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What are the necessary items for the production of X-rays in the tube?
Source, Force (accelerator), Decelerator
What is the source for the production of X-rays in the tube?
Electrons from filament or cathode (negative) (mA or mAs)
What is the force (accelerator) for the production of X-rays in the tube?
kVp, energy behind the mA or mAs
What is the decelerator for the production of X-rays in the tube?
Anode (positive); something to smash into to create the X-rays
Electrons have _______ energy. (Energy in motion)
So what is the process of using the machine and turning it on?
The technologist sets up the amperage (mA), time (ms) and voltage (kVp), then hits the rotor, then depress the exposure switch, and then the x-ray production occurs from two interactions in the anode.
What happens when you hit the rotor?
Electricity flows through the circuit, Electrons flow to the filament (waiting for exposure), and the anode spins.
Electrons boil off the filament which causes thermionic emission and the electron cloud is space charge
What happens when you depress the exposure switch?
- More electricity flows through the circuit, This electricity pushes the electrons at the filament across to the anode, and then the X-rays are created through this interaction.
- Electrons move from the filament to the target which is the anode focal spot. When the x-rays are created the electron kinetic energy is 100% and the conversation for xray production is 99% (99.8) heat and 1% (0.2) x-rays.
What percentage is electron kinetic energy?
What is the percentage for the conversation for x-ray production?
99% (99.8) of the electrons kinetic energy is changed to heat and 1% (0.2) of the electrons kinetic energy is changed to x-rays
The boiled electrons travel at ____ the speed of light in the tube from the filament (cathode) to the target (anode).
Electricity moves from _____ to _____.
What happens in the target?
The projectile electrons coming from the filament are interacting with the atoms in the target.
What is the anode or target made out of?
What is the symbol for Tungsten?
What is the atomic number of Tungsten?
Characteristic radiation is when:
- Projectile electron collides with inner shell electron (k or L) of the target atom.
- Removes that electron from orbit and ionize the atom.
- Now a hole exists in the inner shell
- An electron from the next or outer shell will fall into its place
- As electron fills in the space, energy is given off in the form of an x-ray photon
- Now a new hole is in that shell, so the step happens again from the next outer shell, that electron fills the vacancy and another photon is created.
- This occurs until each shell is full; the outer most shell will be filled by some stray electron in the target.
- Each photon created has a specific energy level, equal to the difference between the binding energies of the two shell involved.
- Only photons created at the k-shell are strong enough for DX use.
- Since the photons created are specific or characteristic of the binding energies or atomic numbers of the atom involved or better said the target material, they are called characteristic x-rays.
- Characteristic x-rays are produced at about 70 kVp, but only in small number.
- Binding energies keeps the x-ray photon in place.