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Radiology I > Digital Imaging > Flashcards

Digital Imaging Flashcards

1
Q

How much of a cut in radiation is usually seen when switching from film to digital?

A

50%

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2
Q

How can we reduce it even further?

A

By using a rectangular collimator

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3
Q

What are the 3 types of receptors used in digital imaging?

A

CCD, CMOS, and PSP

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4
Q

Which one of those is used in clinic?

A

PSP

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5
Q

PSP stands for?

A

Photostimulable phosphor plates

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6
Q

How is film resolution measured?

A

In line pairs per millimeter

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7
Q

How is this determined using film?

A

Depends on the grain density, smaller grains gives higher density

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8
Q

What is the highest resolution the human eye can see?

A

12-14 line pairs per millimeter

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9
Q

What is the reported range of resolution?

A

8-20 lp/mm

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10
Q

When a film has low latitude it means?

A

That the image will increase in density quickly as the dosage increases

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11
Q

What is the latitude of digital film and what does this mean for exposure time?

A

High latitude meaning the density will not change much with exposure, thus use less exposure time

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12
Q

What is contrast resolution?

A

How well the film can show minute differences in intensity

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13
Q

Does digital film have higher or lower contrast resolution than regular film?

A

Higher

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14
Q

As mentioned before there are three types of receptors. What are they and what do they stand for?

A

CCD is a charge coupled device
CMOS is a complementary metal oxide sensor
PSP is photostimulable phosphate

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15
Q

Describe the steps in creating an image using CCD/CMOS

A
  1. Exposure to radiation electrically charges pixels
  2. Buildup of charge creates voltage
  3. Voltage values are converted to binary and sent to computer
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16
Q

What piece of hardware is required for CCD/CMOS?

A

A cord

17
Q

What are the 3 types of pixel malfunctions?

A

Hot, dead, and stuck

18
Q

What is a hot pixel?

A

A pixel that reads high on longer exposures and appears white, red, or green

19
Q

What is a dead pixel?

A

One that is always off and appears black

20
Q

What is a stuck pixel?

A

Reads high on all exposures and appears white

21
Q

Post processing involves a process called?

A

Gamma correction, digitally changing the brightness and contrast

22
Q

How can it be used?

A

To bring out the characteristics you want from an image, for example low contrast brings out soft tissue outlines whereas high contrast brings out caries. This way we don’t need multiple radiographs

23
Q

How are PSPs read?

A

Using a ruby laser

24
Q

In terms of exposure time, how does PSP compare to CMOs/CCD?

A

Requires a longer exposure time of approximately 30 seconds

25
Q

When x-rays hit the phosphors, the electrons get trapped inside and we use the ruby laser to release them. What king of light is released?

A

Blue light called photo simulated luminescence

26
Q

What device detects the light?

A

Photomultiplier tube

27
Q

Can PSP be reused?

A

Yes, it is flashed with light using a machine.

28
Q

What is a precaution to take when using PSP/

A

Extra careful handling must be used since the plates can be easily scratched

29
Q

What is the function of the dot on the corner of the film?

A

Telling left from right

30
Q

What is better smaller or larger film?

A

Typically larger because more information can be captured that way

31
Q

Compare the thickness of CCD/CMOS, PSP, and film

A

CCD and CMOS are thick, about 3.5mm

PSP and film are 1mm

32
Q

Can receptors be sterilized?

A

No

33
Q

What do we use to avoid contamination?

A

Barrier protection

34
Q

What is more expensive CMOS or PSP?

A

CMOS is considerably more expensive

35
Q

Is printing digital images useful?

A

No it severely reduces image quality, never do this

Radiology I (9 decks)

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