Test 2 - Chpt 6 & 11 Flashcards
Two interactions that occur in the tungsten target
Characteristic
Bremsstrahlung
How does heat production occur
When the electrons interact with the outer shell electrons of the tungsten target they cause excitation which causes excess energy to give off as infrared radiation (heat)
Characteristic Interactions
Filament electrons enters a target atom and strikes an orbital electron
How does characteristic interactions create photons?
If k shell electron is removed from orbit then an electron from the L shell drops to fill the vacancy. It does this by expending some of its PE which is given off as a photon
What shell is most likely to fill an inner shell
Adjacent shell
For characteristic photons, energy is dependent on the difference of what?
Of the binding energy between the shells involved
Characteristic photon is named for the what?
For the shell being filled in each case
K characteristic = L electron filled a K vacancy
How to find the energy of a characteristic photon
Binding energy of the farther shell is subtracted from that of the closer shell
(Inner shell - outer shell = photon energy)
What must happen for an orbital electron to be removed
Filament electron must have KE equal to or greater than the binding energy of the electron with which it interacts
When the filament electron misses all of the orbital electrons and interacts with the nucleus of the atom
Bremsstrahlung interaction
How is a brems photon created?
When the filament electron slows down and changes direction because of the attraction to the nucleus it loses KE which is released as a photon
How to find the energy of a brems photon
By subtracting the energy that the filament leaves the atom from the energy it had when entering
Why are most of the photons produced brems photons?
- only k shells provide enough energy
- orbital electrons are in constant motion so easy to miss
Where is added filtration placed?
Between the target window and the top of the collimator
Total number of x-ray photons in a beam
Beam quantity
What is associated with beam quantity
Radiation dose
Intensity of a beam is inversely proportional to the square of the distance
Inverse square law
What absorbs low energy photons that do not contribute to the image
Filtration
What is beam quality?
The penetrating power of the x-ray beam
What creates the dark shades of the image?
Photons that reach the image receptor 
What creates the white or clear areas of the image?
Areas where no photons reach the image receptor
The thickness of absorbing material necessary to reduce the energy of the beam to 1/2 its original intensity
Half value layer, HVL
What is the normal HVL of diagnostic beams
3-5 mm Al
The beam that exits the collimator and exposes the patient?
Primary beam
Beam that remains after interaction with the patient and is exiting the patient to expose the IR
Remnant beam
What is formed within the patient due to interactions with matter/tissue?
Secondary photons
For the emission spectrum graph what indicates a change in quantity
Y axis (number of x-rays)
For the emission spectrum graph what indicates a change in the quality
X axis (x-ray energy)
What five factors change the appearance of the x-ray emission spectrum
mA, kVp, tube filtration, generator type, and target material
If you decrease the quantity, what happens to the amplitude of the graph?
It decreases
If you increase mA what happens to the amplitude of both the continuous and discrete portions of the spectrum
Increases amplitude
If you increase kVp, what happens to the amplitude of both continuous and discrete portions of the spectrum in what way does it shift?
Amplitude increases
Shift, right