1,721,042 research outputs found
Magnetic quadrupole simulations for focusing the electron beams emitted by a plasma focus device
No full textA Plasma Focus (PF) device allows for production of electron beams that, through a suitable target interaction, can be converted in X-ray pulses that have been considered for radiobiology or medical applications such as imaging or radiotherapy, in dependence from the working parameters and setup. The Plasma Focus Device for Medical Applications #3 (PFMA-3), hosted at the Montecuccolino Laboratory of the University of Bologna, has been designed for these purposes. In the device, electron pulses are generated during the pinch phase in the order of 1.0 E+15 particles in few tens of ns. One of the main advantages in dealing with the beams emitted by a PF is their self-collimated behavior at the emission time. Unfortunately, during the traveling distance from pinch to target, that collimation can be partially lost due to the repulsive interactions. One solution is to implement a magnetic device based on a quadrupoles triplet able to confine the beam in spots with a few mm diameter. This kind of focusing allows for using the PF as a source for generating extremely short X-ray pulses that could be more easily further managed for specific applications. A computational model of the PFMA-3 has been set using COMSOL© Multiphysics and the Monte Carlo MCNP6 code. The electron spectra used as source for simulations were acquired experimentally using a magnetic spectrometer, while the beam shape entering the magnetic system to be designed has been detected using Gafchromic© HDV2 film dosimeters and used as a benchmark for the numerical models. The magnetic field generated by the quadrupoles has been carefully designed through a parametric study with COMSOL© Multiphysics and the focusing effectiveness verified. The designed geometry has been then modeled in MCNP6 to perform coupled electron-photon transport simulations for estimating electron fluxes, spectra and X-ray doses as modified by the quadrupoles triplet application
Adjoint calculations for multiple scattering of Compton and Rayleigh effects
No full textAs is well known, the experimental determination of the Compton profile requires a particular geometry with a scattering angle close to π. That situation involves a narrow multiple-scattering spectrum that overlaps the Compton peak, making it difficult to analyze the different contributions to the profile. We show how the solution of the adjoint problem can help in devising more useful experimental configurations, giving, through its classical "importance" meaning, a formally clear picture of the whole problem. © 1992
Electron Beams and X-Ray Beams for Interstitial and Intra-Operatory Radiation Therapy.
No full textThe present invention refers to an apparatus for the production of electron beams and X-ray beams for interstitial and intra-operatory radiation therapy, more commonly named IORT (Intra Operative Radio Therapy). More specifically, the invention refers to an apparatus IORT using a Plasma Focus type of machine, coupled to an electron guide which convoys the beam directly to the tissue to be treated with a low-energy, extremely high dose rate of electron or photonic X-ray irradiation
Apparecchiatura per la produzione endogena di radioisotopi, particolarmente per diagnostica tomografica ad emissione di positroni.
No full textApparecchiatura per la produzione di radioisotopi a vita breve tramite tecnologie Plasma Focus. I radioisotopi interessati sono il F-18, O-15, N-13 e F-1
Digital twins in dosimetry and radiotherapy, a survey and some applications
No full textDigital Twins (DTs) are emerging as a powerful tool in several applications, including Dosimetry and Radiotherapy (RT). Indeed, DTs have increased their effectiveness, up to the point that can be considered as virtual replicas of physical objects, processes, or systems. Through predictive modeling, DTs can determine optimal doses in radiation therapy, assist in defining personalized treatment schedules for individual patients, and monitor treatment responses. Moreover, DTs play a pivotal role in designing radioisotope production processes in the field of nuclear medicine. This can help to ensure the most effective treatment possible while minimizing the risk of side effects. As a frontier case example, DTs can be employed in the analysis of a possible new source for flash radiotherapy worth with respect to their effectiveness parameters like Radio-Biological Effectiveness (RBE) or cell Surviving Fraction (SF). Flash techniques involve the delivery of a high dose of radiation in a short time, reducing damage to surrounding healthy tissue while possibly increasing damage to malignant cells. DTs could be used to simulate and collect data about particle interactions with the treated tissues, optimizing the treatment and leading to improved outcomes. The most powerful tools that can be applied in DTs development are the Monte Carlo (MC) codes, particularly those with the highest capability of a detailed material/geometry description through an automatized spatial discretization approach like the one based on Unstructured Mesh (UM), allowing a common mathematical domain for both particle/radiation transport and thermal, fluid-dynamics and mechanical simulations. What comes out from various kind of applications is a common ground in terms of data management, phase space identification, simulation tools, that can be easily recognized even if spanning from cell response to technological devices, making realistic the perspective of the setup of general optimization procedures
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