Digital Imaging

Front 1

An image acquisition process that produces an electronic image that can be viewed and manipulated

Back 1

digital imaging

Front 2

Sharpness of the structural edges recorded in the image

Back 2

spatial resolution

Front 3

smallest element of digital imaging

picture element

Back 3

pixel

Front 4

Does digital imaging relate to a discrete or continuous value

Back 4

discrete (single numeric number)- brightness level

Front 5

Know how the number of pixels relate to spatial resolution

Back 5

increased pixels = increased spatial resolution

Front 6

measured side to side of pixel

Back 6

pixel size

Front 7

Know how pixel size relates to spatial resolution

Back 7

decreased pixel size relates to increased spatial resolution

Front 8

Measured from center of one pixel to center of the adjacent pixel

Back 8

pixel pitch

Front 9

Know how pixel pitch relates to spatial resolution

Back 9

decrease in pixel pitch results in an increase in spatial resolution

Front 10

number of pixels/mm in an image

Back 10

pixel density

Front 11

Know how pixel density relates to spatial resolution

Back 11

increase in pixel density = more pixels in measure area

increase pixel density= increased spatial resolution

Front 12

A combination of rows and columns of small pixels

Back 12

matrix

Front 13

Know the total number of pixels in an image matrix of 1024 columns * 1024 rows

Back 13

1,048, 576 pixels

Front 14

Amount of body part or patient included in the image

Back 14

field of view

Front 15

Know what generally happens to spatial resolution when a larger matrix size includes a greater number of pixels

Back 15

larger matrix size = increase spatial resolution

Front 16

Know how a fixed matrix size and smaller imaging plate relate to the quality of a digital image

Back 16

fixed matrix size, smaller imaging plate = increase in spatial resolution

Front 17

Number of samples per second (or per other unit) taken from a continuous signal to make a discrete or digital signal (sampling analong/at body part/ tissue thickness)

Back 17

Sampling frequency

Front 18

Distance between the sampling frequency

Back 18

Sampling pitch

Front 19

Know how sampling frequency relates to spatial resolution

Back 19

increased sampling frequency results in decrease sampling pitch = increased spatial resolution

Front 20

Determines the highest spatial frequency that can be recorded by a digital detector

Back 20

Nyquist frequency

Front 21

Know what the acronym DEL stands for

Back 21

Detector element

Front 22

The smallest resolvable area in in a flat panel detector

Back 22

DEL's

Front 23

Know how DEL size relates to spatial resolution

Back 23

decreased DEL size = improved spatial resolution = decreased patient dose

Front 24

Portion of the pixel element that is occupied by the sensitive image receptor

Percentage of x-ray capture

Back 24

Fill factor

Front 25

Know the approximate fill factor % for a DEL

Back 25

80%

Front 26

The smallest exposure change or signal difference that can be detected

Back 26

Contrast resolution

Front 27

Know what contrast resolution refers to

Back 27

ability of the digital system to display subtle changes in the shade of gray

Front 28

Know the major advantage of digital receptors compared to film-scree imaging

Back 28

Increased contrast resolution

Front 29

Requires each pixel assigned a unique value

Back 29

Quantization

Front 30

Know which system has higher spatial resolution; digital or screen-film imaging

Back 30

higher spatial resolution is found in film-screen imaging

Front 31

shades of gray available for each pixel

Back 31

bit depth

Front 32

Know which pixel bit depth improves image quality and displays a greater range of shades of gray to represent the anatomic tissues (4-bit, 8-bit, 12-bit, 14-bit)

Back 32

bit depth of 2^14

Front 33

Variation in anatomic details images as white to black brightness levels that can be defined by lp/mm

Back 33

spatial frequency

Front 34

A measure of the imaging systems ability to display contrast of anatomic objects varying in size

"smaller objects are harder to image"

Back 34

Modulation Transfer Function (MTF)

Front 35

Relating to MTF, know what effect low spatial frequencies have on contrast

Back 35

low spatial frequencies (contrast is perserved) high spatial resolution/ high spatial frequencies (contrast is lost) less spatial resolution

Front 36

The range of exposure intensities (range of values) that may be captured by a detector

Back 36

Dynamic range

Front 37

Know which imaging system has a higher dynamic range; digitial or film- screen imaging

Back 37

digital image receptors

Front 38

Visible or brightness or density fluctuation on the image as a result of too few photons reaching the image receptor to form the image

Back 38

Quantum mottle (noise)

Front 39

List two factors that would increase quantum mottle (noise)

Back 39

Low mAs/ high kVp or fast imaging systems

Front 40

Know which imaging system is more affected by quantum mottle; digital or film-screen imaging

Back 40

film screen imaging

Front 41

A method of describing the strength of radition exposure compared with the amount of noise apparant in a digital image

Back 41

Signal-to-Noise ratio

Front 42

Strength or amount of radiation exposure captured by the IR to create the image

Back 42

Signal as it relates to SNR

Front 43

Know what SNR is needed for digital radiography

Back 43

1000:1

Front 44

The contrast resolution compared with the amount of noise apparent in a digital image

Back 44

Contrast-to noise ratio

Front 45

Know which relates to improved contrast resolution; high or low SNR

Back 45

high SNR

Front 46

Know which imaging system scattered radiation affects more; digital or film-screen imaging

Back 46

Digital (CR more sensitive than DR)

Front 47

efficiency of a detector in converting incident x-ray energy into an image signal

Back 47

Detective Quantum Efficiency (DQE)

Front 48

Know what has a higher DQE (DR or CR imaging)

Back 48

Both direct and indirect DR

Front 49

Name 5 layers of a digital CR plate

Back 49

Protective layer, Photostimuable phosphor, reflective layer, base, backing

Front 50

Know the name of the PSPS used in CR imaging

Back 50

barium flourohalide

Front 51

Define latent image

Back 51

invisible image

Front 52

Define manifest image

Back 52

visible image (see on monitor)

Front 53

Define luminesce

Back 53

gives off light

Front 54

Know what the photostimuable phosphor plate actually captures to form the latent image

Back 54

electrons

Front 55

Know what is used to extract the latent image from the PSP

Back 55

red laser light

Front 56

Collects, amplifies, and converts the visible light to an electrical signal proportional to the range of energies stored in the imaging plate

Back 56

Photomultiplier Tube in a CR reader

Front 57

Know what changes the electronic analog signal into a digital signal

Back 57

Analog-digital converter

Front 58

State the rate of fade (loss of latent image) if the PSP imaging plate is not processed within 8 hours of being exposed to radiation

Back 58

25%

Front 59

What type of light is used to erase any residual image on an imaging plate

Back 59

white light

Front 60

Know how often CR imaging plates should be erased if not used

Back 60

48 hours or weekly

Front 61

Gridlines that are projected on the imaging plate when using a stationary grid can interfere with the image resulting in a wavy artifact

Back 61

Aliasing Artifact (moire or zebra artifact)

Front 62

What grid frequency should be used to help prevent the Moire' effect; low of high frequency

Back 62

high grid frequency

Front 63

Know what direction the CR reader should scan the imaging plate to prevent Moire' artifact

Back 63

perpendicular at right angles

Front 64

Solid-state image receptors employing a larger area active matrix array of electronic components in various sizes

Back 64

Flat-panel detectors

Front 65

Know what a thin film transistor is divided into

Back 65

xray converter

DEL's

glass substrate

Front 66

Define thin film transistor

Back 66

DEL's capacitor, switch

Front 67

Name the two categories of flat panel detectors

Back 67

1. Direct Conversion Detectors

2. Indirect Conversion Detectors

Front 68

Convert the exit radiation into visible light

Back 68

Scintillator

Front 69

Name two of scintillators used in indirect conversion detectors and know which one is most commonly used

Back 69

Cesium Iodine-structured most common

Gadolinium oxysulfide- unstructured

Front 70

Know what material in indirect conversion detectors that convert light into electrons

Back 70

amorphous silicon

Front 71

Know what material converts x-rays into electrons in a non-scintillator/ direct conversion flat panel

Back 71

amorphous selenium

Front 72

Know which generally produces less patient dose; direct or indirect flat panel detectors

Back 72

indirect flat panel detectors

Front 73

Name two other types of image receptors used in indirect conversion DR

Back 73

1. Charged Coupled Device

2. Complementary Metal Oxide Semiconductors

Front 74

1. Large Fill Factor

2. faster readout

3. less expensive (in large quantities)

4. less power

5. more susceptible to noise

Back 74

1. CCD

2. CMOS

3. CMOS

4. CMOS

5. CMOS