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Radiographic Procedures II > Radiographic Exposures Final > Flashcards

Radiographic Exposures Final Flashcards

1
Q

While DICOM is concerned primarily with images from the digital image acquisition modalities, HL-7 is concerned mainly with textual information from the __ and __.

A

HIS and RIS

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2
Q

Since PACS contains confidential patient data and information, it is essential that they be secured; hence,___ is of central importance in a digital hospital as well as in a PACS environment.

A

data security

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3
Q

Direct conversion digital radiography systems use detectors that convert x-Rays directly into___________ ___________.

A

electric signals

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4
Q

The conversion of analog signals into digital data is the function of the_____.

A

ADC Analog-to-digital-converter

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5
Q

What class of digital image processing allows measurements and statistics to be performed, as well as image segmentation, feature extraction and classification of objects?

A

Image analysis

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6
Q

Define voxel:

A

(volume element) the information contained in a volume of tissue that is converted into numerical values and expressed in pixels.

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7
Q

What does the width of a histogram imply regarding image contrast?

A

Wide-more contrast

Narrow-less contrast

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8
Q

When the PSP IP is erased by exposing it to a high intensity light beam to get rid of any residual latent image? (At what point in the digital image processing cycle?)

A

After laser scanning

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9
Q

What is likely to occur if there is substantial extraneous exposure on the plate?

A

histogram analysis error

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10
Q

Which exposure causes the system to rescale the image as if the plate is actually underexposed? (high-intensity, low-intensity?)

A

low-intensity exposure

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11
Q

In digital imaging what has more of an effect on image contrast than the kVp?

A

processing algorithm

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12
Q

Because of increased sensitivity to scatter radiation? The kVp should not exceed__for any nongrid radiography, including chest.

A

80

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13
Q

Acquiring one image on the smallest plate available avoids which recognition error?

A

exposure field recognition error

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14
Q

___occurs when a large number of pixels will be at the maximum digital value (black) so that there is no signal difference in the very high exposure areas, resulting in a loss of anatomical structures in that region.

A

Saturation

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15
Q

What is the standard expression for the receptor’s contribution to recorded detail?

A

Spatial resolution

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16
Q

What is the name of the structure that will detect the light from the CsI scintillator I the indirect flat-panel TFT detector?

A

sensing area

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17
Q

What indirect flat-panel TFT digital detectors, what is used to first convert X-Ray photons into the light photons?

A

Scintillator layer (CsI)

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18
Q

Which concept examines the response of the latent image receptor (screen-film detector or digital detector) to the radiation falling upon it?

A

exposure latitude

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19
Q

Which type of image is obtained initially from the detector and contains artifacts due to bad detector elements?

A

flat-field image

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20
Q

Too much edge enhancement produces image noise and creates ________.

A

“halo” effect

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21
Q

Define spatial resolution:

A

sharpness of an image

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22
Q

Define/describe the purpose of: modulation transfer function.

A

(MTF) mathematical function that measures the ability of a detector to transfer it’s spatial resolution characteristics to the image.

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23
Q

An MTF of ___ represents a perfect transfer of spatial and contrast information.

A

1

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24
Q

Which performance characteristic deals with the efficiency of a detector to convert the x-radiation signal at its entrance window into a useful image signal?

A

DQE

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25
Q

In imaging applications, because contrast resolution (the ability to resolve small differences in tissue contrast) is mandatory for diagnostic interpretation,___ is important.

A

it; high signal to noise ratio

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26
Q

Define HL-7:

A

Communication for patient data: demographics, administration, discharge/transfer, radiology reports, image exam type

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27
Q

What are image data sets? How are they described?

A

Matrix size, overall image quality, number of OD slices, study size, inherent spatial resolution, bit depth

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28
Q

What is the data transfer rate network called?

A

bandwidth

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29
Q

What is an HIS used for?

A

Not only patient information, but acts related to hospital administration, billing, accounting, stats, personnel, budgets, material management

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30
Q

In a simple DICOM configuration, a CR unit sends images to a PACS for___.

A

Storage

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31
Q

Distinguish between input and output. What does each use?

A

data entry using hardware devices (keyboard, mouse, etc.)-input
computer processing can be displayed on monitors for viewing by a human observer-output

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32
Q

What does informatics refer to?

A

The process of changing data into information, and therefore computers and communications technologies are central elements to the process.

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33
Q

According to Chapter 9, what is PACS and what is it used for?

A

More recently, the use of picture archiving and communications systems; (PACS) has become a common place in digital imaging.

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34
Q

What is order entry and what is it known as?

A

Requested radiology examinations ordered by physicians are entered into the system.

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35
Q

What is EHR as defined in the text?

A

electronic health record

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36
Q

What is another name for the flowchart of the steps involved in performing a DR exam?

A

processing map

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37
Q

What is metadata?

A

demographic and exam data accompanying the DR image in an electronic file header

38
Q

The DICOM modality worklist (MWL) is a feature designed specifically to take advantage of information that already exists in___.

A

RIS-Radiology Information System

39
Q

Which type of imagining system makes use of photo stimulate or storage phosphors to produce digital images using existing X-ray equipment?

A

Computed Radiography

40
Q

Define scattering. What interaction with matter causes it?

A

Incoming photons that aren’t absorbed, instead lose energy during atom interactions composing the tissue.

41
Q

For every 4-5 cm of tissue, the x-Ray beam quantity is reduced by:

A

50%

42
Q

How does tissue density affect attenuation?

A

muscle tissue has atomic particles that are more dense or compact and therefore attenuate the x-Ray beam more

43
Q

How do tissues with higher atomic numbers appear on a digital image?

A

demonstrate light areas or greater brightness

44
Q

Rank the four types of body tissue from greatest to least attenuation ability.

A

bone
muscle
fat
air

45
Q

How does the energy (quality) of the beam affect attenuation?

A

it decreases with a high-energy x-ray beam;

increased with a low-energy x-ray beam

46
Q

Visibility of the recorded detail is accomplished by balancing_______and_______

A

differences between adjacent densities (contrast)

47
Q

Define contrast:

A

The degree of difference or ratio between adjacent structures.

48
Q

Define scale of contrast:

A

The range of densities visible on a radiographic image.

49
Q

Define high contrast. Is it long-scale or short scale? How many shades of gray (densities) are associated with high contrast (few or many)? Are they very different from one another or similar to each other?

A

A radiograph with few densities, but great differences between them, short-scale contrast.

50
Q

Define low contrast. Is it long-scale or short scale? How many shades of gray (densities) are associated with low contrast (few or many)? Are they very different from one another or similar to each other?

A

A radiograph with a large number of densities but little differences among the long-scale contrast

51
Q

How does kVp level affect x-ray beam transmission?

A

Low quality photons in the beam, high kVp higher quality in kVp decrease wavelength.

52
Q

How does kVp affect x-ray beam quality?

A

higher energy photons

53
Q

Define resolution:

A

The ability of the imaging system to resolve or distinguish between two adjacent structures

54
Q

What type of relationship does mAs have with the quantity of x-rays produced?

A

directly proportional

55
Q

With digital imaging, if the mAs is too high, how will the image appear?

A

brightness-appropriate

56
Q

With digital imaging, if the image receptor is not exposed to enough radiation (mAs), how will the image appear?

A

brightness-appropriate

57
Q

How does increasing kVp affect the energy, quantity, and penetrating power of x-ray production?

A

everything is increased

58
Q

How does kVp that is too low affect digital image brightness?

A

brightness-appropriate

59
Q

The relationship between kVp and quantity of remnant radiation is known as the:

A

15% rule

60
Q

Low kVp produces_____radiographic contrast and high kVp produces_____radiographic contrast.

A

high;low

61
Q

Focal spot size affects only: (which geometric property?)

A

recorded detail

62
Q

The inverse square law describes the relationship between____and____.

A

distance and x-ray beam intensity

63
Q

State the inverse square law formula:

A

I1 over I2 =D2 squared over D1 squared

64
Q

State the formula for (density maintenance)

A

mAs1 over mAs2 =D1 squared over D2 squared

65
Q

How does SID affect magnification/size distortion?

A

X-Ray intensity spreads over a large area decreasing the beam reaching the IR

66
Q

When OID cannot be reduced, in what way is SID adjusted in order to compensate?

A

increase SID

67
Q

State the magnification factor formula:

A

MF=SID over SOD

68
Q

How should radiographic technique be adjusted when performing pediatric chest imaging? (mA,time,high or low, long or short?)

A

kVp lower
mAs lower
short exposure time

69
Q

The variable kVp-fixed mAs technique chart adjusts___as part thickness changes and the ___remains constant.

A

kVp;mAs

70
Q

For radiographic procedures, scatter radiation is primarily the result of what type of interaction with matter?

A

Compton Interaction

71
Q

How does restriction of the primary beam (collimation) to the anatomy of interest of affect patient dose and scatter production?

A

It is used to limit scatter radiation and patient dose.

72
Q

What is most easily adjusted radiographic beam-restricting device?

A

collimator

73
Q

Define grid frequency:

A

expresses the number of lead lines per unit of length in inches, centimeters, or both

74
Q

State the formula for calculating grid ratio:

A

Grid Ratio=h/D

75
Q

What is focused grid? How are the lead strips arranged?

A

Has lead lines that are arranged, or canted, to approximately match the angle of divergence of the primary beam.

76
Q

Define focal range. What is its importance with the use of focused grids?

A

The recommended range of source-to-image receptor distance measurements that can be used with a focused grid.

77
Q

State the formula used when changing from one grid ration to another.

A

GCF=mAs with the grid over mAs without the grid

78
Q

Define grid cutoff.

A

A decrease in the number of transmitted photons that can reach the IR because of some misalignment of the grid.

79
Q

What factors should be considered when determining the grid to be used for a specific examination?

A

increase kVp, over 60 use grid

80
Q

What is the air gap technique? How is it used to reduce scatter radiation to the IR? Why does it work?

A

Based on the simple concept that much scatter will miss the IR if there is increased distance between the patient and IR increased object-to-image distance (OID). The greater the gap the greater scatter reduction. Because less scatter reaches the IR, mAs is changed to compensation.

81
Q

AEC controls the amount of radiation reaching the IR by controlling which prim factors?

A

exposure factor

82
Q

How many AEC detectors are typically used in the Automatic Exposure Control units? How are they configured (how are they arranged?)

A

3; two top cells one bottom

83
Q

Once the electric charge from an AEC detector reaches a present point, what happens to the exposure?

A

terminated

84
Q

Define maximum response time.

A

The shortest exposure time that the system can produce.

85
Q

The maximum length of time that an exposure lasts when using AEC is called____.

A

back up

86
Q

How does using a lower mA station during an AEC examination affect exposure time?

A

longer exposure, increases exposure time

87
Q

How does back-up time affect patient exposure and X-ray tube heat?

A

Protects the patient from unnecessary exposure and X-ray tube from exceeding its heat-loading capacity.

88
Q

If the back-up time is set by the equipment, the exposure time should end when the mAs reaches____mAs.

A

600

89
Q

When the radiographer has the opportunity to set the back-up time, it should be approximately___of the expected exposure time.

A

150%

90
Q

Which is the most critical aspect of successfully performing an examination using AEC?

A

detector selection

Radiographic Procedures II (9 decks)

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