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Enhanced Efficacy of Multiport Synchrotron Microbeam Radiation Therapy for Brain Tumors in Rats
by
, , and
Laura Eling
1,2,*, 
Liam Day
3,
Micah Barnes
4,
Matthew Cameron
5,
Michael De Veer
6,
My-Linh Tempo
1,
Helen Forrester
3,4,
Mitzi Klein
5,
Daniel Hausermann
5,
Jean A. Laissue
7 and
Raphaël Serduc
1,2 1
Institut National de la Santé et de la Recherche Médicale UA7 Synchrotron Radiation for Biomedicine, Bâtiment Biologie B, Université Grenoble Alpes, 38400 Saint-Martin-d’Hères, France
2
Centre Hospitalier Universitaire Grenoble Alpes, Maquis du Grésivaudan, 38700 La Tronche, France
3
School of Sciences, RMIT University, Melbourne, VIC 3000, Australia
4
Centre of Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2500, Australia
5
Imaging and Medical Beamline, Australian Nuclear Science and Technology Organisation (Australian Synchrotron), Clayton, VIC 3168, Australia
6
Monash Biomedical Imaging, Monash University, Clayton, VIC 3168, Australia
7
Faculty of Medicine, University of Bern, 3000 Bern, Switzerland
*
Author to whom correspondence should be addressed.
Radiation 2026, 6(2), 17; https://doi.org/10.3390/radiation6020017
Submission received: 12 March 2026
/
Revised: 20 May 2026
/
Accepted: 22 May 2026
/
Published: 27 May 2026
Simple Summary
We present a novel approach to move towards complete brain tumor control in rats by increasing the number of irradiation ports using synchrotron-generated Microbeam Radiation Therapy (MRT), in which very high peak doses are delivered in a bundle of thin microbeams. Rats bearing 9L brain tumors were treated with eight MRT ports, delivering a cumulated inter-beam valley dose of 10 Gy. This MRT geometry significantly increased tumor control and improved animal well-being and survival. More than eight ports are necessary to reach complete tumor control with multiport MRT, exploiting the full potential of the geometrical MRT approach and advancing this promising technique towards clinical use.
Abstract
Microbeam Radiation Therapy (MRT) is a drastically novel approach of radiosurgery, challenging the understanding of how normal tissues respond to radiation therapy, where X-rays generated by a synchrotron light source are collimated into wafers of high-dose (hundreds of Gray), thin (50 µm) parallel microbeams. Recent work showed that MRT dose prescription must consider a dual approach: separating normal tissue dose constraints tied to the valley dose prescription and anti-tumor effects, depending on the prescribed number of ports. Here, we consolidate this assumption by increasing the number of MRT incidences to irradiate 9L-bearing rats with a cumulated valley dose of 10 Gy. 9L-bearing rats were irradiated by eight ports of conventional Broad Beam (BB) or MRT. Animals were followed up clinically by MR imaging, histopathology and survival analysis. MRI follow-up revealed that MRT significantly amplified antitumor effect and tumor tissue damage while improving the clinical score of animals. Ten Gy, delivered by either BB or MRT, increased median survival time to 15 and 39.5 days after irradiation, respectively. Neither complete ablation of brain tumors nor long-term survival was achieved, but multiport MRT (eight ports) showed an outstanding dose equivalence factor (x2.9), which needs to be tested in a clinical environment.
