Pioneering Model Measures Radiation Exposure in Blood for Precise Cancer Treatments

Scientists have long focused on protecting organs near tumors during radiotherapy, but blood — a vital, circulating tissue — has largely been excluded from dose calculations. Each blood cell passing through a radiation field absorbs small amounts of energy that, cumulatively, can weaken the immune system or trigger hematologic toxicity. A new model now offers a way to measure this exposure and improve the safety of cancer treatment.

Researchers at the University of Navarra (Pamplona, Spain) have developed the FLIP-HEDOS method, the first tool to quantify radiation absorbed by blood during therapy. By combining patient anatomy, blood circulation data, and radiotherapy plans, it simulates when and how much blood is irradiated. This approach treats blood as an “organ at risk” and integrates insights from physics, oncology, and engineering to guide personalized radiotherapy planning.

The researchers conducted a study along with clinicians to validate the framework in a real clinical setting. The results showed that factors such as tumor proximity to major blood vessels, the type of radiation applied, and variations in cardiac output significantly shaped blood irradiation. Findings emphasize that even low doses can damage lymphocytes, impairing immune responses during cancer treatment.

FLIP-HEDOS has gained recognition at leading international forums, including the European Society for Radiotherapy and Oncology (ESTRO) in Austria (May 2025), the Radiation Research Society Conference in the U.S. (September 2024), and the Spanish Society of Medical Physics (May 2025). Portions of the work have also been published in journals such as Radiation Physics and Chemistry, Physics in Medicine & Biology, and Clinical Cancer Research. These achievements highlight the tool’s credibility and its potential role in advancing radiation oncology.

Beyond radiotherapy planning, the method could be applied to simulate drug or radiopharmaceutical distribution and to evaluate strategies for radioprotection. Modeling cumulative exposure creates opportunities to optimize treatment schedules and beam directions to reduce blood damage. Researchers see it as a paradigm shift toward protecting the immune system and enhancing patients’ quality of life in precision oncology.

“Thinking of blood as a dynamic organ to be protected represents a paradigm shift in modern radiotherapy,” said Professor Javier Burguete, Professor of Medical Physics and Biophysics at the University of Navarra and director of the thesis. “This research not only responds to a scientific need, but also a clinical imperative: to offer safer treatments without compromising oncological efficacy.”