Modern Imaging Equipment Flashcards

1
Q

Any imaging technique has a number of stages

A

Image acquisition
Imaging processing
Image display
Image storage

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2
Q

What is digital imaging

A

Technological advancement

Any method of imaging that creates an image that can be viewed/ stored on computer

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3
Q

Digital imaging advantages

A

Increased work flow

No need for processing chemicals

Can be transferred manipulated and enhanced digitally

Less radiation exposure

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4
Q

How an radiographic image is made

A
  1. Anatomy is positioned
  2. X ray exposure is made
  3. Beam is attenuated by patient and captured by receptor
  4. Analogue data to digital data
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5
Q

Analogue

A

Continuous signal that contains time varying quantities/ constant fluctuation

E.g. kitchen clock

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6
Q

Digital

A

Discrete value at each sampling point

E.g. digital wristwatch

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7
Q

Digital imaging methods

A
  1. CR
    (Cassette based)
  2. DR
    (Image detector system)

Both use computers

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8
Q

What is CR

A

Method of capturing radiographic data from conventional X ray unit
Processing data digitally
To produce radiographic image

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9
Q

CR main components

A

CR Cassette
Imaging plate
CR reader

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10
Q

CR Cassette

A

A protective container for imaging plate

Available range of sizes smallest = wrist Cr 18x24cm largest = cxr 35x43cm

Icons identify correct orientation + barcode to link Cassette/ imaging plate and examination to patient examination

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11
Q

CR imaging plate

A

Found within Cassette

Stores the image ( X-ray photons excite phosphate atoms)

Stored energy dissipates quickly so should be out into Cr reader quickly

Cr imaging plates are sensitive to scattered radiation = avoid exposure, should be stored in optimal location regularly rotated

Regularly erased to prevent a build up of background signal

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12
Q

Imaging plate several layers

A

Protective layer = thin, plastic, protects phosphor layer

Phosphor layer = contains photostimulable phosphor = traps electrons during exposure of radiation

Reflective layer = released light in forward direction when in Cr reader

Base layer = semi rigid strengthen image plate

Backing layer == protects back of Cassette

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13
Q

CR reader

A

After exposure, CR Cassette is placed into CR reader - removes the imaging plates

Imaging plate is scanned with laser, release stores electrons

Analogue data into digital data for computer

Once read by laser imaging plate is exposed to white light, it erases the data from the plate so it can be used again

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14
Q

CR reader major components

A

Drive mechanism = move the imaging plate through scanning process

Optical system = laser, optical filters

Photomultiplier

Analogue- digital converter ADC

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15
Q

DR

A

Describes images recorded on an electronically readable device

DR is hard wired to image processing system = combines image acquisition & display

Image acquisition =(CR two stage process)
But I’m DR, detectors have combined image capture and read out capability

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16
Q

DR detectors

A

Sensors are used instead of imaging plate = detect x ray signal

Permanently encased

Image can be manipulated processed and transported and stores electronically

Detectors available in sizes
More fragile and expensive than CR
Automatic functions e.g positioning, centring & collimation

Wide dynamic range in linear response to photon energies. Lower exposure = quantum mottle
High exposure = acceptable image but risk radiation exposure risk

17
Q

Histogram & look up table

A

Graphical representation of optimal densities within area imaged

Comparison made to ore established histogram specific to anatomical part, utilises LUT

18
Q

Exposure index

A

Numeric value indicating level of radiation exposure to image receptor

Excoriate indices are not standardised among digital equipment

19
Q

PACS

A

Picture archive and communications systems