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77 Cards in this Set
- Front
- Back
A glass vacuum tube shaped like a funnel, sometimes used to display ultrasound images, is called what? |
Cathode Ray Tube (CRT) |
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The narrow end of a CRT contains a/an ___ that shoots out a stream of ___ containing video information |
Electron Gun / Electrons |
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The interior surface of the CRT is coated with ___ which glow when struck by electrons |
Phosphors |
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The odd-numbered lines (1-525) which the electron beam writes across the CRT screen first, are called what? |
Odd Field |
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The even-numbered lines (2-524) which the electron beam writes across the CRT screen last, are called what? |
Even Field |
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A combination of one odd field and one even field is called what? |
Frame |
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How much time is required to make a single frame? thus making CRT fame rate what? |
1/30 sec (1/60 + 1/60) |
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When a CRT screen is written by alternating between the odd field and the even field, what is this called? |
Interlaced |
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At what Hz can human no longer detect an interlaced display? |
60 Hz |
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This type of image consists of only two colors: black & white |
Bistable Images/Display |
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This type of image consists of multiple levels of brightness. Different amplitudes are assigned to different shades |
Grayscale Images/Display |
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What two user controls alter display characteristics? |
1) Brightness |
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This user control determines the range of brilliancies within displayed images |
Contrast |
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This user control determines the brilliance of the displayed image |
Brightness |
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This system component converts the sound beam spoke patterns into a digital, interlaced pattern suitable for display |
Digital Scan Converter |
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This type of number can have an unlimited and continuous range of values, and are found in everyday lives |
Analog Numbers |
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This type of number have a limited range of discrete values, and are frequently associated with computer devices |
Digital Numbers |
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For what four reasons are analog scan converters obsolete today? |
1) Image Fade |
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Using computer technology to convert images into numbers is called what? |
Digitizing |
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What are five advantages of digital scan converters today? |
1) Uniformity |
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What is the smallest building block of a digital picture? |
Pixel |
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The number of picture elements per square inch is called what? |
Pixel Density |
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The following factors define what? |
Low Pixel Density |
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The following factors define what? |
High Pixel Density |
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What is the smallest amount of computer memory called? |
Bit |
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What digits are binary numbers based on? Decimal numbers? |
Binary: 0 - 1 |
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A group of eight bits of computer memory |
Byte |
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The computer memory made up of 2 bytes (or 16 bits) |
Word |
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When an image displays many shades of gray, it is said to have this |
Superior Contrast Resolution |
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The following factors define what? |
Fewer Bits/Pixel |
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The following factors define what? |
More Bits/Pixel |
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How do we determine the number of shades of gray? |
Multiply 2 by itself, the same number of times as there are bits |
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What is the number of shades that can be represented by 3 bits? |
2 x 2 x 2 = 8 shades of gray |
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What is the number of shades that can be represented by 8 bits? |
256 shades of gray |
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How many bits are needed to store: |
4 bits |
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What is the primary advantage of digital over analog? |
Digital is less susceptible to signal contamination |
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The FIRST step in converting analog signals to digital, involves converting the electrical signals received by the transducer to strings of 0s and 1s. This is performed by what? |
Analog-to-Digital (A-to-D) Converter |
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The SECOND step in converting analog signals to digital, involves processing of the reflected signals before storage. This is called what? |
Pre-Processing |
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The THIRD step in converting analog signals to digital, involves processing after storage. This is called what? |
Post-Processing |
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The FOURTH step in converting analog signals to digital, involves translating stored digital signals back to analog for display on analog CRT (televisions). This is performed by what component? |
Digital-to-Analog (D-to-A) Converter |
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The FIFTH step in converting analog signals to digital, involves writing the newly converted analog signals to the CRT. This is called what? |
Video Display |
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The manipulation of image data before storage in the scan converter. This manipulation cannot be reversed |
Pre-Processing |
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The manipulation of image data after storage in the scan converter. This manipulation can be reversed |
Post-Processing |
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The following are handled when? |
Pre-Processing |
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The following are handled when? |
Post-Processing |
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The following are handled when? |
Either Pre- or Post-Processing |
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Zoom can also be called what? |
Magnification |
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Image visualization can be improved by enlarging a portion to fill the entire screen. This is called what? |
Magnification |
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This form of magnification occurs after image storage in the scan converter. It consists of 3 steps: |
Read Magnification |
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Read magnification can be used on a frozen image, and thus is considered what? |
Post-Processing |
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This form of magnification occurs during data acquisition, before storage in the scan converter. It consists of 4 steps: |
Write Magnification |
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If the number of pixels or scan lines in the region of interest is greater than in the original image (improved spatial resolution), name the form of magnification used |
Write Magnification |
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If the number of pixels or scan lines in the region of interest is the same as the original image (same spatial resolution), name the form of magnification used |
Read Magnification |
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Write nagnification cannot be used on a frozen image and thus is considered what? |
Pre-Processing |
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The following describes what kind of magnificaiton? |
Read Magnification |
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The following describes what kind of magnificaiton? |
Write Magnification |
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Name the storage media: |
Paper Media |
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Name the storage media: |
Magnetic Media |
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Name the storage media: |
Chemically Mediated Photographs |
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Name the storage media: |
Optical Media |
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This describes the digital ultrasound lab in which images and reports are digitized and stored on a large computer network |
PACS - Picture Archiving and Communications System |
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What are three advantages of PACS? |
1) Instant access to archived studies |
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This describes a form of storage based on a combination of magnetic and optical technology, which is often used by PACS |
Magneto-Optical (MO) Storage |
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What are two advantages of magneto-optical storage? |
1) can store large amounts of data on a single disc |
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All of the following are true of ordinary CRTs, except: |
C (525 lines, interlaced format) |
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Which of the following correctly describes a typical television display? |
A |
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Which electronic component is required for grayscale imaging? |
D |
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All of the following are disadvantages of analog scan converters except: |
B |
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Which of the following scan converters will provide the best spatial resolution? |
D |
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Which of these statements regarding a bit of computer memory is false? |
A |
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How many gray shades can be represented by a group of 4 bits? 2 bits? |
16 shades |
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Which of the following statements regarding a pixel is false? |
C |
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Are the following procedures usually pre- or post-processing? |
A. post-processing |
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Are the following forms of information usually digital or analog? |
A. analog |
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All of the following are characteristics of write magnification except: |
C |
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What is the primary disadvantage of video tape and computer disc storage? |
B |
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All of the following are advantages of PACS systems except: |
D |