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APPH 226 > PACS > Flashcards

PACS Flashcards

1
Q

PACS introduction

A
  • PACS is used to refer to a broad range of technology which is used for digital radiography
  • with a computer network, PACS allows the integration of image acquisition devices, workstations, and storage systems
  • workflow, accessibility of images (including remote access), turnaround times, and patient care
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2
Q

PACS

A
  • requires many complex components that must function collaboratively
  • in addition to the hardware and software, a necessary component of PACS is a skilled IT team to keep it running smoothly
  • techs need to have a basic understanding of PACS (networking, digital image formation, image acquisition, workstations, data storage and image distribution)
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3
Q

Networking

A

-a group of two or more computers linked together is a network
-network and PACS are two distinct entities, but they play a major role with each other
-if the network is poorly designed, it will affect the PACS system
(Techs not able to send images, radiologists are unable to view/read images, physicians unable to access images or reports)

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4
Q

Network classifications

A

-LAN (local area network)
🔹linked computers that are close together (ex in the same building)
-WAN (wide area network)
🔹computers that are further apart and must be connected by telephone lines, cables or radio waves)

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5
Q

LAN

A
  • least expensive to install, and faster than WANS due to their smaller size
  • has fastest communication technology as equipment and resources are required to complete the network
  • can have several LANS connected to create the WAN
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6
Q

WAN

A
  • network spans a large area: city, province, country, continent or world
  • used to connect computers that are not physically connected with cables, but connected through phone lines, satellite links, or other types of communication devices
  • more expensive type of network
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7
Q

Networks: peer- to - peer

A
  • aka P2P
  • popular set up for home network or small businesses
  • each party has the same capability and any party can initiate communication
  • every computer is considered equal (in control of its own information and operation)
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8
Q

Client- server based network

A

-computers are classified as either clients or servers
-centralized computer (server) that controls operations, files and sometimes computer programs (clients) that are attached to the network server
-computer that facilitates communication between and delivers information to other computers
-centralized location for storage and retrieval of information
-passive, waits for requests from other computers (clients)
🔹allows users to move from computer to computer and access files from a central location
-can accept connection from a large number of clients

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9
Q

Client-server network

A

-client
🔹can connect to a small number of servers at one time
🔹can be reffered to as a node
🔹used to request information
-the server can send entire file for processing. When completed the client sends the entire changed file back to the server for storage
-another option (client network)- instead of entire file being sent for processing, the server processes the resource as requested by the client, and only the results are returned to the client, not the entire file

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10
Q

Network components

A

Typical for three types of computers to be found on a network

  • server
  • thin client
  • thick client
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11
Q

Network components: server

A
  • manages resources for other computers, serves and networked devices
  • can also serve as data storage, house applications or perform other tasks
  • usually is dedicated to one task for the network ex print server, archive server
  • is the most robust computer on the network
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12
Q

Network components: thin client

A
  • any device found on a network that requires a server to complete its tasks
  • requests services and resources from the server
  • almost anything attached to the network can be a thin client ex computer, printer
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13
Q

Network components: thick client

A

-computer that can work independently of the network
-can process and manage its own files
-networked so that it can share resources
-typically a high end computer that does high level processing for specific purposes
Ex CT post processing, 3D reconstruction

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14
Q

Topology

A
  • geometric arrangement of computer system
  • common topologies are:
  • star
  • bus
  • ring
  • mesh
  • LAN be a combination of these
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15
Q

Bus topology

A
  • all devices are physically attached to and listen for communication on a single wire
  • single point of failure: the wire
  • if there is a break anywhere on the wire, the entire network will go down (just like if one Christmas light is burnt out)
  • all the information is broadcast and received by the computers connected to the single wire
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16
Q

Ring topology

A
  • devices are connected in a circle
  • data travels in one direction until it reaches the correct receiver (if there is a break anywhere, the network comes to a halt)
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17
Q

Star topology

A
  • devices connected to a central hub or switch
  • data sent through the hub to the destination device
  • data transmitted can be through another hub or switch to an adjacent network or directly to the device
  • most commonly used network topology
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18
Q

Mesh topology

A
  • multiple pathways to connect devices and networks
  • redundancy built in (more than one pathway between devices)
  • most often used to connect networks to other networks
  • lots of failsafes
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19
Q

DICOM

A
  • is a set of standards for medical image interchange- allows medical images to be exchanged among networked devices
  • not every device will conform to every part of DICOM, but just the parts required to perform the tasks
  • ensures all devices and equipment are speaking the same language
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20
Q

Health level seven (HL-7)

A
  • universal standards used for most clinical and administrative data
  • generally used in communication between HIS (hospital information system) and RIS (radiology information system)
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21
Q

HIS (hospital information system)

A
  • holds patients full medical information

- billing information, inpatient orders

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22
Q

RIS

A
  • holds all radiology specific patient data

- ex scheduled exams, radiologists report

23
Q

EMR

A
  • electronic medical record
  • can be part of HIS or run along side it
  • contains all the patients records
  • includes lab results, radiology reports, pathology reports, notes
  • interfaces with systems to retrieve reports to be viewed in one place
  • also interfacing with PACS to view images
24
Q

PACS fundamentals broken down into

A
  • image acquisition
  • display workstations
  • archiving
25
Q

Image acquisition

A

-images are acquired in a digital format
-can be transferred by a computer network
-allows for soft copy reporting
🔹no need for films in hardcopy for radiologist to read
-images must comply with DICOM standards

26
Q

Types of workstations

A

Hardware and software is dependent on purpose

  • review workstation (for referring physicians)
  • radiologist workstation
  • technologist workstation (QC for technologists)
  • image management workstation (file room personnel)
27
Q

Review workstation

A
  • any computer than can be used to view a digital image
  • most INTERACTIVE part of PACS
  • can be used inside and outside the department
  • receives images from the archive or modalities for viewing
  • has software to allow minor image manipulation to optimize viewing of the image
  • most common monitor configuration is 2 to 4 screens
  • LCD screens, better resolution and less heat production
  • not for the primary diagnosis (can be used by referring physicians, techs etc)
28
Q

Radiologist workstation

A
  • used by a radiologist making a primary diagnosis
  • has the highest quality hardware, and the best quality monitor- 5K minimum
  • computer hardware is usually very robust, requiring little downtime
  • generally there is access to a nearby RIS with a dictation system, or it could be connected to the PACS station
29
Q

Review workstation

A
  • step down from radiologist workstation
  • typically has the same level of software, but with some of the functions removed
  • important feature is the ability to view current and previous reports alongside the images (important for referring Drs)
  • major improvement on patient care with digital, physicians can consult, access images and radiologist reports from anywhere with PACS access vs physically meeting radiologist to consult
30
Q

Technologists workstation

A

-for reviewing images after acquisition but before sending to radiologists
-QC station used to
🔹adjust image characteristics
🔹verify demographic information
🔹often this is in the department as a pass-through to ensure images have met standard
🔹review previous images
-generally has a 1K monitor
-techs are NOT TO SAVE any changes to the original acquired image (this can affect the ability for the radiologist to manipulate the image)

31
Q

Image management workstation

A
  • used to look up examinations or print copies of image
  • file room personnel may be responsible for correcting patient demographics
  • if incorrect demographic information is attached to an image and sent to archive, it is difficult to locate the images later
32
Q

Common functions of workstations

A
  • navigation
  • image manipulation/enhancement
  • image management
  • advanced
33
Q

Navigation functions

A
  • used for moving through images, series, studies and patients
  • work list of all images/exams (customizable to user, can select/deselect parameters ex only CT exams performed today)
  • hanging protocols (can customize how images will be displayed)
  • can set it to display previous studies with current studies
34
Q

Study navigation

A
  • study is the current or previous examination being viewed (can be a single image, multiple images or several series of exams)
  • can page through images with either the scroll wheel of the mouse or arrows on the keyboard
  • various icons for allowing used to move through studies, view previous, close current study
35
Q

Image manipulation

A 
-when image is displayed, many tools are available to manipulate the appearance of it
🔹window level/width
🔹annotations 
🔹rotation
🔹magnification/zoom
🔹measurements
36
Q

Image management

A
  • query/retrieve function
  • CD burning (usually in the file room)
  • printing (usually only done in file room)
37
Q

Advanced workstation functions

A

-usually on the radiologists workstation, but some can be found on the techs QC station
-techs QC station advanced functions: stitching, post processing (smoothing, edge enhancement)
-common ones are:
-multiplanar reconstruction (MPR) most commonly used for 3-D rendering techniques (for CT)
🔹when CT images are attained, the axial image slices are loaded into the software and reconstruction in another place can be done without re-irradiating patient (ie coronal slices)
-maximum and minimum intensity projection (MIP and minIp), used for visualizing vessels and air filled structures, often after contrast injection in CT/MRT
-volume rendering technique (VRT) similar to MIP but user can assign colours to different densities (tissue, contrast air etc)
-shaded surface display (SSD) uses a range of pixel intensity values, everything below is removed, and everything above will be assigned a colour and shown as a 3D objection

38
Q

PACS archiving

A
  • Electronic archive of PACS is like a file room and warehouse for all DICOM imaging modalities
  • stores all patient and image data
  • controls the receipt, storage and distribution of new and historic images
  • comprised of a complex arrangement of computers and storage space
  • can be divided into two categories:
    1. Image manager
    2. Image storer or archive server
39
Q

Image manger

A
  • contains the master data base of everything that is in the archive
  • receipt, retrieval, and distribution of the images it stores
  • controls all the DICOM processes running within the archive
  • interfaces with RIS and HIS allowing the database to collect additional patient information
  • plays a role in populating image information into the hospital electronic medical record
  • runs a reliable commercial database (ex oracle)
  • mirrored data base (two identical databases are running at the same time, so if one fails the other system can run and their is no downtime)
  • database contains only the image header information, not image data ex pt name, ID number, exam date etc
40
Q

Image manager process:

A
  • order into RIS
  • images completed and sent to archive
  • image manager extracts image header from each image and assigns a pointer to each image or series
  • database files the information into various fields and communicates with the RIS to verify info
  • when the study is queried, pointers locate the images on the archive server and send images to the workstation
41
Q

Image storage

A

-image storage or archive server
-this is the actual physical storage device of the archive system
-usually consists of 2 or 3 tiers of storage
🔹short-term (available within seconds)
🔹mid-term (not always included)
🔹long-term (images that must be retrieved from a device, could take 1-5 minutes)

42
Q

Short term storage

A
  • commonly a RAID (redundant array of independent disks)
  • RAID is made up several magnetic disks or hard drives that are linked as an array
  • RAID configurations divide or replicate data over multiple hard drives
  • drives are designed to work together and appear to the computer as one single storage device
43
Q

RAID levels

A
  • several levels of RAID
  • expands to 11 levels, mostly different combinations of the first 5 levels
  • 4 levels most commonly used are RAID 0,1,3 and 5
  • most PACS archives will use RAID 5
44
Q

RAID levels

A

-RAID 3
🔹data striped across all the disks, but one disk is set aside for error correction (parity disk)
🔹rarely used
-RAID 5
🔹similar to RAID 3, but the parity disk is striped along all the disks
🔹this provides adequate redundancy and fault tolerance
🔹most commonly used for PACS archive

45
Q

RAID

A

-striping data increases reliability and performance
🔹if one disk fails, the data from that disk can be recovered using redundancy of data on other disks
🔹data can be accessed all at the same time
-error correction detects transmission errors, and data regenerates based on information from other disks

46
Q

Long term storage

A

-RAID commonly used also
-other products are:
🔹optical disk
🔹tape (these use a jukebox to hold the tapes/disks)
🔹magnetic disk (uses an array)

47
Q

Optical disks

A 
-magneto-optical disk (MOD)
 🔹similar to a CD or DVD, but is housed in a plastic cartridge
 🔹reliable, robust- can handle years of reading
 🔹cost a bit higher per gigabyte 
-digital versatile disk (DVD)
 🔹higher capacity than CDs 
 🔹least expensive method- per gigabyte 
-ultra density optical 
 🔹new generation MOD
 🔹high capacity, comparable with DVDs
48
Q

Tape

A

-tape libraries provide greatest scalability- can continually grow and expand storage limits (can add libraries onto original)
-low cost medium, various sizes
-tapes are contained within a jukebox with multiple drives
🔹can have 10-1448 tapes in one library
🔹robot arm moves tapes in and out of the drives
-disadvantage is over multiple uses, can become unreliable
-can wear out with heavy use and become damaged
-longer access time compared to optical disks

49
Q

Magnetic disk

A

-as price of magnetic disk storage comes down, RAID storage is becoming more feasible
-RAID arrays can be configured into:
🔹DAS (direct attached storage), coupled to system with cable connections, shows up on the computer
🔹NAS (network attached storage), stand- alone RAID arrays attached to the network
🔹SAN (storage area network), high speed, special purpose network that links data storage devices with data servers. Can be used by different departments and has extremely fast response times

50
Q

Image compression

A
  • reduction in the size of the image information to be stored without degrading the image quality to an unacceptable level
  • helps to save on storage space
  • two methods of image compression
    1. Lossy (losing info), reduces storage by eliminating some information, not diagnostic quality-‘conversational’ quality
    2. Lossless (not losing anything), exact replica of the original
51
Q

PACS peripheral devices

A
  • film digitizers (film scanners) can be used to scan analog films and produce a digital image
  • two main types
    1. Laser film digitizer, considered to be the gold standard. Cons: expensive and quality control is critical
    2. CCD film digitizer, less expensive than laser digitizer, but slower. Can have issues with extreme light/dark areas
52
Q

Why are digitizers needed?

A
  • teleradiology (allows radiologist to read from any location)
  • comparison (comparing film image with PACS image, outside films vs current films)
  • duplication (sometimes hard copy is required, digitize film and print a copy on an imager ex if travelling out of country)
  • computer aided diagnosis (CAD), new technology in mammo, computer analyzes image for densities and alerts radiologist
53
Q

Imagers

A

-film printers: printing off digital images
-two major types:
1. Wet imager
🔹uses chemicals to process the film
🔹needs darkroom, well ventiliated area with drains
🔹less popular due to having more requirements
2. dry laser imager
🔹uses heat to process film
🔹exposed with laser
🔹quality slightly lower as compared to wet imager
🔹takes up less space, no special location needed
🔹only requires an outlet, very convenient to use

54
Q

Why are imagers needed?

A
  • backup if PACS isn’t available (in case PACS goes down or OR suites where there isn’t enough room for a workstation)
  • outside physicians (referring dr may want to see images while reading report
  • legal cases
  • teaching purposes

APPH 226 (23 decks)

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