SR workshop Intro slide 1 SR Workshop Copyright OTech Inc all rights reserved DICOM explained in the context of Structured Reporting Herman Oosterwijk, OTech Inc. NEMA workshop, Washington DC March 29-30, 2000

SR workshop Intro slide 2 SR Workshop Copyright OTech Inc all rights reserved Objective: To get a basic understanding of DICOM services and objects in the context of Structured Reporting: DICOM objects (IODs) DICOM encoding: Data elements, VR, sequences, Codes DICOM exchange media

SR workshop Intro slide 3 SR Workshop Copyright OTech Inc all rights reserved Parts of the Standard: 1. Overview 2. Conformance 3. Information Objects 4. Services Class Specifications 5. Data Structures and Semantics 6. Data Dictionary 7. Message Exchange

SR workshop Intro slide 4 SR Workshop Copyright OTech Inc all rights reserved Parts of the Standard: 8. Network Support 9. Point to point 10. Media Storage and File format 11. Media Storage Application Profiles 12. Physical Media 13. Point to point Print mgt 14. Greyscale display function standard xx. Supplements!!!

SR workshop Intro slide 5 SR Workshop Copyright OTech Inc all rights reserved Common Information Model Conformance claims to define functionality: Matching is critical Roles: SCU/SCP Unique Identification of objects: Each DICOM object is unique Documentation tools such as Macros DICOM key parts:

SR workshop Intro slide 6 SR Workshop Copyright OTech Inc all rights reserved SOP Instance C-Store Mrs. Smith SR Key DICOM concept==SOP Class (Service defn + Information Object Defn): DIMSE C-Store Service Elt. Info Object SR Object Defn (IOD) SOP Class C-Store SR

SR workshop Intro slide 7 SR Workshop Copyright OTech Inc all rights reserved Service Class Information Object Definition(IOD) DIMSE Service Elements Service Object Pair (SOP) Class (=SOP Class) IOD-->Module-->Attrib C-Store C-Get C-Find C-Move C-Echo N-Create N-Set N-Get N-Delete N-Action N-Event-rep DCM 3 DCM 7 DCM 4 Service Elements: SVC Classes: Verification Storage Study notf. Print Mgt Patient Mgt Study Mgt Results Mgt Storage Commnt Query/Retrieve BasicWlist Mgt DCM 5,6 Relationship between:

SR workshop Intro slide 8 SR Workshop Copyright OTech Inc all rights reserved IOD Description; i.e. what is the real world object (Information Entities-IE) that is represented. Can be one or more IEs (Composite, Normalized) Examples: Image IOD: Patient, Study, Equipment, Image ----> Composite Patient IOD: Patient info ---->Normalized Information Object Definition (IOD):

SR workshop Intro slide 9 SR Workshop Copyright OTech Inc all rights reserved IOD Entity-Relationship model; provide the context (relationships) between the IEs Information Object Definition (IOD): This information model is critical! IOD Module table; which modules provide the attributes for the IOD Modules are defined for convenience reasons (all patient info together, all image info together....) Modules contain Attributes (Pat. name, etc.)

SR workshop Intro slide 10 SR Workshop Copyright OTech Inc all rights reserved Patient Study is the subject of contains spatially defines creates Equipment Modality LUT VOI LUT Frame of Reference Image Overlay Curve contains Series 0,1 0,n 111 1,n 0,n 1,n 1 1 Stored Print 0,1 Presentation State 0,n SR Document 0,n SR Information Model:

SR workshop Intro slide 11 SR Workshop Copyright OTech Inc all rights reserved

SR workshop Intro slide 12 SR Workshop Copyright OTech Inc all rights reserved

SR workshop Intro slide 13 SR Workshop Copyright OTech Inc all rights reserved Module Definition: Attribute Name, Tag, Type, Description

SR workshop Intro slide 14 SR Workshop Copyright OTech Inc all rights reserved Defined Terms: Can be extended (e.g. Modality: CT,MR, ES, SR, etc.) Enumerated values: No extensions, additions (e.g. Patient Sex: M, F, O) Value of data elements can belong to a Set: Value Multiplicity: More than one value, requires separator (e.g. Other Patient Names)

SR workshop Intro slide 15 SR Workshop Copyright OTech Inc all rights reserved 1: Required (e.g. pixel spacing) 1C: Required when condition met (e.g. pixel aspect ratio) 2: Required, can be 0 if unknown (e.g. Patient Name, Accession number) 2C: Conditional (e.g. patient positioning) 3: Optional (e.g. Other Patient Name) Type Designation:

SR workshop Intro slide 16 SR Workshop Copyright OTech Inc all rights reserved Data Element Tag, Optional Value Representation, Length, Value Field TagVRValue Length Value Field Data Elem Data Elem Data Elem Data Elem DICOM Part 5-6 Data set and structures:

SR workshop Intro slide 17 SR Workshop Copyright OTech Inc all rights reserved Tag: Identifies Attribute Value representation (VR): Groups similar attributes for identification and definition purposes, e.g.: Patient name, Physician name, Other Patient names, etc.: VR is PN Birth date, Exam date, etc.: VR is DA VR syntaxes specified in part 5 Data set and structures (ctd):

SR workshop Intro slide 18 SR Workshop Copyright OTech Inc all rights reserved Implicit VR: Assumed based on tag Explicit VR: Explicitly specified Note: VR is negotiated during association! Explicit VR: 0010,0010 PN 10 Smith^John Implicit VR: 0010, Smith^John Data set and structures (ctd):

SR workshop Intro slide 19 SR Workshop Copyright OTech Inc all rights reserved Example of a DICOM Message:

SR workshop Intro slide 20 SR Workshop Copyright OTech Inc all rights reserved Sequences: VR =SQ Sequence contains zero or more items, which contains a set of Data Elements Used to encode repeating sets Accommodates multilevel nesting (recursion) Explicit length SQ: value of bytes in length field Undefined length SQ: requires flag in length field and SQ and item delimiters (sppt rqd)

SR workshop Intro slide 21 SR Workshop Copyright OTech Inc all rights reserved Document Root Node CONTAINER " Chest X-ray " (Document Title) Hasobs context Content Node PNAME " Recording Observe r = Smith^John^^Dr^" * Relationship Modes = By-value = By-reference contains inferred from Content Node CODE " finding = mass" Heading Node CONTAINER " Conclusions " Heading Node CONTAINER " Specific Image Findings " Content Node CODE " conclusion = probable malignancy" Content node SCOORD " best illustration of findings " Leaf Node IMAGE " Baseline " contains Leaf Node NUM " diameter = 1.3 cm" margination infiltrative" has properties Leaf Node CODE " = has properties inferred from Leaf Node IMAGE selected from Hasobs context Content Node UIDREF " Study Instance UID of Evidence Directly Examined by RO = " Hasobs context Content Node PNAME " Patient-Data-Acquisition Subject =Homer^Jane^^^" has concept mod Leaf Node CODE " Views = PA and Lateral " SR Example:

SR workshop Intro slide 22 SR Workshop Copyright OTech Inc all rights reserved margination infiltrative" has properties Leaf Node CODE SR Example:

SR workshop Intro slide 23 SR Workshop Copyright OTech Inc all rights reserved SNOMED: Systematized Nomenclature for Human and Veterinary Medicine; maintained by College of American Pathologists (CAP); anatomic identifiers, observations, etc. Requires license fee LOINC: Logical Observation Identifiers, Names and Codes (LOINC); measurements No license (free) CPT, ICD9: Procedure Codes BI-RADS: Mammography 99SDM, SDM, DTMR Codes:

SR workshop Intro slide 24 SR Workshop Copyright OTech Inc all rights reserved Human language is not exact, many variations are possible: e.g. Exam type is: Chest Thorax Chest PA/LAT chest Codes, Why?:

SR workshop Intro slide 25 SR Workshop Copyright OTech Inc all rights reserved From CAP, DUKE website, in supplements, eventually in new DICOM Supplement 53. Encoding: Coding Scheme Version # Code Meaning Optional Extended coding for context information Codes, where, how to encode:

SR workshop Intro slide 26 SR Workshop Copyright OTech Inc all rights reserved Example from Digital X-Ray (DX) IOD: Makes extensive use of Coded data entries using standard vocabulary: Instead of specifying sagittal for View Code, one specifies: Code Value: R Coding Scheme: SNOMED Scheme Version: Version 1.0 Meaning: Sagittal

SR workshop Intro slide 27 SR Workshop Copyright OTech Inc all rights reserved MR Information System Modality Worklist Management Performed Procedure Step Storage Print Query/Retrieve Verification Storage Commit DICOM Services:

SR workshop Intro slide 28 SR Workshop Copyright OTech Inc all rights reserved SCP level of conformance: Level 0 (local): user defined subset will be stored only Level 1 (base): Type 1 and 2 attributes will be stored, others may be discarded. SCP is not required to validate the Attributes Level 2 (full): Type 1,2,3 will be stored SCP is not required to validate Attributes Patient ID, Study Instance UID and Series Instance UID may be coerced (negotiated) Storage Service class (ctd):

SR workshop Intro slide 29 SR Workshop Copyright OTech Inc all rights reserved Why yet another way of encapsulating waveforms ? Current mechanisms are proprietary; timing seems ripe for standardization Relationship between images and waveforms is key Existing Curve specification in DICOM was not sufficient Waveforms:

SR workshop Intro slide 30 SR Workshop Copyright OTech Inc all rights reserved Waveforms: Relate Images

SR workshop Intro slide 31 SR Workshop Copyright OTech Inc all rights reserved DICOM Media Specifications: DICOM Application Entity Medical Imaging Application OSI Upper layer svc boundaryDICOM File svc boundary 50 pin OSI TCP/IP ABC Media Format Media Format Media Format Phys. Medium Phys. Medium Phys. Medium DCM Presn.

SR workshop Intro slide 32 SR Workshop Copyright OTech Inc all rights reserved DICOM Media Specifications (ctd): DICOM Application Entity Service / Object Pairs Basic Dir. DICOM File Format Media Formats: e.g. File data structures Physical Media: e.g. CD-R; 90 mm MOD, etc. part 10 part 11 part 12

SR workshop Intro slide 33 SR Workshop Copyright OTech Inc all rights reserved DICOM SOP Instance DCM File Meta Info DICOM Data Set DICOM SOP Instance DCM File Meta Info DICOM Data Set FILE SET