Chapter 3 Flashcards
What determines the energy and penetrating power of radiation?
wavelength
X-rays with shorter wavelengths are ___, have more ___ and more ___ power.
stronger; energy; penetrating
What is used to describe the mean energy and penetrating power of an x-ray beam?
quality
what is controlled by kilovoltage?
quality
what is a measurement of force that refers to the potential difference between two electrical charges?
voltage
If voltage is ___ , the ___ of electrons is increased.
increased; speed
T/F. Electrons strike targets with greater force and energy resulting in penetrating x-rays and short wavelengths.
true
1 kV = ___ volts
1000
T/F. The greater the kV, the less penetrating dental x-rays are. They use less energy and have longer wavelengths.
False, the greater the kV, the MORE penetrating dental x-rays are. They use MORE energy and have SHORTER wavelengths.
Today’s units use ___ - ___ kV.
60 - 70
What does 70 kVp mean?
the peak/maximum voltage is 70,000 volts of an alternating current (AC)
kV regulates ___ across the x-ray tube and controls the ___ of electrons.
voltage; speed
what is the overall darkness or blackness of an image.
density
high kV = ___ density = too ___
low kV = ___ density = too ___
high; dark
low; light
What refers to how sharply dark and light areas are differentiated or separated on an image?
contrast
high contrast = ___ kVp
low contrast = ___ kVp
low
high
What controls the length of exposures in impulses or seconds?
exposure time
60 impulses = ___ seconds
30 impulses = ___ seconds
15 impulses = ___ seconds
- 00
- 25
- 25
kV = quaLity and mA = quaNity
k-l-m-n
what measures the number of electrons flowing thru the cathode filament?
ampere
Increasing amperage ___ number of electrons traveling from cathode to anode.
increases
What controls the temperature of the cathode filament?
milliampere (mA)
What milliampere produces an excessive amount of heat?
> 15 mA, today’s units 6-8 mA
what controls the amount of current that flows through the cathode filament?
milliampere (mA)
The higher mA, the ___ the filament temperature and the ___ the number/quanity of electrons.
higher; greater
high mA = ___ density = too ___
low mA = ___ density = too ___
high; dark
low; light
Exposure time and mA are ___ related.
inversely
increase mA = decreases time
decrease mA = increase time
Define intensity.
quantity x quality / area x exposure rate
T/F. Increases in kV, mA, time and distance all increase intensity.
False, kV, mA, and time increase intensity. Distance DECREASES intensity
What is the inverse square law?
intensity of radiation is inversely proportional to the square of the distance from the source of radiation
if the distance is DOUBLED —- beam is ___ as intense
if the distance is HALVED —- beam is ___ as intense
If the distance is TRIPLED —- beam is ___ as intense
If the distance is QUADRUPLED —- beam is ___ as intense
1/4
4 times
1/9
1/16
If the PID length is changed from 8” to 16” (doubled) how is the intensity of the beam affected?
1/4 as intense
if the PID length is changed from 16” to 8” (halved), how is the intensity of the beam affected?
4 times as intense
The thickness of ___ placed in the path of the x-ray beam reduces the intensity by 1/2
aluminum
What does it mean if an x-ray beam with a half-value layer (hvl) of 2.7mm?
that a thickness of 2.7mm of aluminum is placed in the path of the beam to reduce the intensity by 1/2
Aluminum filters are place in the path of the beam to remove ___ energy x-rays.
low
