Deid does two things, generally cleaning pixels and headers of dicom images. We do this by way of a file called a deid recipe. Here is a quick example that is intended for dicom images:
FORMAT dicom
%filter dangerouscookie
LABEL Criteria for Dangerous Cookie
contains PatientSex M
+ notequals OperatorsName bold bread
coordinates 0,0,512,110
%header
ADD PatientIdentityRemoved YES
REPLACE PatientID var:id
REPLACE SOPInstanceUID var:source_id
Don’t worry that we haven’t talked about this format yet! Generally, you could probably guess that we are going to create a filter called “dangerouscookie” based on some set of criteria, and perform some actions on image headers. Let’s first discuss each of the sections.
Sections
A section is a part of the recipe that starts with a “%”. You can think of
a section as a chunk of text that is parsed for some purpose. For example,
%filter is a section where it’s expected that you’ve defined filters, and
%header is expected to have actions to update and change headers.
| Section | Description | Example |
|---|---|---|
| %filter | a named set of filter criteria used when running the DicomCleaner | %filter filterName |
| %header | actions to be taken to update, or otherwise change an image header | %header |
| %labels | extra metadata (key value pairs) to add to a recipe | Maintainer @vsoch |
What functions do the recipe sections correspond to?
Good question! Let’s talk about the two primary functions of deid, and how to write recipes to do those things.
Clean Pixels
The general application flow of the clean function is the following:
[define criteria] -> [filter] -> [clean images] -> [save]
The “filter” tag broadly encompasses an inspection of the header data. The “clean” action corresponds with either:
- an action applied to a header field, like “REPLACE FieldA with value B” or
- replacing pixels in the image with a black box to hide text and other identifiers
For reading more about how the Deid software does this by way of a file called a deid recipe, read about deid recipe filters.
Clean Headers
The general application flow to clean headers looks like this:
[define actions] -> [get identifiers] --> [update identifiers] --> [replace identifiers]
And then optionally save the updated files!
More detail is provided about cleaning headers in the recipe headers pages.
Where do I go from here?