Types of Imaging Workflows
The two types of imaging workflows are "Order-based" and "Encounter-based." The diagram below is a very simplified version of the two different workflows.
As you might have guessed, the workflow is a little more complicated than the simplified diagram above. There are several reasons for this including:
PACS systems and EMRs use different languages. They need an interface program to work.
An EMR requires "an order" for a diagnostic result to be created and placed in the patient's chart
Both the EMR and PACS need a way to confirm that the patient in front of you is indeed the correct patient that is registered in the system
These requirements add additional complexity to both workflows. Let's first focus on how the PACS and EMR ensure that the they have identified the correct patient and communicate that with each other.
Correct Patient Verification Process:
When a patient arrives for an encounter with the healthcare system, they must be registered in the EMR. This ensures that the patient presenting for a visit, is indeed the same one that is registered in the EMR. Once this is done, other software systems (like the PACS system that uses a different computer language) gain access to the patient demographic information via an Admission, Discharge, Transfer (ADT) HL7 message (remember HL7 is the language of the EMR). In an order based workflow, when an order is placed, the EMR sends an HL7 Order Message (ORM) to the PACS system. The PACS system takes the order (e.g. order for a comprehensive thyroid ultrasond) and the ADT data from the HL7 message and converts it into DICOM language. The PACS system then sends a notification to a modality worklist (MWL). This MWL can be queried on the ultrasound machine and lets the ultrasound technician know that "patient x" needs a thyroid ultrasond. When the ultrasound technician finds the patient, the technician verifies that the patient in front of them is the same patient displayed on the ultrasound machine by verifying that the MRN, patient name and date of birth are correct. The ultrasound exam is then performed.
In an encounter-based workflow, there are several different places where the ultrasound exam can be linked with the ADT data, however, it needs to occur at some point before it can be sent to the PACS or the EMR. The earlier this can be done in the process, ensures errors are not made. Within the Emergency Department (ED), one way this can be done is to have a dedicated MWL just for POCUS exams. This MWL is populated, not by an HL7 ORM (as in the order-based workflow), but occurs for all patients once registered in the ED. Most ultrasound machines can perform an autoquery of the MWL when the medical record number (MRN) is scanned. This then populates all of the patient demographic information to be displayed on the patient information screen. This is verified by the the physician an the ultrasound exam begins.
