Foundations Midterm/Final

The nuclear force which holds electrons in “orbit” around an atom is called:

• gravity

• charge

• valence force

• binding energy

change from 2 mm Al filtration to 4 mm Al filtration

The curve shifts:

• right

• left

• remains the same

Scatter radiation is mostly a result of the Photoelectric interaction.

• true

• false

change from 2 mm Al filtration to 4 mm Al filtration

The discrete (characteristic) curve shifts:

• right

• left

• remains the same

change from high atomic number target material to low atomic number

The amplitude (height) of the emission spectrum curve would:

• increase

• decrease

• remain the same

change from 82 kVp to 72 kVp

The amplitude (height) of the emission spectrum curve would:

• decrease

• increase

• remain the same

As the atomic number of an element increases, the energy required to remove an inner shell electron _____________________.

• increases

• decreases

• is unchanged

change from high atomic number target material to low atomic number

Which of the following best demonstrates the emission spectrum graph shift?

Red curve = new curve

Black curve = original curve

• 

  a

• 

  b

• 

  c

• 

  d

The end product(s) of the photoelectric effect is/are:

• one ejected electron and an orbital vacancy

• one ejected electron only

• one scattered photon, one ejected electron, and an orbital vacancy

• one scattered photon only

• one orbital vacancy only

Which of the following is NOT an interaction between x-ray photons and matter?

• compton interaction

• photoelectric interaction

• brems interaction

• coherent interaction

The greatest amount of scatter is produced from the _____________________ interaction.

• coherent

• compton

• characteristic

• brems

An 80-kV photon undergoes a coherent scattering interaction with an orbital electron having a binding energy of 8 kV. What is the energy of the resulting scattered photon?

• 88 kV

• 8 kV

• 72 kV

• 80 kV

Filtration is the process of eliminating undesirable ____ by the insertion of absorbing materials into the primary beam.

• low energy x-ray photons

• high energy incident electrons

• high energy x-ray photons

• low energy incident electrons

change from high atomic number target material to low atomic number

The curve shifts:

• left

• right

• remains the same

If the number of protons within an atom’s nucleus is changed, which of the following must absolutely change:

• number of electrons

• element's name

• electrical charge

• number of neutrons

change from 82 kVp to 72 kVp

The curve shifts:

• left

• right

• remain the same

The partial absorption of the x-ray beam as it passes through the body is best referred as:

• absorption

• brems

• heterogeneity

• attenuation

change from 82 kVp to 72 kVp

Which of the following best demonstrates the emission spectrum graph shift?

Red curve = new curve

Black curve = original curve

• 

  a

• 

  b

• 

  c

• 

  d

change from high atomic number target material to low atomic number

The discrete (characteristic) curve shifts:

• left

• right

• remains the same

change from 2 mm Al filtration to 4 mm Al filtration.

Which of the following best demonstrates the emission spectrum graph shift?

Red curve = new curve

Black curve = original curve

• 

  a

• 

  b

• 

  c

• 

  d

If an incident x-ray photon ejects a k-shell electron with a binding energy of 37 keV, and the initial energy of the photon was 40 keV, the ejected electron leaves the atom with _____ keV of kinetic energy.

• 3

• 40

• 37

• 17

Brems is produced by:

• slowing down of an electron by the nucleus

• ionization from ejection of outer shell electron

• excitation and restabilization of an outer shell electron

• creation of a photoelectron

change from 82 kVp to 72 kVp

The discrete (characteristic) curve shifts:

• left

• right

• remain the same

In the diagnostic range, the majority of primary x-rays produced are:

• brems

• compton

• photoelectric

• characteristic

Radiation that turns 180 degrees in direction after interacting with matter is called:

• coherent

• backscatter

• brems

• characteristic

change from 2 mm Al filtration to 4 mm Al filtration

The amplitude (height) of the emission spectrum curve would:

• increase

• decrease

• remain the same

Distortion can be a misrepresentation of

• shape only

• size only

• detail

• shape and size

The difference between two adjacent shades of gray is:

• distortion

• subject contrast

• spatial resolution

• quantum mottle

Spatial resolution is improved when:

• SID decreases

• OID decreases

• SOD decreases

• OID increases

Foreshortening is present if:

• The image of the object is shorter than the object

• The image of the object is larger than the object

• the tube and IR are in alignment

• IR exposure is excessive

change from 20 mAs to 40 mAs

Which of the following best demonstrates the emission spectrum graph shift?

Red curve = new curve

Black curve = original curve

• 

  a

• 

  b

• 

  c

• 

  d

As tube angle increases, shape distortion will _________________.

• increase

• decrease

• remain unchanged

What can negatively impact spatial resolution?

• patient motion

• small focal spot

• minimal OID

• small detectors

change from 3 mm Al filtration to 5 mm Al filtration

Which of the following best demonstrates the emission spectrum graph shift?

Red curve = new curve

Black curve = original curve

• 

  a

• 

  b

• 

  c

• 

  d

Factors affecting spatial resolution include:

• focal spot size

• contrast scale

• kVp

• mAs

A good method for controlling motion when the patient is unable to cooperate is to:

• decrease kVp

• increase focal spot size

• maintaining mAs and decreasing exposure time

• maintaining mAs and decreasing mA

The effect of mAs upon IR exposure is:

• directly proportional

• inversely proportional

• dependent on kVp

Poor spatial resolution is caused by an unacceptable amount of

• umbra

• penumbra

• IR Exposure

• contrast

the unsharpness in an image is affected by all of the following except:

• focal spot size

• mAs

• SOD

• OID

The principal controlling technical factor of remnant beam contrast is

• mAs

• kVp

• focal spot size

• anode angle

As kVp increases, remnant beam contrast scale will _________________.

• lengthen

• shorten

• remain unchanged

An increase in x-ray beam filtration

• increases magnification

• increases the average photon energy of the beam

• decreases patient tissue density

• increases the quantity of photons in the beam

A radiograph with few shades of gray exhibits

• high contrast

• medium contrast

• low contrast

As kVp decreases, spatial resolution will _________________.

• increase

• decrease

• remain unchanged

As filtration increases, IR exposure will _________________.

• increase

• decrease

• remain unchanged

The principal controlling factor of radiographic image receptor exposure is:

• mAs

• kVp

• focal spot size

• tube angulation

With an SID of 40 inches, and an OID of 10 inches, what is the factor of magnification?

• 3x

• 4x

• 1.33x

• 0.25x

Electronic "snow" on a display monitor or TV monitor image is a form of:

• noise

• scatter

• distortion

• IR exposure

As mAs increases, remnant beam contrast scale will _________________.

• lengthen

• shorten

• remain unchanged

A change in kVp, as an exposure factor, affects

• average beam energy

• beam intensity/quantity

• the relative amount of scatter received on the IR

• all of the above

As mAs increases, IR exposure will _________________.

• increase

• decrease

• remain unchanged

As mAs increases, shape distortion will _________________.

• increase

• decrease

• remain unchanged

As SID increases, spatial resolution will _________________.

• increase

• decrease

• remain unchanged

As focal spot size increases, spatial resolution will _______________.

• increase

• decrease

• remain unchanged

The brightness of the image on a viewing monitor is the result of

• tissue thickness

• IR exposure only

• monitor's brightness settings

• tissue density

What should you expect to occur with a decrease in kVp?

• lower contrast

• longer scale of contrast

• more fog/scatter seen on IR

• more photoelectric interactions

Insufficient mAs is likely to contribute to ___ in the image.

• quantum mottle

• motion

• high spatial resolution

• excessive OID

As OID increases, size distortion will _________________.

• increase

• decrease

• remain unchanged

If the signal is 16 and the noise is 4 on a hypothetical radiographic image, what is the Signal to Noise ratio?

• 8

• 12

• 4

• 0.24

Which of the following is equivalent to low penumbra?

• high sharpness/spatial resolution

• low sharpness/spatial resolution

• low distortion

• high magnification

Penumbra decreases as

• SID increases

• OID decreases

• focal spot decreases

• all of the above

If the mA is set at 300 and the total mAs produced is 15 mAs, the exposure time must be:

• 0.5 sec

• 0.05 sec

• 0.2 sec

• 2 sec

Size distortion in radiography can be ___ only.

• magnification

• foreshortening

• elongation

• minimization

What factor influences the average energy of photons reaching the IR?

• mAs

• kVp

• mA

• focal spot size

what is the purpose of a grid

• to absorb low energy photons before they reach the IR

• to absorb scatter before it reaches IR

• to reflect scatter away from IR

• to absorb primary radiation before it reaches IR

grid cut off is due to the absorption of

• scatter radiation

• remnant radiation

• primary radiation

• secondary radiation

What is the grid radius based on?

• SID

• OID

• Tube angle

• Object thickness

What causes the moire effect?

• the grid lines are parallel to scan lines of processor

• the grid lines are perp to scan lines of processor

• misalignment of the grid and beam

• incorrect SID used

What is the most critical factor in a grid's efficiency?

• grid frequency

• grid ratio

• lead content of grids

• grid dimension

What is the purpose of a compensating filter?

• balance the exposure

• dramatically change the contrast scale

• reduce the remnant beam

• protect tech from scatter radiation

The purpose of PBL is

• to allow techs to not worry about collimation

• ensure the field size is never larger than cassette

• allow for easy collimation

• automatically set field size

For soft tissue techniques, kVp is

• increased by 20%

• decreased by 20%

• remains the same as C-spine

Volume of the irradiated tissue increases as

• field size decreases

• patient thickness increases

• mAs decrease

• all answers are correct

The half-value layer (HVL) is used to measure

• mAs level

• the penetrability of the xray beam

• the grid ratio

• the amount of xrays in the beam

Photon absorption within the body occurs as the result of

• compton interactions

• scatter radiation

• photoelectric interaction

• all answers are correct

The computer distinguishes the anatomy of interest from background exposure outside collimated field during:

• exposure

• automated field recognition

• automated rescaling

• field uniformity corrections

How dark or light a digital image appears on a display monitor is known as

• contrast resolution

• brightness

• spatial resolution

• density

In generic digital imaging terms, the average brightness level of the image is called the:

• window level

• window width

• density

• scale of contrast

In a digital image histogram graph, the vertical height of any data point along the plotted curve (measured against the y axis of the graph), indicates the:

• image contrast

• pixel value (brightness)

• number of pixels possessing the value

• S1

On an image histogram, an unusual spike to the left of the main bell-shaped lobe of the curve most likely represents:

• osteoporosis

• background exposure

• a large metallic object

• air in the lungs

The larger the number of pixels in an image matrix, the:

• shorter the acquisition time

• greater the resolution of the image

• greater the number of gray shades in the image

• all answers are correct

Which of the following is an example of a Field Uniformity Correction?

• creation of a best fit line for the raw detector data

• a flattening of the histogram curve as needed

• application of a kernel across the matrix

• evening out of brightness to account for irregularities in the hardware of the IT across the image field

Many imaging systems present the histogram with an averaged gray scale curve overlying the histogram. The steeper the slope:

• lighter the image

• the darker the image

• longer the image gray scale

• higher the image contrast

The development of which of the following enabled DR systems to use a flat-shaped receptor plate:

• photostimulable phosphor plates

• thin-film transistors (TFTs)

• the photomultiplier tube

• CCDs

In digital imaging processing, what is segmentation?

• a graph plotting signal intensity for each pixel

• identification of the exposed area of the IR

• the anatomy on which the exam is performed

• a look up table

Which of the following terms, all contractions, most accurately describes the individual hardware elements of a DR flat panel receptor that detect radiation in the remnant x-ray beam?

• the dexel

• the pixel

• the voxel

• the rexel

The selection of a narrow window width will:

• decrease the size of each pixel

• decrease overall brightness of the image

• increase contrast in the image

• increase magnification of the central portion of the image

Which of the following modalities create images with the highest spatial resolution?

• ct

• nuclear medicine

• ultrasound

• digital radiography

Adjustment of the window width of the image will change

• the brightness of the image

• the level of IR exposure

• the spatial resolution of the image

• the scale of contrast of the image

For digital imaging, each image displayed consists of a discrete number of rows and columns of picture elements called the:

• signal plate

• display table

• matrix

• detector array

The larger the number of pixels in an image matrix, the:

• greater the number of gray shades in the image

• shorter the acquisition time

• greater the spatial resolution in the image

• all answers are correct

• no answers are correct

A system with a high S/N ratio displays:

• low noise and high signal

• low signal and high noise

• equal amounts of signal and noise

• no signal and no noise

Which factor influences the average energy of photons reaching the IR?

• kVp

• mA

• time

• focal spot size

As kVp decreases, spatial resolution will _________________.

• increase

• decrease

• remain unchanged

In the diagnostic range, the majority of primary x-rays produced are:

• characteristic

• photoelectric

• brems

• compton

As kVp increases,

• scatter increases

• remnant beam contrast scale lengthens

• all answers are correct

• image receptor exposure increases

The amount of scatter reaching the image receptor is affected by all of the following EXCEPT:

• SID

• Amount of Collimation

• kVp

• grid ratio

The larger the number of pixels in an image matrix, the:

• greater the resolution

• greater amount of shades of gray in the image

• shorter acquisition time

• all answers are correct

As the lead content of a grid increases,

• image receptor exposure increases

• the contrast decreases

• The ability of the grid to remove scatter increases.

• The ability of the grid to remove scatter decreases

In production of a radiograph, which of the following is considered the controlling factor of beam penetration and remnant beam scale of contrast?

• kVp

• mAs

• time

• filtration

The principal controlling factor of radiographic image receptor exposure is:

• kVp

• mAs

• focal spot size

• tube angulation

Image level parameters (window level) control image

• brightness

• contrast

• density

• darkness

All of the following are true of pixel pitch except:

• it is measured from center-center of pixels

• it is affected by changes in the matrix size

• it is determined by the size of the dels in flat panel systems

• it is not related to spatial resolution

Which of the following is NOT a component of a detector element?

• capacitor

• charged coupled device

• semiconductor layer

• thin film transistor

A phosphor screen or scintillator

• fluoresces when exposed to light

• fluoresces when exposed to xrays

• ionizes selenium when exposed to x-rays

• ionizes selenium when exposed to light

The percentage of the surface area of a flat panel detector element devoted to the semiconductor layer is:

• DQE

• Fill factor

• detector ratio

• capacitance

The purpose of the ADC is to convert the _______ signal to a _________ signal.

• analog; digital

• digital; analog

• analog; detector

• acquired; detected

• detector; digital

In a DR flat panel image receptor, which electronic devices directly account for the plate’s ability to store a latent image until it is sent into the computer?

• capacitor

• tfts

• data lines

• gate lines

• semiconductor layer

What is the size of each pixel for an image with a 1024x1024 matrix using a 30x30 cm field of view:

• 30 cm

• 0.3 mm

• 3 cm

• 3 mm

The ratio of SID to SOD is the primary control for:

• magnification

• shape distortion

• scatter production

• sharpness of recorded detail

In a DR flat panel image receptor, most of the square area of each del is dedicated to what portion of the detector element: