Card Set Information

2012-10-25 22:36:35
PACS kortney21

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  1. 3 major categories of QC tests?
    • 1. acceptance testing
    • 2. routine maintenance
    • 3.Error maintenance
  2. Qc standard for image acquisition, processing, & equipment maintenance all contribute to?
    TQM or CQI
  3. Radiation physicsts responsibilities?
    • 1. maintain base-line values
    • 2.exposure trends
    • 3.reject rate analysis
    • 4.QC record review
    • 5.Service history analysis
  4. Preventative maintenance performed by service personnel (QC) responsibilities?
    • 1. Xray generator tube
    • 2.CR reader
    • 3.Phosphor accuracy testing
    • 4.Image processing functions
    • 5.image display testing
    • 6.reader erasure functions
    • 7.spatial frequency response testing
  5. preventative maintenance takes place how often?
  6. PM
    preventative maintenance
  7. Monthly QC duties for technologists?
    • 1. reject analysis 
    •   a)reject reasons
    •   b)positioning errors
    •   c)marker errors
    •   d)Equipment malfunction errors
    • 2.clean imaging plates
    • 3.artifact identification 
    • 4. problem reporting
  8. The complicated & delicate nature of digital equipment necessitates?
    frequent & consistent oversight to avoid errors & unnecessary pt exposure
  9. 3 areas that define digital image quality?
    • 1.contrast
    • 2.resolution
    • 3.noise
  10. CQI?
    continuous quality improvement
  11. TQM?
    total quality management
  12. The following QC activities should take place?
    • 1.Daily & monthly/ quarterly monitor QC
    • 2.Printer image quality
    • 3. speed assessment
    • 4. Data QC
  13. Compression protocols need to be established by?
    radiologists & radiation physicist
  14. PACS CQI
    • 1. recognition of undiagnostic Images 
    • 2. System up-time
    • 3.System training
  15. Compression is used to reduce?
    the size of the image files to increase the speed of the network transfer of the images
  16. Another test for data integrity is?
    periodically pull up images from the archive to make sure the same images sent initially are still in the study after archival
  17. A constant measure to be monitored is?
    whether all images completed @ the modality make it to PACS
  18. Image transfer speed should be monitored?
    from the modality to PACS & from the archive to a workstation
  19. Dry laser Imager Daily/weekly QC?
    • 1. Monitor each film
    • 2.print test patteren
    • 3.observe the printed test
    • 4.measure steps using densitometer
    • 5. complete prventative maintenance
  20. wet Laser Imager Daily/ weekly QC?
    • 1. monitor each film
    • 2.paint a test pattern from PACS
    • 3.observe-steps of test pattern
    • 4.measure- steps of test pattern
    • 5. monitor- processing mechanism
    • 6.complete all preventative maintenance
  21. photometer
    device used to measure the luminescence of areas on the monitor
  22. The highest quality monitors are?
    the radiologist workstation
  23. The Joint Commission is formerly known as?
    the joint commission on the accreditation of Healthcare organizations (JCAHO)
  24. Most health care institutions are accredied by?
    the joint commission (TJC)
  25. TJC is?
    voluntary but necessary to obtain medicaid certification, hold certain licenses, obtain reimbursement from insurance companies & recieve malpractice insurance
  26. CQI?
    continuous quality improvement
  27. TQM?
    total quality management
  28. QUality assurance?
    a plan for the systematic observation & assessment of the different aspects of a project, service, or facility to make  certain that standards of quality are met
  29. QA services are focused around what?
    people & service
  30. Most QA activities will produce?
    quantitative data that can be analyzed
  31. Quantitative data can be used for what?
    to monitor the processes & determine whether the process is working as it should & whether the standard of quality has been met
  32. Quality Control?
    a comprehensive set of activities designed to monitor & maintain systems to produce a product
  33. Why are QC measurements taken?
    • ~ensure procedures are performed safely 
    • ~appropriate for the pt
    • ~performed efficiently
    • ~produce a high-quality image
  34. Why are tests performed on a room?
    make sure that all the parts are functioning properly such as the collimator, generator & focal spots
  35. _________ measures are required by law to maintain the license for the room or dept.
  36. Most QC activities are part of what?
    a QA program
  37. Monitor has a direct effect on?
    quality of the image that is presented to the radiologist for reading or to the referring physician
  38. Often the weakest link in the digital imaging chain?
    the monitor
  39. AAPM suggests that testing be performed?
    on acceptance & annually
  40. ACR suggests QC tasks be performed?
    atleast monthly
  41. What test is performed to ensure continuity of measurements?
    society of motion pictures & television engineers test pattern
  42. ACR?
    American college of Radiology
  43. What is the most important concept to understand with CQI?
    all levels of people within the organization must be involved in the process of improvement
  44. CQI focuses on?
    improving the process or system within which the people function as team members rather than focus on an individuals work
  45. The QA/QC programs focus on?
    maintaining a certain level of quality, not improving to a higher quality
  46. If the process is good?
    healthcare workers will follow it and service will be good 
  47. Continuous Quality Improvement?
    focuses on process rather than people
  48. Error maintenance?
    • ~if corrective action must occur
    • ~performed by service personel employed by the vendor
  49. Acceptance testing is used?
    to determine whether the equipment is performing within the vendors specifications as promised
  50. When is acceptance testing performed? By whom?
    ~Before newly installed or majorly repaired equipment can be accepted by the dept

    ~Designated tech, radiation physicist, or service personnel
  51. Digital imaging systems have _______ DQE latitude than screen/film systems?
  52. Each pixel contains a photodiode and does what?
    generates electrical charges

    absorbs light from scintillator
  53. What is spatial frequency resolution?
    detail or sharpness
  54. In direct conversion DR TFT;the info is?
    discharged onto the data colums & is read out with dedicated electronics
  55. DR technology has increased DQE over CR bc it does not have the _______ conversion step & bc of this, less dose is required than for CR & higher Quality images are produced?
    light (no light increase)
  56. In flat- panel detectors that use indirect conversion technology convert _______ to _______ _______.
    xray photons to electrical signals
  57. DR is what?
    • ~hard-wired
    • ~cassetteless
    • ~detectors are permanently enclosed inside a rigid protective housing
  58. WHat if the transistor that includes a photosensitive array and small pixels?
    thin-film transistor
  59. Low KVp gives a _______ histogram & high Kvp gives a ______ histogram?
    wider; narrower
  60. Process of direct capture dtectors?
    • 1.xray photons are absorbed by the material
    • 2.Photons are immediately converted into an electrical signal
    • 3. Electrical signal is detected by TFT array
  61. What is high-pass filtering?
    when frequencies of areas of interest are known, those frequencies can be amplified & other frequencies suppressed
  62. Loss of detail in a digitally processed image occurs bc of the number of conversions. T of F.
  63. Excessive digital processing can affect spatial resolution in cassetteless system which can lead to what?
    excessive noise
  64. Exposure latitude for digitally imaging is less than that of film/screen imaging. T or F.
    false; greater
  65. Archive Query?
    software function that allows historical info to bo gathered from digital storage, such as multiple exams, a range of dates, or by pathology
  66. Typically, ________ pixels/ row are adequate for most diagnostic examinations?
  67. Specialized silicon integrated circuits are?
    connected along the edges of the detector matrix

    (Direct conversion DR TFT)
  68. Used to describe images recorded on an electronically readable device?
    digital radiography
  69. The DR plate has a radiation-conversion material or scintillator typically made of a- Se. This material absorbs x-rays & converts them to electrons, which are stored in the ______ detectors?
    TFT detectors thin-film transistor
  70. When dealing w/ Amorphous  silicon detectors photodiodes are coated with what?
    • a crystalline cesium iodide scintillator
    • a rare-earth scintillator
  71. field-effect transistor?
    • Isolates each pixel element
    • reacts like a switch to send the electrical charge to the image processor
  72. TFT?
    thin film transitor
  73. A histogram displays the useful signal by locating the ______ (S1) and _______ (S2) signal within the anatomical region of interest on the image.
    minimum (S1); maximum (S2)
  74. Explain edge enhancement
    occurs when fewer pixels in the neighborhood are included in the signal average; the smalle the neighborhood, the greater the enhancement
  75. explain what you would do to the Look-up table (LUT) to increase or decrease contrast & what you would do to change the brightness (MAS)?
    • contrast=by changing the slope of the graph
    • brightness=by moving the line up or down the y-axis
  76. Image stitching?
    process of "sewing" together mulitiple image to form one continuous image
  77. If too few pixels are sampled, the result will be _______ resolution?
  78. MTF?
    • (modulation transfer function) 
    • ability of a system to record available spatial frequncies
  79. A device that acts like a camera in an indirect conversion detector is known as ______ _______ device.
    charge-coupled devices (CCDs)
  80. Which of the following has the greatest spatial resolution?
    film/screen radiography
  81. Pixel pitch refers to the ?
    the spacing between the pixels 
  82. DR includes?
    computed radiography & direct or indirect methods of digital image capture
  83. An FET or silicon TFT does what?
    • isolates each pixel element
    • reacts like a switch to send the electrical charges to the image procssor
  84. Flat-panel detectors consists of?
    a photoconductor such as amorphous selenium, which converts the xray photons directly into electrical signals
  85. Flat-panel detectors consists of?
    a photoconductor such as amorphous selenium (converts the xray photons directly into electrical signals)
  86. When dealing with Amorphous silicon detectors, the light photons are?
    converted into an electric charge by the photodiode arrays
  87. The device that acts like a switch to send electrical charges to the image processor; Also isolates each pixel?
    field-effect transistor (FET)
  88. Explain smoothing (AKA low-pass filtering)
    smoothing occurs by averaging each pixel's frequency with surrounding pixel values to remove high-frequency noise
  89. How efficiently a system converts the x-ray input signal into a useful output images(this is the measurement of the percentage of x-rays absorbed) is known as?
    detective quantity efficiency (DQE)
  90. Data collected within the collimated area is represented by a ________?
    the vendor- specific exposure data
  91. Amorphous selenium? 
    Holds a charge on its surface that can then be read out by a TFT
  92. During Indirect conversion light strikes the amorphous silicon allowing what?
    the conduction of electrons into the detector
  93. Automatic rescaling means that images are produced, regardless of the amount of exposure with uniform contrast  & density. T of F. 
    False; with uniform brightness & contrast
  94. A line of TFT switches allows?
    electrical charge info to discharge when switches are closed
  95. Each pixel contains what?
    a photodiode
  96. What is image sampling? 
    amount of information gathered from pixel storage
  97. The DQE of detectors changes with changes in _____?
  98. What does the transport layer of the OSI model do?
    makes sure data packets are sequenced correctly and that they do not contain errors
  99. In conventional radiography  was film used or phosphor plates?
  100. What are the different parts that make up a PACS system?
    • reading stations
    • physician review stations
    • web-access
    • tech quality control stations
    • administrative stations
    • archive system
    • interfaces
  101. A network in which all devices are physically attached to & listen for communication on a single wire
  102. Special type of memory chip that uses small rechargable or lithium battery to retain info about the PCs hardware while comp. is on?
  103. BIOS oversees what?
    the basic functons of recieving & interpretting signals from the keyboard & interchanging info with various ports
  104. CMOS?
    complementary metal oxide semiconductor
  105. In CR & DR mAs has more influence on what?
    Image processing LUTs
  106. With conventional radiography density is controlled by?
  107. What are some common In-put devices?
    • keyboard
    • mice
    • microphones
    • bar code readers
    • touch screens
    • image scanners
  108. CPU stands for what?
    central processing unit
  109. What are the 3 main types of CD/DVD drives available in todays market?
    • ROM (read-only memory)
    • R (write once-read many)
    • RW (read & write many times)
  110. In CR & DR, contrast is primarily controlled by?
    linear, wide exposure latitude; kvp & LUTS
  111. In conventional  radiography contrast is primarily controlled by what?
    kvp & film response curve
  112. What are the components of the motherboard?
    • CPU basic input
    • output systems
    • memory
    • bus ports
    • complementary metal oxide semiconductors (CMOS)
  113. The intermediary between the operating systems & the hardware?
  114. a computer that manages resources for other computers,servers, & networked devices; many also house applications, provide storage for files or manage various other  networked tasks
    a server
  115. CPU?
    a small chip found on the motherboard
  116. Aspect ratio?
    the ratio of the width of the monitor to the heighth of the monitor
  117. What are the different types of monitors?
    • cathode ray tube (CRT)
    • liquid crystal display (LCD)
    • plasma screen
  118. Operating system?
    the software that controls the computer hardware & acts as a bridge between applications  & hardware
  119. The measurement of how close the dots are located to one another within the pixel;
    smaller the dot the finner the resolution
    dot pitch
  120. Small area of network with a series of cables & wireless access points that allow comp. to share info & devices on the same network(much faster)
  121. In Direct Capture, typically using a photoconductor for what?
    as the xray absorber & send the electrical signal to the computer for processing & viewing
  122. CR was first introduced commercially in the United States by whom?
  123. In what decade was MRI first introduced? CT?
    early 1980's; 1970's
  124. What was the last modality to incorporate digital imaging?
  125. What is used in Radiology?
    CRT; bc of its superior resolution
  126. Scatter radiation is more sensitive with what type of system?
    DR & CR
  127. Where was the first full scale PACS system?
    VA medical center in Baltimore in 1993
  128. What is WAN?
    • *wide area network
    • A network that spands a large area-city, state nation, continent or world
  129. Resolution?
    number of pixels on a display
  130. digital imaging & communication tech standard that allows network communication between modality & PACS?
  131. No computer has ultimate control over another, this describes what?
  132. 2 types of keyboards are?
  133. centralized computer that controls the operations of the network
    client based
  134. Has a centralized storage & retrieval on the network
    server based
  135. What does PACS stand for?
    picture archival & communicaton system
  136. An individual collection of dot triads (a group of one red, green, & blue dot)
  137. Device with 2/3 buttons that allows the user to move comp cursor to activate & perform function within software?
  138. What is digital radiography/
    cassetteless system
  139. Explain indirect capture?
    devices absorb x-rays
  140. provides interface between the network & computer
    network interface
  141. DICOM is accepted where?
    almost universally accepted standard for exchanging medical images amoung networked medical devices
  142. sends data only to devices to which the data are directed
    network switch
  143. A physical  wired connection from one network segment to another?
    network bridge
  144. Advice found on a network that requests services & resources from a server?
  145. Sound card can be in what form?
    expansion card or built in 
  146. DICOM
    digital imaging & communications in medicine
  147. The network layer breaks up data & what?
    decides which network path the frame will take to its destination
  148. Network card
    • *AKA* network interface card*
    • will have an RJ-45 adaptor jack @ the rear of PC
    • enables PC to connect to other on same network
  149. What advantage does DR  have over conventional & CR?
    • It is done right at the room's console
    • Images appear in 3 to 5 seconds (this allows the tech to know if the image needs to be repeated)
  150. With PACS you can review stations from where?
    In other departments in the hospital
  151. LUT stands for what?
    Look-up table
  152. A programmable electronic device that can store, retrieve, & process data?
    a computer
  153. What is a binary code based on?
    1s & 0s
  154. Delivers all electricity to the PC & contains a fan to cool the computer & also contains transformer that converts the current to the appropriate one for that device?
    power supply
  155. Main repository for programs & documents on a PC
    Hard drive
  156. DR takes how long for the image to appear?
    3 to 5 sec
  157. What is the most common connection medium for a LAN?
    Twisted-pair wire (cat 5)
  158. What are real-time operating systems found?
    modern  x-ray equipment
  159. 2 or more objects sharing resources?
    a network
  160. What are the 2 component role classifications?
    peer-to-peer (considered equal)

    server/client based
  161. Explain the processing of film in conventional radiography?
    • Image processed by chemicals
    • Image appearance based on tech factors & film/screen combination
  162. What are some of the image processing capabilities that the PACS reading stations can have?
    It allows Radiologists  to remain @ their workstations & do 3D reconstructions of a CT, stitch a complete spine together to perform specialized measurment functions for scoliosis, some orthopedic surgeons can plan jt replacement surgery before even beginning the operation
  163. What is another name for exposure latitude?
    dynamic range
  164. Maps the image gray scale values into some visible output intensity on a monitor or printer film?
  165. Most modern computers use?
    • SDRAM-DDR 
    • ~for higher graphics some may use RDRAM
  166. What are some factors to consider when designing a PACS system for an institution?
    • volume of pts
    • #of areas where images are interpreted
    • locations where images are viewed by physicians other than radiologists
    • money available for purchase
  167. Output devices?
    • monitors
    • printers
    • speakers
  168. Indirect capture converts energy into what?
    converts into light
  169. What is the info highway of the computer?
  170. A PC with a 3.0-GHZ CPU would have a system clock that would what?
    tick 3 billion times per sec
  171. Most modern keyboards connect using what kind of connection into the back of the box?
    IBM programming system 2 (PS/2) connection
  172. What is a box?
    the computer encasement mode from a heavy metal
  173. What is the most fragile type of network connections?
    fiberoptic cable
  174. What was the early storage capacity?
    10 WB could be accessed in about 80 ms
  175. Information storage capacity of a DVD is what?
    • 9.4 single sided 
    • 17 GB double sided
  176. Converts the incident xray energy directly into an electrical signal
    direct capture
  177. What is known as the brain of the computer?
    central processing unit (CPU)
  178. Computer that can work independently of the network & process & manage its own files
  179. Explain the processing of the film in CR?
    • Processed by light
    • Takes place in a quality control station based on preset image algorithms
  180. The personal computer's box (AKA microprocessor)
  181. The measurement of how fast the monitor rewrites the screen or the # of lines that the image is redrawn on display each sec
    refresh rate
  182. RAM?
    random access memory
  183. Why would some keyboards use a USB?
    bc of its versatility & ease
  184. What is the current capacity?
    • modern-100GB
    • access speed of 8.7 ms
  185. Different types of RAM are?
    • DRAM
    • EDO
    • RAM
    • VRAM
    • SRAM
    • SDRAM
    • SIMM
    • DIMM
    • ECO
  186. What are found in configurations?
  187. Give examples of bytes?
    128 MB, 512MB & 1GB
  188. What is the location of the system clock?
  189. Which 2 modalities were easily converted to digital imaging?
    ultrasound & nuclear medicine
  190. A series of connections, controllers, & chips that creates the info highway of the computer
  191. Contains all the circuitry 4 recording & reproducing sound on the PC
    sound card
  192. A rectangular or square table of #s that represent the pixel intensity to be displayed on the monitor
  193. What are the 2 major geographic categories for networks
    • local area network (LAN) ~~~ Least expensive
    • WAN- wide area network
  194. What does the network interface plug into?
    The motherboard
  195. Network in which the devices are connected  in a circle
  196. What is the biggest advantage of wireless networks?
    mobility & convenience
  197. Agreed on set of rules that allows data to travel along the network; most send in packets from one device to another 
    network protocol
  198. made by using either infrared or radio frequencies as its means of communication
    wireless connections
  199. Cable that is similar to telephone wiring
    Coaxial cable
  200. Coaxial cable is used for what? where is it found?
    cable television that is run into a house; in the network infrastructure throughout a building

    ~sturdiest wire used~
  201. faster then its metal counter parts, more expensive & much more fragile; uses glass threads to transmit data on the network consists of a fiberoptic core that is surrounded by a plastic protective case
    fiberoptic cable
  202. similar to a telephone wire,except it consists of four twisted pairs of copper wire that are insulated & bundled together with an RJ-45 terminator
    twisted-pair wire
  203. Temporary memory?
  204. Memory is measured in?
  205. When is the BIOS used?
    contains a simple set of instructions for the computer used by the micrprocessor during the boot up process of the comp. to help bring it to life

    also runs the start-up diagnostics to make sure the peripherals are functioning properly
  206. BIOS=
    Basic input/ output systems
  207. Memory is generally talked about in?
    • kilobytes
    • megabytes
    • gigabytes 
    • terabytes
  208. the largest circutory board inside the computer
  209. What are the functions of a box?
     holds the components in a relatively cod, clean, & safe environment

    should the outside environment from the ratio frequncies being emitted by the electronic components of the computer
  210. Made up of 8 bits & is the amount of memory needed to store one alphanumeric character
  211. a single unit of data
  212. A machine language
    binary code
  213. A collections of connectors sticking out of the back of the PC that link adaptor cards, drivers, printers,scanner,keyboards,mice, & other peripherals
  214. How is conventional radiography & CR similar?
    both use cassette & are rated the same in the terms of ease & efficiency
  215. A bucky apparatus is replaced w/ what?
    a detector 
  216. the digital acquisition modality that uses storge phosphor plates to produce projection images (cassette-based)
    computed radiography
  217. moving images via telephone lines to & from remote locations
  218. Digital imaging was first used with what? By whom?
    the intro of the computed tomography; Godfrey Hounsfield
  219. Used to store info currently being processed with the CPU?
    memory of the computer
  220. Early PACS were developed by whom?
    U.S. military
  221. Digital imaging?
    an electronic image that can be viewed & manipulated on a comp; can be sent through a couputer network to a host of locations
  222. What is the 1st step in acquiring an Image in CR?
    the remnant beam interacts with electrons in the barium fluorohalide crystals contained within the imaging plate 
  223. when the exposure is made, this interaction gives energy to electrons in the crystals allowing them to enter the conductive layer where they are trapped in an area of crystals known as the color or phosphor center~ this describes which step in acquiring an image?
    Step #2
  224. The cassette is fed into a reader that removes the imaging plate from the cassette & scans it w/ a laser to release the stored electrons~ this describes which step in acquiring an Image in CR?
    Step #3
  225. the atoms or molecules of a crystal are excited so that more of them are at high energy levels rather than low energy levels~ this describes which step in aquiring an image?
    Step #4
  226. Surfaces at both ends of the laser cantainer reflect energy back & forth as atoms baombard eachother , stimmulating the lower energy atoms to emit secondary photons the same frequency as the bombarding atoms~this describes which stpe in acqiring an image?
    step #5
  227. As the energy builds, the atoms discharge as a burst of coherent light~this describes which step in acquiring an image?
    Step #6
  228. Laser beam passes through beam-shaping optics to an optical mirror thaat directs the laser beam to the surface of the plate~ this describes which step in acquiring an image?
    step #7
  229. The gray level is determined by what?
    how many photons struck the imaging plate in that particular location
  230. The image is digitized by?
    position & by intensity
  231. Explain what the phosphor center is?
    electrons are trapped in an area of crystal
  232. Grid construction can be described by what?
    grid frequency & grid ratios
  233. Typical # of pixels in a matrix can range from?
    2500 X 2500
  234. Each pixel contains bits of info & the # of bits per pixel defines the shade of each pixel & this is known as?
    bit depth
  235. Where is info about a grids construction?
    tube side of grid
  236. What happens as the plate moves through the reader?
    it is scanned multiple times & this is called translation
  237. Horizontal white lines may be caused by?
    dirt on the light guide in the plate reader
  238. In conventional Radiography how is speed determined?
    by the size & layers of the crystals in emulsion
  239. What is the exposure indicator number?
    how much radiation is absorbed by the plate or in pt
  240. The latitude value of the histogram is fixed & only a small reading is used~ this describes which mode?
    Semiautomatic mode
  241. What happens if you use the wrong imaging plate size?
    decrease in resolution
  242. Using an imaging plate that is much larger than the part being examined will _______ resolution?
  243. Exposure indicator for Agfa?
  244. What causes quantum mottle?
    a grainy appearance due to insufficient light being produced
  245. What will the image look like if you have insufficient light produced by the imaging plate phosphor?
    grainy/quantum mottle
  246. Do you use more Kvp with conventional radiography screens or CR systems?
    CR systems
  247. What is the range of kvp that can be used with CR?
  248. In the early days of CR, what the kvp values set at?
  249. kvp must be chosen for _______ & the type & amount of ________ desired?
    penetration; contrast
  250. CR Imaging plates are erased by what?
    flooding the plate with bright light
  251. How often should imaging plates be erased?
    every 48hrs
  252. Typical cassette through put is?
    50 cassettes/ HR
  253. The process of scanning the moving imaging plate?
  254. The laser scans the imaging plate in what kind of pattern?
  255. The laser beam passes through _______ to an optical mirror that directs the laser beam to the surface of the imaging plate?
    the optics
  256. Coherent light is formed by the laser bc the photons travel in what direction?
    same direction
  257. During laser beam formation, both ends of laser energy back & forth so that the atoms _______ eachother?
  258. What is the purpose of the barcode label?
    for pt info
  259. In which type of grid pattern could a cross table work?
    linear Grid pattern
  260. Crossed or cross-hatched?
    lines that run @a rt angle to one another
  261. Lead lines run in only one direction in which Grid?
    Linear grid
  262. Most popular grid pattern? Why?
    Linear grid; allows for angulation of the tube along the length of lead lines 
  263. What are the 2 types of grid pattern?
    • linear
    • cross-hatched
  264. The linear pattern of the lead lines of a grid are?
    Grid pattern
  265. What is the ratio of the height of the lead strips to the distance between them?
    grid ratio
  266. What separates lead lines?
    radiolucent interspace material typically made of aluminum
  267. When is a grid used?
    when the anatomic part being imaged is 10cm or more (knee) & more than 60 kvp is appropriate for the exam
  268. The more shades of gray, the more what?
    detail the image can display
  269. Kilovoltage peak, mAs & distance are chosen in exactly the same manner as for ______  _____ radiography?
    film screen
  270. Grid frequency?
    number of lead lines per unit length in inches, centimeters or both
  271. Which type of grid requires more beam centering?
  272. Relationship between height of strips & space between them?
    grid ratio
  273. Image recognition is accomplished through complex mathematical computer algorithms, and if the improper part of position is selected the image will be displayed improperly. It results in improper______ & ______?
    contrast & density
  274. Histogram is?
    numerical values of the xray exposure
  275. Shuttering is?
    black backgrounds is added (post exposure manipulation)
  276. Collimation to a smaller area does what to Compton interaction?
  277. Grid lines per inch is what?
    grid frequency
  278. What type of grid info is located on the tube side?
    • type of interspace material used
    • grid frequency
    • grid ratio
    • grid size
    • info about the range of SID
  279. Grid use for CR examinations is more critical  than in film/screen radiography  bc CR....
    imaging plates are very sensitive to scatter radiation
  280. What is the moire' artifact in what & why?
    • if the grid lines & scanning layer are parallel
    • they should be perpendicular
  281. The higher the # of pixels in a matrix, the higher the what?
    image resolution
  282. What happens as the # of pixels in a matrix increases?
    • the smaller the pixels have to be to fit into that area
    • the smaller the pixels
    • the greater the spatial resolution
  283. The electronic signal is digitized by?
    an analog to dogital converter
  284. Why are mirrors used?
    to ensure that the beam is positioned consistently
  285. Translation can be divided into 2 directions?
    slow scan direction

    fast scan direction
  286. The trapped electrons escape what layer?
    active layer
  287. The red light scans the plate is what pattern?
    a raster pattern & gives energy to the trapped electrons
  288. What scans the imaging plate?
    the laser
  289. What directs the laser beam to the imaging plate surface?
    the laser beam passes through beam shaping optics to an optical mirror that directs the laser beam to the surface of the plate
  290. What is spatial resolution?Lower in cassette-based or CR?
    detail; lower in cassette based
  291. Each pixel contains bits of information called?
    bit depth
  292. If a pixel has a bit depth of 8, then the # of gray tones that pixel can produce is?
    2 to the power of the bit depth or 256 shades of gray
  293. Some CR systems have bit depths of?
    • 10 or 12 resulting in more shades of gray
    • 2 to the power of 12 would result in 4096 shades of gray
  294. The bit depth is a factor in determining what?
    the quality of the image
  295. A bit value of 21 or one represents what?
    a black & white image
  296. When was the grid invented? By whom?
    1913; Gustave Bucky
  297. What is a grid?
    device that has very thin interspaced lead strips intended to absorb scatter radiation emitted fom the pt b4 it strikes the IR
  298. Grids are made up of what?
    lead strips or lines that have a precise height, thickness, & space between them
  299. Grid ratio formula?
    Grid ratio=h/D
  300. Why should good collimation practices be applied?
    bc if its bad it affects the histogram
  301. Exposure indicator for Fuji?
    S or sensitivity number
  302. High-ratio grids do what?
    remove or clean up more scatter radiation than lower-ratio grids & increase contrast
  303. The phosphor layer is made of phosphors for what?
    Barium fluorohalide
  304. Bit depths determine the shades of gray which the gray level is a factor in determining?
    the quality of the image
  305. What directs the laser beam to the imaging plae surface?
    the laer beam passes through beam shaping optics to an optical mirror that directs the laser beam to the surfaces of the plate
  306. Devices that create & amplifies a narrow, intense beam of coherent light
  307. Where photons are traveling in the same direction @ the same frequency?
  308. The laser light is emitted @ what?
  309. The active layer is where the electrons emit what?
    visible blue light at an energy of 3 ev as they relax
  310. The entire image is divided into what?
    a matrix of pixels based on the brightness of each pixel
  311. Logarithim of medium expose, Agfa uses
  312. ADC?
    analog to digital converter
  313. fast scan direction
    describes the movement of laser across the imaging plate
  314. Slow scan direction?
    describe the movement of the imaging plate through the CR reader
  315. 2eV is necessary for what?
    to energize the trapped electrons
  316. Backscatter from the cassette/ detector influences what from creating images?
    dark lines artifacts; grid lines
  317. When switching from conventional radiography to computed radiography? What must be adjusted? why?
    tech factors; bc we are using a difficult speed; speed changes mAs; kvp for penetration
  318. What is a laser?
    scans the imaging plate
  319. Different layers of the imaging plate?
    • protective layer
    • phosphor or active layer
    • reflective layer
    • color layer
    • support layer
    • backing layer
  320. Aliasing?
    when spatial frequency is greater than the Nyquist frequency & the sampling occurs less than twice per cycle; info is lost & a fluctuating signal is produced
  321. The layer the bit depth, the more what?
    shades of gray possible
  322. What does a beam deflector do?
    moves the beam rapidly back & forth across the imaging plate to stimulate the phosphors
  323. The ADC assigns each pixel a?
    value that corresponds to the level of brightness
  324. Fixed mode?
    • good for cross-tbl hips
    • similar to film screen
    • user selects the exposure index or sensitivity # and value of the latitude
  325. What are the components of the CR cassettes?
    • durable,lightweight plastic material
    • backed by a thin sheet of aluminum~absorbs xrays~
    • antistatic material(protects against static electricity, build up, dust,& mechanical damage)
  326. CR system speeds are a reflective of what?
    amount of PSL given off by the imaging plate
  327. What are 2 things that determines the selection of the CR cassette?
    type & size standards & high resolution
  328. Area of interest is selected by the tech & the image is derived from the selected areas imaged in semiautomatic mode~ this explains? 
    multiple manual selection mode
  329. What are other names for a laser?
    helium-neon laser beam

    solid-state laser diodes (more recent systems)
  330. Automatic data recognition mode automatically adjusts what?
    the image recording range is automatically determined & adjust reading:lattitude & sensitivity
  331. The light collection optics do what?
    direct the released phosphor energy to an optical filter & then to the photomultiplier
  332. Overexposure for carestream?
  333. Overexposure for Agfa?
  334. Underexposure for Agfa?
  335. position=
    spatial location
  336. underexposure for carestream?
    <1600 tabletop

    <1800 bucky
  337. intensity=
    gray level
  338. Support layer?
    semirigid material that gives the imaging sheet some strength
  339. Sends light in a forward direction when released in the cassette reader; may be black to reduce spreed of stimulating light & the escape of emitted light; & some detail is lost~ this describes which layer?
    reflective layer
  340. located between the active layer & the support that absorbs the stimulating light but reflects emitted light~this describes which layer?
    color layer
  341. conductive layer?
    absorbs & reduces static electricity
  342. A phosphor layer?
    • aka~active layer~
    • layer of photostimulable phosphor tht "traps" electrons during exposure
    • usually made of phosphors from barium fluorohalide family
  343. 4 common artifacts?
    • plate artifacts 
    • plate reader artifacts
    • image processing
    • printer artifacts
  344. Backing layer?
    soft polymer that protects the back of the cassette
  345. Allows the tech to match the image formation with the pt identifying barcode on the exam request? This explains what?
    Barcode label (aka barcode sticker)
  346. In Cr speed is determined by?
    size & layers of crystals in the film & screen
  347. a graphic representation of the numerical tone values of an xray exposure
    a histogram
  348. Kvp must be chosen for?
    penetration & the type & amount of contrast desired
  349. In early days  of CR, kvp minimum values were set at?
    about 70 kvp
  350. Kvp values now range from?
    around 45 to 120
  351. Quantum mottle?
    • aka quantum noise
    • when suddicient light is produced, the image is grainy
  352. Exposure indicator for carestream?
    (EI) or exposue index
  353. Collimation results in increased what? why?
    contrast; as a result of reduction of scatter as fog
  354. Bc of high sensitivity of CR imaging plate to scatter?
    using a grid is key
  355. Printer artifacts?
    fine white lines may appear
  356. What is the plate reader artifact?
    horizontal white lines caused by dirt
  357. Kvp, mAs, & distance are chosen?
    in exactly the same manner as for conventional film/screen radiography
  358. A wavy artifact caused by grid lines that are projected onto the imaging plate when using stationary grid? (Grid selection)
    • a moire' pattern
    • lines are parallel
    • should be perpendicular
  359. Underexposure for Fuji/Philips/Konica Minolte?
    • >250 tabletop
    • >400 bucky
  360. Overexposure for Fuji/Philips/Konica minolta?