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The Magic of Spatially Fractionated Radiation

S Chang1*, (1) UNC School of Medicine, Chapel Hill, NC


(Sunday, 7/14/2019) 4:00 PM - 5:00 PM

Room: Exhibit Hall | Forum 3

Purpose: Spatially-fractionated radiation therapy (SFRT) is considered an experimental therapy that has been used in clinics and preclinical research for decades. SFRT has demonstrated some incredibly high therapeutic ratios that simply cannot be explained by our current understanding of radiobiology. To encourage more much needed research on SFRT we summarize some highlights of our and other’s preclinical work on the subject.

Methods: Preclinical SFRT studies on mouse and rat models were conducted on either conventional animal irradiators with special collimators or with a carbon nanotube field emission x-ray system to generate small scale SFRT (microbeam/minibeams). In these studies, a single fraction SFRT radiation was compared with a corresponding seamless radiation of the same integral dose for tumor control, toxicity, immunotherapy enhancement (abscopal effect), and enhancement of nanoparticle drug tumor delivery. The effect of radiation spatial fractionation under equal tumor integral dose was also systemically investigated in terms of tumor control and toxicity indicators.

Results: For the same tumor integral dose seamless radiation has the best tumor control compared to various spatial frequency of SFRT treatments. For similar tumor controls, the seamless radiation has a higher toxicity indicator (body weight loss) than the microbeam radiation. When used as an induction therapy, microbeam radiation is more effective than seamless radiation in enhancing nanoparticle drug tumor delivery and in enhancing anti-PD-L1 immunotherapy as shown in abscopal effect. Compared to seamless radiation microbeam radiation induces drastically different modulation in tumor microenvironment including tumor microvasculature, which may be a key for the magic of spatially fractionated radiation.

Conclusion: Spatial fractionation opens up new opportunities to advance cancer control by radiation, especially for drug- or radiation-resistant tumors, large tumors, and tumor retreatment. More translational and mechanistic research is needed to realize the promising potential of SFRT in cancer treatment.

Funding Support, Disclosures, and Conflict of Interest: Chang filed a provisional patent on fractionated radiation protection method and technology.


Not Applicable / None Entered.


TH- Radiobiology(RBio)/Biology(Bio): RBio- Photons

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