TEST 1 Flashcards by Shelby Moss

What does the central processing unit (CPU) do?

coordinates the operations of entire computer

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What is the purpose of primary memory?

stores info for specific applications, working storage & temporary storage. memory is critical for computer to function

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RAM

Random access memory: memory that is stored anywhere on a chip or disc, can be changed and accessed easily.

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ROM

read only memory: memory cannot be changed by user and generally runs foundational programs

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What is a basic input/output system? (BIOS)

internal ROM that directs the flow of information between the CPU and peripherals.

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What is housed by the motherboard?

CPU,RAM & ROM chips, USB connections and audio

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Local Area Network (LAN)

network that is contained within a single building or business

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Wide Area Network (WAN)

network that extends to multiple businesses or geographical areas

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The speed of transmission across a network in bits per second. (bps)

BAUD RATE

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What is teleradiology?

Remote transmission of medical images outside a facility to a radiologists home.

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What is the unit used for binary numbers?
What is binary?

Bit.
on or off, yes or no

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How many bits are in one byte?

8 bits

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CONVERT 100011:

35
THIRTY TWOS:1 SIXTEENS: 0 EIGHTS: 0 FOURS: 0 TWOS: 1 ONES: 1
32+2+1

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What is the smallest unit of a digital image?

pixel

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How would a decreased pixel size effect spatial resolution?

increased spatial resolution

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How would an increased pixel size effect spatial resolution?

decreased spatial resolution

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pixel size limited by:

Detector element size. DEL

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The pattern of pixels laid out in rows and columns

Matrix

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The physical area of the image:

Field of View (FOV)

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when digitizing an analog image, creating the matrix would be considered:

scanning

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when digitizing an analog image, measuring intensity would be considered:

sampling

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when digitizing an analog image, assigning a value would be considered:

Quantization

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What is bit depth?

max range pixel values that a computer can manage or store

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How many shades of gray can the human eye distinguish?

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How many shades of gray exist in a bit depth of 5?

How many shades of gray exist in a bit depth of 8?

256 shades of gray *common for non medical imaging

How many shades of gray exist in a bit depth of 10?

1024. # of shades in a remenant bean

What is dynamic range?

Range of shades of gray that a system is capable of generating

How do you control brightness?

Window level

How should the window level be adjusted to decrease brightness?

Increase window level LB

How do you control contrast?

Window Width CW

How would window width be adjusted to decrease contrast?

increase window width

Greatest benefit of digital imaging

The ability to control contrast resolution

image matrix- NM US MRI CT DX MAMMO

image matrix* NM: 64X64 US:128X128 MRI:512X512 CT:512X512 DX:1024X1024 MAMMO:3328X3328

Dynamic Range NM: US: MRI: CT: DX: MAMMO:

Dynamic Range = bit depth NM:8 US:8 MRI:12 CT:12 DX:12 MAMMO:14*

File size NM: US: MRI: CT: DX: MAMMO:

File Size: NM:125kb US:262kb MRI:524kb CT:524kb DX:18mb MAMMO: 27mb*

Operations that are automatically completed by the computer on "raw" image data before the initial image is visible

Pre-Processing

_____________ makes corrections

pre processing

_______________ makes refinements

post processing

What is a preprocessing step used to correct flaws in the electronic & optics of the ir system?

Flat field Uniformity *does not account for anode-heel effect*

What happens when an individual del returns no data?

Noise reduction. to compensate, the surrounding 8 DELS average the data and assign the value to the malfunctioning DEL

What error occurs when the computer sees multiple images as one image?

segmentation. *only in CR*

Which error occurs when the computer analyzes raw radiation outside the anatomy of interest?

Exposure field recognition

What is a histogram?

Bar graph created by counting # of pixels (DELS) @ each brightness level

Which side of the histogram represents the dark pixels?

right

Which side of the histogram represents white pixels?

left

What is the maximum pixel values used for histogram analysis?

Smax

Why are #s higher than Smax excluded from analysis of histogram?

mostly raw radiation and adds 0 diagnostic value

What is the minimum pixel values use for histogram analysis?

Smin

Why are #s lower than Smix excluded from histogram analysis?

Represents lead shields, markers, prostheses, contrast, ect.

Type 1 histogram analysis

Detects Smax & removes value to the right that represents raw radiation

Type 3 histogram analysis

Detects Smin and removes values to the left that represents metal or contrast.

Type 2 histogram analysis

assumes no raw radiation to the right of Smax and identifies Smax as the highest value

What does Value of interest (VOI) refer too?

Different value ranges within the histogram that are selected to highlight specific anatomy. ex: tissue or soft tissue

What are histogram processing errors ?

segmentation: duplicates/ artifact exposure field recognition error unexpected objects in data set: lead drape too little/too much radiation mispositioning

Rescaling belongs to which part of processing?

initial processing of an image to make images appear normal

What does rescaling primarily affect?*

brightness

What is the goal of a look up table (LUT)

Adjust input so image looks "normal"

What processing is based on the location of a pixel in the overall matrix?

spatial domain

What processing is based on the size of an object in an image?

Frequency domain

What does graduation processing primarily control?

Contrast

What is the graduation amount? (GA)

Appears as slope or angle of processing curve

What does GA affect?

Contrast

Data Clipping

limited bit depth causing limited ability to adjust brightness or contrast

If the ends of the processing curves are clipped this means:

limited ability to adjust brightness or contrast as a result of data clipping

Breaking down an image into larger and smaller objects based on how many pixels are used to create it

detail processing

What size objects has long waves and low frequency?

large objects. *LLL*

What size object has short waves and high frequency

small objects *SHS*

High pass filters mute:

large objects. only high freq. passes

Low pass filters mute:

small objects. only low freq. passes

What is a kernel?

A small matrix used to apply effects to a small section of an image, or the image overall.

How does dual energy subtraction occur?

option 1: obtain 2 different images @ 2 different energies. option 2: use 2 imaging plates w/ a filter inbetween

How is speed class determined?

based on imaging systems sensitivity to radiation

Speed class is always ___________ related to the amount of exposure required to produce an adequate signal @ the image receptor.

INVERSLEY

How does increasing the speed class affect patient dose?

reduce/ decrease

How does increasing speed class effect quantum mottle?

increase

At what speed class can a modern CR & DR operate @ without substantial quantum mottle?

400

What do digital images lack that indicate the correct technical factors?

visual cues

is the exposure indicator an actual exposure reading taken at the IR?

What is the median point on a histogram between Smin and Smax representing?

exposure indicator (EI)

What unit is standardized EI based on?

Microgray

the "ideal" exposure to IR for a particular projection is termed:

Target EI (EIT)

What does the Deviation Index (DI) identify?

How far away the technique is from ideal

Which DI # should likely be considered for repeat due to quantum mottle?

-3.0

How would the DI change for a 25% increase in exposure?*

+1.0

How would the DI change for each 20% decrease in exposure?

-1.0

Extreme over- exposure (10x) that overwhelms the digital detection system and causes a loss of data:

Saturation. results in a flat black appearance.

What is considered alternative processing?

Processing a knee as a hand - using a different algorithm not typically used for the specific order

How can the alternative processing effect radiologist?

limits the ability to window and adjust image data

What is dark masking?

Darkening of the collimated areas

What is the min. spatial resolution when reviewing an image @ a work station?

6 LP/mm

What is the only common controlling factor for film and digital imaging?

Distortion: v shape distortion= ^alignment and also size distortion... I guess.

To produce the highest quality image possible:

Signal should be as high as possible and the noise should be as low as possible

Mutes large objects and enhances smaller objects (including artifacts)

Edge enhancement