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Proton Sound Detectors (ProSDs) sense (at low latency, RMS) after 50 ms acquisition (77.56 Gy total dose deposition).

At the Paul Scherrer Institute (PSI), the superconducting cyclotron “COMET” delivers a 250 MeV proton beam for radiation therapy in pulses of 1ns at the cyclotron-RF frequency of 72.85 MHz. Accurate measurement of the beam position at proton beam currents of 0.1–10 nA in the beam transport line downstream of the degrader is of crucial importance for the treatment safety and quality, beam alignment and feedback systems. This is essential for efficient operation and beam delivery. These measurements are usually performed with intercepting monitors such as ionization chambers (ICs). In this paper, we present a novel non-intercepting position sensitive cavity resonator. The resonant monitor, tuned to the second harmonic of the cyclotron's RF, is based on the detection of the transverse magnetic dipole mode of the EM field generated by the beam. This mode is only excited for off-center beam positions and is measured with the help of four floating cavities within a common grounded cylinder. This paper discusses the BPM fundamental characteristics, design optimization and the underlying parametric investigations involving the contribution of the different modes and crosstalk. We estimate the expected signals from the prototype BPM for position offsets from simulations and compare them with test-bench measurements and beam measurements with the prototype and the improvised BPM design. We conclude by summarizing the achieved position sensitivity, precision, and measurement bandwidth.

Background: in this study, two proton beam delivery designs, i.e. passive scattering proton therapy (PSPT) and pencil beam scanning (PBS), were quantitatively compared in terms of dosimetric indices. The GATE Monte Carlo (MC) particle transport code was used to simulate the proton beam system; and the developed simulation engines were benchmarked with respect to the experimental measurements. Method: a water phantom was used to simulate system energy parameters using a set of depth-dose data in the energy range of 120–235 MeV. To compare the performance of PSPT against PBS, multiple dosimetric parameters including Bragg peak width (BP W50), peak position, range, peak-to-entrance dose ratio, penumbra(90-10)%, penumbra(80-20)%, M 95% and dose volume histogram have been analyzed under the same conditions. Furthermore, the clinical test cases introduced by AAPM TG-119 were simulated in both beam delivery modes to compare the relevant clinical values obtained from Dose Volume Histogram (DVH) analysis. Results: the parametric comparison in the water phantom between the two techniques revealed that the value of peak-to-entrance dose ratio in PSPT is considerably higher than that from PBS by a factor of 8%. In addition, the BP_W50, penumbra(90-10)%, penumbra(80-20)%, and M 95% in PSPT was increased by a factor of 7, 51, 37, and 2.7%, respectively compared to the corresponding value obtained from PBS model. TG-119 phantom simulations showed that the difference of PTV mean dose between PBS and PSPT techniques are up to 1.8% while the difference of max dose to organ at risks (OARs) exceeds 50%. Conclusion: the results of this simulation show that although the passive scattering design method has a slightly higher ability to adjust the dose in target volume, but the active scanning proton therapy systems was superior in dose painting, and lower out-of-field dose compared to passive scattering design.

A method for monitoring the misalignment of the magnetic axis in solenoids is proposed. This method requires only a few measurements of the magnetic field at fixed positions inside the magnet aperture, and thus overcomes the main drawback of sturdy moving mechanics of other Hall sensor-based methods. Conversely to state-of-the-art axis determination, the proposed method can be applied also during magnet operations, when the axis region and almost the whole remaining magnet aperture are not accessible. Moreover, only a few measurements of the magnetic field at fixed positions inside the magnet aperture are required: thus a slow process such as the mapping of the whole aperture of a magnet by means of moving stages is not necessary. The mathematical formulation of the method is explained, and a case study on a model of a multi–layer solenoid is presented. For this case study, the uncertainty is assessed and the optimal placement of the Hall transducers is derived.

Silicon Carbide (SiC) has been recently proposed and patented as a material for the realization of radiation dosimetry detectors. SiC properties, including its high sensitivity, radiation damage resistance and its extremely small sensitivity region, make it an amazing device susceptible to radiation dosimetric applications of direct ionizing radiations. In this work, a dosimetric characterization of a 10 μm thick SiC detector, irradiated with 62 MeV monochromatic and clinical SOBP proton beams, is reported. Short term reproducibility and linearity with the absorbed dose demonstrate that SiC can be profitably used as radiation dosimetry in proton therapy applications.

The present work investigates methods for dose and dose rate measurements in proton beams using the luminescence of beryllium oxide (BeO). Experiments are carried out to determine the response of the optically stimulated luminescence (OSL) of BeO aswell as the radioluminescence (RL) of BeO within the depth dose profile of a 190 MeV scattered proton beam. The acquired data is compared to an ionization chamber reference and a Monte Carlo simulation. Both dose readings from the RL and OSL measurements show accurate values in the entrance path with an increasing underestimation in the high LET region of the Bragg peak. The amount of this quenching is different for RL and OSL so that the ratio of RL to OSL dose measurements opens venues to correct the measurements to the accurate dose.

To fully exploit the physics potentials of particle therapy in delivering dose with high accuracy and selectivity, charged particle therapy needs further improvement. To this scope, a multidisciplinary project (MoVeIT) of the Italian National Institute for Nuclear Physics (INFN) aims at translating research in charged particle therapy into clinical outcome. New models in the treatment planning system are being developed and validated, using dedicated devices for beam characterization and monitoring in radiobiological and clinical irradiations. Innovative silicon detectors with internal gain layer (LGAD) represent a promising option, overcoming the limits of currently used ionization chambers. Two devices are being developed: one to directly count individual protons at high rates, exploiting the large signal-to-noise ratio and fast collection time in small thicknesses (1 ns in 50 μm) of LGADs, the second to measure the beam energy with time-of-flight techniques, using LGADs optimized for excellent time resolutions (Ultra Fast Silicon Detectors, UFSDs). The preliminary results of first beam tests with therapeutic beam will be presented and discussed.

Proton Computed Tomography (pCT) is a medical imaging method with a potential for increasing accuracy of treatment planning and patient positioning in hadron therapy. A pCT system based on a Silicon microstrip tracker and a YAG:Ce crystal calorimeter has been developed within the INFN Prima-RDH collaboration. The prototype has been tested with a 175 MeV proton beam at The Svedberg Laboratory (Uppsala, Sweden) with the aim to reconstruct and characterize a tomographic image. Algebraic iterative reconstruction methods (ART), together with the most likely path formalism, have been used to obtain tomographies of an inhomogeneous phantom to eventually extract density and spatial resolutions. These results will be presented and discussed together with an estimation of the average dose delivered to the phantom and the dependence of the image quality on the dose. Due to the heavy computation load required by the algebraic algorithms the reconstruction programs have been implemented to fully exploit the high calculation parallelism of Graphics Processing Units. An extended field of view pCT system is in an advanced construction stage. This apparatus will be able to reconstruct objects of the size of a human head making possible to characterize this pCT approach in a pre-clinical environment.

Proton and carbon ion therapy is an emerging technique used for the treatment of solid cancers. The monitoring of the dose delivered during such treatments is still a matter of research. A possible technique exploits the information provided by single photon emission from nuclear decays induced by the irradiation. This paper reports the measurements of the spectrum and rate of such photons produced from the interaction of a 80 MeV=u fully stripped carbon ion beam at the Laboratori Nazionali del Sud of INFN, Catania, with a Poly-methyl methacrylate target. The differential production rate for photons with energy E > 2 MeV and emitted at 90 o is found to be dNg=(dNCdW) = (2:92 0:19) 10 2 sr 1 .

20 páginas, 9 figuras, 2 tablas.-- Trabajo presentado al International Symposium on Electron Beam Ion Sources and Traps (EBIST2010), celebrado en Estocolmo (Suecia/ Abril 2010).-- This work is part of a collaboration with the CLIC group, which is working at CERN on high-gradient electron-positron colliders.-- El PDF es la versión pre-print.-- et al., Charged particle therapy, or so-called hadrontherapy, is developing very rapidly. There is large pressure on the scientific community to deliver dedicated accelerators, providing the best possible treatment modalities at the lowest cost. In this context, the Italian research Foundation TERA is developing fast-cycling accelerators, dubbed `cyclinacs'. These are a combination of a cyclotron (accelerating ions to a fixed initial energy) followed by a high gradient linac boosting the ions energy up to the maximum needed for medical therapy. The linac is powered by many independently controlled klystrons to vary the beam energy from one pulse to the next. This accelerator is best suited to treat moving organs with a 4D multipainting spot scanning technique. A dual proton/carbon ion cyclinac is here presented. It consists of an Electron Beam Ion Source, a superconducting isochronous cyclotron and a high-gradient linac. All these machines are pulsed at high repetition rate (100–400 Hz). The source should deliver both C6+ and H2+ ions in short pulses (1.5 μs flat-top) and with sufficient intensity (at least 108 fully stripped carbon ions per pulse at 300 Hz). The cyclotron accelerates the ions to 120 MeV/u. It features a compact design (with superconducting coils) and a low power consumption. The linac has a novel C-band high-gradient structure and accelerates the ions to variable energies up to 400 MeV/u. High RF frequencies lead to power consumptions which are much lower than the ones of synchrotrons for the same ion extraction energy. This work is part of a collaboration with the CLIC group, which is working at CERN on high-gradient electron-positron colliders., The authors warmly thank A.D.A.M. S.A. and the Vodafone Foundation for their generous financial support of TERA research activities.

The development of Radiation Imaging Detectors dedicated to specific front edge use is a rapidly expanding galaxy taking force from a healthy mixture of growing ambitions within basic science targets and applicative use in many contiguous fields. The growth of the high technology imaging tools market is a relevant motivating element. On the scene of this conference a flow of very accurate and informative presentations has allowed to gather a vivid image on the almost frantic target oriented work, the results shown have often surpassed the most visionary expectations.

Particle Therapy (PT) is an emerging technique, which makes use of charged particles to efficiently cure different kinds of solid tumors. The high precision in the hadrons dose deposition requires an accurate monitoring to prevent the risk of under-dosage of the cancer region or of over-dosage of healthy tissues. Monitoring techniques are currently being developed and are based on the detection of particles produced by the beam interaction into the target, in particular: charged particles, result of target and/or projectile fragmentation, prompt photons coming from nucleus de-excitation and back-to-back ??s, produced in the positron annihilation from ??+ emitters created in the beam interaction with the target. It has been showed that the hadron beam dose release peak can be spatially correlated with the emission pattern of these secondary particles. Here we report about secondary particles production (charged fragments and prompt ??s) performed at different beam and energies that have a particular relevance for PT applications: 12C beam of 80 MeV/u at LNS, 12C beam 220 MeV/u at GSI, and 12C, 4He, 16O beams with energy in the 50?300 MeV/u range at HIT. Finally, a project for a multimodal dose-monitor device exploiting the prompt photons and charged particles emission will be presented.