kV: radiographic technique

technique

systematic procedure to produce a high-quality radiograph

• includes the ability to select appropriate factors to produce an x-ray beam that will penetrate the body part

• provides the appropriate level of density and contrast on the image

factors that control density

• kilovoltage

• mAs

• distance

kilovoltage (kV)

the force that accelerates the electrons from cathode to anode

what is the energy/quality of the x-ray beam determined by?

the kV selected

wavelength

distance from one crest of the wave to the crest of the next wave

increase in kV will produce x-ray photons of ________ wavelength

shorter

increase in kV produces more x-ray photons having _________ energy levels

higher

kVp control factors

contrast and density

as kV increases, radiation reaching the image receptor _______ and will produce ______ density on the image

increases, more

TRUE or FALSE - kV produces more x-ray photons

FALSE

what allows more x-rays to penetrate the body part and produce increasing density of the image?

increase in energy

fifteen percent rule - increase in kV by 15%

results in doubling the amount of overall density on the image

fifteen percent rule - decrease in kV by 15%

reduces the overall density of the image by ½

when is the 15% rule used?

used when changes in kV are necessary to control the amount of exposure to the image

what must be adequate to penetrate the body part?

the selected kV

what does penetration of the part mean?

x-ray photons have sufficient energy to pass through the part and emerge as remnant radiation

TRUE or FALSE - kV is the primary choice for controlling density on the image

FALSE

what is kV selected based on?

average body part thickness

TRUE or FALSE - selection above 60kV is adequate for part penetration

TRUE

what is a factor in the production of scatter radiation?

kV

what happens as x-ray photons strike the body part with higher kVs?

x-ray photons undergo a change in direction

higher kV leads to _______ scatter radiation and _______ fog on image

increased, increased

what does lower kV lead to?

not enough penetration and most of the radiation is absorbed by the patient

what is kV primarily used to control?

radiographic contrast