29 Questions
What does the client send to the server to initiate the connection termination process?
A FIN segment with the FIN bit set to 1.
What state does the server enter after receiving the FIN segment from the client?
CLOSE_WAIT state.
What state does the client enter after receiving the acknowledgement from the server?
FIN_WAIT_2 state.
What does the server send to the client to terminate the connection?
A FIN segment with the FIN bit set to 1.
What state does the client enter after sending an acknowledgement to the server?
TIME_WAIT state.
What are the five primary areas of functionality addressed by the services and information objects at the application layer in DICOM?
Transmission and persistence of complete objects, query and retrieval of such objects, performance of specific actions, workflow management, and quality and consistency of image appearance.
What is the purpose of negotiation in DICOM's network protocol?
To permit peers to agree on the functions to be performed
How many data types are defined in DICOM, and what compression algorithm is used in message encoding?
24 data types, and JPEG compression (with 17 variants)
What is the purpose of the UID mechanism in DICOM?
To provide a robust unique identifier mechanism
What is the purpose of service classes in DICOM?
To define classes of service for specific applications, such as image management and printing
What is the purpose of the data dictionary in DICOM?
To include a large number of new data elements
What is the purpose of the N-EVENT-REPORT service in DICOM?
To report an event about a SOP Instance to a DIMSE-service-user.
What is the main function of the N-GET service in DICOM?
To request the retrieval of information from a DIMSE-service-user.
What is the purpose of the DICOM file header?
To store information about the patient's name, the type of scan, image dimensions, etc.
What is the role of the Service Class User/Provider (SCU/SCP) in DICOM?
To facilitate communication between devices in a DICOM network.
What is the purpose of the Unique IDentifier (UID) in DICOM?
To uniquely identify a DICOM object or instance.
What is the significance of Transfer Syntax in DICOM?
It defines the rules for encoding and decoding DICOM data.
What is the format of the Patient Date of Birth in DICOM?
The format is an 8 characters string following the format YYYYMMDD.
What is the difference between Explicit VR and Implicit VR in DICOM?
Explicit VR means the VR is sent in the DICOM Message, while Implicit VR means no VR is sent and the product must use its own internal dictionary.
How many basic data types are defined in the DICOM standard?
There are 27 basic data types, known as Value Representations (VRs).
What is the purpose of Value Representations (VRs) in DICOM?
VRs are used to encapsulate all possible clinical data types, each with its own abbreviated two-letter name, definition, and data length.
What information is defined for each Value Representation (VR) in DICOM?
Each VR has its own abbreviated two-letter name, a definition of what it represents, a description of what characters are allowed in its data, and a prescribed data length.
How are Value Representations (VRs) identified in DICOM?
VRs are identified with two capital letters.
What is the primary unit of DICOM that everything is based on?
SOP classes
What are the two categories of DIMSEs?
Operations and notifications
What is the total number of DIMSEs used for composite and normalized information objects?
11
What is formed by combining service classes and information objects?
SOP
What is the purpose of DICOM service classes?
To build complex services
What is the abbreviation of Digital Imaging and Communications in Medicine?
DICOM
Study Notes
DICOM Service Classes
- Composite and normalized services are built using DICOM message service elements (DIMSEs)
- There are 5 DIMSEs for composite information objects (DIMSE-C) and 6 for normalized information objects (DIMSE-N)
- Two categories of DIMSEs: operations (e.g. "store") and notifications (e.g. "event report")
DICOM Service-Object Pair (SOP)
- The service classes and information objects are combined to form SOP
- The SOP class is the elemental unit of DICOM
- Everything that DICOM does is based on the use of SOP classes
DIMSE-N Services
- N-EVENT-REPORT service: report an event about a SOP Instance to a DIMSE-service-user
- N-GET service: request the retrieval of information from a DIMSE-service-user
- N-SET service: request the modification of information by a DIMSE-service-user
- N-ACTION service: request a DIMSE-service-user to perform an action
- N-CREATE service: request a DIMSE-service-user to create an instance of a information object
- N-DELETE service: request a DIMSE-service-user to delete an instance of a information object
DICOM Terminology
- DICOM File Format: Information Object Definition (IODs)
- Application Entity Title (AE Title)
- Service Class User/Provider (SCU/SCP)
- Unique IDentifier (UID)
- Transfer Syntax
- Value Representations (VR)
DICOM File Format
- A single DICOM file contains:
- A header (stores information about the patient's name, the type of scan, image dimensions, etc)
- Image data (in uncompressed or compressed form)
DICOM Technology Overview
- The services and information objects address five primary areas of functionality:
- Transmission and persistence of complete objects
- Query and retrieval of such objects
- Performance of specific actions
- Workflow management
- Quality and consistency of image appearance
DICOM Features
- Network protocol: DICOM incorporates negotiation to permit peers to agree on the functions to be performed
- Message encoding: DICOM defines 24 data types and supports multiple character repertories
- Object data model: DICOM is based on a completely specified data model
- Data dictionary: DICOM includes a large number of new data elements
- Service classes: DICOM defines classes of service for specific applications and conformance levels
Value Representations (VR)
- VR is a 2-letter code that describes the type and format of the information sent in a DICOM Data Element
- Explicit VR: the VR is sent in the DICOM Message
- Implicit VR: no VR is sent in the message, and the product uses its own internal dictionary
- DICOM standard defines 27 basic data types, known as value representations (VRs)
Learn about the steps involved in terminating a TCP connection, including the FIN segment, acknowledgements, and state transitions. Understand how the client and server communicate to close the connection.
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