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  • Shareable Clinical Pathways Tutorial Part 1 – Basic BPMN Events, Tasks, and Gateways

We will first begin with modeling shareable clinical pathways using the Business Process Model and Notation (BPMN) standard. If you want to follow along, please see the introductory post to this series for links to free modeling tools you can immediately use.

In this tutorial we will model a basic radiation therapy consult workflow from the perspective of the radiation oncologist. The final end result of the workflow is shown beneath.

Basic Radiation Therapy Consult Workflow in BPMN

To create the workflow yourself follow the tutorial using a BPMN modeling tool such as at bpmn.io. If you need help, watch the video beneath where we show the entire model creation.

Please note that in BPMN the term “process” is used, rather than workflow. We may use the terms interchangeably throughout this series, but in the BPMN terminology we use processes to implement the workflows.

One of the great aspects of BPMN is it makes workflows transparent, and easily understandable by even those without training in BPMN. If you have no experience in BPMN, you can probably understand the workflow in the diagram. Even better, is the workflow isn’t hard-coded and embedded in software code that is not available to the user, and would be difficult to understand even if it were available.

In this process we have a single lane denoting the radiation oncologist as the participant. We could have other participants with their own lanes, such as the patient, and other clinical staff such as nurses. For now we will stick with one participant.

Step 1: Create a lane and name it “Radiation Oncologist”.

This process starts with a New Patient Consult Started event. In BPMN events are depicted by a circle. In this case we have a start event, denoting the start of the process. In a process being executed by software, the start event could be triggered manually through a user interface, or automatically when a patient checks in for their consult. Once started, the workflow executes.

Step 2: In the lane create a start event and label it “New Patient Consult Started”.

Once the process starts the first step is a consult between the radiation oncologist and the patient. This is modeled as a user task in BPMN. Tasks of various kinds all have a rounded rectangle. The person icon indicates this is a user task, to be performed by a person. The process waits until this task is complete before proceeding. In software this could be completed manually from a task list, or it could be completed automatically when the patient checks out from the consult. These are implementation details beyond the current scope.

Step 3: Create a new user task, and label it “Consult with Patient”. Make sure the start event is connected to this task.

Once the consult task is complete, the radiation oncologist must determine if radiation therapy is indicated. In the present example we will assume that if radiation therapy is indicated the patient also decides to undergo radiation therapy. In a more realistic model we would also handle the decision from the patient. The decision if radiation therapy is indicated would be selected by the radiation oncologist in a user interface as a simple Yes/No choice.

Step 4: Create a new user task and label it “Determine if Radiation Therapy Indicated”. Make sure the consult task is connected to this new task.

Once the decision is made regarding if radiation therapy is indicated, there are two different flows. BPMN uses gateways with a diamond shape to direct flows within a process. Decisions are not made in gateways, but must happen before the gateway. In this example an exclusive gateway, also know as XOR is used, which only allows one path to be executed out of the gateway.

Step 5: Create a new XOR gateway, and connect the previous task to it. Set the label for the gateway to “Radiation Therapy Indicated?”.

In the current example if radiation therapy is not indicated, we end the consult and for the sake of this example, assume there is nothing further to do in this workflow. If radiation therapy is indicated, a Start Radiation Therapy event will be generated, using a BPMN signal event depicted by two circles with a solid triangle in the middle. Signal events broadcast to other processes to react to. In this case a separate process could be triggered from this signal to start a new radiation course workflow automatically. Finally, once the signal is generated, the process ends with an end event.

Step 6: Create an end event beneath the gateway and label it “Patient Consult Ended”. Connect the gateway to the event, and mark the flow as the default. Finally, label the flow “No”.

Step 7: Create a signal event to the right of the gateway and label it “Start Radiation Therapy Course”. Finally, create an end event and label it “Patient Consult Ended”.

Your workflow should now look like our diagram, and you have created a basic clinical workflow. To make it executable, one would normally add a few more details, such as the candidate group for the task (radiation oncologist), as well as create the implementation details for the start new radiation course signal.

In this tutorial you have been introduced to the following BPMN symbols: lanes, start/signal/end events, user tasks, and XOR gateways. To learn more, follow our blog and we also encourage you to sign up for our mailing list.

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Gabe Colburn

Gabe strives to create innovative solutions to solve real-world problems effectively. Currently he’s focused on improving Radiation Oncology and healthcare workflow and interoperability, with previous experience in the defense industry, quantum computing, and healthcare. He holds a B.S. in Engineering Physics from Colorado School of Mines and an M.S. in Medical Physics from Oregon Health & Science University. He is also certified by the American Board of Radiology in Therapeutic Medical Physics. He resides in Bend, OR where he enjoys the beautiful outdoors hiking, climbing, and camping with his wife and kids.

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