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De-Identification Process Decisions

Not every research study and hospital is the same. Therefore, there are several decisions which need to be taken upfront. These decisions can be split into organisational and technical, as explained below.

Organisational decisions

These decisions are mostly influenced by the processes and collaboration efforts of participating centres in your study.

Collecting imaging data: upload directly or collect centrally before upload?

As a coordinating centre, the first question is whether you want to collect all data before uploading, or to have centres upload the data directly. The first option gives more control and overview for the coordinating centre. Whereas the second option is faster in terms of data transfer, however it introduces more work and responsibilities for participating centres. Our experience is that direct upload by participating centres is preferable, as data upload can be integrated in the participating centre’s workflow. We are aware that installation of software in local hospitals is often cumbersome and not always feasible. Therefore, the option for de-centralised upload is often difficult or not possible.

Installation of upload tool in participating centres

Irrespective of the previous decision (upload directly or central collection), centres that wish to upload data need to install the de-identification software (called CTP).

If participating centres wish to only upload a few patient images at a time, Health-RI is evaluating a alternative solution where CTP does not need to be locally installed. Please contact us to discuss this option.

 

Technical Decisions

These decisions are mostly influence by the needs of the study regarding the information that is kept in the uploaded files after de-identification and can be guided by Health-RI.

Using one strict or multiple tailored de-identification profiles?

De-identification profiles need to be set-up. Although the DICOM standard defines the structure and placeholders (tags) for metadata, it also supports additional (non-standardised) additional information. This non-standardised information can be different for different manufacturers, modalities (e.g. CT/MR/PET scanners), or even software versions of the same modalities.

To be sure that XNAT does not contain patient-related information (retrieved from the DICOM metadata), we can support the creation of de-identification pipeline. In general, we provide a generic (strict) anonymisation pipeline (compliant to DICOM supplement 142, following HIPAA laws) which should be applicable to every study. The downside of this strict pipeline is possibly the loss of detailed information specifically needed for certain research questions and / or data management. Many patient-related information (e.g. weight) is missing, which limits applicability for research questions. For example:

a)     Computation of PET Standard Uptake Values (SUV) or DEXA or MRI measures of body composition, which are based on body weight, body surface area or lean body mass.

b)    The data stored in private tags by some vendors are required for specific image analysis. E.g. for PET-Scans from Philips two private tags needed to be preserved for a particular study.

To overcome these problems, we support tailoring of anonymisation profiles, however this means that every submitting site must have it’s own, tailored anonymisation profile. This propagates into the next steps, as several tasks should be done for every participating centre (e.g. defining de-identification profiles).

 

As a standard, Health-RI requests studies to follow a standard de-identification policy. It is up to the study to define variations to this policy, and justify these choices

The steps to define and implement the de-identification profile are described below:

# Short description Actor Long description
a) Define patient id replacement Study coordinator

Decide which option to use:

- CTP look-up-table

b) Create CTP collection de-identification template Health-RI Create CTP collection de-identification template based on the approved Collection De-identifcation profile
c) Implement patient id replacement Submitting site Implement patient id replacement in CTP
d) Implement CTP collection de-identification template Submitting site Implement CTP collection de-identification template based on the provided CTP collection de-identification template
e) Clean burned pixel data Submitting site
f) Random visual inspection Submitting site (Random) visual inspection of tags for each submitting site

If the strict pipeline does not comply with the needs of the study, the following also needs to be done:

g) Define collection de-identification profile Study coordinator Define deviations from DICOM-142 supplement
h) Approve collection de-identification profile Principal Investigator Approval of collection de-identification profile

Repeat steps a-f

 

Depending on Health-RI's involvement and effort in the implementation of these deviations, costs may be incurred by the study. For more details, see XNAT's Freemium and Fair use policy.

 

Next: Deliver test images per submitting site and Install CTP-Client in Submitting Sites

Previous step: Request collection and user account