242 DICOM Gateways Whats Inside the Box

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242 DICOM GatewaysWhats Inside the Box

• Presented by Brent Fugett
• VAMC Huntington, WV

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Introduction

• VistA Imagings DICOM Gateways
• Major Hub of VistA Imaging Processing
• Responsible for a wide range of DICOM
  communications
• In fact, is the DICOM conduit
• Questions at the end of class.

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Outline

• VistA Imaging Overview
• DICOM Overview
• DICOM Gateway Where it Fits In
• DICOM Gateway Pieces and Parts
• DICOM Text Gateway
• DICOM Image Gateway
• Optimization, Disaster Recovery, and Error
  Correcting

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VistA Imaging Overview

• VistA
• Veterans Information System and Technology
  Architecture.
• Primary system for storing and maintaining the
  patient electronic medical record. Text based
  Not designed for Images
• Imaging
• Parallel system linked with VistA
• Both systems use program code written in Mumps
  and run in the Cache Database environment.

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Terms to Know

• PACS Picture Archival and Communication System.
  System designed to store and retrieve a
  patients medical Images. Historically
  Radiology-centered.
• DICOM Digital Imaging and COmmunication in
  Medicine.
• HL7 Medical text communication protocol.
  (Health Level 7)
• Modality per the dictionary means Conforming
  to a Standard. In Imaging it is simply an image
  capture/processing device that complies with
  DICOM.
• CPRS Computerized Patient Record System (GUI
  for VistA)

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DICOM Fundamentals

• To create a standard to allow a common set of
  rules and protocols between vendors in the
  medical field, specifically Radiology (at least
  initially).
• Originally called ACR-NEMA 1.0 (85) and then 2.0
  (88), and finally DICOM 3.0 (93).
• DICOM Standard available at
• http//medical.nema.org/dicom/

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DICOM Parts of Standard

• 1-Introduction and Overview
• 2-Conformance
• 3-Information Object Definitions
• 4-Service Class Specifications
• 5-Data Structures and Encoding
• 6-Data Dictionary
• 7-Message Exchange
• 8-Network Message Support for Message Exchange
• 9- RETIRED
• 10-Media Storage and File Format for Media
  Interchange
• 11-Media Storage Application Profiles
• 12-Media Formats and Physical Media for Media
  Interchange
• etc

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DICOM Fundamentals

• SCU (Service Class User) Device taking a client
  role (example device that sends print jobs)
• SCP (Service Class Provider) Device that takes
  a host role (Example DICOM print server).
• AE Title (Application Entity Title) DICOM name
  that distinguishes DICOM devices communicating
  with each other.

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DICOM File Format

• DICOM Images are a Composite Format
• Image Data for the actual picture
• A Header area at the beginning of the file that
  contains the DICOM Header organized in tags.
  This area is for text data associated with the
  image, containing
• Patient Identifying information
• Exam information (date of exam, accession number,
  case number)
• Information about acquisition modality
  (manufacturer, model)
• Image information (geometry, attributes)
• And lots of other stuff

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DICOM Header Tags

• A Tag represents a single piece of information.
• Tags are unique identifiers denoted with a Group
  and Element number.
• Group and Element numbers are in Hexadecimal
  format.
• Part 6 of the DICOM Standard Data Dictionary.

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DICOM Header Tags
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DICOM Header Private Tags

• Uses Odd Group numbers. (i.e. 0009,xxxx)
• Not recognized or defined by the DICOM Standard.
• Generally used for vendor propriety information.
• VI cannot use any of this information.

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DICOM Association
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Info Required for Association

• AET
• IP Address
• Port
• Good idea to keep a spreadsheet with above info

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DICOM Association

• Use option 4-1-2 to view DICOM message log to see
  association details

Connection with 127.0.0.1 on
AUG 06, 2002 at 080113

Recving PDU Type 01H (A-ASSOCIATE-RQ) PDU
len206 d\DICOM\DATA1\LOGDCM.292\INCOMING.PDU

Receiving
A-ASSOCIATE-REQUEST on AUG 06, 2002 at 080113

PDU Type 01H
(A-ASSOCIATE-RQ)
Length206 Version1 Called AE
"DICOM_STORAGE" Calling AE
"DICOM_ECHO" ITEM Type 10H (Application Context
Item) Length21 Application
Context 1.2.840.10008.3.1.1.1 (DICOM
Application Context Name) ITEM Type 20H
(Presentation Context Item)
Length46 Presentation Context ID 1
Result0 -- Transfer
Syntax(es) -- SUBITEM Type 30H (Abstract Syntax
Sub-Item) Length17 Presentati
on Context 1.2.840.10008.1.1 (Verification SOP
Class) SUBITEM Type 40H (Transfer Syntax
Sub-Item) Length17 Transfer
Syntax 1.2.840.10008.1.2 (Implicit VR Little
Endian) -- End of Transfer
Syntax(es) --
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DICOM Association - Release

• Whoever initiated the connection must also close
  it

Sending PDU Type 04H (P-DATA-TF) Length 90
(90) d\DICOM\DATA1\LOGDCM.292\OUTGOING.DCM PDU
len96 PDV hdr3, pc1, len90 Recving PDU
Type 05H (A-RELEASE-RQ) PDU len4 d\DICOM\DATA
1\LOGDCM.292\INCOMING.PDU Sending PDU Type 06H
(A-RELEASE-RP) Length 4 d\DICOM\DATA1\LOGDCM.29
2\OUTGOING.PDU
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DICOM Gateway-Where It Fits In
Worklist
Image Capture
QA/Storage
Patient Two 000-28-1665 X2056 Y1998
?
Patient Two
Patient, Two 000-28-1665 X2056 Y1998
Patient Two 000-28-1665 X2056 Y1998
DICOM Text Gateway
DICOM Image Gateway
Background Processor
Patient Two
Image Storage (RAID - Magnetic)
VistA
Patient Two 000-28-1665 X2056 Y1998
Patient Two
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VistA Imaging DICOM Gateways

• Characteristics
• Runs on Windows 2003 Server
• Runs using the VHAxxxIA account
• Runs on Cache by Intersystems
• Database Environment compatible with VistA
• Provides communication with VistA (M2M Broker) to
  share information.
• Image Gateway, Text Gateway, and Routing Gateway
  CAN be on the same box, but
• Typically 1 Text, Multiple Image, running routing

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Roles of the DICOM Gateways

• DICOM Text Gateway
• DICOM Imaging Gateway
• DICOM Secondary Storage
• Image Routing
• All the above use the same software
  functionality is turned on and off as needed.

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The DICOM Gateway Pieces/Parts

• Cache Database Console (Brains of the Operation)
• Telnet Windows
• DICOM Storage Servers (on Image Gateways)

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The DICOM Gateway Console

• When Caché is inactive, this icon is grey
• When Caché is active, this icon is blue
• This icon can be used to start and stop the Caché
  server. Under normal circumstances, the Caché
  server is started automatically when the computer
  is restarted, and users only need to stop and
  restart Caché when this is needed for maintenance
  purposes.

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The DICOM Gateway Console

• GUI based management tools.

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The DICOM Gateway Console
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The DICOM Gateway Console

• Log Files

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Telnet Windows

• Separate shortcuts for each gateway function
  (processing, status, etc.)
• Points to 127.0.0.1 (self)
• Can be used remotely (be careful!)
• HOST file entries associate 127.0.0.1 with a
  named entry
• Shortcuts include menu path to appropriate entry
• Process DICOM Images 2-3
• Image Gateway
• Process DICOM Images

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DICOM Storage Servers

• Serves connection from DICOM Instruments
• Uses MAG_CSTORE.exe to receive Image(s)
• More later

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DICOM Text Gateway

• Supplies Modality Worklist from order entry in
  VistA to DICOM modalities.
• Continuously updates worklist database from
  VistA's MAGDHL7 global into the local global
  called MAGDWLST.
• Provides stored worklist items upon request from
  modality worklist query

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DICOM Text Processing (Modality Worklist)
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DICOM Text Gateway 1-1
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DICOM Text Gateway Status 1-4
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DICOM Text Processing (Modality Worklist)

• VistA DICOM Text Gateway -- Huntington DICOM
  Text Gateway
• 1 Start Processing Text Messages from HIS
• 2 (Send DICOM Text Messages to Commercial
  PACS or Broker)
• 3 Display Text Gateway Statistics
• 4 Display Modality Worklist Statistics
• 5 Modality Worklist Query
• 6 Display a HL7 Message
• 7 Display a DICOM Message
• 8 Modify the HL7 Message Pointer
• 9 Generate a Daily Summary Report
• 10 Purge Old Modality Worklist Entries
• 11 Purge Old DICOM Message Files
• 12 Purge Old HL7 Transaction Global Nodes
• 13 Purge Old Audit Records
• OPTION

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DICOM Dictionaries Worklist.DIC

• TOPCON123CONOPHTHLONGTOPCON Eye Camera
• Picker_1RADMRISHORTPhilips RF room 1
• ECAM1123RADNMLONGSiemens Rm. 3A118
• XR1CR950123RADRADLONG/NODASHKodak CR1
• Field 1 Application Entity Title of Modality
  (Calling AET).
• Field 2 Site code or Location.
• Field 3 Imaging Service (Either RAD or CON).
• Field 4 Imaging Type
• RAD General Radiology
• CT Computed Tomography
• MRI Magnetic Resonance
• Field 5 Accession Number Format/dashes or no
  dashes in SSN
• Accession number SHORT radiology case number
  only (1234)
• LONG datecase number
  (031106-1234)
• Field 6 Description

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DICOM Dictionaries - Importing

• Option 4-2-8

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DICOM Dictionaries Worklist.DIC
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DICOM Dictionaries Worklist.DIC
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DICOM Image Gateway

• Receives DICOM Images for storage to VistA
  Imaging
• Process corrections for Images that fail to
  process
• Components
• Cache Console
• Modality Instrument SCP (Provider)
• Storage Processor
• Image Status Indicates Corrections

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DICOM Image Processing
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DICOM Image Processing CStore Server

• Storage Server receives image from modality
• Stores incoming DCM file in Image_IN folder,
  ready for next step.
• Uses Instrument.DIC for configuration.
• First place to look for failed transmissions

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DICOM Image Processing Image_In

• Image_In folder should contain files only during
  processing. Older files probably need
  corrected.
• Recommend Move to a subfolder rather than
  deleting!

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DICOM Dictionaries Instrument.DIC

• Computed Radiography
• CR1Kodak CR642RAD60100A
• CR2Kodak CR642RAD60101A
• DR1Kodak DR642RAD60110A
• DR2Kodak DR642RAD60111A
• Ultrasound
• US1Philips iu22642RAD60300A
• US2ATL642RAD60301A

• Dictionaries are Text files
• Config values may require support to set
• Recommend all DICs reside on shared network
  drive.

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DICOM Image Processing Process Images

• Text Window Option 2,3
• As Images appear in Image_IN
• Reads DICOM Header
• Checks VistA for a match on Name, SSN, and
  Accession (ALL must match)
• Puts portion of DICOM header in TXT file
• Creates ABS, TGA, and DCM files.
• Stores Image set (TXT, ABS, DCM, etc) on RAID
• Notifies VistA of path to image files.

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DICOM Dictionaries - Modality.DIC
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DICOM Dictionaries - Modality.DIC
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DICOM vs TGA Processing

• Image Gateway parses the original DCM file
• Pulls Text from header into TXT file
• Generates a thumbnail (ABS, or Abstract) from
  Image data
• Creates object Image for retrieval
• Object image may be either DICOM or TGA format
• Determined by Modality.DIC entry

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DICOM vs TGA Processing

• TGA (Targa) Processing
• Object Image is a TGA format, uncompressed Image
  bits from DICOM file
• TGA file
• Whole image from lower res images (CT, US,
  smaller CR)
• Reduced Image from higher res images
• BIG file
• Whole image from higher res images
• Pre DICOM solution. Not ideal.

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DICOM vs TGA Processing

• DICOM Processing
• Stores the Original DICOM Image file (DCM)
• Ideal because it preserves the original image as
  sent from the Modality
• Still creates a TXT file
• Still creates an ABS file

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DICOM Image Processing

• Displaying DICOM Text Header

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DICOM Image Processing

• Displaying DICOM Text Header

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DICOM Corrections

• Image Processing requires 3 pieces
• SSN
• Name
• Assession Number (071308-012)
• Only EXACT match of ALL elements allows storage.
• If there is an error, Image will be stuck on
  the DICOM Image Gateway
• Must either Correct or Delete
• Can be corrected via VistA Option MAGD FIX

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DICOM Corrections Performed on VistA

• You have 3 new messages. (Last arrival
  11/01/05_at_0839)
• Select Systems Manager Menu Option correct
  RAD-DICOM File Entries
• Select one of the following
• P Patient
• L Loop thru file
• D Specify a Date Range
• Update entries by Loop thru file
• Processing entry
• PATIENT Patient, One
  SSN 000000000
• RADIOLOGY CASE 1110105-8401
• Equipment CEMAX
  Model CT
• Date Processed NOV 1,2005
  Problem with BAD CASE
• Comment
• Correcting file on Image gateway server ID A
• D\DICOM\IMAGE_IN\A0089914.DCM

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DICOM Corrections - Continued

• Please review the following
• Previous name Patient, One
• New name Patient, One
• Previous ssn 000000000
• New ssn 000000000
• Previous case 1110105-8401
• New case 110105-8401
• Radiology case number different. Update?
  (Y/N/D/Q/P)// y
• Will change the following
• Please review the following
• Previous name Patient, One
• New name Patient, One
• Previous ssn 000000000
• New ssn 000000000
• Previous case 1110105-8401
• New case 110105-8401
• Are you sure you want to correct this entry? ?
  No// y (Yes)
• Updating the file....

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Image Routing

• Facilitates transmission of Images to remote
  reading stations (VistaRad, Telerad servers, etc)
• Autorouting Process Automatically pushes images
  as acquired based on rules. (Route.DIC)
• Route on Demand Images are sent by selecting on
  VistaRad.
• Uses two processors One to queue the autoroute
  images, another to transmit.
• Use one transmission processor per destination.

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Optimization Strategies

• Text/Image Processing Keep them separate
• Modality Separation
• Volume of Images (Illustrate processing speed of
  Storage server vs Imaging Processor)
• Multi-slice Modalities
• Redundancy
• Isolation Must be dedicated (don't put on
  storage servers!)

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DICOM Dictionaries - Importing

• Ready to build all of the DICOM Master Files?
  YES// yes
• Building the DICOM Element Dictionary --
  MAGDICOM(2006.51)
• Ready to read dictionary file "C\DICOM\DICT\ELEME
  NT.DIC"? y// yes
• Building the DICOM Message Template Dictionary --
  MAGDICOM(2006.52)
• Ready to read dictionary file "C\DICOM\DICT\TEMPL
  ATE.DIC"? y// yes
• PASS 1 STARTED
• PASS 2 STARTED
• - DONE -
• Building the DICOM UID Dictionary --
  MAGDICOM(2006.53)
• Ready to read dictionary file "C\DICOM\DICT\UID.D
  IC"? y// yes
• Updating the extended SOP negotiation table...
  done!
• Updating the PDU TYPE table... done!

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Disaster Recovery/PM

• Plan to Fail - Don't Fail to Plan!
• REALLY good idea to have a spare DIG.   Use for
  testing purposes, patch pre-install, etc.
• Along with other Imaging Components, requires
  DAILY monitoring.
• Dont assume silence is golden
• Ignorance is not Bliss!!!

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Gateway Alerting

• Option 4,2,2 Gateway Configuration Parameters
• Send emergency e-mail notices to G.IRMNOTIFY
  _at_HUNTINGTON.MED.VA.GOV
• Use a group for ease of maintenance
• Messages are not particularly descriptive, but
  the alert itself is valuable.

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Text Gateway Failure

• Ensure failed Text Gateway is down
• Add Text Gateway IP address to the emergency DIG
• Add Text Processing role to emergency DIG
• Start Worklist Processing and Test
• Set HL7 Pointer to Catch up

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Image Gateway Failure

• Ensure failed system is down
• Add Failed IP to recovery DIG(s)
• Edit Modality.DIC appropriately (remember
  balance!)
• Regenerate storage server shortcuts
• Execute Added servers and test

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Common Errors

• 1) The writing of image file "\\VHAxxxCLUA\IMAGE3
  \J0\85\88\J0858809.TGA"
• failed"
• "The error message was "-53 (Unknown Error
  Code)""
• "Imaging entry 858809 successfully removed"
• Resolution
• Gateway was temporarily unable to access the
  share - probably due to some network "bobble".
  Site restarted DICOM Process window and image
  processed.
• Other possible causes
• Permission problem VHAxxxIA (account on
  gateways) is not getting access to the cluster
  shares.
• Steps
• Ping share
• Map share using IA account.

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Common Errors

• DICOM IMAGE PROCESSING ERROR
• The writing of image file
  "\\VHABHSCLU2A\IMAGE1\Q7\53\10\Q7531063.ABS"
  failed
• The error Message was "1"
• Imaging entry 7531063 successfully removed
• 
  Please call Support Personnel
• Routine MAGDIR2B
• Meaning
• The error message describes a scenario in which
  the Image Gateway is unable to completely process
  the image successfully. This can be caused by
  numerous reasons (network, corrupt image,
  permission problem to the shares, etc.).
• The entry removed is actually the deletion of
  MAG(2005,IEN) initially created within Vista.
• Steps
• CTR-C DICOM Process Window first.
• Restart Process_DICOM_Images_2_3

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Common Errors

• If it still fails, you may need to bump the Image
  Pointer value past that image. Run option 2 -
  Image Gateway, then 4 - Increment DICOM Image
  Input pointer
• VistA DICOM Image Gateway -- TEST MACHINE
• 4 Increment DICOM Image Input Pointer
• OPTION 4
• The last image in the "C\DICOM\IMAGE_IN"
  directory is number 294.
• There are no images waiting to be processed.
• The current image processing pointer value is
  293.
• Do you wish to increment the image processing
  pointer? n// y --
• INCREMENTED
• Press ltEntergt to continue...
• Use the DICOM header dump capability in
  Option 9 to determine Patient Name, SSN, and
  accession number. The image then can be resent
  from the modality.

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• Questions