PACS COMPONENTS, STANDARDS AND THEIR IMPLEMENTATION IN A PROTOTYPE APPLICATION. A Dissertation submitted in partial fulfillment of the requirements for the award of Masters degree in Computer Applications. By: Francis Batte Supervised by: Dr. Chen

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PACS COMPONENTS, STANDARDS AND THEIR
IMPLEMENTATION IN A PROTOTYPE APPLICATION.A
Dissertation submitted in partial fulfillment of
the requirements for the award of Masters degree
in Computer Applications.ByFrancis
BatteSupervised byDr. Chen
TianzhouDepartment of Computer Science, Zhejiang
University.
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Structure of this thesis
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Thesis outline

• Introduction
• PACS Hardware Components
• PACS Software Components
• DICOM
• PACS Prototype Application
• WebXray Real-time Teleconsultation Tool.

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Examination cycle in a conventional radiology
Department
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Major limitations of the conventional radiology
practice

• Wasted time - implying diagnostic results many
  not be obtained in a timely manner.
• High risk of loss or miss filing patient
  examination data - implying they have to retake
  the examination
• With a manual filing system, retrieval time of
  films from the film library maybe in order of
  minutes if not hours.
• Turn around time in obtaining results by the
  referring physician(s) varies from hours to Days.
• It is difficult to obtain a copy of the image
  without the need for the digitized hard copy to
  be regenerated.

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Consultation among medical personnel.

• Consultation is a very important activity in
  health care treatment. During this consultation
  process, information about patients cases and
  opinions need to be exchanged between attending
  physicians and specialists. Traditionally, this
  consultative process occurs through face-to-face
  meetings, telephone conversation, or a series of
  written messages passed between physicians. Face
  to face consultations require both the physician
  and the specialist be in the same place at the
  same time. Since physicians and specialists have
  multiple responsibilities and given the fact that
  they may be separated by a long distance from the
  referring physician. This whole process in
  general turns out to be time-consuming,
  inefficient and causes delay in patient
  treatment.

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• The limitations of the conventional radiology
  department and consultation among medical
  personnel can be solved by deploying a Digital
  environment Using Picture Archiving and
  Communication systems (PACS). PACS represents an
  alternative to film and paper in image
  interpretation, distribution and management.
  Based on digital computer technology, a PACS
  handles images in electronic form with the sole
  objective of attaining a more efficient and
  cost-effective means of examining, storing and
  retrieving diagnostic images .
• The challenge still facing PACS is clinical
  acceptance as opposed to traditional practice.
  Therefore successful implementation of PACS is a
  complex problem that requires a concerted effort
  across a wide range of disciplines. Attaining a
  fully digital environment, will also require the
  enhancement of PACS for remote consultation or
  teleconferencing.

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What are PACS?

• According to National Electrical Manufacturers
  Association (NEMA), a PACS should be able to
  offer
•   Medical image viewing at diagnostic, reporting,
  consultation and remote workstations,
•   Archiving on magnetic or optical media using
  short or long-term storage devices,
• Communication using local or wide area networks
  or public communications services,
• Systems integration with other healthcare
  facility for example image acquisition
  modalities, gateway computers and departmental
  information systems.

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• PACS HARDWARE COMPONENTS
• Image Acquisition systems
• Communication Networks
• Data archive Systems
• Display workstations

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Image Acquisition Systems are composed of medical
imaging modalities devices and acquisition
gateway computers which interface the imaging
devices to the PACS archive server as illustrated
in the figure below.
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• The role of the Acquisition gateway computer is
  to
• Acquire image data from radiological imaging
  device
• Convert the data from the manufacturers
  specification to the PACS standard format
  compliant with the ACR-NEMA/DICOM data formats
• Perform pre- Image processing functions like
  background removal, orientation, resizing etc.
• Image Acquisition methods.
• Two methods are used for image acquisition
  Direct digital acquisition and Digitization of
  plain films.
• Direct digital acquisition. Recently developed
  direct X-ray detectors can capture the X-ray
  image without going through an additional medium
  like the imaging plate. This method of capture is
  sometimes called direct digital radiography.
  Images obtained from 30 of radiology
  examinations for example CT, NM, MRI, US, DF and
  DSA are already in digital form when generated
  making them inherently suitable for PACS
  integration
• Digitization of plain films Since computers can
  process only digital images, and 70 of the
  radiology departments still use projection
  radiology which uses X-ray films a pre requisite
  for attaining a digital radiology environment is
  the conversion of the radiolographic images from
  films to digital format. This is achieved using
  film/image digitizers like Laser film Scanner
  and Charge-coupled device (CCD).

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Communication networks

• PACS communication networks enable the movement
  of medical data between modality imaging devices,
  gateway computers, PACS server, display
  workstations, remote locations for diagnosis and
  consultation and other Hospital information
  systems like HIS/RIS.
• The most commonly used network technologies in
  building PACS networks are
• The Ethernet based on IEEE standard 802.3,
  Carrier Sense Multiple Access with Collision
  Detection (CSMA/CD) protocol. Suitable for LANs
  and can operate at 10Mbits/Sec on half-inch
  coaxial cable, twisted pair wire or fiber optic
  cables.
• FDDI can be used for medium speed communication.
  Runs on optic fiber at 100Mbits/sec over a
  distance of 200kms with upto 1000 stations
  connected.
• ATM Can be used to combine LAN and WAN
  application. ATM is a Virtual circuit- oriented
  packet switching network with transmission speed
  ranging from 51.84 Mbits/sec 2.5 Gbits/sec.

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PACS Network Topology

• Topology refers to the way the network is laid
  out physically or logically. Two or more devices
  connect to a link, then two or more links form a
  topology. Five basic topologies are possible
  Bus, star, tree, mesh and ring.The topologies
  used depend on the medical environment being
  network.
• Conceptually three main types of networks may be
  used to transport radiology images
• A LAN linking imaging devices, data storage units
  and display devices within one departmental area.
• A larger LAN for intra-hospital transport linking
  departments,
• And a tele-radiology network for transmission of
  images to other hospitals in the region or to and
  from remote sites for diagnosis at a distance.

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Data storage and Archive

• Image storage and communication can be based on
  either a centralized or distributed architecture.
  In centralized storage system all the acquired
  images are forward to a central archive system
  to which every modality or workstation is
  attached on a point-to-point basis. Whereas a
  distributed architecture is composed of linked
  local storage subsystems or file servers. Each
  server has its own short-term storage unit
  (usually a small RAID), one or more image
  acquisition modalities, and several
  diagnostic/review workstations.
• Each of these architectures has its own
  advantages and disadvantages. However distributed
  storage architecture has been found suitable for
  large-scale PACS and centralized architecture for
  miniPACS.

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Storage Media

• PACS storage devices should hold gigabytes of
  data with relatively efficient access time.
  Research continues to consistently improve PACS
  by providing storage media that can hold many
  images and have quick access time. A PACS needs
  at least two levels of archive (short-term and
  long-term). Images should be retrievable from the
  short-term archive in 2 seconds. Images from the
  long-term archive should take no more than 3
  minutes to retrieve.
• Examples of storage media that can be used for
  PACS archiving include
• Redundant array of inexpensive disks (RAID) for
  immediate access of current images.
• magnetic disks for faster retrieval of cached
  images,
• erasable magneto-Optical disks for temporary
  long term archive,
• write once read many (WORM) in the optical disk
  library, which constitute the permanent archive,
• Recently developed digital versatile discs
  (DVD-ROM) for low cost permanent archive
• And the digital linear tapes for backup storage

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Display Workstation

• This is the hardware component radiologists
  compare to the manual light box or Alternator, it
  therefore plays an important role in the clinical
  acceptance of PACS.
• Most radiologists today view diagnostic films in
  a reading room using light boxes or alternators.
  Light boxes are lighted panels on which about a
  dozen films may be hung at a time for inspection
  and manually rotate about 8 out of 200 films
  into position for viewing. Using the alternators,
  rudimentary image processing functions operations
  like zooming using a magnifying glass and
  annotation of films is performed.
• Therefore a display workstation is a replacement
  of the alternator to provide high quality digital
  viewing and appropriate image processing
  capability. The image processing capabilities
  provided by a display workstation depend on the
  type of workstation. Some of the basic image
  processing functions include
• Access Image storage/retrieval, data
  compression, interpretation of file formats and
  communication (esp. ACR-NEMA, DICOM), study
  handling, multiple image display,
• Manipulation Image processing operations (e.g.
  zoom, pan, mirror, contrast/brightness
  adjustment, reorientation, negate, arithmetics,
  window/level contrast adjustment),
• Evaluation Local/global greyvalue statistics and
  geometric properties (2D/3D distance, angle,
  profile, image annotation..)
• Documentation Image annotation, report
  transcription and hardcopy,

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PACS Software Components.

• PACS software is composed of various software
  modules performing different functions depending
  on the size of the PACS Application.
• For Example
• Image Acquisition Software responsible for image
  Acquiring, Formatting, preprocessing, sending,
  deleting and Archival
• Archive Server software for image receiving,
  stacking, routing, study grouping, platter
  management, retrieving and prefetching.
• Workstation image processing and analysis
  software
• PACS database for patients data storage and
  organization.

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Industrial standards

• It is important to take into consideration
  defacto industrial standards when building PACS
  infrastructure to enable portability of the
  system to other computer platforms. For example
  the following industrial standards should be used
  in a PACS infrastructure design UNIX operating
  system, Windows NT, TCP/IP and DICOM protocols,
  SQL (Structured Query language) as the database
  query language, ACR-NEMA and DICOM for image data
  format, HL7 for database information exchange
  between PACS, HIS and RIS.

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Digital Imaging and Communication in
Medicine(DICOM)

• DICOM is a popular standard which has emerged as
  a result of the initial efforts by ACR and NEMA
  joint committee formed in 1993 to
• Promote communication of digital image
  information regardless of device manufacturer
• Facilitate the development and expansion of PACS
  that can also interface with other systems of
  hospital information
• Allow the the creation of diagnostic information
  databases that can be interrogated by a wide
  variety of devices distributed geographically.

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• Since its inception, DICOM 3.0 has gone through
  a lot of modifications and additions, the latest
  version released in 1998, consists of 14 parts
  identified by numbers PS 3.X YYYY where X is
  part number and YYY is year of release (see
  Appendix A).
• For example PS 3.2 (Conformance statement)
  describes how a manufacturers device or its
  associated software components conform to a
  subset of DICOM standard. A device or software
  needs only to conform to a subset of DICOM to be
  DICOM compliant. For example a Laser film
  digitizer needs to conform only to the minimum
  requirements for the digitized images to be in
  DICOM format and the digitizer should be a
  service class user to send the formatted images
  to a second device (e.g. magnetic disk), which is
  a service class provider.

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WEBXRAY APPLICATION.

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Database Design

• WebXray Database is an object oriented database
  model implemented using SQL server 7.0, running
  on Windows NT operating system.
• The database is broken down into three
  components.
• Storage system
• Storage Management
• Case Tree

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The Schematic diagram summaries the design
architecture of the WebXray database.
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Storage System

• Contains three tables
• Case table containing patients demographic and
  registration information Attributes in the table
  include Patients ID, name, sex, birthday,
  address and Case_ID as primary key
• Items table stores patients diagnosis
  information after examination Attributes in the
  table include inspection cause, date, site,
  diagnosis result, doctor and date with Items_ID
  as the primary key
• Image table stores image data and related
  information i.e Image_ID, title, View result,
  annotation.

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Schematic diagram showing Data capture and table
relationships
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• Storage management is performed by Stored
  procedures implemented in the SQL server script,
  enable updating, querying and client server
  communication with the database. Stored
  procedures are used in this case as opposed to
  the execution of similar queries activated from
  the client to reduce network traffic.
• Case Tree
• The case tree, the front-end hierarchical Tree
  View of the database embedded in the Graphical
  User Interface. It facilities the communication
  between the user and the SQL database server
  during database manipulation and image display.
  With the case tree it is possible to switch
  between the 3 database forms easily in the
  Graphical user interface to enter new data or
  view existing data

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DICOM Compatibility

• DICOM File tool.
• WebXray acquires DICOM images through DICOM
  CD-ROMs, CD-ROMs specifically designed for
  medical application. WebXray uses DICOM single
  file format. A single DICOM file contains a file
  header and the actual image data. (see appendix B
  for WebXray DICOM header)
• TDICOMObject is used in WebXray to open and read
  the DICOM file stream into memory and to convert
  the memory stream from DICOM format to BMP for
  display on the workstation. (page 48/49).

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DICOM Display tool
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Demonstration of the DICOM display Tool Effect on
the same image using different window level
settings.
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Computer aided diagnosis tools.

• These tools are incorporated into the user
  interface to aid image processing and analysis.
  They include Graphics format tool for annotation
  of images with text and graphics symbols during
  image analysis. Annotations help doctors isolate
  regions of interest on the image for further
  examination.

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Image Tool

• This tool has most of the image processing tools
  mention earlier Image scanning, zooming,
  loading, geometric transformation, smoothening,
  sharpening and displaying the edges of the image
  e.t.c

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Graphical User interface Design

• In addition to the case tree, image tool and
  graphics tool already mentioned earlier, the
  Graphical User Interface has additional features
  like Menu Bar, Toolbar and three forms used to
  enter, edit, manipulate and display the patients
  data stored in the database.

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Figure shows the image form used to display and
manipulate data in the Image table.
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WebXray Hardware requirements

• A Server with
• CD-R, at least 64MB of RAM, Windows NT operating
  system and MS SQL Server for database management.
• CD-ROMS for short term and long term archiving
• High resolution Pentium computers with memory not
  less than 64MB as Clients.
• Digital film scanner for digitizing X-ray films.
• Laser printers for producing a hard copy
  diagnosis report and conference notes
• 10 M/bits Ethernet or better .

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WebXray Real-time Teleconsultation Tool.

• Consider the scenario
• A doctor in a hospital ward wants to consult the
  radiologist about the results written for one of
  the patients in the ward, without having to leave
  the ward and walk all the way to the radiology
  department. This is one of the many scenarios
  teleconsultation is trying to address.
• Teleconsulation is a situation in which two or
  more physicians located in different departments
  of the hospital or geographically dispersed need
  to discuss the same patients image data without
  leaving their locations.
• Simple solutions have come up like Televideo and
  application sharing software for example
  NetMeeting from Microsoft, Proshare by Intel, PC
  Anywhere by Symantec and many others but have
  found little applicability to the medical
  environment due to lack of image processing
  tools. This therefore calls for integration of
  the teleconsultation component component with
  medical imaging component. This can be achieved
  in several ways each with its distinct advantages
  and disadvantages

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• 1) Conventional application-sharing software
  could be used in conjunction with PACS software.
  This can be realized first but will have poor
  performance as already mention above.
• 2) A CSCW toolkit can be used to add the
  communication functionality to existing medical
  imaging software. This may have draw back because
  of lack of total integration of the two of
  software
• 3)   A PACS medical imaging software can be
  created from the ground up with the communication
  facilities built in. This option is more complex
  but provides optimal performance since all the
  system components will be fully integrated into
  the system.
• In our system we adopt the third approach to
  develop the webXray remote consultation tool
  (referred to as Nettalk) by adding communication
  functionality to the WebXray application using
  TCP/IP.

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• The purpose of adding Nettalk in the WebXray PACS
  application is to enable physicians exchange
  comments in real-time during a tele-consultation
  session.
• In addition to the above, the application
  provides
•  A friendly multi-user graphical interface,
  containing a user menu and toolbar to quickly
  access commonly used commands.
•   Shared Text view visible to all conference
  participants and a private text editor for
  posting text to the conference.
•   Client/server communication using TCP/IP.
•   Print facility to enable printing conference
  notes
•   Basic software functions like save, open ,
  print preview. Etc..

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Nettalk Communication Design

• Nettalk is based on a replicate model for
  client-server process communication. In a
  replicate model each participating site runs a
  copy of the conferencing software with identical
  functionalities. Any conferencing data generated
  by a participating site will be disseminated to
  other participating sites and maintained locally.
  The replicate model has striking advantages such
  as better system performance, that is why it is
  chosen as the implementation model for nettalk.
• TCP/IP protocol is used in implementing
  client-server communication architecture. In
  client-server communication architecture,
  communication generally takes the form of a
  request message from the client to the server
  asking for a service to be delivered. The server
  then processes the service and sends back a reply
  

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Illustration of client-server model using TCP/IP
as the communication protocol.
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• To add TCP/IP functionality to nettalk,
  client/server sockets are used. Delphi provides
  two VCL (Visual Component Library) classes,
  TClientSocket and TServerSocket, which allow
  creating TCP/IP socket connections to communicate
  with other remote applications.
• TserverSocket.
• TServerSocket is used to manage server socket
  connections for TCP/IP server. TServerSocket
  object is added to nettalk design form to turn it
  into a TCP/IP server. When the application is
  running, TServerSocket listens for requests from
  TCP/IP connections from remote machines, and
  establishes connections when requests are
  granted.
• TclientSocket.
• TClientSocket is used to manage socket
  connections for TCP/IP client. TClientSocket
  object is added to nettalk design form to turn it
  into a TCP/IP client. TClientSocket specifies a
  desired connection to nettalk TCP/IP server,
  manages the connection when it is open, and
  terminates the connection when the application is
  through.

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SendText and ReceiveText

• Some of the main procedures I used in this
  program to activate socket connections are
  sendText and receiveText.
• SendText
• function SendText(const S string) Integer
• This procedure writes a string S to the socket
  connection
• ReceiveText
• function ReceiveText string
• ReceiveText is used to read a string from the
  socket connection in the OnClientRead event
  handler of a socket component
• For Example
• .
• for j0 to i do
• serversocket1.Socket.Connections
  j.SendText (label1.Caption' ' edit1.text)
• edit1.Clear
• end
• Will broadcast to all connected sections the text
  in sendtext()
• ..

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Discussions, conclusions and Future Work

• Future advances PACS in workstation display
  resolution, network speed, data storage capacity,
  computer speed and electronic components will
  help make PACS a powerful alternative to
  Hard-copy system.
• From this research in chapters 2 through 3 it is
  realized that building PACS demands a lot in
  terms of hardware and software and depends
  greatly on the currently available technologies.
  Therefore in a mid of limited resources, the
  computerization process in hospitals should be
  stepwise, first hospitals need to set up RIS and
  HIS which are less demanding before setting up
  PACS. Mini PACS with the possibility for
  expansion can be a hopeful solution for small
  radiology departments .
• Chapter 5.0 analyzed the implementation of PACS
  components in a prototype application (WebXray).
  WebXray is implemented on the Windows NT
  operating system platform because Windows NT is
  the most widely used network operating system
  running on PCs and support TCP/IP communication
  and multitasking. It therefore provides a low
  cost software development platform for medical
  imaging applications in a PC environment.

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• Chapter 6.0 is an effort we adopted to address
  the problem of consultation among medical
  personnel. To enable referring physicians use
  WebXray for Remote consultation, Nettalk was
  developed.  With nettalk, unlimited number of
  referring physicians can easily exchange comments
  with their colleagues scattered in different
  parts of the hospital while analyzing the same
  image, bridging space and time very critical in
  health care delivery.
• However, WebXray needs more enhancements to be a
  full medical multimedia conferencing system. More
  program modules need to be added to support
  exchange of graphic annotations, voice and video,
  which this research was not able to accomplish in
  a limited time frame.

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MY SINCERE THANKS TO THE DEFENSE COMMITTEE

• AND
• EVERYONE PRESENT FOR SPARING YOUR VALUABLE TIME
  TO ATTEND THIS PRESENTATION.