Pseudonymising Pathology, Radiology, and Imaging Reports – UK GDPR-compliant anonymisation per UK GDPR Art. 9
A pathology or radiology report is a diagnostic record constituting special-category health data under UK GDPR Article 9, embedding patient identifiers in report headers and DICOM metadata. The NHS Records Management Code of Practice 2023 requires pathology records to be retained for 8 years. anonym.legal pseudonymises patient name, NHS number, and accession numbers in document text and DICOM tags, preserving diagnostic findings for clinical or medicolegal use.
When this applies
This task applies when pathology results, radiology reports, or DICOM image sets are shared with external radiologists for second-opinion review, disclosed in personal-injury litigation, or submitted as anonymised case studies for medical education, and the clinical findings must be preserved but patient identity must be protected. Breaches involving imaging data can attract fines of up to £17.5 million or 4% of annual global turnover under DPA 2018 s.157.
How anonym.legal handles it
- Upload the pathology report (PDF or DOCX) or export the DICOM study; anonym.legal processes both document and DICOM header formats.
- The engine detects patient identifiers in PDF headers, free-text report bodies, and DICOM tag fields (PatientName, PatientID, PatientBirthDate, InstitutionName).
- Each patient's identifiers are replaced with consistent pseudonyms across all images and report pages in the study.
- Diagnostic findings, imaging measurements, Hounsfield-unit values, and pathological grading are preserved in full.
- Requesting clinician and reporting radiologist names are pseudonymised.
- A mapping table and a de-identified DICOM export are produced with UK data residency.
What you provide
- Pathology report (PDF or DOCX) or DICOM study export
- Accession number list (to verify study completeness)
- Any accompanying clinical request form naming the patient
Limitations & cautions
- DICOM pixel data that overlays patient information (burned-in annotations) requires additional image-processing de-identification beyond header tag removal — confirm whether your DICOM series includes burned-in PHI before relying on header-only de-identification.
- The tool pseudonymises header data but does not validate the diagnostic accuracy of the report. According to the ICO's Anonymisation Code of Practice (2012, updated 2021–22), pseudonymised records remain personal data under UK GDPR.
- Rare imaging findings may carry residual re-identification risk in small-population clinical settings; consider suppressing ultra-rare pathological grades in datasets of fewer than 5 cases.
FAQ
Does the DICOM de-identification comply with DICOM PS3.15 Attribute Confidentiality Profiles?
anonym.legal applies pseudonymisation to the patient-identifiable DICOM tags in line with the ICO's 2021–22 guidance on pseudonymisation as a risk-reduction measure. For compliance with a specific PS3.15 profile (e.g. Basic Application Level Confidentiality), configure the tag-removal profile to match the profile's required attribute actions.
Can I share pseudonymised DICOM studies with overseas radiologists for second opinion?
After pseudonymisation, the study no longer contains personal data identifiable to a specific individual, so international transfer restrictions applicable to personal data under UK GDPR would not apply to the pseudonymised version. The ICO reprimanded Royal Free London in 2017 for sharing 1,600,000 patient records with DeepMind without a proper lawful basis — this case illustrates the importance of correct de-identification before any external data transfer. Confirm with your Data Protection Officer.
Are accession numbers and study instance UIDs replaced or removed?
Accession numbers and study UIDs that could link back to an identifiable patient record are replaced with synthetic values. New UIDs are generated consistently so multi-series studies remain internally coherent. The 8 Caldicott Principles (Principle 8 added 2020) require that data flows are documented and justified even after pseudonymisation.