Newswise \u2014 SACRAMENTO, Calif. \u2014 Ionizing radiation is one of our oldest and most valuable tools in the fight against cancer, and is still employed in the treatment of approximately half of all new cancer cases. Traditionally administered in small daily doses (“fractions”) of 2 Gray over several weeks, the field of radiation oncology has increasingly shifted toward alternative dosing schemes in which very large per-fraction doses are utilized. These are stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). In these modalities, an ultra-large fraction (possibly 10+ Gray) is delivered to a tumor within a single day, and treatment only occurs on one or a handful of days.\u00a0<\/p>\n
However, a major obstacle to optimizing the success of SRS and SBRT has been an inability to predict, with acceptable accuracy, how effective such ultra-large fractions will be at killing cancer cells. That is because the mathematical model most commonly used to make this prediction\u2014the linear-quadratic (LQ) model\u2014is known to be inaccurate when the per-fraction dose is very large.<\/p>\n
A recently published paper by mathematical biologist Dr. Lydia Bilinsky, formerly of Duke University and the U.S. Food and Drug Administration (FDA), and currently a Research Fellow at the Ronin Institute for Independent\u00a0Scholarship 2.0, offers a powerful solution to this problem.\u00a0<\/p>\n
Published in BIOMATH, a journal of the Bulgarian Academy of Sciences, Dr. Bilinsky\u2019s peer-reviewed paper introduces a new dose-survival equation which accurately predicts cell survival across the entire clinically relevant per-fraction dose range\u2014including the very high end that is utilized in SRS and SBRT.\u00a0<\/p>\n
The new equation also helps to overcome another critical hurdle for the success of SRS and SBRT, which is that some cell-cycle phases are more radiosensitive than others. In conventional multi-week fractionation, cancer cells are naturally caught on some days in their more radiosensitive phases, a fact which is relied upon for treatment success (“redistribution\u201d). This effect is not present in SRS and SBRT, since radiation is only administered on one or a handful of days.\u00a0<\/p>\n
Dr. Bilinsky\u2019s model addresses this problem by uncovering the hidden dose-survival relationship which governs cells while they are in their less-radiosensitive phases, shown in blue in the figure. By utilizing this relationship rather than the phase-averaged one (shown in black) to select fraction size, clinicians could theoretically eliminate the need for radiation to ever catch cells in their more radiosensitive phases.\u00a0<\/p>\n
Although conventional fractionation suffices for the successful treatment of many types of tumor, a large number of clinic visits is required, increasing costs and inconveniencing patients. Furthermore, some tumors are known to be treated more successfully using larger fraction sizes. Incorporating Dr. Bilinsky\u2019s equation into the design of future clinical trials investigating SRS and SBRT should do much to increase their success rates, ultimately improving treatment options available to cancer patients.\u00a0<\/p>\n
About the Article\u00a0<\/p>\n
The research was conducted by Dr. Lydia Bilinsky, a Fellow at the Ronin Institute for Independent Scholarship 2.0, a distributed research organization supporting independent scholars. Full computational materials and reproducibility protocols have been archived for independent verification. The views, findings, and conclusions expressed in the paper and this release are those of the author, Dr. Bilinsky, and do not necessarily represent the views or positions of the Ronin Institute for Independent Scholarship 2.0.\u00a0<\/p>\n
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About the Ronin Institute for Independent Scholarship 2.0\u00a0<\/p>\n
The Ronin Institute for Independent Scholarship 2.0 supports a global community of scholars pursuing research outside of traditional academic institutions. By providing infrastructure, collaboration networks, and scholarly identity, the Institute enables rigorous, independent inquiry across the sciences and humanities. Website: ronininstitute.org\/\u00a0<\/p>\n
Note to editors:\u00a0<\/p>\n
The article is available online at:\u00a0<\/p>\n
https:\/\/biomath.math.bas.bg\/biomath\/index.php\/biomath\/article\/view\/j.biomath.2025.07.035<\/p>\n
The author welcomes inquiries regarding the framework’s methodology and implications.\u00a0<\/p>\n