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An overview of the recent operations and the main results of cesium injection in the Source for the Production of Ions of Deuterium Extracted from Rf plasma (SPIDER) negative ion source are described in this contribution. In experiments without cesium injection, all SPIDER plants were tested to verify the basic expectations on the operational parameters (e.g., electron cooling effectiveness of magnetic filter field) and to determine its operational region. For beam properties, it was shown that the current density varies across the beam in the vertical direction. In preliminary cesium experiments, the expected increase of negative ion current and simultaneous decrease of co-extracted electrons were found, along with the influence of the control parameters (polarization of the plasma electrodes, magnetic filter field) on the SPIDER beam uniformity in the horizontal and vertical directions. It was shown that non-Gaussian tails can be identified in the angular distribution on the plane perpendicular to the beam propagation direction. Stray particles, nonhomogeneous beam and large divergence might result in unexpected heat and particle loads over ITER neutral beam injector (NBI) accelerator grids; it is the goal of SPIDER to assess and possibly to identify suitable methods for controlling these beam features. A major shutdown, planned for late 2021, to solve the issues identified during the operation and to carry out scheduled modifications, is outlined. Such improvements are expected to allow SPIDER to pursue the ITER requirements in terms of negative ion current, electron-to-ion ratio, and beam duration.

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities.In order to enable such development, a Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, called SPIDER and MITICA. SPIDER is dedicated developing and char-acterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accel-erator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full perfor-mances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign, in particular events/issues occurred during operation, which led to the identification of improvement opportunities/necessities (e.g. RF discharges, local burns, water leaks, other damages, configuration/design upgrades to maximize chances/margin to quest target parameters).Parallelly, developments on MITICA, the full-scale prototype of the ITER Neutral Beam Injector (NBI) featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of the beam source, accel-erator and the beam line components, while power supplies and auxiliary plants, already installed, are under final testing and commissioning.Integration, commissioning and tests of the 1 MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. 1.2 MV dc insulating tests of high voltage components were successfully completed. The integrated test to confirm 1 MV output by combining invertor systems, DC gener-ators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, said events have been addressed and solutions for the repair and the improvement of the system were developed.Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion. The lessons learned during the implementation on NBTF and future perspectives are here discussed.

PURPOSE To assess the dosimetric advantages of apertures in intracranial single fraction proton radiosurgery. MATERIALS AND METHODS Six neuroma and 10 meningioma patients were investigated. For each patient, six plans were computed, with two spot spacing and three aperture settings (no apertures, 5 and 8 mm margin between aperture and clinical target volume [CTV]). All plans were optimized on the CTV with the same beam arrangement and the same single-field robust optimization (2 mm setup errors, 3.5% range uncertainties). Robustness analysis was performed with 0.5 and 1.0 mm systematic setup errors and 3.5% range uncertainties. CTV coverage in the perturbed scenarios and healthy brain tissue sparing in the surrounding of the CTV were compared. RESULTS Meningiomas were larger and at a shallow depth than neuromas. In neuromas, spot spacing did not affect OAR doses or the robustness of CTV coverage and the apertures reduced brain dose without any significant impact on CTV robustness. In meningiomas, smaller spot spacing produced a reduction in brain V5Gy and improved robustness of CTV coverage; in addition, an 8 mm margin aperture reduced low and medium brain tissue doses without affecting robustness in the 0.5 mm perturbed scenario. A 5 mm margin aperture caused a reduction of plan robustness. CONCLUSION The optimal use of apertures is a trade-off between sparing of low and medium dose to the healthy brain and robustness of target coverage, also depending on size and depth of the lesion.

The first ever built full-scale prototype of the ITER heating neutral beam injector is the MITICA experiment at PRIMA-NBTF (Neutral Beam Test Facility), under realization in Padua, Italy. The MITICA experiment includes many auxiliary plants; this paper is focused on the simulation and verification of the air cooling system of the High Voltage Power Supply (−1 MVdc), hosted in a Faraday cage (HVD1, High Voltage Deck1) inside a dedicated Building (High Voltage Hall, HVH) at PRIMA-NBTF. The HVD1 hosts the MITICA ISEPS (Ion Source Power Supply) in a two-floor cage, air insulated to ground for -1MVdc, with huge dimensions 12.5 m (L) × 8.4 m (W) × 9.6 m (H). Severe cleanliness constraints are required in the HVH hosting the HVD1, due to the high voltage operative conditions (the −1 MVdc Faraday cage is air insulated). The thermal behavior and air distribution in HVH are investigated as described in this paper.

The first ever built full-scale prototype of the ITER heating neutral beam injector is the MITICA experiment at PRIMA Neutral Beam Test Facility, under realization in Padova, Italy. This experiment consists of several in-vessel components: most of them are actively cooled by a large Cooling Plant, still under construction. Coolant is deionized water produced by a Chemical Control System (CCS). In the PRIMA facility, a cryogenic plant (currently in manufacturing phase) is also foreseen to serve the cryopumps to be installed in the MITICA Beam Line Vessel. During the installation of cooling plant and the design phase of cryogenic plant, two different issues came into evidence: waste water (produced by the CCS during operations) could not be delivered directly into the public network and the warm compressor of the cryogenic plant, originally air-cooled, changed to a water-cooled system. For the first issue the solution was found in a Water Treatment Unit (WTU) that requires the supply of hot water to distil the wastewater and to concentrate it. The second issue and the need to balance the heat loads and the cost and space constraints lead to an innovative system: it is essentially based on a high temperature water-water heat pump, by means of which the heat rejected by the warm compressor is used to heat up the WTU. Moreover this will reduce the operational costs by introducing a significant energy saving.

To reach fusion conditions and control the plasma configuration in ITER, the next step in tokamak fusion research, two neutral beam injectors (NBIs) will supply 16.5 MW each, by neutralizing accelerated negative hydrogen or deuterium ions. The requirements of ITER NBIs (40A/1 MeV D- ions for ≤1 h, 46A/870 keV H- ions for ≤1000 s) have never been simultaneously attained. So in the Neutral Beam Test Facility (NBTF, Consorzio RFX, Italy) the operation of the full-scale ITER NBI prototype (MITICA) will be tested and optimised up to full performances, focussing on accelerator (including voltage holding), beam optics, neutralisation, residual ion removal. The NBTF includes also the full-scale prototype of the ITER NBI source with 100 keV particle energy (SPIDER), for early investigation of: negative ion production and extraction, source uniformity, negative ion current density and beam optics. This paper will describe the main results of the first two years of SPIDER operation, devoted to characterizing plasma and beam parameters, including investigation of RF-plasma coupling efficiency and magnetic filter field effectiveness in reducing co-extracted electrons. SPIDER is progressing towards the first caesium injection, which aims at increasing the negative ion density. A major shutdown, planned for 2021, to solve the issues identified during the operation and to carry out programmed modifications, will be outlined. The installation of each MITICA power supply and auxiliary system is completed; in-vessel mechanical components are under procurement by Fusion for Energy (F4E). Integration, commissioning and test of the power supplies, procured by F4E and QST, as the Japanese Domestic Agency (JADA), will be presented. In particular, 1.0MV insulating tests were carried out step-by-step and successfully completed. In 2020 integrated tests of the power supplies on the accelerator dummy load started, including the assessment of their resilience to accelerator grid breakdowns using a short-circuit device located in vacuum. The aggressive programme, to validate the NBI design at NBTF and to meet ITER schedule (requiring NBIs in operation in 2032), will be outlined. Unfortunately, in 2020 the coronavirus disease infection affected the NBTF activities. A solution to proceed with integrated power tests despite the coronavirus is presented.

Corrosion-erosion phenomena occurred in the cooling circuits of primary heat transfer systems of the prototype of the ITER-like ion source named SPIDER, in particular during the first phase of the experiment activity which began in May 2018. Demineralised water circulating in cooling channels of components subjected to high heat loads reacts with inner channel surfaces made of copper alloys, aluminium, and stainless steel thus producing thinning of cooling channel walls. Then, resistivity degradation phenomenon of the demineralised water occurred and resistivity was measured before and after a working cycle to plan water treatment operations in order to maintain maximum availability of the SPIDER plants. This degradation was observed to be particularly fast during experimental campaigns: despite predictions, this effect is more significant in the less complex cooling circuit linked to Ion Source and Extraction Power Supply (ISEPS), feeding the Ion Source polarized to ground at -100 kV dc. Corrosion-erosion phenomena were investigated considering dissolved O2 and CO2, pH, flow velocity and turbulence, galvanic corrosion at dissimilar metal junctions, leakage current through high voltage cooling breaks, temperature, and water conductivity. This paper presents the first data of water parameters, monitored during experimental sessions by using the Cooling Plant and ISEPS Local Control Systems. Basing on collected data, some hypotheses were put forward on the behaviour of circuits and components, in order to propose possible mitigation actions and to reduce the frequency at which the cooling water should be renewed to keep the resistivity value in the required operative range.

The in-vessel actively cooled components of the SPIDER Beam Source shall be drained and dried in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and to allow the execution of vacuum leak tests of the circuits before re-installation inside the vacuum vessel. These operations are needed after the first phase of experiment exploitation of SPIDER begun in May 2018. Drying system consists of evaporation by mass transport of coolant from dead volumes to the dried nitrogen. The drying system capabilities are set for ranges of gas pressure 2-8 bar(a) and heating temperature (70-110 °C) consistently with design and manufacturing in accordance with the Sound Engineering Practice (low hazard level without CE marking applying the Pressure Equipment Directive). On the other hand, the maximum drying temperature is careful evaluations to avoid risks of damage due to excessive thermal deformations, in particular at joints between dissimilar materials and ceramic breaks. Heating up calculations demonstrate the need to increase the gas inlet pressure up to the maximum allowable value in order to decrease the time required for heating: the estimated time to heat up the Electron Dump decreases from about 10 to 3 minutes by increasing the nitrogen pressure from 2.0 bar(a) to 8.0 bar(a). Drying out calculations show that the evaporation capacity of nitrogen increases with the gas inlet temperature; moreover, higher pressures will reduce the drying out duration from about 11 minutes at 2.0 bar(a) to about 3 minutes at 8.0 bar(a). All the calculated values demonstrate the feasibility of the drying system with parameters to be monitored, in particular the gas humidity at the inlet and at the outlet of the component to be dried. A dedicated procurement was set for the realization of the Drying System as a portable skid.

SPIDER is a 100 kV negative hydrogen/deuterium ion beam source, under operation at Consorzio RFX, which will be exploited for assessment and optimization of the radio frequency source that will be employed in the ITER Neutral Beam Injectors. The in-vessel actively cooled components shall be drained in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and finally to allow the execution of vacuum leak tests of the circuits before re-installation of the Beam Source inside the Vacuum Vessel. Draining of hydraulic circuits is first foreseen by gravity after opening of the end connections of hydraulic circuits and then by blowing-out with inert gas. Injection of pressurized nitrogen is simulated by means of one-dimensional models to perform transient two-phase analyses of the blowing-out process with identification of flow regimes. Moreover, three-dimensional transient two-phase analyses are used to deeply investigate the behaviour of components made of complex geometries. Parametric simulations as function of the inlet pressure are carried out to characterize the blowing-out process in terms of flow rate, evacuation time and draining efficiency. The gas and water flow rates are evaluated recognising Rayleigh-Taylor instabilities which occur when the light nitrogen is pushing the heavy water. The maximum allowable pressure for blowing out, in accordance with the Pressure Equipment Directive (PED), is fixed to 1.1 MPa in order to stay in the Sound Engineering Practice category (low hazard level without CE marking). Among all the applied draining pressures, the range between 0.15-0.4 MPa is considered to perform the blowing out process in order to limit the gas speed and take into account possible pressure fluctuations. The analyses were fundamental to design a blowing-out system capable of satisfying the requirements of the different components belonging to the SPIDER Beam Source.

Background: Different modern radiation therapy treatment solutions for breast cancer (BC) and regional nodal irradiation (RNI) have been proposed. In this study, we evaluate the potential reduction in radiation-induced skin morbidity obtained by intensity modulated proton therapy (IMPT) compared with intensity modulated photon therapy (IMXT) for left-side BC and RNI. Material and Methods: Using CT scans from 10 left-side BC patients, treatment plans were generated using IMXT and IMPT techniques. A dose of 50 Gy (or Gy [RBE] for IMPT) was prescribed to the target volume (involved breast, the internal mammary, supraclavicular, and infraclavicular nodes). Two single filed optimization IMPT (IMPT1 and IMPT2) plans were calculated without and with skin optimization. For each technique, skin dose-metrics were extracted and normal tissue complication probability (NTCP) models from the literature were employed to estimate the risk of radiation-induced skin morbidity. NTCPs for relevant organs-at-risk (OARs) were also considered for reference. The non-parametric Anova (Friedman matched-pairs signed-rank test) was used for comparative analyses. Results: IMPT improved target coverage and dose homogeneity even if the skin was included into optimization strategy (HIIMPT2 = 0.11 vs. HIIMXT = 0.22 and CIIMPT2 = 0.96 vs. CIIMXT = 0.82, p < .05). A significant relative skin risk reduction (RR = NTCPIMPT/NTCPIMXT) was obtained with IMPT2 including the skin in the optimization with a RR reduction ranging from 0.3 to 0.9 depending on the analyzed skin toxicity endpoint/model. Both IMPT plans attained significant OARs dose sparing compared with IMXT. As expected, the heart and lung doses were significantly reduced using IMPT. Accordingly, IMPT always provided lower NTCP values. Conclusions: IMPT guarantees optimal target coverage, OARs sparing, and simultaneously minimizes the risk of skin morbidity. The applied model-based approach supports the potential clinical relevance of IMPT for left-side BC and RNI and might be relevant for the setup of cost-effectiveness evaluation strategies based on NTCP predictions, as well as for establishing patient selection criteria.

Heating neutral beam (HNB) injectors, necessary to achieve burning conditions and to control plasma instabilities in ITER, are characterized by such demanding parameters that a neutral beam test facility (NBTF) dedicated to their development and optimization is being realized in Padua (Italy) with direct contributions from the Italian government (through Consorzio RFX as the host entity) and the ITER international organization (with kind contributions from the ITER domestic agencies of Europe, Japan and India) and technical and scientific support from various European laboratories and universities. The NBTF hosts two experiments: SPIDER, devoted to ion source optimization for the required source performance, and MITICA, the full-size prototype of the ITER HNB, with an ion source identical to SPIDER. This paper gives an overview of the progress towards NBTF realization, with particular emphasis on issues discovered during this phase of activity and on solutions adopted to minimize the impact on the schedule and maintain the goals of the facilities. The realization of MITICA is well advanced; operation is expected to start in 2023 due to the long procurement time of the in-vessel mechanical components. The beam source power supplies, operating at 1 MV, are in an advanced phase of realization; all high-voltage components have been installed and the complex insulation test phase began in 2018. At the same time, construction and installation of SPIDER plant systems was successfully completed with their integration into the facility. The mechanical components of the SPIDER ion source were installed inside the vessel and connected to the plants. Integrated commissioning with the control, protection and safety systems ended positively and the first experimental phase has begun. The first results of the SPIDER experiment, with data from operational diagnostics, and the plans for the 1 MV insulation tests on the MITICA high-voltage components are presented.

Rosette-forming glioneuronal tumors (RGNTs) are rare, grade I, central nervous system (CNS) tumors typically localized to the fourth ventricle. We describe a 9-year-old girl with dizziness and occipital headache. A magnetic resonance imaging (MRI) revealed a large hypodense posterior fossa mass lesion in relation to the vermis, with cystic component. Surgical resection of the tumor was performed. A RGNT diagnosis was made at the histopathological examination. During follow-up, the patient experienced a first relapse, which was again surgically removed. Eight months after, MRI documented a second recurrence at the local level. She was a candidate for the proton beam therapy (PBT) program. Three years after the end of PBT, the patient had no evidence of disease recurrence. This report underlines that, although RGNTs are commonly associated with an indolent course, they may have the potential for aggressive behavior, suggesting the need for treatment in addition to surgery. Controversy exists in the literature regarding effective management of RGNTs. Chemotherapy and radiation are used as adjuvant therapy, but their efficacy management has not been adequately described in the literature. This is the first case report published in which PBT was proposed for adjuvant therapy in place of chemotherapy in RGNT relapse.

In June 2018 the SPIDER device, which is the full-size prototype of the negative ion source and extractor for the ITER Heating Neutral Beam has entered the first operation phase at the Neutral Beam Test Facility (NBTF) in Padova, Italy. This paper describes the present status of the device, the experimental plans and the results obtained during the first experimental campaign of the radio-frequency driven plasma source.

The ITER tokamak requires two injectors of neutral beams resulting from the neutralisation of accelerated negative hydrogen/deuterium ions. To optimise the source operation, a specific test facility ("PRIMA") was established in Padova, comprising the experiment SPIDER (full-size negative ion source with 40A beam, 100keV particle energy). The design of SPIDER accelerator was based on the most advanced numerical codes available for the investigation of the expected beam properties. Several diagnostic systems will characterise source and beam during the experiments. In view of the operation, this paper describes the preparation of the experiments by means of numerical simulations of the accelerator. The simulations provide also estimates of the current and power deposited onto the accelerator grids and will be the basis for further work aimed at computing the expected measurements by the various beam diagnostics.

Purpose The gradient-optimized methods are overcoming the traditional feathering methods to plan field junctions in craniospinal irradiation. In this note, a new gradient-optimized technique, based on the use of a background dose, is described. Methods Treatment planning was performed by RayStation (RaySearch Laboratories, Stockholm, Sweden) on the CT scans of a pediatric patient. Both proton (by pencil beam scanning) and photon (by volumetric modulated arc therapy) treatments were planned with three isocenters. An ‘in silico’ ideal background dose was created first to cover the upper-spinal target and to produce a perfect dose gradient along the upper and lower junction regions. Using it as background, the cranial and the lower-spinal beams were planned by inverse optimization to obtain dose coverage of their relevant targets and of the junction volumes. Finally, the upper-spinal beam was inversely planned after removal of the background dose and with the previously optimized beams switched on. Results In both proton and photon plans, the optimized cranial and the lower-spinal beams produced a perfect linear gradient in the junction regions, complementary to that produced by the optimized upper-spinal beam. The final dose distributions showed a homogeneous coverage of the targets. Discussion Our simple technique allowed to obtain high-quality gradients in the junction region. Such technique universally works for photons as well as protons and could be applicable to the TPSs that allow to manage a background dose.

The realization of the ITER Neutral Beam Test Facility (NBTF) and the start the experimental phase are important tasks of the fusion roadmap, since the target requirements of injecting to the plasma a beam of Deuterium atoms with a power up to 16.5 MW, at 1MeV of energy and with a pulse length up to 3600s have never been reached together before. The ITER NBTF, called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy; it includes two experiments: MITICA, the full-scale prototype of the ITER injector and SPIDER, the full-size negative ion source. The realization promoted by the ITER organization is carried out with the contribution of the European Union, channeled through the Joint Undertaking for ITER (F4E), of the Consorzio RFX which hosts the Test Facility, the Japanese and the Indian ITER Domestic Agencies (JADA and INDA) and several European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFECulham, CEA-Cadarache. The early start of operation of PRIMA experiments is urgent because sufficient experimental time is necessary to face and solve the issues related to the achievement of the desired performance in time for the ITER operation, requiring NBI since the beginning. Substantial progresses have been recently achieved: the buildings construction, begun in October 2012, has been completed by the end of 2015 and the installation of some components has been started since the end of 2014. The SPIDER realization is well advanced: the installation phase is proceeding in good agreement with the general plan; it is expected to be almost completed by the end of 2016. In parallel, the commissioning of the SPIDER power supply (PS) and auxiliary plant systems is being proceeding. Tests at full power and remote control are planned, including also those addressed to reproduce the grid breakdowns and to test the relevant protections. The design of the MITICA injector components was completed in 2015their procurement is being made through a number of tenders, some of them already launched. The HV Power Supply system of the MITICA 1MV accelerator, provided by JADA, was delivered on site in December 2015. The challenging installation of these components, including the step-up transformers and the SF6 gas insulated transmission line, started soon after and will go on throughout 2016. The present phase, with the PRIMA buildings continuously filled with new components, with the installation activities progressing and with also the commissioning and testing phase starting represents a substantial step forward toward the main target. The paper will describe the main challenges the Project Team has dealt during this phase and the important feedback derived for the ITER HNB systems both from the technical and the organizational standpoints.

SPIDER is one of two projects of the ITER Neutral Beam Test Facility under construction in Padova, Italy, at the Consorzio RFX premises. It will have a 100 keV beam source with a full-size prototype of the radiofrequency ion source for the ITER neutral beam injector (NBI) and also, similar to the ITER diagnostic neutral beam, it is designed to operate with a pulse length of up to 3600 s, featuring an ITER-like magnetic filter field configuration (for high extraction of negative ions) and caesium oven (for high production of negative ions) layout as well as a wide set of diagnostics. These features will allow a reproduction of the ion source operation in ITER, which cannot be done in any other existing test facility. SPIDER realization is well advanced and the first operation is expected at the beginning of 2018, with the mission of achieving the ITER heating and diagnostic NBI ion source requirements and of improving its performance in terms of reliability and availability. This paper mainly focuses on the preparation of the first SPIDER operations - integration and testing of SPIDER components, completion and implementation of diagnostics and control and formulation of operation and research plan, based on a staged strategy

The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPIDER and MITICA have been recognized as necessary to make the future operation of the ITER heating neutral beam injectors efficient and reliable, fundamental to the achievement of thermonuclear-relevant plasma parameters in ITER. This paper reports on design and R&D carried out to construct PRIMA, SPIDER and MITICA, and highlights the huge progress made in just a few years, from the signature of the agreement for the NBTF realization in 2011, up to now - when the buildings and relevant infrastructures have been completed, SPIDER is entering the integrated commissioning phase and the procurements of several MITICA components are at a well advanced stage

Neutral beam injection is one of the most important methods of plasma heating in thermonuclear fusion experiments, allowing the attainment of fusion conditions as well as driving the plasma current. Neutral beams are generally produced by electrostatically accelerating ions, which are neutralised before injection into the magnetised plasma. At the particle energy required for the most advanced thermonuclear devices and particularly for ITER, neutralisation of positive ions is very inefficient so that negative ions are used. The present paper is devoted to the description of the phenomena occurring when a high-power multi-ampere negative ion beam travels from the beam source towards the plasma. Simulation of the trajectory of the beam and of its features requires various numerical codes, which must take into account all relevant phenomena. The leitmotiv is represented by the interaction of the beam with the background gas. The main outcome is the partial neutralisation of the beam particles, but ionisation of the background gas also occurs, with several physical and technological consequences. Diagnostic methods capable of investigating the beam properties and of assessing the relevance of the various phenomena will be discussed. Examples will be given regarding the measurements collected in the small flexible NIO1 source and regarding the expected results of the prototype of the neutral beam injectors for ITER. The tight connection between measurements and simulations in view of the operation of the beam is highlighted.

BACKGROUND Stereotactic radiosurgery (SRS) is an important treatment option for intracranial lesions and several photon-SRS techniques have been developed. Proton therapy (PT) has special characteristics that allow normal tissues to be spared better as well as greater homogeneity than with the use of photons, but limited data are available for proton-SRS. Nowadays, PT-SRS is delivered only with passive scattering technique while active pencil beam scanning (PBS) that is considered the most advanced proton technique has not been reported for SRS treatments yet. Here we report early clinical outcomes of PBS PT SRS. MATERIAL AND METHODS Between June 2017 and January 2019, 14 patients (pts) with 20 lesions underwent PBS PT SRS at our institution. Median age was 62 years (range, 28–87). Median Karnofsky performance status was 90 (range, 70–100). Six were male. Tumors included 16 meningiomas (MG) and 4 vestibular schwannomas (VS). Median GTV was 1.05 cc (range, 0.2–2.71). Dose prescription was 12 Gy radiobiologic equivalent (RBE) in one fraction for VS and 15 GyRBE in one fraction for MG. Pts were immobilized using a frameless system: Type-S proton overlay and Type-S proton mask (CIVCO medical solutions, Kalona, IA, USA) together with Moldcare headrest (Q-Fix systems, Avondale, PA, USA). All pts were treated with PBS PT using 2–3 fields with single field optimization technique, and using min-max robust robust optimization (2 mm setup errors, 3.5% range uncertainties), with a Monte Carlo algorithm and 1 mm grid size. Toxicity was assessed using Common Terminology Criteria for Adverse Events version 4.0. RESULTS Median follow-up (FU) was 9 months (range, 3–22). All pts completed the treatment with excellent compliance and no side effects were registered during the procedure. Registered acute side effects include grade 1 (14%) fatigue, grade 2 (7%) headache, and grade 2 (28%) alopecia. There were no grade 3 or higher acute toxicities. Registered late side effects include grade 1 (7%) headache, and grade 1 (14%) alopecia. There were no grade 3 or higher late toxicities. Currently, absolute tumor control is 100% regardless the type of tumor. Despite the short FU radiological reduction was registered in 9 lesions (45%). CONCLUSION PBS PT SRS is a feasible and safe treatment in pts with MG or VS. A high radiological response rate was observed. Longer FU is necessary to assess definitive safety and efficacy.

PRIMA (Padova Research Injector Megavolt Accelerated) is the name of the ITER neutral beam facility currently under construction at the RFX Consortium located in Padua – Italy. PRIMA consists of two injectors which will test at the same time the ion source (SPIDER) and the whole system (MITICA). Both injectors accelerate negative deuterium and hydrogen ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER, with a maximum beam current of 40 A. Accelerated ions are stopped on a CuCrZr alloy calorimeter. Operation in deuterium leads to production of an intense neutron flux through D–D and D–T reactions on the calorimeter panels which is likely to activate materials and components around the injectors, among which the corrosion products formed in the cooling loops; the radioactivity of the activated corrosion products (ACPs) may persist even after injector shutdown, representing a relevant radiation protection issue during repair and inspection activities. In the present paper the occupational radiation exposure (ORE) is evaluated. The total amount of radioactivity produced inside the cooling loops is calculated under different operative conditions and the radiation dose received by workers carrying out maintenance activities on the injector is also assessed for both experiments.

The ITER torus and neutral beam cryopumps are complex vacuum pumps which will be designed to the build-to-print level stage for the call for tender for manufacturing. Although being completely different in size, the pumps share the same concept of cryosorption on activated charcoal. Thus, the design procedure itself can follow the same generic workflow. The requirements on the pumps are summarized and the status of design evolution is described. Both design packages require specific R&D for experimental clarification and design validation. Two examples for this approach are given, namely the characterization of the closing forces of the torus pump inlet valve, and the measurement of hydraulic resistance coefficients of hydroformed components.

This paper presents a proposal of Cooling Plant for two new Neutral Beam experiments called MITICA and SPIDER to be realized in Padova (Italy). A large amount of Power (up to 70 MW) has to be removed from in-vessel components and auxiliary systems belonging to these two experiments. Different experimental scenarios (pulse duration ranging from few seconds up to 3600 s), requirements for operating temperature, coolant quality and voltage holding are taken into account in this conceptual design proposal. To reduce the radiological risks due to possible presence of activated corrosion products (ACP) in some water cooled components suitable design choices have been analysed. This work was carried out by considering carefully a lot of different aspects like operability, standardization of components, maintenance and repair, optimization of the installed power and the overall costs of the plant. Experiment components with similar requirements are grouped in the same primary circuits where fine temperature regulation, water quality monitoring and calorimetric measurements are the main characteristics. Each primary circuit (PC) is connected to secondary circuits which allow thermal dissipation and, in some cases, also component preheating. Secondary circuits are connected to two large basins the water of which is cooled down by active cooling rejection system such as cooling towers and air coolers. In this way the requirement for impulsive heat dissipation is fulfilled by the water basins allowing to install a less powerful active rejection system and so reducing the total costs. A large effort was done to guarantee good plant integration with the Experiment Main Hall (in which MITICA and SPIDER are located) and other technical supplies, buildings and areas. Other special requirements for stand-alone systems like Draining and Drying System, Pressure Test System and Chemical Control System are also part of this work.

BACKGROUND: To report preliminary results of re-irradiation with proton therapy (PT) with or without chemotherapy (CHT) in difficult-to-treat recurrent glioblastoma (rGBM): patients (pts) were selected for PT because of the large tumor size or proximity to dose-limiting organs at risk that previously had received near-maximum dose tolerance during the first radiation course MATERIAL AND METHODS: Between January 2015 and January 2018, 34 pts with rGBM were re-irradiated with PT. All pts had been previously treated with Stupp regimen. Twenty-nine (85%) were re-irradiated at first relapse/progression, 5 at the second/third one. Nine pts (26%) were re-irradiated after partial tumor resection. Median (med) age and KPS at re-irradiation were 56 years and 90%, respectively. Med time between prior radiotherapy and PT was 13 months. Target definition was based on CT, MR, and 18F-DOPA PET imaging. Gross Tumor Volume (GTV) included any area of contrast enhancement after contrast medium administration plus any pathological PET uptake regions. Clinical Target Volume (CTV) was generated by adding to GTV a 3-mm margin. Med CTV volume was 47 cc (range, 13–153 cc). All pts received 36 GyRBE in 18 fractions. PT was delivered with or without chemotherapy as follows: eight (23.5%) pts (Group 1) also received concomitant TMZ (75 mg/m2/die, 7 days/week); 4 (12%) pts (Group 2) also received concomitant (as above) and adjuvant TMZ (150–200 mg/m2/die, 5 days/month); 9 (26.5%) pts (Group 3) received PT only; 13 (38%) pts (Group 4) received PT followed by CHT (different regimens/drugs). All pts were treated with active pencil beam scanning PT. Registered side effects were graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Treatment response was assessed according to Response Assessment in Neuro-Oncology criteria. Survival and progression-free survival after re-irradiation were calculated from initiation of PT until tumor progression or death (by any cause), using the Kaplan Meier method RESULTS: All pts completed the treatment without breaks. There were no grade 3 or higher acute toxicities. One pts developed TMZ-related grade 1 neutropenia. There were no grade 3 or higher late toxicities. During follow-up five pts (15%) developed radionecrosis (diagnosed at imaging) with mild symptoms controlled with steroids. The med progression-free survival (PFS) was 6.3 months, while 6-month PFS rate was 60%. The med PFS was 6.8, 4.3, 5.4, and 5.5 for Group 1-2-3-4, respectively. Med overall survival (OS) after PT was 10.7 months CONCLUSION: PT re-irradiation of difficult-to-treat rGBM showed to be feasible and safe even with concomitant and adjuvant chemotherapy administration. Despite the small number of patients of this series and the retrospective nature of the study PFS and OS rates are promising and deserve further evaluation in a larger pts sample to assess the most effective strategy

BACKGROUND: To report preliminary results of active beam scanning proton therapy (PT) for large skull base benign meningiomas. MATERIAL AND METHODS: Thirty-three patients (pts) with large skull base meningiomas were treated with PT between January 2015 and February 2018. Median age was 53 years (range, 28–82) while KPS ranged between 60 and 100 (median 90); 26 were female (79%), and 7 were male (21%). Twelve pts (36%) had histologically proven World Health Organization (WHO) Grade I tumors. In remaining pts diagnosis was based on the typical imaging appearance of benign meningioma. All patients received PT for residual, progressive or non-operable lesions. Newly diagnosed tumors received total dose of 50 GyRBE (RBE: relative biologic effectiveness) while progressing meningiomas 54 GyRBE. All the treatments were delivered at 2 GyRBE per fraction. Treatment planning was based on morphological magnetic resonance imaging (MRI) with contrast enhancement medium administration. All pts received also 68-Ga-DOTATOC-PET. Any area of contrast enhancement on MRI was used to identify the gross tumor volume. We used the pathological distribution of 68Ga-DOTATOC in brain tissue to identify the so-called Biological Tumor Volume. Gross tumor volume ranged from 21 to 107 cc. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.0. Median follow-up time was 9 months (range, 3–37). RESULTS: All pts completed the treatment without breaks. Acute side effects include grade 1 (21%) and grade 2 (9%) skin erythema, grade 1 (9%) and grade 2 (9%) alopecia, grade 1 (48%) fatigue, grade 1 (6%) and grade 2 (15%) conjunctivitis, grade 1 (15%) pain, grade 1 (15%) blurred vision, grade 1 (15%) headache, and grade 2 (15%) skin hyperpigmentation. One pt experienced grade 3 pain. There were no further grade 3 or higher acute toxicities. Late side effects include grade 1 (9%) and grade 2 (9%) alopecia, grade 1 (21%) fatigue, grade 1 (9%) and grade 2 (6%) headache, grade 1 (6%) dizziness, grade 1 (6%) blurred vision, grade 1 (6%) and grade 2 (6%) pain, grade 1 (6%) dry eye, and grade 1 (15%) skin hyperpigmentation. One pts experienced grade 3 pain. There were no further grade 3 or higher late toxicities. One pts (3%) with cavernous sinus meningioma experienced complete obstruction of intracavernous carotid artery with mild transient symptoms that resolved in few days and brain tissue ischemia detected at MRI (grade 2). Before irradiation this pts already had a meningioma-related near-complete obstruction of the intracavernous carotid artery and received a vascular surgery evaluation. Currently, absolute tumor control is 100%. Moreover, relief of symptoms recorded before irradiation occurred in 24% of pts. CONCLUSION: PT is feasible and safe treatment for pts with large skull base benign meningiomas. Longer follow-up is necessary to assess definitive efficacy.

In the framework of the strategy for the development and the procurement of the NB systems for ITER, it has been decided to build in Padova a test facility, including two experimental devices: a full size plasma source with low voltage extraction and a full size NB injector at full beam power (1 MV). These two different devices will separately address the main scientific and technological issues of the 17 MW NB injector for ITER. In particular the full size plasma source of negative ions will address the ITER performance requirements in terms of current density and uniformity, limitation of the electron/ion ratio and stationary operation at full current with high reliability and constant performances for the whole operating time up to 1 h. The required negative ion current density to be extracted from the plasma source ranges from 290 A/m2 in D2 (D−) and 350 A/m2 in H2 (H−) and these values should be obtained at the lowest admissible neutral pressure in the plasma source volume, nominally at 0.3 Pa. The electron to ion ratio should be limited to less than 1 and the admissible ion inhomogeneity extracted from the grids should be better than 10% on the whole plasma cross-section having a surface exposed to the extraction grid of the order of 1 m2. The main design choices will be presented in the paper as well as an overview of the design of the main components and systems.

The CNR area was built in the 1970s in Padova (Italy): many buildings hosting different Institutes are served by the central heating and cooling system and a common Medium and Low voltage supply. Costs division criteria, mainly based on the number of personnel units and the size of buildings of each Institute, were used in the past; due to current high costs of energy, these criteria have been revised and based on more objective parameters. This paper deals with the methods that have been studied to reduce thermal and cooling energy consumption, based on the operative conditions of buildings and specific characteristics of area HVAC (Heating Ventilation and Air Conditioning) plants. As a result of this optimization, some plant modifications have been evaluated and implemented. The results of new plant configuration and energy consumption are presented and discussed.

The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A beam of negative deuterium ions, to deliver to the plasma a power of about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary to setup a test facility, PRIMA (Padova Research on ITER Megavolt Accelerator), in Italy, including a full-size negative ion source, SPIDER, and a prototype of the whole ITER injector, MITICA, aiming to develop the heating injectors to be installed in ITER. This realization is made with the main contribution of the European Union, through the Joint Undertaking for ITER (F4E), the ITER Organization and Consorzio RFX which hosts the Test Facility. The Japanese and the Indian ITER Domestic Agencies (JADA and INDA) participate in the PRIMA enterprise; European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFE-Culham, CEA-Cadarache and others are also cooperating. Presently, the assembly of SPIDER is on-going and the MITICA design is being completed. The paper gives a general overview of the test facility and of the status of development of the MITICA and SPIDER main components at this important stage of the overall development; then it focuses on the latest and most critical issues, regarding both physics and technology, describing the identified solutions.

Intensity modulated radiation therapy (IMRT) is increasingly employed in glioblastoma (GBM) treatment. The present work aimed to assess which clinical-dosimetric scenario could benefit the most from IMRT application, with respect to three-dimensional conformal radiation therapy (3D-CRT). The number of organs at risk (OARs) overlapping the planning target volume (PTV) was the parameter describing the clinical-dosimetric pattern. Based on the results, a dosimetric decision criterion to select the most appropriate treatment technique is provided. Seventeen previously irradiated patients were retrieved and re-planned with both 3D-CRT and IMRT. The prescribed dose was 60 Gy/30fx. The cases were divided into 4 groups (4 patients in each group). Each group represents the scenario where 0, 1, 2 or 3 OARs overlapped the target volume, respectively. Furthermore, in one case, 4 OARs overlapped the PTV. The techniques were compared also in terms of irradiated healthy brain tissue. The results were evaluated by paired t-test. IMRT always provided better target coverage (V95%) than 3D-CRT, regardless the clinical-dosimetric scenario: difference ranged from 0.82% ( p = 0.4) for scenario 0 to 7.8% ( p = 0.02) for scenario 3, passing through 2.54% ( p = 0.18) and 5.93% ( p = 0.08) for scenario 1 and 2, respectively. IMRT and 3D-CRT achieved comparable results in terms of dose homogeneity and conformity. Concerning the irradiation of serial-kind OARs, both techniques provided nearly identical results. A statistically significant dose reduction to the healthy brain in favor of IMRT was scored. IMRT seems a superior technique compared to 3D-CRT when there are multiple overlaps between OAR and PTV. In this scenario, IMRT allows for a better target coverage while maintaining equivalent OARs sparing and reducing healthy brain irradiation. The results from our patients dataset suggests that the overlap of three OARs can be used as a dosimetric criterion to select which patients should receive IMRT treatment.

Purpose To compare helical tomotherapy (HT) and intensity modulated proton therapy (IMPT) on early stage prostate cancer treatments delivered with simultaneous integrated boost (SIB) in moderate hypofractionation. Material/methods Eight patients treated with HT were replanned with two-field IMPT (2fIMPT) and five-field IMPT (5fIMPT), using a small pencil beam size (3 mm sigma). The prescribed dose was 74.3 Gy in 28 fractions on PTV1 (prostate) and PTV2 (proximal seminal vesicles), 65.5 Gy on PTV3 (distal seminal vesicles) and on the overlap between rectum and PTVs. Results IMPT and HT achieved similar target coverage and dose homogeneity, with 5fIMPT providing the best results. The conformity indexes of IMPT were significantly lower for PTV1+2 and PTV3. Above 65 Gy, HT and IMPT were equivalent in the rectum, while IMPT spared the bladder and the penile bulb from 0 to 70 Gy. From 0 up to 60 Gy, IMPT dosimetric values were (much) lower for all OARs except the femur heads, where HT was better than 2fIMPT in the 25–35 Gy dose range. OARs mean doses were typically reduced by 30–50% by IMPT. NTCPs for the rectum were within 1% between the two techniques, except when the endpoint was stool frequency, where IMPT showed a small (though statistically significant) benefit. Conclusions HT and IMPT produce similar dose distributions in the target volume. The current knowledge on dose–effect relations does not allow to quantify the clinical impact of the large sparing of IMPT at medium-to-low doses.

This paper summarizes the main achievements of the RFX fusion science program in the period between the 2008 and 2010 IAEA Fusion Energy Conferences. RFX-mod is the largest reversed field pinch in the world, equipped with a system of 192 coils for active control of MHD stability. The discovery and understanding of helical states with electron internal transport barriers and core electron temperature >1.5 keV significantly advances the perspectives of the configuration. Optimized experiments with plasma current up to 1.8 MA have been realized, confirming positive scaling. The first evidence of edge transport barriers is presented. Progress has been made also in the control of first-wall properties and of density profiles, with initial first-wall lithization experiments. Micro-turbulence mechanisms such as ion temperature gradient and micro-tearing are discussed in the framework of understanding gradient-driven transport in low magnetic chaos helical regimes. Both tearing mode and resistive wall mode active control have been optimized and experimental data have been used to benchmark numerical codes. The RFX programme also provides important results for the fusion community and in particular for tokamaks and stellarators on feedback control of MHD stability and on three-dimensional physics. On the latter topic, the result of the application of stellarator codes to describe three-dimensional reversed field pinch physics will be presented. © 2011 IAEA, Vienna.

This paper reports the highlights of the RFX-mod fusion science programme since the last 2010 IAEA Fusion Energy Conference. The RFX-mod fusion science programme focused on two main goals: exploring the fusion potential of the reversed field pinch (RFP) magnetic configuration and contributing to the solution of key science and technology problems in the roadmap to ITER. Active control of several plasma parameters has been a key tool in this endeavour. New upgrades on the system for active control of magnetohydrodynamic (MHD) stability are underway and will be presented in this paper. Unique among the existing fusion devices, RFX-mod has been operated both as an RFP and as a tokamak. The latter operation has allowed the exploration of edge safety factor q edge < 2 with active control of MHD stability and studies concerning basic energy and flow transport mechanisms. Strong interaction has continued with the stellarator community in particular on the physics of helical states and on three-dimensional codes. © 2013 IAEA, Vienna.

To reach fusion conditions and control plasma configuration in ITER, a suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33 MW hydrogen/deuterium particles electrostatically accelerated to 1 MeV; efficient gas-cell neutralisation at such beam energy requires negative ions, obtained by caesium-catalysed surface conversion of atoms inside the ion source. As ITER NBI requirements have never been simultaneously attained, a Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Italy), including two experiments. MITICA is the full-scale NBI prototype with 1 MeV particle energy. SPIDER, with 100 keV particle energy, aims at testing and optimising the full-scale ion source: extracted beam uniformity, negative ion current density (for one hour) and beam optics (beam divergence

Purpose:To report preliminary results of re-irradiation with proton therapy (PT) in large-volume recurrent glioblastoma (rGBM).Matherial/Methods:Between January and December 2015 ten patients (pts) with rGBM were re-irradiated with PT. All pts were previously treated with photon radiotherapy (60 Gy) with concomitant and adjuvant TMZ for 1–20 cycles (median, 7). Seven pts were re-irradiated at first relapse/progression. Four patients were re-irradiated after partial tumor resection. Median age and Karnofsky performance status at re-irradiation were 57 years (range, 41–68) and 80%, (range, 70–100), respectively. Median time between prior radiotherapy and PT was 9 months (range, 5–24). Target definition was based on CT, MR, and 18F-DOPA PET imaging. GTV included any area of contrast enhancement after contrast medium administration plus any pathological PET uptake regions. CTV was generated by adding to GTV a 3-mm uniform margin manually corrected in proximity of anatomical barriers. CTV was expanded by 4 mm to create PTV. Median PTV volume was 90 cc (range, 46–231). All pts received 36 GyRBE in 18 fractions. Four pts also received concomitant temozolomide (75 mg/m2/die, 7 days/week). All pts were treated with active beam scanning PT using 2–3 fields with single field optimization technique.Results:All pts completed the treatment without breaks. Registered acute side effects (according to Common Terminology Criteria for Adverse Events version 4.0 - CTCAE) include grade 1–2 skin erythema, alopecia, fatigue, conjunctivitis, concentration impairment, dysphasia, and headache. There were no grade 3 or higher toxicities. One patient developed grade 1 neutropenia. Five pts started PT under steroids (2–7 mg/daily); two of them reduced the dose during PT, while three kept the same steroids dose. None of remaining pts needed steroids therapy. Registered late side effects (according to CTCAE version 4.0) include grade 1–2 alopecia, fatigue, concentration impairment, and dysphasia. During follow-up two pts (20%) developed radionecrosis (diagnosed at imaging) with mild symptoms controlled with steroids. There were no grade 3 or higher toxicities. The median progression-free survival (PFS) was 6.4 months, while the 3-, 6- and 9-month PFS rates were 80%, 67% and 22%, respectively. Median overall survival (OS) after PT was not achieved, while the 6- and 12-month survival after PT rates were 100% and 60%, respectively.Conclusion:PT re-irradiation of large-volume rGBM showed to be feasible and safe even with concomitant chemotherapy administration. Despite the small number of patients and the retrospective nature of the study PFS and OS rates were promising and deserve further evaluation in a larger pts sample.

The negative-ion based neutral beam injector for heating and current drive of the ITER plasma (ITER HNB) is under development, at present focusing on the optimization of the full-scale plasma source in the SPIDER test stand. The production of H− or D− ions in the ion source is based on the low work function surfaces obtained by caesium evaporation. This paper describes the caesium conditioning procedure and the corresponding beam performances during the first operation of SPIDER with caesium. Technical solutions to overcome present limitations of the test stand are described. The influence of source parameters on the caesium effectiveness was investigated in short beam pulse operation; with total radio-frequency (RF) power of 400 kW and filling pressure below 0.4 Pa, and a limited number of extraction apertures, a negative ion current density of about 200 A m−2 was extracted in hydrogen, with beam energy lower than 60 keV. Beam optics and beam uniformity were assessed thanks to the acceleration of isolated ion beamlets. A possible procedure to accelerate a uniform beam was demonstrated at low RF power. The results obtained in this first investigation provided key indications on the operation of one of the largest existing sources of accelerated negative hydrogen-like ions.