1. Robert Horn, Agfa Corporation
DICOM Configuration
Robert Horn, Agfa Corporation

2. Supplement 67 Existing Industry Protocols Existing Configuration Tools
NTP (Network Time Protocol)
DHCP (Dynamic Host Configuration Protocol)
DNS (Domain Name System)
LDAP (Lightweight Directory Access Protocol)
Existing Configuration Tools
Existing support databases
DICOM specific information model for LDAP databases

3. DICOM Configuration Goals
Support New Functions
Security and Privacy
Synchronized Multi-device Acquisitions
Reduce Operational Costs
Network Administration
AE-Title management
Service location management
Feature location management

4. Time Synchronization For Multi-device simultaneous acquisitions
Cardiac Catheterization laboratory
Coordination
Security Logs, Procedure Logs
Convenience

5. Synchronization Specification
Specify error relative to time reference(s)
Acceptable absolute time error (relative to UTC)
o( 1s ) security logs
o( 100s ) cardiac catheterization
Acceptable synchronization error within a Time Source (0018,1801) (relative to local source)
o( 1s ) security logs
o( 10ms) cardiac catheterization (a few percent of one cycle of a rapidly beating heart).

6. NTP - Network Time Protocol
Widely available
Suitable for both low precision time and high precision time synchronization
SNTP (Simple NTP) clients for low precision and limited capability systems.
Extensively documented and explained on

7. Accuracy capability of NTP
o(1s) Either client (NTP,SNTP), network capable OS, Internet, GPS, or radio connection
o(250ms) NTP client, interrupt driven OS, NTP clock controls
o(100ms) local network topology
o(10ms) OS clock, OS design
o(1 ms) OS/application design, network topology
o(100 us) Hardware assist, OS/application design
o(10 us) Instrumentation clock, custom OS
o(1 us) Atomic clock, extensive hardware assist

8. How NTP works Mathematical Magic happens Query Time Sent (Ta) Response
Time Query Received (Ti)
Time Response Sent (Tj)
Current Time Parameters (TP)
Redundant Servers
NTP Server
Client Provides
Old Network Parameters
Old Time Parameters
Query
Response
Mathematical Magic happens
Client Sets and Fine Tunes System Clock
SNTP performs only the clock setting
NTP includes the network delay estimation,
optimal estimation mathematics and
fine tuning of the system clock.
NTP Client
NTP clients may utilize redundant servers
NTP clients may utilize instrumentation grade
pulse generators (e.g. Atomic Clocks)

9. Typical NTP configurations
Internet
NTP Server
GPS Receiver
Campus
Network
NTP Clients
Switching Hub
Local NTP Server

10. Network admin DHCP (Dynamic Host Configuration Protocol)
Assigns IP address, hostname
Informs DNS of assignment
Provides routing, NTP, DNS, etc. information to client
DNS (Domain Name System)
Provides hostname to IP lookup services
Provides server location lookup services
LDAP (Lightweight Directory Access Protocol)
Provides simple information directory services

11. DHCP
Widely used
Support stable IP allocation (needed for transition and legacy equipment)
Supports dynamic IP allocation
Understood by IT administrators
Documents network IP configuration in file
Devices only need their "name"

12. DNS Widely used Provides translation from hostname to IP
DHCP uses DDNS option to maintain coordination with dynamic IP assignments
RR SRV records provide location of LDAP server

13. LDAP Widely used (known as Active Directory in Windows)
Simple query oriented network database
Simple information model. Schema provided as part of Supplement 67.
Alternatives examined
CIM: very attractive, but a much larger effort to define and implement. Not yet widely used.
SNMP, DMTF: interesting but deal with different aspects of network administration and management.

14. Locate AE-title (internal operation)
LDAP Server
Where is AE-X
AE-X is at hostname, port
Database
Where is hostname?
DNS Server
Hostname is x.y.z.w
DICOM
Traffic

15. Beyond Finding AE-Titles
Installation and Network Configuration oriented
AE Configuration
Obtain new unique AE-Title
SOP Classes supported (SCU/SCP, Transfer Syntaxes)
IHE Actor
Vendor extension
Device Configuration
Description
Hospital extension

16. Pre-configured Installation
Large network addition
Multiple vendors
Reduce coordination and scheduling delays
Reduce configuration errors
Reduce staging requirements

17. Pre-configured Installation
Vendor A Preparation
LDAP
Prepared
Configurations
LDIF
IT Organization
DHCP
Network
Planning A A
LDIF A
Prepared
Configurations A B B B
Vendor B preparation

18. Add another machine DHCP Install Hardware Assign Name DNS LDAP
Get IP, hostname, etc.
DHCP
Install Hardware
Assign Name
Find LDAP Server
DNS
LDAP
Query Configuration
Configure System
Obtain Unique AE Titles
Update Configuration

19. Hospital network reconfiguration
DHCP Server
Shutdown (DHCP)
Revise DHCP Configuration
Resume DHCP
Modify network hardware
Clients Resume

20. Customer Assisted Maintenance
Simple device swap
Remote reconfiguration
Local reconfiguration