Privacy Leakage in Federated Learning in Radiology Reports: A Comparative Evaluation of Tokenizer-Driven Privacy Risks
Researchers investigate the privacy risks of federated learning in radiology reports, focusing on the impact of tokenizer design on gradient-based text reconstruction.
Intelligence analysis by Llama

Federated learning in radiology reports is vulnerable to privacy risks, particularly when using certain tokenizers. The study compares the performance of three tokenizers and finds that even with domain-specific designs, substantial portions of report text can be recovered from shared model updates.
Imagine you're a doctor, and you want to train a computer to help you read medical reports. But you don't want to share the reports themselves with the computer. That's where federated learning comes in. It's like a secret handshake between the doctor and the computer, where they work together without sharing the reports. But, just like how a secret handshake can be guessed, a bad guy might try to guess the reports from the handshake. This study looked at how well a bad guy can guess the reports and found that even with special tools, they can still get a lot of the information. This means that doctors and computers need to be extra careful when using federated learning to keep patient information safe.
Analysis
A Comparative Evaluation of Tokenizer-Driven Privacy Risks
Federated learning (FL) has emerged as a promising approach for training machine learning models on sensitive data without sharing the raw data itself. However, gradient inversion attacks can reconstruct sensitive information from shared model updates, raising concerns about privacy risks. In this study, we investigate the extent of this leakage for radiology reports and the role of tokenizer design in mitigating or exacerbating these risks.
We compared the performance of three tokenizers - GPT-2, RadBERT, and LLaMA-2 - on a GPT-2-style transformer model trained on public radiology corpora. Our results show that even with domain-specific tokenizers, substantial portions of report text can be recovered from shared model updates. The extent of this leakage ranged from 31% to 44% across tokenizers, with RadBERT yielding the highest reconstruction fidelity and recovering the most clinical terms.
Our findings have significant implications for the development and deployment of FL in radiology NLP. Tokenizer design influences leakage severity and is a privacy-relevant decision, not just a utility one. To meet regulatory requirements like HIPAA and GDPR, safeguards such as secure aggregation and differential privacy may be necessary. This study highlights the need for further research into the design and deployment of FL in sensitive domains like radiology.
The Role of Tokenizer Design in Mitigating Privacy Risks
Tokenizer design plays a crucial role in determining the severity of privacy risks in FL. Our study shows that even with domain-specific tokenizers, substantial portions of report text can be recovered from shared model updates. This suggests that tokenizer design is a critical factor in mitigating or exacerbating these risks.
Implications for the Development and Deployment of FL in Radiology NLP
Our findings have significant implications for the development and deployment of FL in radiology NLP. To meet regulatory requirements, safeguards like secure aggregation and differential privacy may be necessary. This study highlights the need for further research into the design and deployment of FL in sensitive domains like radiology.
Conclusion
In conclusion, our study highlights the importance of considering tokenizer design as a privacy-relevant decision in FL, particularly in sensitive domains like radiology. The findings suggest that safeguards like secure aggregation and differential privacy may be necessary to meet regulatory requirements.
Key points
- Federated learning in radiology reports is vulnerable to privacy risks, particularly when using certain tokenizers.
- The study compared the performance of three tokenizers and found that even with domain-specific designs, substantial portions of report text can be recovered from shared model updates.
- Tokenizer design influences leakage severity and is a privacy-relevant decision, not just a utility one.
- Safeguards like secure aggregation and differential privacy may be necessary to meet regulatory requirements like HIPAA and GDPR.
The study's findings highlight the importance of considering tokenizer design as a privacy-relevant decision in FL, and the need for further research into the design and deployment of FL in sensitive domains like radiology. This could lead to the development of more secure and effective FL systems that protect patient information.
The study's findings also suggest that even with domain-specific tokenizers, substantial portions of report text can be recovered from shared model updates. This raises concerns about the potential for privacy risks in FL, particularly in sensitive domains like radiology.


