Overall Flashcards
What are some areas where clinical scientists may work with medical IT?
Access patient records, patient calculations, patient reports, system management, R&D, software development, data acquisition and analysis, computer modelling, procurement, corporate user (emails etc)
The role of the clinical scientist is in every part of the life cycle of a system, what are the stages of the lifecycle?
Planning, specification, procurement, installation, acceptance, commissioning, QA, maintenance, clinical user, decommissioning
Instead of a comprehensive electronic health/patient record that includes all information, what typically happens?
Subset of a patients record focussed on a particular discipline (eg radiology system) that communicate data with each other, could all look like one system from the outside
How do we ensure that the system knows patient A in one system is the same as patient B in a different system?
Master patient index (MPI), links a unique identifier (eg NHS number) and the real patient (links patient data across various sources)
What is a patient administration system (PAS)?
Central admin system that knows about the patients new into the organisation and their appointments. Might include basic info of test results and their doctors. (could include master patient index but not always)
What are the main radiology systems?
Radiology Information System (RIS) and Picture Archive and Communications System (PACS)
What is the purposes of a Radiology Information System (RIS)?
Scheduling of imaging, resource management, inventory tracking, reporting of imaging, presentation of reports, report sign-off, billing
What is the purposes of a Picture Archive and Communications System (PACS)?
Storage of images and other data, visualisation of images and data transfer between systems
Instead of having a PACS workstation to access the PACS server and a RIS workstation to access the RIS server, what do we usually have instead?
Have a web server that collects information from the PACS and RIS servers, then a workstation accesses this central point to show the end user both together
What is a modality in medical IT?
Any computer controlled clinical equipment (eg scanners, workstations, potentially software packages)
What does it mean that most imaging equipment (eg scanners) are standalone equipment?
Not reliant on other components so they can work in isolation and perform their basic function (eg could scan without workstation working)
Is a server (could be one or multiple machines) a virtual central point that everything is going through?
Yes
What is connected to a server (eg for PACS or OMS) in medical IT?
A database, storage, client applications and modalities (client = using data, modality = adding to data, could be the same thing)
What does a database tend to store?
Basic text data and numbers (eg records, file names of images)
What does ‘storage’ from a server tend to store?
Images (binary type data) - larger files than database
What are the main radiotherapy systems?
Treatment Planning System (TPS), dose checking system, Record and Verify (RV or VR) System (at linac) and Oncology Management System (OMS) (equivalent to EHR, RIS, PACS and PAS together)
What does networking allow?
- A complex system to be made up of connected individual components
- One clinical system to communicate with another
- Multiple systems to be used in the care of a patient
What are the two ways that a network can be represented diagramatically?
Logical diagram (how systems link to each other and focuses on flow of data) and physical diagram (physical connections between components)
What are different types of architecture of network applications?
Client/server, standalone, hybrid and peer to peer
What is the client-server architecture of network applications?
Separates tasks between the providers of a resource or service called servers and service requester called clients
What is the peer to peer architecture of network applications?
One system sends direct to another without going through some sort of intermediary (like a server)
Why should we be sceptical of client-server architectures?
It can be confusing as to where the client is
What is an extreme form of the client/server architecture?
Application servers (applications presented via a web browser and all processing performed on server)
What does the acronyms in the ISO OSI model of networking stand for?
ISO = International Standards Organisation
OSI = Open Systems Interconnection
Why is a model of networking like the ISO OSI model required in order to transfer data instead of sending data directly?
It wouldn’t work because there’s different operating systems, different suppliers and different protocols
What is the ISO OSI model of networking for?
Standardised model of transferring information by breaking the data down until you can physically transfer the data (eg cable, microwave transfer etc) before rebuilding the data until it can be interpreted on the other side
What are the 7 stages on each side of the ISO OSI model of networking?
Application layer, presentation layer, session layer, transport layer, network layer, data link layer and physical layer
What model has replaced the ISO OSI model of networking and the one we typically use for hospital networks?
TCP/ IP model (Transmission Control Protocol/ Internet Protocol)
How many layers are in the TCP/ IP model?
5
What are the layers of the TCP/ IP model?
Application layer, transport layer, internet layer, data link layer and physical layer
Which layer does the Transmission Control Protocol (TCP) operate in the TCP/ IP model?
Transport Layer
What layer does the Internet Protocol (IP) operate in the TCP/ IP model?
Internet Layer
What could be counted as the Application Layer of TCP/ IP model?
What we interact with on the computer (PACS or email client for example)
The Internet Protocol (IP) in the TCP/ IP model is implicitly referring to what version?
4
What other version is sometimes used in the Internet Protocol (IP) in the TCP/ IP model?
6
Why was version 6 of the Internet Protocol introduced?
There was a concern that we would run out of addresses with version 4
What is the Internet Protocol (IP) in the TCP/ IP model for?
It is a way of uniquely identifying a device’s interface on a network to facilitate data transfer to that interface
An IP version 4 address is how many bits and represented by how many bytes?
32 bit number represented by a series of 4 bytes. (4 lots of 3 numbers)
A byte in an IP v4 address is a number in what range?
0 to 255 (2^8=256 values)
How is an IP v4 address usually represented?
aaa.bbb.ccc.ddd
How many possible address are there for the IP v4 format?
2^32 (4 billion)
What restrictions must an IP address have?
It must be unique on a network, each byte between 0-255 and other devices know how to reach each
Two computers on a network will both have what?
Each have a network card with an IP address on
There’s a rule with the Internet Protocol that network devices are only allowed to accept what information?
Information that has been intended for that network device (so information may get sent along a network connection but get rejected at the device)
What are methods of transferring data between devices in a network with IP address?
Direct connection, connection via hub, connection via switch, connection via gateway
What is the connection via hub method of transferring data to different connected devices with IP addresses?
The hub passes data to all connected devices, which gets rejected by all except the one that it is intended for (don’t often see hubs today)
Why did switches replace hubs for transferred data between devices?
It is inefficient to send large volumes of data to every device so the network can easily be paralysed
What is the connection via switch method of transferring data to different connected devices with IP addresses?
The switch passes data on to the intended device in the network
What is the benefits of using a connection via switch to transfer data to different connected devices with IP addresses?
More secure and efficient
Do switches have an IP address itself and why?
Yes because bigger networks have multiple switches for each subnet that send data between them before going to a different device
What number do switch IP addresses use as the final number?
1 by convention (not always)
With multiple switches in a bigger network, how do they communicate with each other to transfer data to a connected device?
Via the ‘gateway’ of the first switch (or router) before going to the next switch
When is a gateway required when transferring data with IP addresses?
When you need to transfer data outside of your network
What is a router?
A special class of a switch and its job is to connect lots of networks together so connected to lots of other routers or switches
What is the group name for these devices: hub, switch, gateway, router?
Infrastructure components or network devices
What is a subnet?
It is a sub-network that is part of a larger network
What two pieces of information defines a subnet?
Subnet address (any address in the range but usually the first one) and a netmask
What do the numbers in the netmask represent?
Which numbers are allowed to change or not
What is the purpose of a network?
It allows us to work out what’s on the same network
Do you ever have a zero in the middle of a net mask?
No
If a netmask is 255.255.255.0, what does this mean?
The first three sets of numbers of an IP address aren’t allowed to change in order to be in the same network but the fourth number is
In technical documentation, a representation of an IP address will have a / sign then the number of bits, how is this calculated?
In the netmask, each 255 is 8 bits and 128 is 1 bit (240 is 4 bits) so add them up
What are private subnets?
Private IP address ranges which can be allocated at will but must not appear on the internet
How many private subnets are there?
3 (technically 4)
Why are private subnets used? (could be at home or internally within organisations)
Convenient as can allocate at will and secure as they do not appear on the internet
What are the 3 IP addresses that are private subnets?
10.0.0.0 (class A)
172.16.0.0 (class B)
192.168.0.0 (class C)
What is the netmask for the private subnet 10.0.0.0 (class A) and how many bits are in it?
255.0.0.0 and 8
What is the address range for the private subnet 10.0.0.0 (class A)?
10.0.0.0 - 10.255.255.255
What is the netmask for the private subnet 172.16.0.0 (class B) and how many bits are in it?
255.240.0.0 and 12
What is the address range for the private subnet 172.16.0.0 (class B)?
172.16.0.0 - 172.31.255.255
What is the netmask for the private subnet 192.168.0.0 (class C) and how many bits are in it?
255.255.0.0 and 16
What is the address range for the private subnet 192.168.0.0 (class C)?
192.168.0.0 - 192.168.255.255
What is Network Address Translation (NAT)?
A mechanism by which traffic from a host on a private subnet can be directed to the Internet and it allows ranges of addresses to be reused
What handles Network Address Translation (NAT)?
Switches and other network infrastructure components
How do you get replies when using a private subnet and network address translation?
The traffic from your address is tagged in transit so replies are routed back to your private address
What is the 4th type of private subnet called?
Loopback address
What is the IP address for the loopback address?
127.0.0.1
What is the purpose of the loopback address?
It directs traffic back to the local computer without it reaching any ‘real’ network interface so it allows network services to operate without a network being present
What is the address range for the loopback address 127.0.0.1?
Any address in 127.0.0.0/8 (so any address starting with 127)
How many bits is an IP version 6 address?
128
Why are IPv6 sometimes not used in a healthcare environment?
Compatibility issues
In an IP version 6 address, how many sections are there that are bounded by a colon?
8 (8 lots of 4 characters)
What is the Transmission Control Protocol (TCP)?
It manages data transfer as a series of bundles of information called packets, which each have a series of bytes, instead of all the data and these are sent across a network then reassembled
What is the structure of a TCP packet from top to bottom?
TCP header, length, source port, destination port, sequence number, checksum, other information and data
What does the TCP header in the TCP packet do?
It identified it as a TCP packet (useful for a switch)
What do the sequence number in the TCP packet do?
It allows assembly of the data block by describing what order the packets should be place in
What is the checksum in the TCP packet?
It is a number generated from a calculation of the data and if it is repeated with a different result, we will know corruption has occurred
Behind every IP address, there could be multiple applications communicating on that device, what are these called?
Ports or internet sockets
What is the form of a port number?
Any 16 bit integer (0 - 65,535)
How is the port number identified for a certain IP address?
It is following a colon after the IP address
Below what port number is reserved for specific applications?
1024
Other than TCP packets, what other type of packet could there be?
Universal Datagram Protocol (UDP)
For TCP packets, are packets acknowledged as they are received?
Yes
What is the structure of UDP packets?
UDP header, source port, destination port, checksum, and data
Are UDP or TCP packets more simple?
UDP
When are UDP packets used?
Streaming information when data integrity is not as important but it is quicker
For UDP packets, are packets acknowledged as they are received?
No
Who allocates the standard reserved ports?
Internet Assigned Numbers Authority (IANA)
What is the Media Access Control (MAC) Address and what is its format?
Physical address of a physical device eg the hardware (IP address is a virtual address on a network). 6 lots of 2 separated by colons
What layer of the IP/TCP model does the Media Access Control (MAC) address operate?
Data Link Layer
How is the Media Access Control (MAC) Address represented?
By 6 bytes with a unique prefix for the manufacturer
Typically, does every network interface have a globally unique MAC address or can they be reused?
Globally unique
What terms are used to describe the scale of a network?
Local Area Network (LAN), Wide Area Network (WAN) and Metropolitan Area Network (MAN)
What does a Local Area Network (LAN) refer to?
Small geographical area (could be a hospital or a room, difficult to define exactly)
What is a Metropolitan Area Network (MAN)?
Special case of a WAN (Wide Area Network) distributed over a city
What is the Health and Social Care Network (HSCN)? (used to be N3)
Private network linking NHS and special care organisations (can include private suppliers)
What does the Directory Name Service (DNS) do?
They link hostnames (eg website address) to IP address
What do Virtual Private Networks (VPN) do?
Allow secure connections to networks from external locations
How do VPNs work in hospitals?
It creates an encrypted tunnel from the network device (eg home PC) back to the hospital server
What is the ethernet?
A family of wired computer networking technologies used in LANs, WANs, MANs.
What is network bandwidth sometimes referred to as?
Maximum throughput
What is the network bandwidth?
The rate at which data can be transferred in one direction
What is the units for network bandwidth?
Data volume per unit time, eg Megabits per second (Mbps)
What factors could affect the network bandwidth?
Data transport process speed (eg a packet must be acknowledged every time it is received for TCP), connection may be half or full duplex
What does it mean for a network connection to be half or full duplex?
Half duplex is when only one party can communicate at a time whereas full duplex, both parties can communicate simultaneously
How many bytes are in one kilobyte?
2^10 bytes = 1024 bytes
How many bytes are in one megabyte?
2^10 x 2^10 bytes
How many bytes are in one gigabyte?
2^10 megabytes
What is the definition of network latency and its units?
The time taken for a packet to travel from the sender to receiver. Units of time, usually milliseconds
What are some of the purposes of a ping?
It verifies a route between source and destination exist, measures network latency, for example
What are the main two data exchange standards that we are concerned with?
DICOM and HL7
Why are data exchange standards required?
Standardised language is important so that different components (with different manufacturers) can communicate with each other
What is an open standard?
A standard that is available to everyone (may be free or not) that anybody who wants to implement that standard is able to follow the rules
Are DICOM and HL7 open standards?
Yes
Are TCP/IP and UDP open standards?
Yes
What are the different levels of sources of standards and an example of each?
International Standards Organisations (eg ISO), National Standards Organisations (eg BSI), Professional Standards (eg IPEM, NEMA) and Corporate/Organisational Standards (eg NHS DAPB)
Is adherence to standards voluntary or mandatory?
Generally voluntary but it may be written in law eg Health and Social Care Act (depends on the country whereas the standard is the same regardless of where its implemented)
What does DICOM stand for?
Digital Imaging and COmmunications in Medicine
What does DICOM cover?
Digital images and associated data (eg date and time, name of operator, respiratory motion)
What body coordinates DICOM?
NEMA
Who is DICOM mainly for?
Mostly manufacturers but also users
What version of DICOM are we on?
3.0 (different years after but always 3.0)
What is the scope of DICOM?
Standard data types and services, transfer of data across a network, storage onto media, compatibility between systems (conformance with standards), data compression, security, image display and output
What is a data element according to DICOM?
Unit of information with defined data type and structure. Standard elements are uniquely indexed by a tag and name (eg patients name, slice position)
What is an information object according to DICOM?
Set of elements which together describe a physical entity (eg CT slice, digital radiograph). Subcategory of this is an instance
What is a service class/ group according to DICOM?
Action that can be performed on information objects (eg transferring data, archiving, printing)
What is a Service Object Pair (SOP) in DICOM?
A defined action which can be performed on a particular object (eg storage of a CT slice)
What is the name and its acronym for the group of service classes in DICOM?
DICOM Message Service Element (DIMSE)
What are the most common DIMSE service classes under DICOM?
Verification, storage, query, retrieve, printing
What three pieces of information is needed to uniquely identify a system in a DICOM environment?
IP address or hostname, port for receiving data, Application Entity Title (AET)
Under DICOM, service classes can by implemented by application software by who?
Service Class User (SCU) or Service Class Provider (SCP)
What could be an example of Query/Retrieve under DICOM?
A user querying a piece of information from PACS and then PACS sending it back
What are Unique Identifiers (UIDs) that are used in DICOM (not only DICOM uses this)?
String of up to 64 characters (0-9 and full stops) in length that are assigned to SOP (Service Object Pair) classes and assigned to instances of objects. Globally unique
What does each part for the Unique Identified (UID) under DICOM represent?
DICOM. country, root owner (eg manufacturer) and any numbers to make it unique
A DICOM file has what prefix to show it is a DICOM file?
DICM
What is an example form of a tag in a DICOM file that is unique to the data type?
Example (0010, 0010)
What is the Endian in DICOM?
Transfer syntax - the way in which bytes are numerically stored
What are the different types of Endian?
Implicit VR Little Endian, Explicit VR Little Endian and Explicit VR Big Endian
What form of Endian must every system be able to speak?
Implicit VR Little Endian
What is DICOM conformance?
How a system has been designed to implement a standard
What is a DICOM conformance statement?
It specifies supported information objects, service classes, SOPs. communication protocols and storage protocols (says what it does, not what it doesn’t do)
What are the benefits of DICOM?
Widely accepted standard format (improve compatibility and well defined standard objects/ services), robust, reliable format
What are the limitations of DICOM?
Conformance does not guarantee compatibility, complex standard and very broad scope, may require complex local configuration
What could be some issues with DICOM?
Incompatibility between systems, configuration problem, unexpected results, proposed development of service
What does HL7 stand for?
Health Level 7
Whereas DICOM is more in the realm of clinical scientists, who manages HL7 in a healthcare organisation?
IT and informatics departments
Who manages HL7?
HL7 Consortium
What type of data is HL7 concerned with?
Communication of message between clinical information systems (text or numerical data, not image) eg patient demographics, scheduling infor, lab results, radiology results
If PACS looks at DICOM mostly (not strictly), what standard does RIS use typically?
HL7
What is the name of how to convert an appointment list in HL7 to DICOM?
DICOM worklist format from PACS
What is the HL7 message format?
A message is a series of segments which themselves contain a series of composites (fields)
What versions of HL7 do we typically use?
Version 2.x (2.6 most commonly used) or Version 3 (mostly NHS)
What is the form of HL7 version 2.x messages?
Binary or ASCII
What is the form of HL7 version 3 messages?
XML
What are Integration Engines (also called Trust Integration Engines/ TIEs in the NHS)?
Convert one HL7 feed into multiple feeds by data mapping between input feed and outputs (eg change NHS number to hospital number for a particular system)
When is the only time physicists are involved with HL7?
If it affects a physics managed system (eg radiotherapy OMS)
What does the organisation with the acronym IHE stand for?
Integrating the Healthcare Enterprise
What do IHE do?
They work with manufacturers to improve compatibility between systems
What are IHE Profiles?
Standard ways of communicating between systems, typically using DICOM and HL7, for particular real-world applications
What are the ‘Integration Statements’ that manufacturers release?
Which IHE Profiles they meet with a particular product