IAEA Study Reveals Ionizing Radiation's Health Impact

An IAEA research project involving 27 countries has strengthened global understanding of how exposure to ionizing radiation affects human health. The project focused on the clinical applications of biodosimetry - how measuring biological responses can be used to estimate the amount of ionizing radiation a patient receives. Over several years, it generated new data which expands on the potential of dosimetric biomarkers - biological indicators that reflect the amount of ionizing radiation a person has been exposed to.

"Within everyday clinical practice, the move towards personalized medicine requires assays to accurately assess radiation exposure at the individual level. Beyond ensuring patient safety, these specialized tests are critical for predicting how normal tissues respond to clinical procedures involving ionizing radiation," said Oleg Belyakov, an IAEA radiobiologist and the project's technical officer. "While previously validated biological indicators offer a promising foundation, there are a number of knowledge gaps and methodological limitations which need to be addressed before these markers can serve as a reliable tool to inform routine clinical decision-making."

To address this challenge, the IAEA launched a coordinated research project (MEDBIODOSE) in 2017 to examine the role of biodosimetric markers and methods within radiation oncology, nuclear medicine and diagnostic and interventional radiology. Thirty-one institutions from Argentina, Australia, Brazil, Canada, Chile, China, Cuba, France, Ghana, India, Indonesia, Israel, Japan, Lithuania, Mexico, Philippines, Russian Federation, Saudi Arabia, Singapore, Slovakia, South Africa, Sudan, Thailand, Ukraine, United Kingdom, Uruguay and Viet Nam joined the project. Each team collected and analysed patients' biodosimetric data - biological measurements and observations used to estimate a person's radiation exposure. This included cytogenetic data (chromosomal aberrations) and molecular data (protein markers associated with damaged DNA and any changes in gene expression).

With over 100 publications resulting from their analyses, researchers identified a number of new biomarkers that signalled a biological response to radiation. These indicators were validated in terms of their relevance and reliability and used to generate calibration curves for estimating the absorbed dose. By using cells from multiple donors, the project's participants could examine variations in radiation response - enabling the identification of radiosensitive individuals who may require specific radiation procedures and protection measures.

Laboratory experiments simulating uneven or partial radiation exposure at high doses provided important baseline data to improve existing methods for checking radiation exposure with clinical environments. The study's scientists also developed new devices for the rapid - and in some cases automated - analysis of radiation biomarkers.

Among other outcomes, researchers demonstrated that standard biodosimetric methods are capable of detecting any chromosomal breaks in a patient's lymphocytes - a type of specialized white blood cell - after a single computed tomography (CT) scan. Since low-dose CT scans for screening lung cancer do not appear to damage human DNA, this finding can help address concerns around increased risks of radiation-induced cancer, other research participants in the study showed.

Within radiation oncology, researchers explored how radiosensitivity at the chromosomal and cellular level could serve as a predictor for the effects that ionizing radiation can have on surrounding healthy tissues.

"MEDBIODOSE has established invaluable in-vivo and in-vitro datasets and validated new radiation-response biomarkers, thereby helping to shape the future of biodosimetry by providing a stronger scientific foundation for personalized radiation medicine," said Satoshi Tashiro, professor at Hiroshima University's Research Institute for Radiation Biology and Medicine. "Its achievements in developing high-throughput and automated biodosimetry technologies - including PNA-FISH, flow-cytometry-based systems and advanced image analysis software - as well as in fostering routine collaboration between biodosimetrists and clinicians have significantly strengthened the clinical application of biodosimetry - for example by supporting its use in optimizing radiological diagnostic procedures and predicting radiotherapy-related side effects."

"By building a robust operational research network and harmonizing methodologies across participating laboratories, MEDBIODOSE has helped countries maintain and further advance their national expertise in biodosimetry," he added.