Imaging Chapter 12

Front 1

The range of exposure intensities an image receptor can accurately detect determines its __________.

Back 1

dynamic range

Front 2

Film screen image receptors have a _______ dynamic range when compared to digital image receptors.

Back 2

narrow

Front 3

Which type of image receptor can accurately detect very low and very high exposure intensities.

Back 3

Digital

Front 4

These are used to convert radiographs recorded on conventional film into digital images.

Back 4

film digitizers

Front 5

Name the class of radiography that instantly produce digital images following exposure.

Back 5

Direct digital

Front 6

True or False

With conventional film image, the image is not permanent and further adjustments can still be made.

Back 6

False

A restriction to conventional film image is that the image is permanent and further adjustments
cannot be made.

Front 7

Name some drawbacks of conventional film-screen imaging.

Back 7

processing time
image is permanent, no changes possible
limited contrast resolution (difficulty in recognizing differences between tissues of nearly identical subject contrast)
archiving limitations/issues

Front 8

What are the similarities of digital and conventional imaging

Back 8

1.)Exposure Factor selection
2.)Accurate positioning
3.)Accessory devices such as grids and collimators are still used
4.) A latent image is still produced, and is processed to form a manifest image

Front 9

True or False

In digital imaging, moderately underexposed or overexposed images will still be of acceptable diagnostic quality.

Back 9

True
Because digital image receptors can respond to a wider range of x-ray exposures.

Front 10

is the response of the image receptor in digital imaging curvilinear or linear.

Back 10

linear

Front 11

A matrix is a combination of _______ and _________

Back 11

rows and columns

Front 12

What is a pixel?

Back 12

The smallest component, (picture element) of the matrix.

Front 13

What does FOV stand for?

Back 13

Field of view

Front 14

increasing the matrix size _________ the # of pixels.

Back 14

increases

Front 15

A larger matrix has more pixels and better ____________ ?

Back 15

spatial resolution

Front 16

____________ is a combination of zeros and ones to process and store computer information.

Back 16

Binary Number System

Front 17

What is a computers basic unit of information?

Back 17

A bit

Front 18

When FOV is decreased, what happens to the resolution

Back 18

Resolution improves

Front 19

Pixels representing highly attenuating tissues (like bone) are assigned a (low/high) value for higher brightness.

Back 19

Low

Front 20

Digital imaging typically involves which three conceptual steps.

Back 20

1.) Image Acquisition
2.) Image Processing
3.) Image Display


Remember *( A public display ) of affection

Front 21

In digital fluoroscopy the exit radiation is absorbed by the ___________ and converted into electrons.

Back 21

input phosphor

Front 22

in digital fluoroscopy, once the exit radiation is absorbed by the input phosphor, and converted into electrons, where is it sent next?

Back 22

to the output phosphor

Front 23

in digital fluoroscopy, name the sequence of events that exit radiation goes through in order to be transmitted to the television monitor

Back 23

1.) Input phosphor
2.) Converted in electrons
3.) Output phosphor
4.) Released as Visible light
5.)Television camera converts to electronic video signal for transmission to the television monitor

Front 24

Name some advantages of digital imaging as compared to Film screen imaging

Back 24

-Images acquired and displayed quickly
-transmission of images, processing of images, interpretation of images on a display monitor, stored, retrieved via electronic means
-Provide greater dynamic range
-Greater contrast resolution

Front 25

A larger matrix has *(more/less) pixels?

Back 25

more

Front 26

If you are looking at an x-ray, and your FOV (field of view) is decreased what happens to the images resolution

Back 26

The resolution is improved

(because as long as it's the same picture with the same matrix size you can see pixels better when they are farther away, and as your field of view is decreased (like zooming out on a photo) you see it better.

Front 27

What is a high attenuating tissue? Why is it high attenuating?

Back 27

Bone
Because it makes x-rays lose intensity a lot faster than air.

Front 28

How is the numerical value of a pixel determined.

Back 28

relative attenuation of x-rays passing through the corresponding volume of tissue

(like the value for bone is low because it's harder for x-rays to pass through bone, and low value = high brightness (low density)

Front 29

bit depth simply means the __________ of bits in each pixel.

Back 29

number

Front 30

What controls the exact pixel brightness and the precision with which the exit radiation is recorded?

Back 30

The bit depth

Front 31

Name the four main principles involved in Computed Radiography.

Back 31

1.) The radiation exits the patient and interacts with the imaging plate.
2.)Photon intensities are absorbed by the photostimulable phosphor (PSP)
3.)Some of the energy is released as luminescence (visible light)
4.) Energy is captured in the plate to produce a latent image

Front 32

In CR, the imaging plate is put into a reader which converts the _______ image into a ________ image.

Back 32

analog
digital

Front 33

In CR, once the imaging plate is placed in the reader, it is scanned with a ____________ which ________________.

Back 33

helium - neon laser which releases stored energy into visible light

Front 34

What does PMT stand for?

Back 34

photomultiplier tube

Front 35

What's the role of the photomultiplier tube in CR?

Back 35

In the reader, it collects, amplifies, and converts light to an electrical signal.

Front 36

True or False

Photostimuable phosphors can be reused up to 10,000 times before they need to be replaced.

Back 36

True

Front 37

What does ADC stand for?

Back 37

Analog - to - digital converter

Front 38

Explain how the reader in CR erases the imaging plate before it is returned to service.

Back 38

it is exposed to an intense white light to release any residual energy

Front 39

What indicates the level of x-ray exposure received by the CR imaging plate.

Back 39

numerical exposure indicator

Front 40

Why is it important for the radiographer to consider the numerical exposure indicator.

Back 40

because exposure errors affect the quality of the image and the exposure dose to the patient.

Front 41

What percentage of underexposure may produce noisy images.

Back 41

50% or greater

Front 42

How does the radiographer know the expected range of x-ray exposure sufficient to produce a quality image

Back 42

Each CR system specifies the expected range of x-ray exposure needed to produce a quality image.

Front 43

What are the advantages of using a CR system?

Back 43

1.) It's compatibility with existing FS equipment
2.) Higher dynamic range versus film screen

Front 44

What are the disadvantages of using CR.

Back 44

1.) The amount of time needed for processing and image readout
2.) increased x-ray exposure when trying to achieve comparable image quality to film screen methods.

Front 45

following exposure, using a DR system, when are images available?

Back 45

almost instantly

Front 46

how are DR images processed?

Back 46

by a computer workstation

Front 47

What is a limitation of the charged coupled device.

Back 47

limited to small field of view applications

Front 48

When using a CCD, each pixel element functions as a __________, which stores a charge proportional to the intensity of incident light.

Back 48

capacitor

Front 49

___________ is a solid state array of light sensitive sensor elements, such as that found in digital cameras.

Back 49

CCD
charged - coupled device

Front 50

in order for a CCD to function as an x-ray detector, it must be coupled with a _______________

Back 50

scintillator

Front 51

Flat panel digital receptors are constructed using _____________ arrays below a layer of attenuating material which converts x-rays into electrical charge.

Back 51

TFT ( thin film transistor)

Front 52

In Flat Panel Direct Capture Systems, what three things are already integrated into the flat panel device?

Back 52

signal storage
signal readout
digitizing electronics

Front 53

What are the advantages of flat panel direct capture systems?

Back 53

1.) highly dose efficient
2.) provide quicker access to higher resolution compared with FS and CR

Front 54

What are the disadvantages of flat panel direct capture systems?

Back 54

1.)incompatibility with existing equipment
2.)difficulty in mobile imaging

Front 55

The first image that is seen after acquiring a digital image is based on the _________ for that image.

Back 55

histogram

Front 56

Why is it important for the radiographer to indicate the correct radiographic prodecure?

Back 56

So that the correct algorithm is performed

Front 57

Following histogram analysis of a digital image, __________ provide a method of altering the image to change the display of the digital image.

Back 57

LUT's look up tables

Front 58

LUT's alter the ______ and _______ of an image.

Back 58

brightness and contrast

Front 59

What does this graph represent

Back 59

no pixel value change because of the straight line.

Front 60

What does this graph represent

Back 60

pixel value change because of the curved line

Front 61

Once the image has been processed in a digital format it can be

A. displayed on a monitor (CRT) or (LCD)
B. printed on film
C. sent to a distant location
D. Stored on magnetic tape or optical disk.
E. All of the above

Back 61

E. all of the above

Front 62

Visualizing a digital image of similar quality to a conventional film image requires that the display monitor have high spatial resolution, how many lines must a monitor have to achieve this?

Back 62

1024 lines

2048 preferred

Front 63

_______ is manipulation by the radiographer or the radiologist for soft-copy viewing.

Back 63

post-processing

Front 64

a post-processing technique that can remove superimposed structures so that the anatomic area of interest is more visible

Back 64

subtraction

Front 65

A post-processing technique that alters the pixel value to increase image contrast.

Back 65

contrast enhancement

Front 66

This image demonstrates an ____________ postprocessing technique

Back 66

edge enhancement

Front 67

This image demonstrates a ______________ postprocessing technique.

Back 67

Black and White reversal postprocessing technique.

Front 68

Which post processing technique suppresses image noise (quantum mottle).

Back 68

Smoothing

Front 69

Which postprocessing technique reverses the grayscale from the original image.

Back 69

black/white reversal

Front 70

Which post processing technique may degrade spatial resolution.

Back 70

Smoothing

Front 71

Which post-processing technique improves visibility of small, high contrast structures.

Back 71

Edge enhancement

Front 72

image noise may be slightly increased while using this post-processing technique.

Back 72

edge enhancement

Front 73

While the computer can adjust for under or overexposure, the radiographer should choose exposure factors based on __________ .

Back 73

ALARA

Front 74

Underexposure affects ________ and overexposure affects _________.

Back 74

quantum mottle

patient dose

Front 75

when technologists inadvertently increase dose to avoid the appearance of noise in underexposed images.

Back 75

dose creep

Front 76

This sets the midpoint of the range of densities visible in the digital image.

Back 76

Window level

Front 77

greater window level > = (what type of brightness)

Back 77

greater brightness

Front 78

(less) < level = (what type of brightness)

Back 78

less brightness

Front 79

WIDE window width displays __________ with lower contrast differences

Back 79

more densities

Front 80

NARROW window width shows __________ with more differences from one another thus higher contrast.

Back 80

fewer densities

Front 81

Long Scale contrast = _______ window width

Back 81

Wide window width

Front 82

Short scale contrast = ________ window Width

Back 82

Narrow window width

Front 83

Manipulating ______ for desired level of contrast is not required with digital imaging because the computer can adjust the radiographic contrast.

Back 83

kVp

Front 84

_________ varies the range of densities visible

Back 84

window width

Front 85

How can a radiographer correct noise in digital imaging?

Back 85

by increasing the mAs (photons)

Front 86

The contrast resolution of the human eye is limited to about ________ shades of gray.

Back 86

32

Front 87

If the entire range of densities is displayed on an image (wide window width) the image has ________ contrast.

Back 87

lower

Front 88

When a smaller range of densities is displayed on an image (narrow window width) the image has ________ contrast.

Back 88

higher

Front 89

True or False

quantum mottle will always be visible on the radiographers monitor

Back 89

False

Front 90

What can a radiographer refer to when trying to determine if an image has quantum mottle?

Back 90

exposure index number in CR

Front 91

What does PACS stand for.

Back 91

picture archival and communication system

Front 92

Why is it helpful to integrate RIS
(radiology information systems, HIS (hospital information systems), and PACS.

Back 92

So that images, patient data, and interpretations can be viewed simultaneously by people at different workstations.

Front 93

a communication standard for sharing information between PACS and imaging modalities.

Back 93

DICOM (digital imaging and communication in Medicine)

Front 94

What does DICOM stand for

Back 94

digital imaging and communication in medicine

Front 95

a communication standard for medical information

Back 95

HL7

Front 96

How many bits are in a byte?

Back 96

8

Front 97

Recording Radiographic images as numerical data is _____________

Back 97

Digital imaging