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Supplement 212: XA Protocol Storage

This supplement by DICOM Working Group-02 proposes a method for storing X-ray angiography (XA) acquisition protocols to improve healthcare practices. The new IODs, XA Defined Procedure Protocol and XA Performed Procedure Protocol, aim to centralize protocol editing, maintain consistency in clinical trials, and manage protocol distribution. The interactive nature of XA protocol usage during procedures necessitates recording both predefined parameters and actual parameter applications. Various XA Defined Protocols can be used within a single XA procedure, offering flexibility and efficiency. The proposal includes detailed examples of defined acquisition and procedure protocols, outlining the parameters and acquisition techniques involved. Implementation of these protocols can lead to better protocol management and enhanced healthcare quality.

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Supplement 212: XA Protocol Storage

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  1. Supplement 212:XA Protocol Storage Supplement is developed by DICOM Working Group 02 (WG-02 Projection Radiography and Angiography)

  2. Contents • Background & Rationale • Overview of the Proposal • XA Protocol Parameters • Changes to the Standard

  3. Background & Rationale • Existing Standard • Supp 121: Defines a method for storage and retrieval of CT acquisition protocols. • Limitations • Supp 121 includes CT modality only. • XA Image IODs include only a few protocol-related attributes, typically related to the appearance of the images. • Goals • To define a method for storage and retrieval of XA acquisition protocols • Similar use cases as for CT: • Centralized edit of protocols and distribution to other systems of same model • Distribution of best practice protocols and general/specific protocols to maintain consistency in clinical trials • Store the protocol(s) used for a particular study, to repeat or perform comparable follow-up, and access to more detailed information about the acquisition protocol used • Export defined protocols from devices to a central repository to facilitate management of consistency and dose. Refer to [NEMA XR-27] “X-ray Equipment for Interventional Procedures User Quality Control Mode” • New Work Item Proposal approved: [2018-09-A] XA_ModalityProtocolStorage

  4. Overview of the Proposal • New IODs • The work will introduce two new IODs • XA Defined Procedure Protocol • XA Performed Procedure Protocol • These IODs will use the constructs of the existing CT protocol management IODs introduced by Supp 121. • XA Protocols Content • XA protocol usage during the procedure is more “interactive” than CT, changing continuously the acquisition modes (Fluoroscopy, DSA, Rotational Angio…) and the parameters (Field of View, frame rate, IQ/Dose levels). • XA Defined Protocol will contain all the acquisition modes and all their pre-defined parameters allowed in that protocol. • Each acquisition mode willcorrespond to one Protocol Element. • XA Performed Protocol will record the actual parameters applied during the various acquisition modes. • Several XA Defined Protocols may be used during one single XA procedure

  5. Overview of the Proposal Example of Defined Acquisition Protocol Selection in the acquisition equipment Modality Console Parameters loaded into the system: Carotid Acquisition Protocol List: Neuro category: DSA Acquisition Protocol Element Aneurysm Acquisition Parameters for DSA Carotid CHASE Acquisition Protocol Element Cardiac category: Occlusion Acquisition Parameters for CHASE Heart Diagnostic ROTA Acquisition Protocol Element Acquisition Modes: Heart Intervention Acquisition Parameters for Rotational NOSUB ROTA DSA CARDIAC Acquisition Parameters for Rotational SUB Fluoroscopy Acquisition Protocol Element User Settings: Acquisition Parameters Fluoro SUB Fluoroscopy Radioscopy Acquisition Parameters Fluoro NOSUB Acquisition Parameters Fluoro ROADMAP SUB SUB • Example of Parameters: • Frame Rate • Field Of View • Focal Spot • IQ level [H/M/L] • Filters [ON/OFF] • Auto-injection settings NOSUB NOSUB ROADMAP

  6. Overview of the Proposal Example of Defined Procedure Protocol database in the acquisition equipment Protocol Library 0-n Defined Protocol 0-n E.g.Fluoro, DSA, Rotational… Acquisition Protocol Element Acquisition Parameters Set of acquisition techniques: E.g.frame rate, FOV, focal spot 0-n E.g.High Resolution, Subtracted Volumes… Reconstruction Protocol Element Reconstruction Parameters Set of reconstruction formats : E.g.volume size, voxel size, subtraction… 0-n E.g.Angio Storage, Cardiac Storage…. Storage Protocol Element Storage Parameters Set of storage rules : E.g. Send all the Series to Angio PACS…

  7. Overview of the Proposal CT Defined Procedure Protocols: example of acquisition & 3D reconstruction workflow Perform CT Scan Acquisition CT Raw data • CT ACQUISITION Parameters: • KVP • X-Ray Tube Current in mA • Revolution Time • Single Collimation Width • Total Collimation Width • Spiral Pitch Factor • Exposure Modulation Type • CTDIvol Notification Trigger • DLP Notification Trigger • CTDIvol ACQUISITION PROTOCOL ELEMENT Perform 3D Image Processing for DISPLAY Perform 3D RECON DICOM ORIGINAL 3D CT voxels Displayed 3D volume • 3D RECONSTRUCTION Parameters: • Reconstruction Algorithm • Convolution Kernel • Reconstruction Diameter • Reconstruction Field of View • Slice Thickness • Pixel Spacing • 3D Image DISPLAY Processing Parameters: • Window Center • Window Width RECONSTRUCTION PROTOCOL ELEMENT

  8. Overview of the Proposal Defined Procedure Protocols: XA example of DSA acquisition & 2D Processing for Display Perform 2D Image Processing for DISPLAY Perform DSA Acquisition Perform 2D Raw Image Processing XA Raw data at detector output DICOM ORIGINAL 2D XA Pixels Displayed 2D image • Clarifications of the meaning of Acquisition and Reconstruction Protocol Elements: • Acquisition: creation of X-Ray output data (Raw data) • Reconstruction: manipulation of output data (raw data) to create a DICOM Instance (or an object for storage) • Notes: • 1- Parameters to display an image on a non-persistent device (e.g. monitors) should not be in the protocols, it should be part of another Presentation workflow  To Be Discussed • 2- Reconstruction elements includes 2D processing parameters… sounds strange in XA. Anyway, even if the 2D processing parameters are defined within the same module and same sequence as the 3D reconstruction parameters, in the implementation the 2D and 3D parameters will appear in two different elements of the sequence. • X-Ray ACQUISITION Parameters: • Frame Rate • Field Of View • Focal Spot • IQ level [H/M/L] • Filters [ON/OFF] • Auto-injection settings • 2D Image DISPLAY Processing Parameters: • DSA masking • DSA LUTs • Windowing • Spatial filters • 2D RAW Image Processing Parameters: • Detector Binning • Bad pixel correction • Dynamic range opt. ACQUISITION PROTOCOL ELEMENT RECONSTRUCTION PROTOCOL ELEMENT DICOM DERIVED 2D XA Pixels

  9. Overview of the Proposal Defined Procedure Protocols: XA example of rotational acquisition & 3D reconstruction workflow Perform 2D Image Processing for DISPLAY Perform Rotational Acquisition Perform 2D Raw Image Processing XA Raw data at detector output DICOM ORIGINAL 2D XA Pixels Displayed 2D image • 2D RAW Image Processing Parameters: • Detector Binning • Bad pixel correction • Dynamic range opt. • 2D Image DISPLAY Processing Parameters: • DSA masking • DSA LUTs • Windowing • Spatial filters • X-Ray ACQUISITION Parameters: • Frame Rate • Field Of View • Focal Spot • IQ level [H/M/L] • Filters [ON/OFF] • Auto-injection settings ? ACQUISITION PROTOCOL ELEMENT Perform 3D RECON Perform 3D Image Processing for DISPLAY DICOM ORIGINAL 3D XA voxels Displayed 3D volume • 3D RECONSTRUCTION Parameters: • volume size • slice thickness • artifact removal algorithms • spatial filtering • 3D Image DISPLAY Processing Parameters: • Window Center • Window Width • MIP • Volume Rendering ? RECONSTRUCTION PROTOCOL ELEMENT

  10. Overview of the Proposal • Green text are changes proposed to the Part 3 of the Standard. • Section 3.8 DICOM Information Object Definitions • Protocol Element – a sequential component of a protocol, consisting of all the parameters necessary to perform that component of the protocol. • Acquisition Protocol Element – A sequential component of anthe acquisition portion of a protocol, that contains the SCANNING PARAMETERS parameters necessary to perform a single SCANacquisition. In the case of CT this would correspond to tube voltage, tube current, rotation time, spatial location, etc. and an Acquisition Protocol Element also corresponds to an XR-25 PROTOCOL ELEMENT. In the case of XA this would correspond to technical factors and control algorithms designed to perform the image acquisition, e.g. kVp, mA, pulse width, Dose Related Parameters, IQ targets, rotation range, etc. • Reconstruction Protocol Element– a sequential component of a the reconstruction portion of a protocol. In the case of CT this would correspond to ,such as generating CT thin images or multiplanar reformats. In the case of XA this would correspond to the processing parameters applied before (and after?) the creation of the X-Ray 2D images (such as binning, bad pixel correction, dynamic range optimization, DSA masking, DSA LUTs, windowing, spatial filters, etc.) and the reconstruction and processing parameters before (and after?) the creation of the X-Ray 3D volume (such as volume size, slice thickness, artifact removal algorithms, spatial filtering, MIP, Volume Rendering, etc.). • Storage Protocol Element – a sequential component of athe storage portion of a protocol, such as sending a series of images to a PACS or an archive or a processing workstation.

  11. Overview of the Proposal Example of XA Procedure Step – Acquisition and Reconstruction on same device Export Perform Recon Perform Fluoro Perform Fluoro Perform DSA Perform ROT XA Select Equipment Sequential Tasks Defined Protocol UID #1 Note: In this example, Fluoroscopy is not stored as a DICOM instance Fluoro Fluoro Acquisition Protocol Element Specification Sequence (0018,991F) Acquisition Protocol Element #1 Fluoroscopy Acq Parameters (1.A1) DSA Acquisition Protocol Element #2 Rotational DSA Acq Parameters (1.A2) Acquisition Protocol Element #3 3D Reconstruction Rotational Acq Parameters (1.A3) Source Acq. Element (0018,9938) #3 Reconstruction Protocol Element Specification Sequence (0018,9933) Reconstruction Protocol Element #1 Source Acq. Element (0018,9938) #2 Reconstruction Parameters (1.R1) Source Recon Element (0018,993A) #1 Storage Protocol Element Specification Sequence (0018,9935) Send 3D to PACS Storage Protocol Element #1 Recon Storage Parameters (1.S1) Send DSA to PACS Storage Protocol Element #2 DSA Storage Parameters (1.S2)

  12. Overview of the Proposal Performed Protocol Storage Example of one single Series Performed Element numbers are sequential in the order of execution Study with XA Images and Protocols STUDY 1 Scheduled Procedure Step#1 References to Defined Protocol #1 SERIES 1 - XA SERIES 101 - XAPROTOCOL  Select Defined Acquisition Protocol #1 Defined Acquisition Protocol Element #1 (Fluoro) Performed Acquisition Protocol #1 Parameters (1.a1- default) IMAGE 1 IMAGE 2 IMAGE 3 IMAGE 4 Acquisition Protocol Element #1 (Fluoro) Parameters (1.a1-default) Acquisition Protocol Element #2 (Fluoro) Parameters (1.a1-modified) Parameters (1.a1-modified) Modified by the user or automatically Acquisition Protocol Element #3 (DSA) IMAGE 5 Parameters (1.a2-default) Defined Acquisition Protocol Element #2 (DSA) Acquisition Protocol Element #4 (DSA) Parameters (1.a2-default) Parameters (1.a2-modified) IMAGE 6 IMAGE 7 Note: In Sup212 need to add time stamps of the start of each performed protocol element Parameters (1.a2-modified) Modified by the user or automatically IMAGE 8 IMAGE 9

  13. XA Protocol Parameters Protocol Parameters: DICOM Attributes to be included as XA protocol parameters

  14. XA Protocol Parameters Protocol Parameters: DICOM Attributes to be included as XA protocol parameters Note: Need to create new attributes if the intended usage is different from the definition in Part 3 (e.g. Type of Radiation in Acq. And Recon)

  15. Changes to the Standard: new IODs & modules

  16. Changes to the Standard

  17. Changes to the Standard

  18. Author Contacts • Nicholas Bevinsnickb@rad.hfh.edu • Heinz Blendinger heinz.blendinger@siemens.com • Steve Massey steve.massey@pacshealth.com • Donald Peck donaldp@mtu.edu • Pritham Shetty pritham.shetty@philips.com • Francisco Sureda (Editor) francisco.sureda@med.ge.com • Annalisa Trianniannalisa.trianni@asuiud.sanita.fvg.it • DICOM Secretariat: dicom@medicalimaging.org Thank you for your attention!

  19. Appendix APPENDIX

  20. XA Protocol Storage • Protocol • A Protocol is a specification of actions prescribed by a Procedure Plan to perform a specific Procedure Step. A Scheduled Procedure Step (from Modality Worklist) contains only one Protocol, which may be conveyed by one or more Protocol Codes. • A Protocol may be specified by a Defined Procedure Protocol to be used on any appropriate patient. A Protocol can be documented, once a Procedure Step has been performed, in a Performed Procedure Protocol. • Defined Procedure Protocol • A Defined Procedure Protocol describes a set of parameters and associated details for the prescribed action. The Defined Procedure Protocol may provide specific values for relevant parameters, or may provide constraints on those parameters (such as an acceptable range) to guide the choice of specific values. • Defined Procedure Protocol is not associated with any particular Patient or Scheduled Procedure Step. A Defined Procedure Protocol may contain parameters specific to a particular model or version of device, or it may be generic in that it only describes parameters common to multiple device models. • A Defined Procedure Protocol may include information such as the clinical purpose, indications, and appropriate device models, intended for selection and management. • Performed Procedure Protocol • A Performed Procedure Protocol encodes the parameter values used. A Performed Procedure Protocol is always associated with a specific Patient and Performed Procedure Step. The Performed Procedure Protocol may reference the Defined Procedure Protocol on which it was based, but does not otherwise record the orginal constraints and whether or not they were satisfied by the final values as recorded in the Performed Procedure Protocol.

  21. XA Protocol Storage • Workflow: • Modality Worklist, Scheduled Procedure Step • Protocol and Protocol Codes • Defined Procedure Protocol • Performed Procedure Protocol • Next slide: Mapping between Modality Worklist, Defined Procedure Protocol, Images and Performed Procedure Protocol

  22. XA Protocol Storage DICOM Modality Worklist DICOM Patient Study . • STUDY: • STUDY UID • Study ID • Performed Procedure Code(s) • Requested Procedure: • STUDY UID • Procedure ID / Description • Procedure Code • SERIES: • Modality <CT, XA…> • Requested Attributes Sequence • Requested Procedure ID / Desc. • SPS ID / Description • Scheduled Protocol Code(s) • Protocol Name • Performed Protocol Code(s) • Reference to Performed Procedure Protocol SOP Instance(s) • Scheduled Procedure Step: • SPS ID / Description • Modality <CT, XA…> • Referenced Defined Protocol UID • Scheduled Protocol Code(s) 1-n 1-n The Modality selects one Scheduled Procedure Step (SPS) and maps it to one Defined Procedure Protocol • IMAGE: • SOP Instance UID / Irradiation Event UID • Acquisition Protocol Name • Acquisition Mode • Acquisition Settings/Parameters 1-n Acquisition Equipment Protocol Library • SERIES: • Modality <CTPROTOCOL, XAPROTOCOL…> • Reference to Defined Procedure Protocol SOP Instance(s) 1-n • DEFINED PROCEDURE PROTOCOL: • SOP Instance UID • Potential Scheduled Protocol Code(s) • Protocol Parameters (pre-defined) 1 • PERFORMED PROCEDURE PROTOCOL: • SOP Instance UID • Protocol Parameters (actually used) 1-n

  23. XA Protocol Storage Defined Procedure Protocol • Open Point: • If the defined protocol can ONLY contain attributes that are defined in the Performed Protocol, but the “AAPM Defined Protocols” don’t know yet what will be the Performed Protocols… How does it work? • Action:  Add a use case of taking a generic protocol (e.g. AAPM) and transforming it into a specific device that does not support all the parameters defined by AAPM. And with parameters not defined yet in DICOM Part 3 (e.g. new features on the vendor model).

  24. XA Protocol Storage • DEFINED Procedure Protocol • Comparison between CT and XA

  25. XA Protocol Storage DEFINED Protocol

  26. XA Protocol Storage CT Procedure Step Example of Defined Protocol Do Scan 1 Do Recon 1 Modify Parameters Do Scan 2 Do Recon 2 Export 3D1 and 3D2 CT Equipment Sequential Tasks Select Within the Defined Protocol, in order to say to the 3D workstation that the Reconstruction Element #1 shall be applied to acquisitions of the Acquisition Element #1 of the Defined Protocol UID #1: Need to use the following tags as selector attributes in the Reconstruction Element Sequence : (0018,9938)Source Acquisition Protocol Element Number = #1 (0008,1155) Referenced SOP Instance UID = UID1. Similarly, to say what objects to be stored (e.g. to PACS), use the following tags as selector attributes in the Storage Element Sequence : (0018,9938)Source Acquisition Protocol Element Number = #1 (0018,993A)Source Reconstruction Protocol Element Number = #1 (0008,1155) Referenced SOP Instance UID = UID1. Defined Protocol UID #1 Acquisition Protocol Element Specification Sequence (0018,991F) Scout Acquisition Protocol Element #1 Axial Acquisition Parameters (1.A1) Source Acq. Element (0018,9938) #1 Acquisition Protocol Element #2 Acquisition Parameters (1.A2) Reconstruction Protocol Element Specification Sequence (0018,9933) Source Acq. Element (0018,9938) #2 Reconstruction Protocol Element #1 Reconstruction Parameters (1.R1) Send to PACS Reconstruction Protocol Element #2 Reconstruction Parameters (1.R2) Source Recon Element (0018,993A) #1 and #2 Storage Protocol Element Specification Sequence (0018,9935) Storage Protocol Element #1 Storage Parameters (1.S1)

  27. Overview of the Proposal To Do: EXAMPLES of usage of Defined Procedure Protocols Describe two scenarios: 1- One single device for acquisition and reconstruction Three sets of protocols (Acquisition, Reconstruction, Storage) on the Acq System 2- Two devices (acquisition system & 3D workstation): Two sets of protocols in Acq System (Acquisition, Storage) and Two sets of protocols on the 3D station (Reconstruction, Storage) Show examples of how the protocols can be selected: • A: user selects one protocol of each family • B: user selects one Acq protocol, the others are selected automatically • C: in workstation, select the protocol automatically based on the content of the image header Add scenario 2 to Part 17

  28. XA Protocol Storage Data Structure of CT Acquisition Workflow Example of usage of Defined Protocols and mapping with Worklist protocols: CT Images Worklist Requested Procedure 1 STUDY 1 Requested Procedure #1 Defined Acquisition Protocol #1 Sch. Procedure Step #1 Scheduled Procedure Step 1 SERIES 1 Defined Reconstruction Protocol #1 Defined Protocol SOP Class UID Defined Protocol SOP Instance UID CP 1716 IMAGE 1 Parameters (1.a1) Acquisition Protocol Element #1 IMAGE 2 … Parameters (1.r1) Reconstruction Protocol Element #1 Scheduled Protocol Code #1.1 Scheduled Protocol Code #1.2 Scheduled Protocol Code #1.3 … Defined Acquisition Protocol #2 Scheduled Procedure Step 2 SERIES 2 Sch. Procedure Step #2 Defined Reconstruction Protocol #2 IMAGE 1 Defined Protocol SOP Class UID Defined Protocol SOP Instance UID CP 1716 Acquisition Protocol Element #1 Parameters (2.a1) IMAGE 2 … Scheduled Protocol Code #2.1 Scheduled Protocol Code #2.2 Scheduled Protocol Code #2.3 … Reconstruction Protocol Element #1 Parameters (2.r1)

  29. XA Protocol Storage Data Structure of XA Acquisition Workflow Example of usage of Defined Protocols and mapping with Worklist protocols: XA Images Worklist Requested Procedure 1 Requested Procedure #1 STUDY 1 Defined Acquisition Protocol #1 Scheduled Procedure Step 1 SERIES 1 Sch. Procedure Step #1 Defined Display Protocol #1 Defined Protocol SOP Class UID Defined Protocol SOP Instance UID CP 1716 Parameters (1,a1) Acquisition Protocol Element #1 IMAGE 1 Parameters (1,d1) Display Protocol Element #1 DSA Scheduled Protocol Code #1.1 Scheduled Protocol Code #1.2 Scheduled Protocol Code #1.3 … Parameters (1,a2) Acquisition Protocol Element #2 IMAGE 2 Display Protocol Element #2 Parameters (1,d2) Rotational Defined Reconstruction Protocol #1 SERIES 2 Sch. Procedure Step #1 Defined Display Protocol #2 Scheduled Procedure Step 2 IMAGE 3 Parameters (1.r1) 3D Reconstruction Protocol Element #1 Defined Protocol SOP Class UID Defined Protocol SOP Instance UID CP 1716 3D Volume Defined Acquisition Protocol #2 Scheduled Protocol Code #2.1 Scheduled Protocol Code #2.2 Scheduled Protocol Code #2.3 … Sch. Procedure Step #2 SERIES 3 Defined Display Protocol #3 Parameters (2,a1) Acquisition Protocol Element #1 IMAGE 5 Display Protocol Element #1 Parameters (2,d1) Fluoro

  30. XA Protocol Storage • PERFORMED Procedure Protocol • Comparison between CT and XA

  31. XA Protocol Storage • PERFORMED Protocol

  32. CT Protocols IODs & modules

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