Establishment of Microbeam Radiation Therapy at a Small-Animal Irradiator

Purpose Microbeam radiation therapy is a preclinical concept in oncology. It spares normal tissue more effectively than conventional at equal tumor control. The field consists of peak regions with doses several hundred gray, whereas between the peaks (valleys) are below tolerance level. Widths and distances beams submillimeter range for microbeam therapy. A similar alternative beam widths millimeter presented by minibeam Although both methods were developed large synchrotron facilities, compact sources have been proposed recently. Methods Materials small-animal irradiator was fitted special 3-layered collimator that used research produces microbeams flexible width up to 100 μm. Film dosimetry provided measurements dose distributions compared Monte Carlo predictions. Moreover, micronucleus assay Chinese hamster CHO-K1 cells as biological dosimeter. focal spot size emission angle x-ray tube modified optimize rate, peak-to-valley ratio (PVDR), shape, homogeneity. An equivalent slit 500 μm produced minibeams allowed comparison characteristics. Results setup achieved entrance rates 8 Gy/min PVDRs >30 microbeams. Agreement simulations film generally better larger widths; qualitative validated predicted results. smaller enhances reduces penumbras but substantially rate. reduction improves PVDR, penumbras, rate without impairing Minibeams showed characteristics same distance had agreement simulations. Conclusion already use vitro experiments soon vivo irradiations. Deviations attributed scattering surface manufacturing inaccuracies matter ongoing research.