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