Monday, November 18, 2019

DICOM Modality Installation Checklist.

One of the typical responsibilities of a PACS administrator is adding a new image acquisition
modality to the PACS system. It is also one of the more challenging tasks as it is often hard to predict how the device will interact as these are still not quite “plug-and-play.” To make it worse, this is often a visible and highly anticipated task, as in many cases the new modality has been expected for a long time. So, when it finally arrives at the loading dock, users want to see it up and working as soon as possible.
With proper preparation prior to and during the actual installation, the success rate of the install can be increased and the time to get it up and running can be greatly reduced and frustration kept to a minimum.

This is the check list I recommend prior to the install:
1.       Do a “paper validation” between the modality and its connections, i.e. DICOM worklist provider, DICOM destination(s) for image Store, Storage Commitment, Modality Performed Procedure Step, and Structured Reports. Get the DICOM conformance statements for these devices and compare them against each other. Make sure you get the right version of these conformance statements as functionality can differ substantially between different releases. Specifically look for the following in these documents:
a.       Make sure that there is support for the type of DICOM files (SOP Classes) you will be exchanging. Be aware of and look for support of the new “enhanced” SOP Classes such as for CT, MR, Angio, RF, breast tomosynthesis, IV-OCT and others.
b.       If you want to compress the images at the modality, make sure there is support of the type of compression at the source and destination(s) (JPEG lossless, lossy, Wavelet, MPEG for video, etc.)
c.       If you want to use Storage Commitment, make sure its behavior between the SCU and SCP matches with regard to the handling of the associations for the reply.
d.       If you want to use Modality Performed Procedure Step (MPPS), make sure that the implementation matches your workflow, for example, you don’t want to have MPPS report the study being complete if there are still images to be sent, processed, or imported.
e.       Match the worklist attributes between the modality and worklist provider and look for alternate mapping in case attributes might be missing on the modality side. An example would be to map missing patient weight or allergies in a Patient Comment field if that is required at the modality but not displayed.
2.       Do a “file validation” by asking the vendor to send you a CD with images, making sure that each type of image is on the CD. In addition, get sample Structured Reports, such as dose reports for CT or measurements for ultrasound and echo. Import these files on a test PACS, Voice Recognition and Dose management system and verify proper display of the images and measurements.  Make sure that the hanging protocols work at the workstations and if not, troubleshoot it to find what the cause is (study descriptions, body part, etc.)
3.       Do an “install validation” by using a modality simulator that is able to query a worklist using the same attributes as used by the new modality and simulate Store for the various file type to the test PACS. Simulate the Storage Commitment and MPPS. There are commercial modality simulators available (e.g. OT-DICE) as well as open source ones (DVTK). When doing the simulation, use the same IP address, port and AE-Title that the new modality would be using. It is strongly recommended to use best practices for the AE-Titles and port numbers, i.e. use an all caps AE-Title that indicates the institution, location and modality, and use the standard port number (11112) as assigned by IANA to DICOM devices. Work with IT so that you get a new, fixed IP address assigned for the new modality and make sure they configure the VLAN and routers to allow access.
If you have taken all these precautions, you should be able to swap out the simulator for the actual device, and the chances are that it might be “plug-and-play” assuming you addressed all the issues during the pre-install phase.
However, if it still does not work, you might want to do some troubleshooting using the tools as described in part 2 of this post.