RT Image Review Worklist Triage

In  this previous post on better image review workflows, David Clunie's noted zombie apocalypse was imminent as we waited for better predictive models for image review behavior.  Well, the zombie apocalypse never happened.  But I have made some progress in sketching a basic model to analyze usage patterns.

The inputs are:

• Time of day of physician login / workstation location
• Time of day of image acquisition
• Time offfset of image approval
• Image feature vector, in some latent space of patient geometry

Then these are regressed to get a prediction of likelihood of image being opened on a workstation, at a given time.

What can be done with this prediction?  Caching on the local drive could be accomplished using:

• Windows Offline Files
• Dokan library, or similar
• BDS Storage for local drive

Additionally, memory caching could be used

• For a WCF-based SoA architectures, memory caching can be implemented either in the client (using a custom binding stack), or in the service as a custom IOperationInvoker.
• MSQ 3D IRW already implements a memory caching for AVS-based cone beam CTs.

So with some implementation for the actual caching, we can fit the model and produce predictions.  If only we had some test data...

Stay tuned for a demo of the model, possibly with only fake input data.

Better Image Review Workflows Part II: DICOM Spatial Registrations

I remember meeting with our colleagues at Varian's Imaging Lab a few years back, to discuss (among other things) better ways of using DICOM Spatial Registration Objects (SROs) to encode radiotherapy setup corrections.  They had been considering support for some advanced features, like 4D CBCT and dynamic DRR generation.  

It was clear that having a reliable DICOM RT Plan Instance UID and referenced Patient Setup module would be immensely useful in interpreting the setup corrections.   But where would this information be stored?  As private attributes in the CBCT slices?  Or in the SRO itself?  The treatment record contains this relationship for each treatment field, but there is no way of encoding a reference to a standalone setup image within the treatment record (or so I've been told)

Siemens has, for years now, used a DICOM Structured Report to encode offset values, in lieu of an SRO, at least for portal images.  I think skipping the SRO entirely was a mistake, but when I look at the state of RT SROs today, it seems in retrospect that a semantically meaningful Structured Report to pull together the other objects (SRO,  treatment record, CBCT slices) would be quite an advanced over current practice.  Looking at some of the defined IODs for structured reports:

• Mammography CAD Structured Report
• Chest CAD Structured Report
• Acquisition Context Structured Report

it does not seem too far fetched to consider an SR encoding relationships among a CBCT or portal image and their context objects.

I've started (again) reading David Clunie's Structured Report book, in hopes of gaining more insight in what can (or should not) be encoded using SRs.  It seems like a quite powerful capability--I'm wondering why the RT domain has not made more use of it...

How to make image review better?

Image review is critical to modern IGRT, and will be equally important for adaptive RT.  Yet today most users complain that it is a painful chore.  So how do we make image review better?

I think three areas are critical:

1. A better image review user experience
2. Better workflows to support image review
3. Advanced analysis tools to assist in the review process

I'll post my thoughts on areas of improvement for each of these.

word2vec

I've been able to analyze some notes using word2vec, and the extracted "meaning" has some interesting properties.  Maybe next I'll run some archived comments from the Mosaiq Users listserv and see how often users talk about

• slow loading of images
• import problems due to inconsistent SRO semantics
• issues with imported structure sets
• re-registering the ImageReview3DForm COM control

[which all point to a need for a better image review capability for Mosaiq users.]