Rad 141 Midterm Quizzes
This interaction occurs when projectile electrons interact with orbital electrons
Characteristic
Exposure rate is measured in __________
R/s
Total radiation exposure is measured in _________
Roentgens
in a graph, the ________ line is represented by the y-axis
Vertical
List the 3 main components of the x-ray tube
anode, cathode, glass envelope
A change in factor A causes an exactly identical change in factor B
directly proportional
One or the other variable is squared and cubed; a small change in one variable will cause a bigger change in the other factor
exponentially proportional
When using a digital imaging system, how can you tell if the proper exposure was made?
exposure indicator
What is one way to increase the signal portion of the SNR?
increase mAs
Which of the following is NOT a cause of shape distortion?
increased kVp
Of the 4 fundamental forces, which is responsible for holding protons and neutrons within the nucleus
the strong nuclear force
What is one way to reduce the noise portion of the SNR?
use a grid
convert 57 milliseconds to seconds
.057
100 mA x ______ seconds= 20 mAs
.2
convert 1/5 into a decimal
.2
What are the 3 requirements for x-ray production
1. source free of electrons 2. made up of accelerating electrons 3. made up of decelerating electrons
An x-ray beam spectrum resembles a bell curve but has a more lopsided bell appearance. When the spectrum is cut in half, the average kilovolts is actually _____ of the maximum kilovoltage used.
1/3
An x-ray is taken using 50 mAs and 88 kVp. The exposure to the IR was sufficient, but the image was over penetrated. In order to reduce penetration but maintain the IR exposure, what new technical factors should be used?
100 mAs
(2.1 X 10 ^5) X (5.4 X 10^-2)
11.34 X 10^3
What is 15% of 90
13.5
200 mA x 0.01 seconds= ______ mAs
2
How many filaments are there on modern x-ray tubes
2
By using the 15% rule to decrease patient dose, the overall patient exposure will be reduced to ______ of the original exposure
2/3
_____ mA x 0.125 seconds = 25 mAs
200
convert 0.024 seconds to milliseconds
24
convert 0.28 into a percentage
28%
A radiographic image is taken at 40" SID and has on SOD of 30". What would the magnification factor be?
33%
What would the SOD be for image taken at 40" SID with an OID of 4"?
36
A 15% increase in kVp alone will increase the quantity of x-rays produced about _____%
40%
Convert to scientific notation 0.000004mm=
4X 10 -6
100 mAs change to _____ mAs 80 kVp 92 kVp
50
During x-ray production_____% is heat and ______% is useful radiation
99.5%, 0.5%
X-rays are best measured using which of the following units?
Angstrom
On an x-ray spectrum, this interaction is represented by a lopsided bell curve
Bremsstrahlung
THis interaction occurs when projectile electrons interact with the nucleus of an atom
Bremsstrahlung
This interaction is a german word meaning "braking"
Bremsstrahlung
This interaction is responsible for producing heterogeneous radiation, or a wide range of energies
Bremsstrahlung
This interaction is responsible for subject contrast
Bremsstrahlung
Which of the following is NOT directly controled by mAs A. quantity of x-rays produced B. IR exposure C. Quality of x-rays produced D. Intensity of x-ray beam
C Quality of x-rays produced
On an x-ray spectrum, this interaction is represented by specific energies as represented by vertical lines
Characteristic
The energy of a photon created by this interaction is dependent upon the binding energy of orbital electrons
Characteristic
This interaction is responsible for producing homogenous radiation , or discreet energies
Characteristic
which of the following is NOT a change that can occur to matter A. heating B. condensation C. Freezing D. All are correct
D
An increase/decrease in variable A causes increase/decrease in factor B, but doesn't specify if it's direct or exponential
Directly related
Which of the following is an example of how heat is transferred in an x-ray tube through radiation?
Emitted as light and x-rays
When changing mA and time combinations, in order to maintain exposure, if you double mA what must be done to the exposure time?
Exposure time is halved
What is the purpose of the focusing cup
Focus electrons toward the focal track
Which of the following is an example of how heat is transferred in an x-ray tube through
Heat travels away from the anode down a metal shank
Which of the following is an example of how heat is transferred in an x-ray tube through convection?
Heated oil is mixed with cooled oil
Which of the following types of contrast is said to be optimum contrast?
Intermediate
If an x-ray is produced due to an orbital electron being knocked from its shell, which shell would produce an x-ray with the greatest energy?
K shell
What is the correct order of operations for math?
Parenthesis, exponents, multiply/divide, add/subtract
The interaction that is responsible for most of the x-ray beam
bremsstrahlung
This interaction is responsible for the polyenergetic nature of the x-ray beam
bremsstrahlung
Which of the following is NOT a type of noise in a digital image?
brightness
The negative side of the x-ray is called the _______ and the positive side is called the __________
cathode, anode
_____________ is the difference between the brightness of two adjacent details.
contrast
Of the 4 fundamental forces, which includes all electrical and magnetic phenomena?
electromagtism
_______ is the ability to cause a change in the motion or state of an object.
energy
What happens to the exposure if only the mA is decreased and exposure time remains the same
exposure is decreased
True or false If an image is under penetrated, the quality of the final image can be improved by increasing
false
x-rays are produced at the
focal spot
what is the specific area on the anode called where electrons strike
focal track
The filaments are embedded in the
focusing cup
_________ is an example of a non-conserved quantity
force
What are the terms used to describe when an image is larger than the size of the actual object?
foreshortening and elongation
Of the 4 fundamental forces, which is the weakest of all forces
gravity
______________ is the radiographic opposite of image contrast.
gray scale
_________ is the flow of internal energy from one object or molecule to another
heat
What is the best kVp/mAs combination to provide quality radiographer images while limiting patient dose
high kVp/ low mAs
What happens to the amount of electrons boiled off during thermionic emission when the mA is increased
increases
two variable change by exactly the same magnitude but in opposite directions
inversely proportional
What is the generic unit of energy?
joule
________ primarily controls the quality and penetration of the beam
kVp
_________ is a measure of electrical force or pressure behind a current of electricity which causes it to flow
kilovoltage
USing the example of a book dropping onto a desk, _________ energy is converted into _________ energy
kinetic, potential
Which of the following has a greater influence on the amount of scatter produced than kVp
large body part and large field size
A long gray scale means the image has __________ contrast.
low
________ is a measure of the quantity of electrical current flowing through a circuit.
mA
What controls the number of electrons that are boiled off?
mA station
Which of the following are reasons that quantum noise may be present on an image?
mAs too low, kVp too low, Rectifier failure
What material is the anode made of?
molybdenum
___________ is the term used to describe the partial shadow projected by an object, or the blurriness around the edges.
penumbra
A _____________ ____________ is present when 2 points in a conductor have opposite charges
potential difference
What is the most important function of kVp
provide at least partial penetration through all body parts
_____________ ___________ is a result of underexposure to the IR and appears as brightness fluctuations across the image
quantum mottle
what are the 3 normal states of matter
solid, liquid, gas
WHat is formed after electrons are boiled off the filament
space charge
__________________ is the sharpness of the structural edges recorded in the image.
spatial resolution
Of the 4 fundamental forces, which is an example of the natural radioactivity discovered by
the weak nuclear force
What is the process called when the filament is heated to the point of incandescence and electrons are liberated?
thermionic emission
What material is the filament made of?
thorium impregnanted tungsten
What are the 3 base quantities of all unit measurements?
time, length, mass
What material is the focal track made of?
tungsten-rhenium alloy
____________ is the term used to describe the pure shadow projected by an object, no blur.
umbra
What is applied to the x-ray tube to accelerate the electrons?
voltage
solve for X: X/5 = 20/4
x=25