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International audience; Background: Resistance to radiotherapy is frequently encountered in patients with glioblastoma multiforme. It is caused at least partially by the high glutathione content in the tumour tissue. Therefore, the administration of the glutathione synthesis inhibitor Buthionine-SR-Sulfoximine (BSO) should increase survival time.Methods: BSO was tested in combination with an experimental synchrotron-based treatment, microbeam radiation therapy (MRT), characterized by spatially and periodically alternating microscopic dose distribution. One hundred thousand F98 glioma cells were injected into the right cerebral hemisphere of adult male Fischer rats to generate an orthotopic small animal model of a highly malignant brain tumour in a very advanced stage. Therapy was scheduled for day 13 after tumour cell implantation. At this time, 12.5% of the animals had already died from their disease.The surviving 24 tumour-bearing animals were randomly distributed in three experimental groups: subjected to MRT alone (Group A), to MRT plus BSO (Group B) and tumour-bearing untreated controls (Group C). Thus, half of the irradiated animals received an injection of 100 mu M BSO into the tumour two hours before radiotherapy. Additional tumour-free animals, mirroring the treatment of the tumour-bearing animals, were included in the experiment. MRT was administered in bi-directional mode with arrays of quasi-parallel beams crossing at the tumour location. The width of the microbeams was approximate to 28 mu m with a center-to-center distance of approximate to 400 mu m, a peak dose of 350 Gy, and a valley dose of 9 Gy in the normal tissue and 18 Gy at the tumour location; thus, the peak to valley dose ratio (PVDR) was 31.Results: After tumour-cell implantation, otherwise untreated rats had a mean survival time of 15 days. Twenty days after implantation, 62.5% of the animals receiving MRT alone (group A) and 75% of the rats given MRT + BSO (group B) were still alive. Thirty days after implantation, survival was 12.5% in Group A and 62.5% in Group B. There were no survivors on or beyond day 35 in Group A, but 25% were still alive in Group B. Thus, rats which underwent MRT with adjuvant BSO injection experienced the largest survival gain.Conclusions: In this pilot project using an orthotopic small animal model of advanced malignant brain tumour, the injection of the glutathione inhibitor BSO with MRT significantly increased mean survival time.

International audience; Synchrotron-generated microplanar beams (microbeams) provide the most stereo-selective irradiation modality known today. This novel irradiation modality has been shown to control seizures originating from eloquent cortex causing no neurological deficit in experimental animals. To test the hypothesis that application of microbeams in the hippocampus, the most common source of refractory seizures, is safe and does not induce severe side effects, we used microbeams to induce transections to the hippocampus of healthy rats. An array of parallel microbeams carrying an incident dose of 600 Gy was delivered to the rat hippocampus. Immunohistochemistry of phosphorylated gamma-H2AX showed cell death along the microbeam irradiation paths in rats 48 hours after irradiation. No evident behavioral or neurological deficits were observed during the 3-month period of observation. MR imaging showed no signs of radio-induced edema or radionecrosis 3 months after irradiation. Histological analysis showed a very well preserved hippocampal cytoarchitecture and confirmed the presence of clear-cut microscopic transections across the hippocampus. These data support the use of synchrotron-generated microbeams as a novel tool to slice the hippocampus of living rats in a minimally invasive way, providing (i) a novel experimental model to study hippocampal function and (ii) a new treatment tool for patients affected by refractory epilepsy induced by mesial temporal sclerosis.

Cisplatin is one of the most effective metal-based anticancer agents, targeting a large number of solid tumours. Despite its efficacy, cisplatin treatment is still limited by severe side effects such as neuro-, hepato- and nephro-toxicity and by resistance phenomena, only partially overcome by the use of new platinum drugs (i.e. oxaliplatin and carboplatin). These problems have stimulated the research and development of alternative therapeutic strategies based on different heavy metals. In this work we investigated the in vitro activity and neurotoxicity of three anticancer complexes: [Cu(PTA)4]PF6, [Cu(thp)4]PF6 and [Au(PTA)4]PF6. Neurotoxicity was evaluated by embryonic rat dorsal root ganglia (DRG) organotypic culture model. Furthermore the extent of proteasome inhibition in rat embryonic DRG neurons was evaluated by fluorimetric assay. After 48 hours of treatment, both copper-based compounds were not neurotoxic even at higher concentrations with respect to the IC50 obtained in A549 and IGROV-1 human cancer cells while [Au(PTA)4]PF6 was neurotoxic at lower concentration than IC50 in cancer cell lines tested. Since the ubiquitin-proteasome system has been identified as molecular target in cancer cells for the heavy metal based-drug, we evaluated their ability to affect the proteasome machinery in DRG neurons. The copper-based compounds, that are not neurotoxic, do not inhibit proteasome activity in DRG neurons. On the contrary, the neurotoxic complex [Au(PTA)4] PF6, induces a significant inhibition of proteasome activity even at concentration lower than the IC50. Furthermore, based on the content in heavy metal-based atoms, the complexes used in this study are suitable candidates for Photon Activation Therapy (PAT). Pretreatment of IGROV-1 cells with [Cu(PTA)4]PF6 induces an increase cell death with respect to drug or synchrotron (SR) alone. Furthermore the SR/[Cu(PTA)4]PF6 combinational treatment induced an increase in DNA damage with respect to single treatments. Our results, together with the low IC50 of the copper compounds compared to the one observed for cisplatin, suggest them as promising compounds in anticancer treatment., Italian Journal of Anatomy and Embryology, Vol 119, No 1 (Supplement) 2014

International audience; Owing to their large range of properties which can be accurately tuned by the chemical composition, the shape and the dimensions, multifunctional nanoparticles appear as promising candidates for imageguided therapy. For achieving this goal, we developed the synthesis of gold nanoparticles which are designed for combining multimodal imaging (magnetic resonance imaging (MRI), scintigraphy (SPECT), ultrasound imaging (echography) and X-ray imaging) and radiotherapy [1-5]. Ultrasmall gold nanoparticles were synthesized by reducing gold salt in presence of various highly hydrophilic dithiolated polyaminocarboxylate ligands (linear (DTDTPA) and macrocyclic (TADOTA, TADOTAGA) ligands). They are composed of a gold core (mean diameter of ~ 2.5 nm) encapsulated within an organic shell of ligands (DTDTPA, TADOTA or TADOTAGA). The gold core is expected to provide a strong X-ray absorption whereas the ligands of the organic shell were chosen for their propensity to entrap gadolinium ions (for MRI) and radionuclides (for SPECT). Since the passive accumulation of the gold nanoparticles in the tumor depends on the nature of theligands, the possibility to follow up the gadolinium chelate-coated gold nanoparticles by MRI is therefore very useful for determining the most opportune delay between intravenous injection and irradiation. Owing to the radiosensitizing effect of the gold core, the combination of microbeamradiation therapy (MRT) and gold nanoparticles based MRI contrast agents led to a great increase in lifespan of the 9L gliosarcoma-bearing rats in comparison to non-treated animals and animals treated only by MRT [5]. Finally, this study demonstrated that gadolinium chelate-coated gold nanoparticles exhibit a real potential for image-guided microbeam radiation therapy.

International audience; Ultrasmall gadolinium-based nanoparticles (GBN, hydrodynamic diameter < 5 nm) were recently developped. Since they are designed for combining renal clearance, magnetic resonance imaging (MRI) and radiosensitization, these nanoparticles appear as attractive agents for image-guidedradiotherapy. Their efficiency to improve the survival time of tumor bearing animals rests on the possibility to determine, from the data collected by MRI, the delay between the irradiation and the intravenous injection of GBN. The attempts to determine this delay were assessed by combining MRT experiments in parallel with MRI and it provided unexpected results. In this talk, we will summarize these results that were achieved through the long term project MD606 (ANR Theraguima) at the ESRF including survival curves of animals as a function of (i) the time delay between injection and irradiation, (ii) the combination between nanoparticles and temozolomide and (iii) the comparison with the radiosensitization issued by the use of Gd chelates instead of GBN. Additionally, the biodistribution of the GBN within the tumor will be presented through MRI results and XRF results (ID21). On going experiments are now focused on the comparison between the efficiency of the GBN using MRT and in parallel a 6MeV irradiator at the local hospital.

The major objective is to adopt, apply and test developed in-house algorithms for volumetric breast reconstructions from projection images, obtained in in-line phase-contrast mode. Four angular sets, each consisting of 17 projection images obtained from four physical phantoms, were acquired at beamline ID17, European Synchroton Radiation Facility, Grenoble, France. The tomosynthesis arc was ±32°. The physical phantoms differed in complexity of texture and introduced features of interest. Three of the used phantoms were in-house developed, and made of epoxy resin, polymethyl-methacrylate and paraffin wax, while the fourth phantom was the CIRS BR3D. The projection images had a pixel size of 47 μm × 47 μm. Tomosynthesis images were reconstructed with standard shift-and-add (SAA) and filtered backprojection (FBP) algorithms. It was found that the edge enhancement observed in planar x-ray images is preserved in tomosynthesis images from both phantoms with homogeneous and highly heterogeneous backgrounds. In case of BR3D, it was found that features not visible in the planar case were well outlined in the tomosynthesis slices. In addition, the edge enhancement index calculated for features of interest was found to be much higher in tomosynthesis images reconstructed with FBP than in planar images and tomosynthesis images reconstructed with SAA. The comparison between images reconstructed by the two reconstruction algorithms shows an advantage for the FBP method in terms of better edge enhancement. Phase-contrast breast tomosynthesis realized in in-line mode benefits the detection of suspicious areas in mammography images by adding the edge enhancement effect to the reconstructed slices.

Recent trends in hard X-ray micro-computed tomography (microCT) aim at increasing both spatial and temporal resolutions. These challenges require intense photon beams. Filtered synchrotron radiation beams, also referred to as `pink beams', which are emitted by wigglers or bending magnets, meet this need, owing to their broad energy range. In this work, the new microCT station installed at the biomedical beamline ID17 of the European Synchrotron is described and an overview of the preliminary results obtained for different biomedical-imaging applications is given. This new instrument expands the capabilities of the beamline towards sub-micrometre voxel size scale and simultaneous multi-resolution imaging. The current setup allows the acquisition of tomographic datasets more than one order of magnitude faster than with a monochromatic beam configuration.

Conventional radiotherapy is a widely used non-invasive form of treatment for many types of cancer. However,due to a low threshold in the lung for radiation-induced normal tissue damage, it is of less utility in treating lung cancer. For this reason, surgery is the preferred treatment for lung cancer, which has the detriment of being highly invasive. Non-conventional ultra-high dose rate (FLASH) radiotherapy is currently of great interest in the radiotherapy community due to demonstrations of reduced normal tissue toxicity in lung and other anatomy. This study investigates the effects of FLASH microbeam radiotherapy, which in addition to ultra-high dose rate incorporates a spatial segmentation of the radiation field, on the normal lung tissue of rats. With a focus on fibrotic damage, this work demonstrates that FLASH microbeam radiotherapy provides an order of magnitude increase in normal tissue radio-resistance compared to FLASH radiotherapy. This result suggests FLASH microbeam radiotherapy holds promise for much improved non-invasive control of lung cancer.

International audience; Microbeam radiation therapy is a novel preclinical technique, which uses synchrotron-generated X-rays for the treatment of brain tumours and drug-resistant epilepsies. In order to safely translate this approach to humans, a more in-depth knowledge of the long-term radiobiology of microbeams in healthy tissues is required. We report here the result of the characterization of the rat sensorimotor cortex tolerance to microradiosurgical parallel transections. Healthy adult male Wistar rats underwent irradiation with arrays of parallel microbeams. Beam thickness, spacing and incident dose were 100 or 600 mu m, 400 or 1200 mu m and 360 or 150 Gy, respectively. Motor performance was carried over a 3-month period. Three months after irradiation rats were sacrificed to evaluate the effects of irradiation on brain tissues by histology and immunohistochemistry. Microbeam irradiation of sensorimotor cortex did not affect weight gain and motor performance. No gross signs of paralysis or paresis were also observed. The cortical architecture was not altered, despite the presence of cell death along the irradiation path. Reactive gliosis was evident in the microbeam path of rats irradiated with 150 Gy, whereas no increase was observed in rats irradiated with 360 Gy

Among the new emerging cancer therapies, Microbeam Radiation Therapy (MRT) is currently showing very promising results in terms of limiting or decreasing tumor growth while keeping the damage to healthy tissue to a minimum. The MRT is able to deliver unprecedented dose rates of up to 20 kGy/s, posing important questions in terms of treatment planning and patient safety during treatment. For this reason, a beam monitoring system must be built, in which a detector acquires the microbeam array profile in real-time. In case of anomalies detection, the detector signals the beam-line to close the shutter as an emergency safety measure. Many sensors technologies for beam monitoring are currently being considered and silicon strip detectors seem to be very promising candidates. In this study the characterisation in full MRT conditions of a novel silicon strip detector is reported explaining strengths and weaknesses of the devices. Modifications to the sensor layout are also suggested in this study.

Defaults in vascular (VN) and neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and neuronal systems is a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and neuronal systems of mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with neither contrast agent nor a destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is a crucial tool for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries. In particular, it should be an optimal tool to resolve the entangled relationship between VN and neuronal system., Comment: 15 pages, 6 figures

Purpose Microplanar X-ray beams (microbeams) originated by synchrotron sources have been delivered to the visual brain cortex regions in rodents to create microscopically narrow lesions. The effects of microbeams mimic those generated by microsurgical subpial transections (also known as multiple subpial transections) but are obtained in a low-invasive way. Methods Image-guided atlas-based microbeam cortical transections have been generated on seven 1 month-old Wistar rats. An array of 10 parallel beams of 25 microns in thickness and spaced of 200 micron center-to-center was centered on the visual cortex and deposited an incident dose of 600 Gy. Results The procedure was well tolerated by rats. After recovery, rats showed regular behavior, no sign of gross visual impairment and regular weight gain. After 3 months, rats were sacrificed and brains histologically examined. Cortical transections resembling those obtained through a surgical incision were found over the irradiated region. Remarkable sparing of the cortical columns adjacent to the transections was observed. No sign of radionecrosis was evident at least at this time point. Conclusions The visual brain cortex transected by synchrotron-generated microbeams showed an incision-like path of neuronal loss while adjacent non irradiated columns remained intact. These preliminary findings, to be further investigated also using other techniques, suggest that microbeam radiosurgery can affect the cortex at a cellular level providing a potential novel and attractive tool to study cortical function.

The Micro-Beam Radiation Therapy (MRT) is a promising newly emerged cancer treatment currently under development at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Several safety requirements must be complied with, prior to the human clinical trials of the MRT such as the ability to send a signal to the emergency beam shutter in case of any beam anomalies, in order to avoid exposing the patient to excess radiation. This will require a beam monitor that can work under the demanding operating conditions of the MRT. A good candidate for this application is a silicon strip detector. A novel device layout has been proposed and numerical simulations were performed to carry out the optimisation of design and fabrication at SINTEF MiNaLab, Oslo, Norway. Simulation results and preliminary electrical measurements on wafer level are reported and discussed.

Microbeam Radiation Therapy (MRT) is an emerging cancer treatment that is currently being developed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. This technique uses a highly collimated and fractionated X-ray beam array with extremely high dose rate and very small divergence, to benefit from the dose-volume effect, thus sparing healthy tissue. In case of any beam anomalies and system malfunctions, special safety measures must be installed, such as an emergency safety shutter that requires continuous monitoring of the beam intensity profile. Within the 3DMiMic project, a novel silicon strip detector that can tackle the special features of MRT, such as the extremely high spatial resolution and dose rate, has been developed to be part of the safety shutter system. The first prototypes have been successfully fabricated, and experiments aimed to demonstrate their suitability for this unique application have been performed. Design, fabrication and the experimental results as well as any identified inadequacies for future optimisation are reported and discussed in this paper., 23 pages, 16 figures