PS-2020a / part17

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>>2D Mating Feature Coordinates Sequence​

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ZZ.5 Implant Template Versions and Derivation​

The Generic Implant Module contains several Attributes to express the relations between different versions of implant templates.​ These Attributes are​

Different versions of Implant Templates reflect the changes a manufacturer is doing on the Implant Templates he issues. The Implant​ Templates that are issued by a manufacturer (or a third party who is acting on behalf of the manufacturer) are always ORIGINAL.​ Softwarevendors,PACSintegrators,orotherstakeholderswilladdinformationtosuchtemplatesfordifferentpurposes.TheInstances​ that are generated by this process is called derivation and the resulting instances are labeled DERIVED. Implantation Plans, i.e.,​ electronicdocumentsdescribingtheresultofimplantationplanning,arespecifiedinaninstanceoftheImplantationPlanSRDocument.​ There, the implants that are relevant for one plan are included by reference. When such plans are exchanged between systems or​ organizationsitislikelythatthereceivingpartyhasaccesstootherversionsoftemplatesasthesendingpartyhas.Inordertomaintain​ readability of exchanged plans, the following is required:​

•​All necessary information about an implant that is relevant to display and understand a plan is present in the ORIGINAL Implant​ Templates that were issued by a manufacturer. This is assured by these Attributes being Type 1 in the IOD.​

•​When deriving Instances, information may only be added but not removed from the ORIGINAL Instance. This information may be​ encoded in standard or private Tags.​

•​Derived Instances contain the information about the source Instances they were derived from. All Instances contain a reference to​ the ORIGINAL Instance they were derived from. If an application receives a plan that references an implant it does not have in its​

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database, it will find the UID of the ORIGINAL Instance in the plan, too. It can query its database for an instance that was derived​ from that Instance and thereby find an Instance it can use to present the plan.​

FigureZZ.5-1showsanexampleoftherelationshipsbetweentwoversionsofamanufacturer'sImplantTemplateandseveraldifferent​ Implant Templates derived by software vendors from these versions.​

Figure ZZ.5-1. Implant Versions and Derivation.​

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AAA Implantation Plan SR Document​ (Informative)​

Fortheimplantationofbonemountedimplants,informationthathasbeengeneratedduringtheimplantationplanningphaseisneeded​ intheOR.ToconveythisinformationtotheOR,aDICOMformatfortheresultsofanimplantationplanningactivityreferringtoimplant​ templates has been introduced. An Implantation Plan SR Document should be utilized by surgeons, navigation devices, and for doc-​ umentation purposes. The Plan contains relevant intraoperative information concerning the assembly of the implant components,​ resection lines, registration information, and relevant patient data. Thus, the Implantation Plan SR Document can help to enhance​ information logistics within the workflow. It does not contain any information about the planned surgical workflow. This information​ may be addressed by other DICOM Supplements. Nevertheless, this SR document may reference to or may be referenced by objects​ containing workflow information.​

Additionally, once an implantation plan has been generated, it can be used as input for a planning application to facilitate adaption​ of a plan in cases where this is necessary due to unforeseen situations.​

The workflow is considered to be the following:​

Some kind of planning application helps the user to perform implantation planning; he can choose the optimal implant for a patient​ using implant templates from a repository. The user aligns the implant template with patient data with or without the help of the applic-​ ation. (Planning without patient data can be stored in the Implantation Plan SR Document as well.)​

Subsequently, an Implantation Plan SR Document Instance will be created that contains the results of the planning. No information​ of the process itself (previously chosen implant templates, methods, etc.) will be stored. However, an Implantation Plan Document is​ considered to contain the important parameters to retrace a planning result.​

TherearetwomaincomponentsanImplantationPlanSRDocumentconsistsof(seeFigureAAA.1-1).Theimplantcomponentselection​ is used to point to a selected implant template in the repository, whereas the assembly is used to describe the composition of the​ selected implant templates. Figure AAA.2-1 shows how the Implantation Plan SR Document parts make references to the implant​ templates. Each Implantation Plan SR Document can contain a single implant component selection and several assemblies but it​ describes only one planning result for one particular patient.​

The recipient of the Implantation Plan SR Document can decide whether to read only the "list" of used implants or to go into detail​ and read the compositions as well. In both cases, he must have access to the repository of the Implant Templates to get detailed in-​ formation about the implant (such as its geometry).​

AAA.1 Implantation Plan SR Document Content Tree Structure​

ThefollowingstructureshowsthemaincontentofanImplantationPlanSRDocument.AscanbeseeninFigureAAA.1-1,theImplant-​ ation Plan consists mainly of the selected Implant Components and their Assemblies.​

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Figure AAA.1-1. Implantation Plan SR Document basic content tree​

AAA.2 Relationship Between Implant Template and Implantation Plan​

TheImplantationPlanSRDocumentistightlyrelatedtoImplantationTemplates(seePS3.3andPS3.16).ThefollowingFigureAAA.2-​ 1 shows the relationship between the Implant Templates and the Implantation Plan.​

Figure AAA.2-1. Implantation Plan SR Document and Implant Template Relationship Diagram​

AAA.3 Implantation Plan SR Document Total Hip Replacement Example​

The following example shows the planning result of a simple THR (Total Hip Replacement) without any registration information. One​ Patient Image was used and one visualization was produced. One Femoral Stem, one Femoral Head, one Acetabular Bearing Insert​ and one Acetabular Fixation Cup were selected to be implanted (see Figure AAA.3-1).​

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Figure AAA.3-1. Total Hip Replacement Components​

Table AAA.3-1. Total Hip Replacement Example​

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