts the size and shape of beam; fits directly over the opening of the metal housing, where the x-rays exit.
Two types of collimators (can be round or rectangular)
Primary and secondary
The primary collimator is made up of a _______ with a small opening
lead
Beam size at the patient’s face can be no larger than _____.
2.75 inches
Secondary collimator is made up of a _____ lined cylinder and directs the beam to the desired area. (Restricts radiation even more)
lead
Rectangular collimation exposes approx. ____ less of a patient’s face per film.
60%-70%
Activation Switch
Preset; maintains function only with continuous pressure.
X-rays travel in two forms. They travel in _____ and ____radiation.
wavelength (what we use in clinic); particulate
Particulate radiation
Beta particles, Cathode rays, Alpha particles
X-ray photon
An x-ray as a bundle of energy
Wave radiation
A grouping or form of traveling radiation. Without mass, travel in oscillating electric and magnetic fields. Termed “electromagnetic radiation”
Electromagnetic radiation
A type of wave radiation
Rank where x-rays fall on the wavelength spectrum from high frequency (short wavelengths) to low frequency.
gamma rays > X-rays > UV > Visible light > Infrared > Microwave > Radio.
It takes ____ energy to knock an electron that is close to the nucleus compared to an electron farther away from the nucleus.
more
Two types of wave radiation
Bremsstrahlung and Characteristic
Bremsstrahlung Production occurs…
as the electron approaches the tungsten target at the anode, the (-) charged electron approachese a (+) charged nucleus. The electron gets deflected from its path and loses kinetic energy.
Bremsstrahlung Production- the deflected electron loses _____ energy. (Brems = braking; NO COLLISION) It goes near nucleus but there is no collision
kinetic
Characteristic Radiation Production (DOES HAVE COLLISION) It collides with inner shell electron
Incoming electron has high energy. It’s strong enough to whack electron from the inner orbital shell —- so the (e) is displaced. vacancy in the shell is filled by an (e) from an outer shell and so on…..
The x-ray energy produced is characteristic to the energy the (e) had when it was in it’s shell
______ radiation comprises ~80% of Diagnostic radiation
Bremsstrahlung radiation
______radiation comprises ~20% of Diagnostic radiation
Characteristic radiation
Characteristic Radiation Production (DOES HAVE COLLISION) It collides with inner shell electron
Incoming electron has high energy. It’s strong enough to whack electron from the inner orbital shell —- so the (e) is displaced. vacancy in the shell is filled by an (e) from an outer shell and so on…. The “energy” left over from the electron falling into the next shell is emitted as the radiation.
______radiation comprises ~20% of Diagnostic radiation
Characteristic radiation
Velocity = _____
speed
Wavelength is measured in _____ / _____
nanometers; meters
Ionization - causes a (-) charged electron and a (+) charged atom to form an ______.
Atoms losing electrons are called + ions
ion pair
Atoms losing electrons are called _____
(+) ions
In ionization, the (+) ions usually return to a ______ state.
stable
Step Down Transformer (operates 1st)
warms filament, < the voltage between 3-5 volts; controls the number of (e) being produced
Kilovolt (kV)
measure of electrical potential-is equal to 1000 volts
Kilovolt peak (kvp)
measure of maximum electrical potential in kv across an x-ray tube
Two types of currents and what each does
Alternating current-flow of (e) in 2 directions; Direct current- flow of (e) in one direction
Step Up Transformer (operates 2nd)
> the potential of the line current; steps up 220 volts to several thousand volts or kiloolts; steps up usually to 50-100 kv
1 kilovolt = _______
1000 volts
The kvP adjusts the _____ of the beam for better/worse images
quality
Milliampere (mA)
Determines the # of electrons available; measures the current; usually 10-15 mA; usually linked and inversely related with time
Milliampere (mA) = _______ampre
1/1000 ampre
Thermionic emission
electrons are boiled off…
The more mA, the more thermionic emission, the more free electrons, the more # x-rays; Basically it is related to ________
Quantity
mA boils off or excites the (e) and results in more ______
quantity
kvP controls the force of these (e) bombarding the target; results in ________of the image.
quality
The process of dental x-ray production (8 steps)
- Electricity from the wall outlet supplies the power to generate x-rays. When x-ray machine turned on, current enters the control panel and travels to tubehead through the wires in the extension arm.
2.
