Medical Device Software Safety — Lessons from Radiation Accidents

Thank you for watching this video from Medical Software Consulting.

This presentation explains the infamous Therac-25 radiation therapy accidents of the 1980s—software-related incidents that shocked the world. These accidents were not merely the result of programming errors; they raised profound questions about system design, organizational culture, and the role of regulation in safeguarding patients.

In this video, we review the sequence of accidents and their causes, and show how today’s international standards have incorporated these lessons. We also go a step further, analyzing the software architecture of the Therac-25 and exploring how it might look if rebuilt using modern design techniques.

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●Table of contents
01:04 The Therac-25 Radiation Therapy Accidents
16:37 Analysis of Accident Causes
38:23 Safe Software Design for Medical Devices: Lessons from the Accidents
44:10 Summary

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📘 Additional Resources

Medical Software Consulting Portal (Japanese)
For companies facing challenges in medical software development and regulatory compliance:
https://www.medicalsoftwareconsulting...

Embedded Software Manufactory Blog (Japanese)
Articles on embedded systems and safety-critical software:
https://embeddedsoftwaremanufactory.b...

💼 Consultation & Inquiries

We support medical device manufacturers, startups, and investors with:
Regulatory compliance (FDA, IEC 62304, IEC 60601-1, cybersecurity regulations)
Software architecture reviews for safety and reliability
PSIRT and SBOM implementation for post-market security
Training and workshops for engineers and management teams

📩 Contact: info@medicalsoftwareconsulting.com
🌐 https://www.medicalsoftwareconsulting...

👉 Inquiries via email or social media can be handled in English.
👉 Please note that all meetings and live consultation sessions are conducted in Japanese only.

👤 About Medical Software Consulting

Founder: Yoshio Sakai

With 39 years of experience at a leading medical device manufacturer, Yoshio Sakai has led software development, project management, regulatory compliance, and digital transformation initiatives. Since 2025, he has worked as an independent consultant to help medical device companies overcome software and regulatory challenges.

Books (in Japanese):

Becoming an Embedded Software Engineer Starting from Real-Time OS
https://www.amazon.co.jp/dp/4434328972/

How to Build Software That Avoids Recalls
https://www.amazon.co.jp/dp/B07VQDF47B/

Practical Guidebook to IEC 62304 (co-author)
https://www.amazon.co.jp/dp/4840748780/

👉 This channel is dedicated to explaining medical software regulations, international standards, and practical engineering methods. If your organization needs support in these areas, feel free to reach out—we are here to help.