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IT & IA > DR p1 > Flashcards

DR p1 Flashcards

1
Q

define elongation

A

type of distortion where anatomical parts appear bigger than norma

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2
Q

define foreshortening

A

type of distortion where anatomical parts appear smaller than normal

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3
Q

what aspect of RT does distortion impact

A

treatment planning

aren’t able to plan accurately

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4
Q

image produced is dependent on 3 main things

A

pt factors - thickess, composition, pathology
exposure factors - kVp, mAs, distance
imagine system characteristics - high voltage gen, filtration, focal spot size

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5
Q

digital vs analog

A

digital - 0s and 1s

analog - stream of info

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6
Q

in the initial stages of digital detectors are signals analog or digital? what happens to them?

A

analog -packets of electronic current

they are converted by a ADC (analog to digital converter) during image readout

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7
Q

the digital image is composed of tiny cells of numerical data in a _____ of ____ and ____

A

matrix
columns
rows

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8
Q

each cell in a matrix is called a ____. they are the smallest elements of a digital image

A

pixel/picture element

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9
Q

greater the number of pixels, the higher the _____

A

spatial resolution

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10
Q

an image is described by how many ______ it contains

A

pixels

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11
Q

what limits the spatial resolution?

A

pixel size

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12
Q

can pixels represent multiple shades of grey?

A

no only one

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13
Q

What is spatial resolution best at measuring

A

recorded detail

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14
Q

what is each pixel assigned

A

a numerical value that corresponds to a shade of grey somewhere between white and black

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15
Q

what is a voxel?

A

volume element (of the pixel)

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16
Q

define dynamic range

A

range of grey scale values that can be assigned to each pixel

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17
Q

does digital imagine have more or less spatial resolution than screen film

A

less spatial resolution

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18
Q

what is special about the monitors displaying digital radiographic images

A

they have liquid crystal displays

19
Q

when an electric current passes through the liquid crystal display what happens

A

causes the molecules to change shape/direction

either letting light pass through or not (if necessary)

20
Q

what type of light do passive screens use

A

fluorescent light

21
Q

what type of light do active screens use

A

LED - light emitting diode

fyi - these are brighter, have superior contrast resolution, and better viewing angles then fluorescent

22
Q

define photometry

A

science of response of the human eye to visible light

23
Q

what are the 2 laws of photometry

define each

A

ISL - luminous intensity decreases in proportion to the inverse square of the distance from the source
Cosine law - maximum luminous intensity occurs when a monitor is viewed straight, luminous intensity and contrast decrease when viewing from an angle

24
Q

define DICOM

A

digital imaging and communication in medicine
protocol/standard to produce, manipulate, exchange, and store imaging data
used so that no data is lost through its transfer
data is viewed consistently

25
Q

what is GSDF

A

grey scale display function

allows for display of DICOM compatible device with consistent gray scale and appearance

26
Q

what are the 5 objectives of DICOM

A 
RT images
RT plan 
RTSS - pt anatomy
RT dose
RT treatment record
27
Q

define PACS

A

picture archiving and communication systems

universal system for DR images to be stored and transffered

28
Q

what are the 4 components of PACS

A

image acquisition
display system
network
storage

29
Q

what does PACS improve

A

image interpretation, processing, viewing, storage and recall

30
Q

what are the 4 stages of digital radiography

A

image acquisition
image processing
image display
image storage

31
Q

what are the 2 main classes of imaging systems

A

indirect and direct radiography

32
Q

define indirect radiography (CR)

A

phosphors react with xrays and store energy for a vrief time until processed

33
Q

define direct radiography

A

sensors detect radiation leaving the pt and send data to a computer in digital format

34
Q

what does PSP stand for
what are other names it goes by
what does it do

A

photostimulable phosphor detector systems
aka storage phosphors or imaging plates
PSP screen traps energy from xrays that can be read out later

35
Q

PSP + Cassette =

A

imaging plate

36
Q

CR cassettes and imaging plates also have integrated _____

A

grids

37
Q

in CR what happens to electrons

A

electrons are trapped in a higher energy metastable state inside the slate
they then become stable in the reader

38
Q

what happens when the electron becomes stable in the reader

A

light is given off

this light is the signal that creates the images

39
Q

which is able to produce more shades of grey screen film or CR

A

CR (16000 while SF is only 32)

40
Q

computed radiography

a) CONVERTS AN ANALOG SIGNAL TO DIGITAL
b) CONVERTS A DIGITAL SIGNAL TO ANALOG
c) HAS A PURE DIGITAL SIGNAL
d) HAS A PURE ANALOG SIGNAL

A

a

41
Q

The image receptor used in CR is:

a) Flat panel receptor
b) Film
c) Digital
d) PSP screen

A

d

42
Q

Spatial resolution (in CR) is determined by:

a. Distance
b. kVp
c. Number of pixels
d. High voltage generator

A

c

43
Q

spatial resolution

a. Is higher in screen-film radiography than digital
b. Is limited by digital file size
c. Allows us to see fine details
d. All of the above

A

d

44
Q

Which of the following is not a part of PACS:

a. A computer for image display
b. An mRI computer
c. A PET scan
d. Hospitals mainframe

A

c

IT & IA (10 decks)

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