Monte Carlo dosimetry for forthcoming clinical trials in x-ray microbeam radiation therapy

The purpose of this work is to define safe irradiation protocols in microbeam radiation therapy. The intense synchrotron-generated x-ray beam used for the treatment is collimated and delivered in an array of 50 μm-sized rectangular fields with a centre-to-centre distance between microplanes of 400 μm. The absorbed doses received by the tumour and the healthy tissues in a human head phantom have been assessed by means of Monte Carlo simulations. The identification of safe dose limits is carried out by evaluating the maximum peak and valley doses achievable in the tumour while keeping the valley doses in the healthy tissues under tolerances. As the skull receives a significant fraction of the dose, the dose limits are referred to this tissue. Dose distributions with high spatial resolution are presented for various tumour positions, skull thicknesses and interbeam separations. Considering a unidirectional irradiation (field size of 2×2 cm2) and a centrally located tumour, the largest peak and valley doses achievable in the tumour are 55Gy and 2.6Gy, respectively. The corresponding maximum valley doses received by the skin, bone and healthy brain are 4 Gy, 14 Gy and 7 Gy (doses in one fraction), respectively, i.e. within tolerances (5% probability of complication within 5 years).Postprint (published version

Survival Analysis of F98 Glioma Rat Cells Following Minibeam or Broad-Beam Synchrotron Radiation Therapy

Background: In the quest of a curative radiotherapy treatment for gliomas new delivery modes are being explored. At the Biomedical Beamline of the European Synchrotron Radiation Facility (ESRF), a new spatially-fractionated technique, called Minibeam Radiation Therapy (MBRT) is under development. The aim of this work is to compare the effectiveness of MBRT and broad-beam (BB) synchrotron radiation to treat F98 glioma rat cells. A dose escalation study was performed in order to delimit the range of doses where a therapeutic effect could be expected. These results will help in the design and optimization of the forthcoming in vivo studies at the ESRF. Methods: Two hundred thousand F98 cells were seeded per well in 24-well plates, and incubated for 48 hours before being irradiated with spatially fractionated and seamless synchrotron x-rays at several doses. The percentage of each cell population (alive, early apoptotic and dead cells, where either late apoptotic as necrotic cells are included) was assessed by flow cytometry 48 hours after irradiation, whereas the metabolic activity of surviving cells was analyzed on days 3, 4, and 9 post-irradiation by using QBlue test. Results

Infrared microspectroscopy to elucidate the underlying biomolecular mechanisms of FLASH radiotherapy.

FLASH-radiotherapy (FLASH-RT) is an emerging modality that uses ultra-high dose rates of radiation to enable curative doses to the tumor while preserving normal tissue. The biological studies showed the potential of FLASH-RT to revolutionize radiotherapy cancer treatments. However, the complex biological basis of FLASH-RT is not fully known yet. Within this context, our aim is to get deeper insights into the biomolecular mechanisms underlying FLASH-RT through Fourier Transform Infrared Microspectroscopy (FTIRM). C57Bl/6J female mice were whole brain irradiated at 10 Gy with the eRT6-Oriatron system. 10 Gy FLASH-RT was delivered in 1 pulse of 1.8μs and conventional irradiations at 0.1 Gy/s. Brains were sampled and prepared for analysis 24 h post-RT. FTIRM was performed at the MIRAS beamline of ALBA Synchrotron. Infrared raster scanning maps of the whole mice brain sections were collected for each sample condition. Hyperspectral imaging and Principal Component Analysis (PCA) were performed in several regions of the brain. PCA results evidenced a clear separation between conventional and FLASH irradiations in the 1800-950 cm <sup>-1</sup> region, with a significant overlap between FLASH and Control groups. An analysis of the loading plots revealed that most of the variance accounting for the separation between groups was associated to modifications in the protein backbone (Amide I). This protein degradation and/or conformational rearrangement was concomitant with nucleic acid fragmentation/condensation. Cluster separation between FLASH and conventional groups was also present in the 3000-2800 cm <sup>-1</sup> region, being correlated with changes in the methylene and methyl group concentrations and in the lipid chain length. Specific vibrational features were detected as a function of the brain region. This work provided new insights into the biomolecular effects involved in FLASH-RT through FTIRM. Our results showed that beyond nucleic acid investigations, one should take into account other dose-rate responsive molecules such as proteins, as they might be key to understand FLASH effect

Clarification of the Three-Body Decay of 12C (12.71 MeV)

Using β decays of a clean source of 12 N produced at the IGISOL facility, we have measured the breakup of the 12 C (12.71 MeV) state into three α particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed

Low-lying resonance states in the Be-9 continuum

Excited states in Be-9 from 2 to 9 MeV are studied via beta delayed particle emission from Li-9. The broad overlapping particle unbound states are investigated using an extension of an experimental method developed for dealing with three-body decays of broad isolated levels. The results confirm the existence of a broad state at 5 MeV, with a width of 2 MeV. Angular correlations are used for firm spin determinations for this and other levels

Low-lying resonance states in the Be-9 continuum

Excited states in Be-9 from 2 to 9 MeV are studied via beta delayed particle emission from Li-9. The broad overlapping particle unbound states are investigated using an extension of an experimental method developed for dealing with three-body decays of broad isolated levels. The results confirm the existence of a broad state at 5 MeV, with a width of 2 MeV. Angular correlations are used for firm spin determinations for this and other levels

Proceedings of the third French-Ukrainian workshop on the instrumentation developments for HEP

The reports collected in these proceedings have been presented in the third French-Ukrainian workshop on the instrumentation developments for high-energy physics held at LAL, Orsay on October 15-16. The workshop was conducted in the scope of the IDEATE International Associated Laboratory (LIA). Joint developments between French and Ukrainian laboratories and universities as well as new proposals have been discussed. The main topics of the papers presented in the Proceedings are developments for accelerator and beam monitoring, detector developments, joint developments for large-scale high-energy and astroparticle physics projects, medical applications.Comment: 3rd French-Ukrainian workshop on the instrumentation developments for High Energy Physics, October 15-16, 2015, LAL, Orsay, France, 94 page