Radiographic Imaging and Exposure Chap 2 Quiz
By filtering the beam after it exits the tube, the result is:
-An increase in the overall average energy of the beam since the weaker x-rays were removed. - Less exposure to the patient without sacrificing image quality. -Removing the x-rays that probably would not be transmitted through the patient.
An exposure of 200 mA for .60 seconds at 88 kVp will produce _____ heat units when done on a high frequency(1.40) x-ray machine
14,784
The US Government states that all x-ray machines capable of 70 kVp or higher must have a total filtration of:
2.5 mm of aluminum or the equivalent
What value of mAs is produced when the radiographer sets a kilovoltage peak of 70 kVp, a milliamperage if 600 mA, and an exposure the of 50 ms?
30 mAs
How many heat units result from an exposure made on a single-phase x-ray unit using a beam current of 400 mA, and exposure time of 0.2 s, and a kilovoltage peak of 70 kVp?
5600 HU
What percentage of the kinetic energy is converted to heat when moving electrons strike the anode target?
99%
The anode heel effect is:
A consequence of the line focus principle that allows the heel of the anode to absorb some of the beam.
Which type of target interaction is responsible for most of the x-rays in the diagnostic beam?
Bremsstrahlung interaction
800 mA at .02 seconds will create the same mAs as 400 mA at 0.8 seconds
False
More than 99% of the electricity used to make an exposure contributes to the production of x-rays
False
The heat units produced by a single-phase machine can be computed by which equation?
Hu = mAs x kVp
To extend the life of the x-ray tube, it is recommended that you
Press down on the rotor button and while making the exposure as soon as possible
The space charge produced when you rotor up an x-ray tube is limited in size. This limting factor is known as
Space charge effect
The controlling factor for beam quality is kVp. However, kVp is also a controlling factor for beam quantity because when kVp is increased
Target interaction efficiency increases at the anode
The area on the target where most of the projectile electrons strike the target anode is known as
The actual focal spot
The two currents that pass through an x-ray tube are
The filament and the tube current.
By placing an angle on the target anode, we can have a larger actual focal spot and still maintain a smaller effective focal spot. This is also known as
The line focus principle.
Beam quantity refers to
The number of x-rays produced during the exposure process
The only part of the x-ray tube that is external to the housing and is used primarily to drive the rotor is
The stators
Thermionic emission takes place in the focusing cup of the x-ray tube
True
The intensity of the x-ray beam is greater on the ______.
cathode side of the tube
according to the line focus principle, as the target angle decreases, the ___
effective focal spot size decreases
Which x-ray tube component serves as a source of electrons for x-ray production?
filament
The most damaging single factor for a tube is
heat
Total filtration in the x-ray beam includes _______.
inherent filtration, added filtration
Which primary exposure factor influences both the quantity and the quality of x-ray photons?
kVp
On the x-ray emission spectrum, the energy of the x-ray beam is measured in
kilo Electron volts
The unit to express tube current is ____?
mA
The cloud of electrons that forms before x-ray production is referred to as ______?
space charge
Electrons interact with the ______________ to produce x-rays and heat.
target
The burning or boiling off of electrons at the cathode is referred to as ______?
thermionic emission
_________ extends x-ray tube life.
warming up the tube after two hours of non use
Increasing the kVp results in :___________.
x-rays with higher energy and more x-rays
