Read the Chart, Bestie
On a radiographic rating chart, this variable is found on the X-axis, while kVp is found on the Y-axis.
What is maximum exposure time?
Which type of x-ray production results when an outer-shell electron fills an inner-shell vacancy?
What is characteristic radiation?
Increasing this exposure factor increases the amplitude of the emission spectrum without changing its position.
What is mAs?
During an exposure, electrons travel from this side of the tube to this side.
X-rays are emitted ______________.
You locate your kVp and exposure time on a radiographic rating chart. Your point falls below the selected mA curve. Good news—this means the exposure is considered this.
I can produce x-ray photons with a range of energies rather than specific discrete energies, and I can occur at any diagnostic kVp. Who am I?
What is Bremsstrahlung radiation?
Unlike increasing mAs, increasing this technical factor causes both the quantity and quality of the x-ray beam to increase.
What is kVp?
Once voltage is applied across the x-ray tube, electrons accelerate from cathode to anode at approximately this speed.
What is 1/2 the speed of light?
Electrons bounce away from the intended focal spot and strike another area of the anode. Name this phenomenon AND give two negative effects it can produce.
What is off-focus radiation?
What is
My purpose is to determine how long you must wait for the anode to reach a desired heat level before making additional exposures.
What is the anode cooling chart?
A projectile electron completely loses its kinetic energy during a Bremsstrahlung interaction. If it began with 80 keV, what is the maximum possible energy of the resulting photon?
What is 80 keV?
Increasing this exposure factor causes the spectrum to increase in amplitude and extend farther to the right.
What is kVp?
A radiographer wants maximum recorded detail and selects 200 mA. This filament/focal spot should be used.
What is the small filament/small focal spot?
You're imaging anatomy with significantly different thicknesses across the field. Which side of the tube should be placed over the thicker anatomy?
What is the cathode side?
This number will be plugged into the HU formula when using a 3 phase or high frequency generator.
What is 1.4?
An exposure is made at 65 kVp using a tungsten target. Which of the two major x-ray production interactions accounts for the photons in the beam?
What is Bremsstrahlung only?
Added filtration preferentially removes these photons from the x-ray spectrum, decreases quantity while doing this to the average energy/quality of the remaining beam.
In this condition, increasing kVp initially increases tube current, but eventually all available electrons have been used and additional increases in kVp cannot increase the number of electrons crossing the tube.
What is saturation current?
Thanks to the line-focus principle, which is always smaller: the actual focal spot or the effective focal spot?
What is the effective focal spot?
A single-phase exposure produces 12,000 HU. If the exact same kVp, mA, and time are used on a high-frequency generator, how many HU will be produced?
What is 16,800 HU?
A tungsten K-shell vacancy is filled by an L-shell electron. If the K-shell binding energy is 69.5 keV and the L-shell binding energy is 12 keV, what is the energy of the resulting characteristic photon?
What is 57.5 keV?
Five factors affect the x-ray emission spectrum. Name at least three of them.
What are mAs, kVp, added filtration, target material, and generator phasing/voltage waveform.
Put these events in the correct order:
A. Electrons strike the focal spot
B. Thermionic emission occurs
C. Electrons accelerate across the tube
D. X-rays are produced
What is B, C, A, D?
Metal envelopes have a longer tube life than a glass envelope for this reason.
What is vaporized tungsten does not collect on the metal envelope, prolonging tube life and preventing electron arcing.