Print Chapter 15 Display and Image Storage flashcards

Chapter 15 Display and Image Storage

front 1 Displays	back 1 A television tube, which is a special form of cathode ray tub (CRT), is a glass vacuum tube shaped like a funnel.
front 2 Electrons	back 2 charged particles
front 3 How does CRT work?	back 3 electrons fly through electronic controlled, time-varying magnetic fields that focus and seep the electron beam across the inside of the wide end of the tube. The interior surface of the screen is coated with phosphors, which glow when struck by electrons
front 4 Fields	back 4 525 closely-spaced lines.

front 5 Odd fields	back 5 The electron beam first writes the odd fields within 1/60 of a sec
front 6 Even fields	back 6 After the odd fields are written the electron beam writes the even fields within 1/60 of a sec or 60 Hz
front 7 Frame	back 7 is the combination of one odd field and one even field time is 1/30 of a second or 30 HZ or 60 Hz
front 8 interlaced	back 8 the way television are written with odd and even fields

front 9 Why are CRTs interlaced?	back 9 Humans can detect flicker in non-interlaced displays with frame rates 30 Hz, but not with an interlaced field of 60 Hz
front 10 Bistable	back 10 Bi means 2 bistable images are composed of only two shades Black and White
front 11 Grayscale	back 11 present multiple levels of grey white, light grey, dark grey etc.
front 12 contrast	back 12 user control determines the range of brilliances within the displayed image.

front 13 High contrast	back 13 bistable images with only black and white
front 14 Brightness	back 14 determines the brilliance of the displayed image.
front 15 Scan converter	back 15 store information and later display The scan converter translates the information from the spoke format into the video format.
front 16 writing	back 16 storage of the image information

front 17 read	back 17 image information is converted from the scan converter for display on CRT
front 18 Digital Scan converters	back 18 scan converters that use computer technology rather than older analog
front 19 Analog numbers	back 19 real world unlimited # of choices continuous value
front 20 Digital numbers	back 20 computer world limited choices discrete values

front 21 matrix	back 21 picture divided into millions of tiny dots, each containing an electrical storage item. The electrons stored in the bucket are read to retrieve the image.
front 22 silicon wafer dielectric matrix	back 22 matrix at the larger end of CRT tube where images are stored
front 23 Spatial resolution	back 23 image detail excellent - large number of storage units within the matrix
front 24 Limitations of analog scan converters	back 24 Image fade - stored charges on the silicon wafer dissipate over time Image flicker - caused by switching between read and write modes instability - picture quality depends on many factors including length of use, room temp, and humidity Deterioration - image degrades as the device ages.

front 25 Advantages of digital scan converter	back 25 Uniformity - consistent grayscale quality throughout the image. Stability - does not fade or drift Durability - not affected by age or heavy use Speed - nearly instant processing Accuracy - error free
front 26 Pixel	back 26 picture element smallest building block of an element
front 27 Pixel Density	back 27 is the # of pixels per inch
front 28 improves with Higher pixel denesity	back 28 Spatial resolution

front 29 Low Pixel Density vs. High Pixel Density	back 29 Low Pixel Density -few pixels/inch -larger pixel -less detail image -lower spatial resolution High Pixel Density -many pixels/inch -smaller pixel -more detail image -higher spatial resolution
front 30 Bit	back 30 is the smallest amount of computer memory a bit is bistable, having values of either 0 or 1
front 31 Binary Number	back 31 is a group of bits and is simply a series of zeroes and ones 0101010011
front 32 Decimal numbers	back 32 used in everyday life are based on ten choices 0 through 9

front 33 byte	back 33 is a group of eight bits of computer memory 10011111
front 34 word of computer memory	back 34 made up of two bytes or 16 bits
front 35 Fewer bit per pixels	back 35 fewer shades of grey degraded contrast resolution
front 36 more bit per pixels	back 36 more shades of grey improved contrast resolution

front 37 Calculating the number of gray shades	back 37 raise 2 by the power of (# of bits)
front 38 What is the number of shades that can be represented by 3 bits?	back 38 8 different shades of gray 2 * 2 * 2 = 8
front 39 What is the number of shades that can be represented by 8 bits?	back 39 256 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 = 256 2^8
front 40 How many bits are needed to store 10, 11, and 15 shades of grey?	back 40 4 4 bits are required to store 9 to 16 shades of grey

front 41 Analog and digital image information	back 41 1. converted from analog to digital for by the analog-to-digital scanner (A-to-D) 2. The digital information is stored in the scan converter's computer memory. Preprocessed 3. processing continues after storage 4. digital signals converted back to analog by a digital-to-analog converter (D-to-A) 5. signal is presented in the video display.
front 42 Preprocessing	back 42 any processing of the electrical signals before storage
front 43 Can the sonographer control preprocessing?	back 43 yes time gain compensation log compression write magnification
front 44 Is preprocessing reversible?	back 44 No

front 45 Postprocessing	back 45 any processing after storage in the digital scan converter
front 46 Can a sonographer control postprocessing?	back 46 yes
front 47 is post processing reversible?	back 47 yes any change after freeze frame black/white incersion read magnification contrast variation
front 48 magnification	back 48 enlarging a portion of an image to fill entire screen

front 49 ROI	back 49 region of interest
front 50 Read magnification	back 50 occurs after storage in the scan converter the system reads and displays only the original data pertaining to the ROI * Spatial resolution is not changes because the number of pixels is unchanged
front 51 Write magnification	back 51 applied during data acquisition, before storage in the scan converter 1. scans an image 2. converted and stored 3. ROI identified 4. image discarded re-scan only the ROI and writes new data increased number of pixels in the image improves spatial resolution
front 52 Can write magnification improve temporal resolution?	back 52 yes if the ROI is shallower than the original image's DOV

front 53 Read magnification vs. write magnification	back 53 Read magnification -uses old data -post processing -larger pixels -same # of pixels -unchanged spatial resolution -unchanged temporal resolution Write magnification -uses new data -pre processing -smaller pixels -more pixels -improved spatial resolution -possible improved temporal resolution
front 54 Paper Media	back 54 Examples -charts from pen writers Advantages -portability -does not require device to read Disadvantages -bulky, hard to store -difficult to make copies -cannot display dynamic images
front 55 Magnetic Media	back 55 Examples -CD -computer memory -magnetic tape -video tape Advantages -can be erased by strong magnetic fields -store huge amounts -can store and play dynamic images -can record color Disadvantages -can be erased by magnetic field
front 56 Chemically mediated photographs	back 56 Examples -photographs -flat film -multiformat camera film Advantages -high resolution -accepted in the medical community -can produce color images Disadvantages -bulky, hard to store and retrieve -requires chemical processing -atifacts can arise from dirt or chemical contamination

front 57 Optical Media	back 57 Examples -laser disc -compact disc Advantages -store huge amounts -inexpensive -not erased by exposure to magnetic field Disadvantages -require a display system -No standardized format for image display and storage
front 58 What is a PACS system?	back 58 picture archiving and communications system describes the digital ultrasound laboratory in which images and reports are digitized and stored on a large computer network.
front 59 PACS advantages	back 59 instant access no degradation store and forward
front 60 What is magneto-optical storage?	back 60 Magneto-optical, or M-O storage is based on a combination of magnetic and laser (optical) technology. PACS often uses M-O disc storage.

front 61 M-O Storage advantages	back 61 store large amounts high degree of security - not erased by magnetic field
front 62 All of the following are true of ordinary cathode ray tubes except: A) it contains large vacuum tubes with a phosphor-coated screen B) Electrons are emitted by a gun and swept across the screen by varying magnetic fields C) There are 600 horizontal scan lines from top to bottom, painted in order from 1 to 600 D) There are 60 fields generated each second that combine into 30 frames per second	back 62 C) There are 600 horizontal scan lines from top to bottom, painted in order from 1 to 600 normal CRT creates images using 256 horizontal scan lines that appear on the screen iin an interlaced format
front 63 Which of the following correctly describes a typical television display? A) interlaced B) progressive scan C) bistable D) non-interlaced	back 63 A) interlaced
front 64 Which electronic component is required for grayscale imaging? A) VCR B) non-interlaced C) computer memory D) scan converter	back 64 D) scan converter

front 65 All of the following are disadvantages of analog scan converters except: A) image fade B) low-resolution image C) image filter D) deterioration	back 65 B) low-resolution image
front 66 Which of the following scan converters will provide the best spatial resolution? A) digital with 256 x 256 pixels B) digital with 512 x 512 pixels C) digital with 128 x 128 pixels D) digital with 1000 x 1000 pixels	back 66 D) digital with 1000 x 1000 pixels
front 67 How many gray shades can be represented by a group of * 4 bits? * 2 bits?	back 67 4 bits = 16 shades 2 * 2 * 2 * 2 = 16 2 bits = 4 shades 2 * 2 = 4
front 68 Which of the following statements regarding a pixel is false? A) smallest part of a digitized image B) a collection of bits, assigned to each pixel, stores the shade of gray. C) it displays up to 3 gray shades, simultaneously D) image quality is improved when the number of pixels is high	back 68 C) it displays up to 3 gray shades, simultaneously

front 69 Are the following procedures usually pre- or post-processing? A) modifying a frozen image B) read zoom C) write zoom D) adjusting the brightness on the CRT E) increasing the receiver gain	back 69 post A) modifying a frozen image post B) read zoom pre C) write zoom post D) adjusting the brightness on the CRT pre E) increasing the receiver gain
front 70 Are the following forms of information usually digital or analog? A) the signal from the transducer to the receiver B) the input signal to the digital-to-analog C) the output signal from the analog-to-digital D) the input signal to the analog-to-digital E) the output signal from the digital-to-analog F) a typical video signal	back 70 analog A) the signal from the transducer to the receiver digital B) the input signal to the digital-to-analog digital C) the output signal from the analog-to-digital analog D) the input signal to the analog-to-digital analog E) the output signal from the digital-to-analog analog F) a typical video signal
front 71 All of the following are characteristics of write magnification except: A) pre-processing function B) more pixels in the region of interest C) identical regions stored in the scan D) it is the preferred method of image magnification	back 71 C) identical regions stored in the scan
front 72 What is the primary disadvantage of video tape and computer disc methods of image archiving? A) these methods are very costly B) the information is vulnerable C) only low resolution images are stored D) only black and white images are stored	back 72 B) the information is vulnerable

front 73

All of the following are advantages of PACS systems except:

A) data will not deteriorate over time
B) images can be delivered to distant locations on the imaging network
C) older, achieved studies and reports can be reviewed easily
D) images have higher resolution than what appears on the system's display

back 73

D) images have higher resolution than what appears on the system's display

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Chapter 15 Display and Image Storage