Материал: part17

BBB.3 Use Cases​

BBB.3.1 Treatment Delivery Normal Flow - Internal Verification​

BBB.3.1.1 Message Sequencing​

Figure BBB.3.1.1-1 illustrates a message sequence example in the case where a treatment procedure delivery is requested and​ performed by a delivery device that has internal verification capability. In the example, no 'setup verification' is performed, i.e., the​ patient is assumed to be in the treatment position. Unified Procedure Step (UPS) is used to request delivery of a session of radiation​ therapy (commonly known as a "fraction") from a specialized Application Entity (a "Treatment Delivery System"). That entity performs​ the requested delivery, completing normally. Further examples could be constructed for discontinued, emergency (unscheduled) and​ interruptedtreatmentdeliveryusecases,butarenotconsideredinthisinformativesection(seeDICOMPart17forgenericexamples).​

In this example the Treatment Delivery System conforms to the UPS Pull SOP Class as an SCU, and the Treatment Management​ SystemconformstotheUPSPullSOPClassasanSCP.Inalternativeimplementationsrequiringon-the-flyschedulingandnotification,​ other UPS SOP classes could be implemented.​

Italic text in Figure BBB.3.1.1-1 denotes messages that will typically be conveyed by means other than DICOM services.​

BBB.3.1.2 Transactions and Message Flow​

This section describes in detail the interactions illustrated in Figure BBB.3.1.1-1.​

1.​'List Procedures for Delivery' on TDS console.​

The User uses a control on the user interface of the TDS to indicate that he or she wishes to see the list of patients available for​ treatment.​

2.​Query UPS.​

The TDS queries the TMS for Unified Procedure Steps (UPSs) matching its search criteria. For example, all worklist items with​ a Unified Procedure Step Status of "SCHEDULED", and Input Readiness State (0040,4041) of "READY". This is conveyed using​ the C-FIND request primitive of the UPS Pull SOP Class.​

3.​Receive 0-n UPS.​

The TDS receives the set of Unified Procedure Steps (UPSs) resulting from the Query UPS message. The Receive UPS is​ conveyed via one or more C-FIND response primitives of the UPS Pull SOP Class. Each response (with status pending) contains​ the requested Attributes of a single Unified Procedure Step (UPS).​

The TMS returns a list of one or more UPSs based on its own knowledge of the planned tasks for the querying device. Two real-​ world scenarios are common in this step:​

•​There is no TMS Console located in the treatment area, and selection of the delivery to be performed has not been made. In​ this case, the TMS returns a list of potentially many UPSs (for different patients), and the User picks from the list the UPS that​ they wish to deliver.​

•​The User has direct access to the TMS in the treatment area, and has already selected the delivery to be performed on the​ console of the TMS, located in the treatment room area. In this case, a single UPS is returned. The TDS may either display​ the single item for confirmation, or proceed directly to loading the patient details.​

- Standard -​

1. ‘List Procedures for Delivery’ on TDS console

2.Query UPS (C-FIND)

3.Receive 0-n UPS

Display list to User

4.‘Select Procedure’ on TDS console (optional, if only one procedure in list)

5.Get UPS details (C-GET) Receive UPS details

Extract input UIDs from selected UPS

5a. Retrieve Archive Objects (C-MOVE)

RT Plan and any other required objects

(e.g., verification images, RT Beam Treatment Records)

6.Change UPS ‘IN PROCESS’ (N-ACTION with Transaction UID)

7.Retrieve TMS objects (C-MOVE)

RT Beams Delivery Instruction

RT Treatment Record Summary

RT Beams Treatment Rec (if not in 5)

8. ‘Start Treatment Sesion’ on TDS console

9. Set UPS 0% complete, Beam ‘1’ (N-SET)

Verify

DELIVER RADIATION

9. Set UPS 50% complete, Beam ‘2’ (N-SET)

Verify

DELIVER RADIATION

10.Set UPS 100% complete, (N-SET)

11.Store RT Treatment Record and other result objects (C-STORE)

12.Set UPS to Final State (N-SET)

13.Change UPS ‘COMPLETED’ (N-ACTION)

14.Indicate ‘Treatment Session Completed on TDS Console’

Figure BBB.3.1.1-1. Treatment Delivery Normal Flow - Internal Verification Message Sequence​

A returned set of UPSs may have more than one UPS addressing a given treatment delivery. For example, in the case where a​ patient position verification is required prior to delivery, there might be a UPS with Requested Procedure Code Sequence item​ having a Code Value of 121708 ("RT Patient Position Acquisition, CT MV"), another UPS with a Code Value of 121714 ("RT​ PatientPositionRegistration,3DCTgeneral"),anotherUPSwithaCodeValueof121722("RTPatientPositionAdjustment"),and​ a fourth UPS whose Requested Procedure Code Sequence item would have a Code Value of 121726 ("RT Treatment With In-​ ternal Verification").​

4.​'Select Procedure' on TDS console​

The User selects one of the scheduled procedures specified on the TDS console. If exactly one UPS was returned from the UPS​ query described above, then this step can be omitted.​

5.​Get UPS Details and Retrieve Archive Objects​

The TDS may request the details of one or more procedure steps. This is conveyed using the N-GET primitive of the UPS Pull​ SOP Class, and is required when not all necessary information can be obtained from the query response alone.​

The TDS then retrieves the required SOP Classes from the Input Information Sequence of the returned UPS query response. In​ response to a C-MOVE Request on those objects (5a), the Archive then transmits to the TDS the SOP Instances to be used as​ input information during the task. These SOP Instances might include an RT Plan SOP Instance, and verification images (CT​ Image or RT Image). They might also include RT Beams Treatment Record SOP Instances if the Archive is used to store these​ SOP Instances rather than the TMS. The TDS knows of the existence and whereabouts of these SOP Instances by virtue of the​ fully-specified locations in the N-GET response.​

- Standard -​

Although the TDS could set the UPS to 'IN PROGRESS' prior to retrieving the archive instances, this example shows the archive​ instancesbeingretrievedpriortotheUPSbeing'locked'withtheN-ACTIONstep.ThisavoidstheUPSbeingset'INPROGRESS'​ if the required instances are not available, and therefore avoids the need to schedule another (different) procedure step in this​ case, as required by the Unified Procedure Step State Diagram State Diagram (PS3.4). However, some object instances dynam-​ ically created to service performing of the UPS step should be supplied after setting the UPS 'IN PROGRESS' (see Step 7).​

6.​Change UPS State to IN PROGRESS​

The TDS sets the UPS (which is managed by the TMS) to have the Unified Procedure Step Status of 'IN PROGRESS' upon​ startingworkontheitem.TheSOPInstanceUIDoftheUPSwillnormallyhavebeenobtainedintheworklistitem.Thisisconveyed​ using the N-ACTION primitive of the UPS Pull SOP Class with an action type "UPS Status Change". This message allows the​ TMS to update its worklist and permits other Performing Devices to detect that the UPS is already being worked on.​

The UPS is updated in this step before the required dynamic SOP Instances are obtained from the TMS (see Step 7). In radiation​ therapy, it is desirable to signal as early as possible that a patient is about to undergo treatment, to allow the TMS to begin other​ activitiesrelatedtothepatientdelivery.IftheTMSimplementstheUPSWatchSOPClass,othersystemswillbeabletosubscribe​ for notifications regarding the progress of the procedure step.​

7.​Retrieve TMS Objects​

In response to a C-MOVE Request, the TMS transmits to the TDS the RT Beams Delivery Instruction and possibly RT Treatment​ Summary Record SOP Instances to be used as input information during the task. These SOP Instances may be created "on-the-​ fly" by the TMS (since it was the TMS itself that transmitted the UIDs in the UPS). The RT Treatment Summary SOP Instance​ may be required by the TDS to determine the delivery context, although the UPS does specify a completion delivery (following​ a previous delivery interruption). RT Beams Treatment Record instances might also be retrieved from the TMS in this step if the​ TMS is used to manage these SOP Instances rather than the Archive.​

8.​'Start Treatment Session' on TDS console​

The User uses a control on the user interface of the TDS to indicate that he or she wishes to commence the treatment delivery​ session. A Treatment Session may involve fulfillment of more than one UPS, in which case Steps 4-13 may be repeated.​

9.​Set UPS Progress and Beam Number, Verify, and Deliver Radiation​

For each beam, the TDS updates the UPS on the TMS just prior to starting the radiation delivery sequencing. This is conveyed​ using the N-SET primitive of the UPS Pull SOP Class.​

The completion percentage of the entire UPS is indicated in the Unified Procedure Step Progress Attribute. The algorithm used​ to calculate this completion percentage is not specified here, but should be appropriate for user interface display.​

The Referenced Beam Number of the beam about to be delivered is specified by encoding it as a string value in the Procedure​ Step Progress Description (0074,1006).​

The TDS then performs internal verifications to determine that the machine is ready to deliver the radiation, and then delivers​ the therapeutic radiation for the specified beam. In the current use case, it is assumed that the radiation completes normally,​ delivering the entire scheduled fraction. Other use cases, such as voluntary interruption by the User, or interruption by the TDS,​ will be described elsewhere.​

If there is more than one beam to be delivered, the verification, UPS update, and radiation delivery is repeated once per beam.​

This example does not specify whether or not treatment should be interrupted or terminated if a UPS update operation fails. The​ successful transmittal of updates is not intended as a gating requirement for continuation of the delivery, but could be used as​ such if the TDS considers that interrupting treatment is clinically appropriate at that moment of occurrence.​

10.​Set UPS to Indicate Radiation Complete​

The TDS may then update the UPS Progress Information Sequence upon completion of the final beam (although this is not re-​ quired), and set any other Attributes of interest to the SCP. This is conveyed using the N-SET primitive of the UPS Pull SOP​ Class.​

11.​Store Results​

- Standard -​

The TDS stores any generated results to the Archive. This would typically be achieved using the Storage and/or Storage Com-​ mitment Service Classes and may contain one or more RT Beams Treatment Records or RT Treatment Summary Records, RT​ Images (portal verification images), CT Images (3D verification images), RT Dose (reconstructed or measured data), or other​ relevant Composite SOP Instances. References to the results and their storage locations are associated with the UPS in the Set​ UPS to Final State message (below). The RT Beams Treatment Record instances might be stored to the TMS instead, if the​ TMS is used to manage these SOP Instances rather than the Archive.​

The required SOP Instances are stored to the Archive in this step before the UPS is status is set to COMPLETED. In radiation​ therapy,itisdesirabletoensurethattheentireprocedureiscomplete,includingstorageofimportantpatientdata,beforeindicating​ that the step completed successfully. For some systems, such as those using Storage Commitment, this may not be possible,​ in which case another service such as Instance Availability Notification (not shown here) would have to be used to notify the TMS​ of SOP Instance availability. For the purpose of this example, it is assumed that the storage commitment response occurs in a​ short time frame.​

12.​Set UPS Attributes to Meet Final State Requirements​

TheTDSthenupdatestheUPSwithanyfurtherAttributesrequiredtoconformtotheUPSfinalstaterequirements.Also,references​ to the results SOP Instances stored in Step 11 are supplied in the Output Information Sequence. This is conveyed using the N-​ SET primitive of the UPS Pull SOP Class.​

13.​Change UPS State to COMPLETED​

The TDS changes the Unified Procedure Step Status of the UPS to COMPLETED upon completion of the scheduled step and​ storage or results. This is conveyed using the N-ACTION primitive of the UPS Pull SOP Class with an action type "UPS Status​ Change". This message informs the TMS that the UPS is now complete.​

14.​Indicate 'Treatment Session Completed' on TDS Console​

The TDS then signals to the User via the TDS user interface that the requested procedure has completed successfully, and all​ generated SOP Instances have been stored.​

BBB.3.2 Treatment Delivery Normal Flow - External Verification​

BBB.3.2.1 Message Sequencing​

Figure BBB.3.2.1-1 illustrates a message sequence example in the case where a treatment procedure delivery is requested and​ performed by a conventional delivery device requiring an external verification capability.​

In the case where external verification is requested (i.e., where the UPS Requested Procedure Code Sequence item has a value of​ "RT Treatment With External Verification"), the information contained in the UPS and potentially other required delivery data must be​ communicated to the Machine Parameter Verifier (MPV). In many real-world situations the Oncology Information System fulfills both​ theroleoftheTMSandtheMPV,hencethiscommunicationisinternaltothedeviceandnotstandardized.Ifseparatephysicaldevices​ perform the two roles, the communication may also be non-standard, since these two devices must be very closely coupled.​

Elements in bold indicate the additional messages required when the Machine Parameter Verifier is charged with validating the beam​ parametersforeachbeam,priortoradiationbeingadministered.ThesecheckscanbeinitiatedbytheUseronabeam-by-beambasis​ ('manual sequencing', shown with the optional 'Deliver Beam x' messages), or can be performed by the Machine Parameter Verifier​ withoutintervention('automaticsequencing').TheTDSwouldtypicallystoreanRTTreatmentRecordSOPInstanceaftereachbeam.​

This example illustrates the case where photon or electron beams are being delivered. If ion beams are to be delivered, instances of​ the RT Conventional Machine Verification IOD will be replaced with instances of the RT Ion Machine Verification IOD.​

Delivery of individual beams can be explicitly requested by the User (as shown in this example), or sequenced automatically by the​ TDS.​

BBB.3.2.2 Transactions and Message Flow​

This section describes in detail the additional interactions illustrated in Figure BBB.3.2.1-1.​

After the TDS has retrieved the necessary treatment SOP Instances (Step 7), the following step is performed:​

- Standard -​

7a. Communicate UPS and Required Delivery Data to MPV​

The MPV must receive information about the procedure to be performed, and any other data required in order to carry out its role.​ This communication typically occurs outside the DICOM Standard, since the TMS and MPV are tightly coupled (and may be the same​ physical device). In cases where standardized network communication of these parameters is required, this could be achieved using​ DICOM storage of RT Plan and RT Delivery Instruction SOP Instances, or alternatively by use of the UPS Push SOP Class.​

After the User has initiated the treatment session on the TDS console (Step 8), the following steps are then performed:​

8a. 'Deliver Beam x' on TDS console​

In some implementations, parameter verification for each beam may be initiated manually by the User (as shown in this example). In​ other approaches, the TDS may initiate these verifications automatically.​

8b. Create RT Conventional Machine Verification Instance​

The TDS creates a new RT Conventional Machine Verification instance on the MPV prior to beam parameter verification of the first​ beam to be delivered. This is conveyed using the N-CREATE primitive of the RT Conventional Machine Verification SOP Class.​

- Standard -​