Final Exam Mock Practice

The measure of electric current is

amperes

another term for electromotive force (emf) is

voltage

an expression of the potential to do work is

voltage

flow of electrons along a conductor is known as

amperes

_____ describes a resistance to current flow

ohms

Equation for inverse square law with mR and SID

I₂ = I₁ (SID₁ / SID₂ )²

HVL is affected by the amount of:

1. kVp

2. beam filtration

3. tissue density

1 & 2 only

tissue of ____ atomic number attenuates more of the x-ray beam than tissue of ____ atomic number

higher;lower

inner-shell (k-shell) binding energy of Tungsten atom is 69 keV

true

Bremsstrahlung interactions result in ionization: true or false

false

(electron is slowed down by nucleus, causing it to lose kinetic energy which is emitted as x-ray photon)

T/F: isotopes are atoms of the same element that have the same number of protons, but a different number of neutrons

true

An increased number of photoelectric interactions in the body may occur due to:

1. Introduction of material with high Z number

2. Introduction of material with low Z number

3. Body tissue with high mass density

4. Body tissue with low mass density

1 & 3 only

How many half-value layers will it take to reduce an x-ray beam of 100 R/min intensity, to under 30 R/min intensity?

2

100% ripple in the x-ray system/circuit means that:

 1. The potential for x-ray production remains at 100% of the kVp selected

 2. The potential for x-ray production fluctuates from 0% to 100% of the kVp selected

 3. The x-ray system is very efficient

 4. The x-ray system is operating at 100%

The potential for x-ray production fluctuates from 0% to 100% of the kVp selected

Which of the following happens last in the following events leading to x-ray production?

1. High amperage is delivered to the filaments

2. Alternating current is delivered to the autotransformer

3. Voltage passes through the secondary side of the filament transformer

4. The kVp meter monitors voltage

1. High amperage is delivered to the filaments

Which of the following is/are components of the filament circuit?

1. Rheostat

2. Filament transformer

3. mA meter

1 & 2 only

The autotransformer (choose all that apply)

 

1. Uses mutual-induction

2. Uses self-induction 

3. Is a single coil of wire

4. Provides energy to both the step-up and step-down transformer

5. Provides energy only to the step-up transformer

2, 3, & 4

A high-frequency generator _________

delivers alternating current (AC) at up to 25,000 Hz

A transformer with 100 turns on the primary side and 50 turns on the secondary side (select as many as apply):

1. Is a step-up transformer 

2. Is a step-down transformer 

3. Is a transformer that works on self-induction

4. Will have 100 times the current on the secondary side

5. Increases current

6. Increases voltage

2 & 5 only

Solid-state diodes in the rectification system help __________.

convert AC to DC

T/F: solenoid is current carrying coil of wire

true

Voltage ripple associated with three-phase, 12-pulse rectified generator is about ____

4%

Amperage in the x-ray circuit is increased at the _____ ______

filament transformer/circuit

The electron cloud within the x-ray tube is the product of a process called _____ ______

thermionic emission

Which of the following will serve to increase the effective energy of the x-ray beam?

1. Increase in added filtration

2. Increase in kV

3. Increase in mA

1 & 2 only

Design characteristics of x-ray tube targets that determine heat load capacity include:

1. the rotation of the anode

2. the diameter of the anode

3. the angle of the anode

1, 2, and 3

Which of the following happens first in the events leading to x-ray production?

1. AC is delivered to the step-down transformer 

2. The kVp meter monitors voltage

3. AC is delivered to the step-up transformer

4. A positive charge is placed on the anode

2. the kVp meter monitors voltage

Which of the following happens last in the events leading to x-ray production?

1. The kVp meter monitors voltage

2. The solid-state diodes convert AC to DC

3. A space charge is created

4. Self-induction increases/decreases voltage slightly

3. A space charge is created

T/F: coherent scattering results in ionization

false

T/F: x-rays behave more like waves than particles

false

(more like particles than waves)

What is the maximum number of electrons the O shell can hold if it is not the outermost shell of an atom?

50

As wavelength increases, frequency _______.

decreases

What is the velocity of a baseball if it travels 30 meters in 2 seconds?

15 m/s

velocity definition

distance / time

Select all of the following types of electromagnetic energy that travel at the speed of light:

1. Ultrasound

2. Visible light

3. Ultraviolet light

4. X-rays

2, 3, and 4

T/F: x-rays can only travel in straight lines

true

What is this an image of

flux lines

The closer an incident electron comes to a Tungsten atom nucleus, the ___________ the Brems x-ray produced.

stronger

The majority (highest quantity) of brems x-rays produced occurs at about ______ of the kVp used.

1/3

As kVp increases ___________ (select all that apply).

1. transmission increases

2. quality of x-rays increases 

3. quantity of x-rays increases

4. quantity of x-ray decreases

1, 2, and 3

Smaller anode angles will result in a _________ effective focal spot size

smaller

spatial resolution

ability to see small objects on an image (like trabeculae)

T/F: The rotor and stator of the x-ray tube operate on mutual induction.

true

T/F: The difference in x-ray strength between the anode and cathode sides can vary by approx. 15%.

false

(much greater than 15)

spatial frequency

expression of spatial resolution in line pairs per millimeter

objects with high spatial frequency, it is a ____ object that is ____ to image

small; difficult

objects with low spatial frequency, it is a _____ object that is _____ to image

large; easier

MTF

how good the system is at accurately representing an object (size & shape)

MTF = 1 means

perfect representation of what was images

(not possible in today’s world)

T/F: Digital radiography has a high MTF closer to 1

true

Contrast resolution

ability to distinguish between different shades of gray (from black to white)

Dynamic range/ exposure lattitude

how many shades of gray a system is capable of

T/F: digital imaging has a much wider range of contrast than screen film

true

Signal to Noise Ratio (SNR)

how much useful info we have compared to just noise

high SNR is best

T/F: Filament current may be described as the movement of a quantity of electrons (through the application of
kVp) from cathode to anode.

false

(tube current)

T/F: SI unit for mass is the kg

true

T/F: The nickel focusing cup of the cathode has a negative charge placed on it.

true

Detective Quantum Efficiency (DQE)

• way of expressing how good x-ray plate will be good at detecting x-rays

• thickness & composition of capture layer helps determine DQE

T/F: lower DQE = less dose needed

false

(higher)

The effect shown in the image is referred to as ______

characteristic cascade

Match these elements, concepts, materials, or terms:

1. Tungsten-thorium

2. Secondary circuit

3. copper

a. rectifier bank

b. anode stem

c. filaments

d. autotransformer

e. focusing cup

1. c

2. a

3. b

opposing voltage created in a conductor by passing alternating current through it describes

self induction

T/F: line focus principle says that the intensity of x-rays is higher on the cathode side of the x-ray beam

false

(anode heel effect)

Which of the following happens first in the events leading to x-ray production?

1. The mA meter monitors current

2. The rectifer bank converts AC to DC

3. The rheostat adjusts current and resistance

4. 120-240 V of AC is delivered to the autotransformer

4. 120-240 V of AC is delivered to the autotransformer

Which of the following is/are components of the secondary, or high voltage, side of the x-ray circuit?

1. Rectification system

2. Filament transformer

3. mA meter

1, 2, & 3

The compton interaction results in:

1. an ejected outer shell electron

2. ejected inner shell electron

3. scattered photon

4. increased/high image contrast

1 & 3 only

The Compton interaction:

1. Can pose a safety hazard to personnel

2. Can produce excessive fog on the image

3. Depends on atomic number

4. Depends on x-ray quality (energy)

1, 2, 4

T/F: Compton interactions are just as likely to happen in bone as they are in soft tissue.

true

The photoelectric effect results in:

1. An ejected outer-shell electron

2. An ejected inner-shell electron

3. A scattered photon

4. Total absorption of the incoming photon

2 & 4

T/F: As kVp increases, Compton interactions are more likely than photoelectric interactions.

true

T/F: As mass density increases, the probability of both Compton and photoelectric interactions increases.

true

Attenuation of x-ray photons can be influenced by:

1. Pathology

2. Atomic number of body tissues

3. Mass density of body tissues

1, 2, 3

Differential absorption is the result of:

1. Compton scattering

2. Photoelectric effect

3. X-ray transmission

2 & 3

The differences between CR and DR include?

1. CR uses imaging plates (IPs)

2. CR has higher DQE and lower patient dose than direct radiography

3. CR images are displayed immediately

1 only

The main difference between direct-capture and indirect-capture DR is that:

direct capture has no scintillator/scintillation step

Direct digital radiography uses which of the following:

Amorphous selenium

Which of the following terms describes the percentage of a pixel that is sensitive to x-rays?

fill factor

Spatial resolution in digital imaging can be improved by:

1. Removing the step of scintillation

2. Decreasing pixel pitch

3. Decreasing matrix size

1 & 2

As matrix size increases, pixel size:

decrease

T/F: Amorphous selenium converts x-ray energy directly to an electronic signal.

true

In computed radiography (CR), the reader contains a laser that:

1. Stimulates the PSP to release trapped x-ray energy

2. Detects the light emitted at the PSP

3. Converts an analog signal to an electronic signal

4. Traps the energy due to x-ray ray exposure at the PSP

5. A reader is not used with CR

1: Stimulates the PSP to release trapped x-ray energy

As the size/diameter of the CR laser decreases:

spatial resolution increases

contrast resolution increases

Which of the following are used alongside barium fluorohalide (BsFl) to capture the latent image in CR?

europium

CCDs are used in indirect DR to:

1. Store the latent image

2. Capture incident x-ray energy

3. Couple the cesium iodide phosphor to the light collecting element

4. Convert light from a scintillator to electrons/electronic signal

5. CCDs are not used with indirect DR

4

Spatial resolution can be improved by/with:

1. Increased collimation

2. Decreased focal spot size

3. Smaller anode angles

2 & 3

Spatial resolution can be influenced (inversely and/or directly) by which of the following?

1. OID

2. Part motion

3. SID

1, 2, 3

Factors impacting spatial resolution (inversely and/or directly) in indirect digital/CR imaging include:

1. Pixel pitch

2. Sampling frequency

3. DEL size of the TFT

1, 2, 3

Which of the following terms/units is used to express the resolution of a digital diagnostic image?

Line pairs per millimeter (LP/mm)

Which of the following components is/are part of the gantry of a CT imaging system?

1. X-ray tube

2. Detector array

3. Control panel/computer

1 & 2 only

________ quantifies how well an imaging system can reproduce the details (spatial frequencies and contrast) of an object in the image.

modulation transfer function (MTF)

The term pixel is associated with all of the following, except:

1. two dimensional (2D)

2. picture element

3. measured in x and y directions only

4. how much of the part is included in the field of view (FOV)/light field

4

The term voxel is associated with all of the following, except:

1. two dimensional (2D)

2. volume element

3. measured in x, y, and z directions

4. computed tomography

2D

As FOV decreases:

1. The amount of tissue exposure decreases

2. DAP decreases

3. Beam intensity increases

1 & 2 only

T/F: Magnification mode in image-intensified fluoroscopy can increase patient dose.

true

In which of the following ways does SID affect spatial resolution?

1. Spatial resolution is directly related to SID

2. Spatial resolution is inversely related to SID

3. As SID increases, spatial resolution decreases

4. SID is not a resolution factor

1. Spatial resolution is directly related to SID

shape and/or size distortion may result from: 

1. misalignment of part and IR

2. misalignment of IR and CR

3. CR angle

4. perpendicular x-ray beam

5. OID

1, 2, 3, 5

T/F: A system with a high dynamic range can accurately represent both the subtle details and the extreme variations in density, resulting in high-quality images with excellent contrast and detail.

true

T/F: Classical scattering is the main cause of fog on an image.

false

(compton scattering)

In indirect digital imaging, electronic signals are converted by the analog to digital converter (ADC).

true

Histograms:

1. are used to measure patient dose during radiographic examinations

2. are graphical representations of image brightness levels and distribution

3. are used to calibrate X-ray machines for optimal image quality

4. help in determining the appropriate exposure factors for radiographic imaging

2