Partial breast irradiation for the treatment of early-stage breast cancer patients can be performed by means of Intra Operative electron Radiation Therapy (IOeRT). One of the main limitations of this ...technique is the absence of a treatment planning system (TPS) that could greatly help in ensuring a proper coverage of the target volume during irradiation. An IOeRT TPS has been developed using a fast Monte Carlo (MC) and an ultrasound imaging system to provide the best irradiation strategy (electron beam energy, applicator position and bevel angle) and to facilitate the optimisation of dose prescription and delivery to the target volume while maximising the organs at risk sparing. The study has been performed in silico, exploiting MC simulations of a breast cancer treatment. Ultrasound-based input has been used to compute the absorbed dose maps in different irradiation strategies and a quantitative comparison between the different options was carried out using Dose Volume Histograms.
The system was capable of exploring different beam energies and applicator positions in few minutes, identifying the best strategy with an overall computation time that was found to be completely compatible with clinical implementation. The systematic uncertainty related to tissue deformation during treatment delivery with respect to imaging acquisition was taken into account.
The potential and feasibility of a GPU based full MC TPS implementation of IOeRT breast cancer treatments has been demonstrated in-silico. This long awaited tool will greatly improve the treatment safety and efficacy, overcoming the limits identified within the clinical trials carried out so far.
•A fast GPU based MC has been developed for IOeRT breast treatment planning.•The input is an ultrasound image with defined PTV and OARs.•Different applicator positions, dimensions and angles and beam energies are tested.•Plan is optimised using absorbed dose maps and related DVHs.•Results in the context of conventional and FLASH irradiations are discussed.
In this work we present two innovative architectures of resistive MPGDs based on the WELL-amplification concept:
– the micro-Resistive WELL (μ-RWELL) is a compact spark-protected single ...amplification-stage Micro-Pattern Gas Detector (MPGD). The amplification stage, realized with a structure very similar to a GEM foil (called WELL), is embedded through a resistive layer in the readout board. A cathode electrode, defining the gas conversion/drift gap, completes the detector mechanics. The new architecture, showing an excellent space resolution, ~50μm, is a very compact device, robust against discharges and exhibiting a large gain (>104), simple to construct and easy for engineering and then suitable for large area tracking devices as well as digital calorimeters.
– the Fast Timing Micro-pattern (FTM): a new device with an architecture based on a stack of several coupled full-resistive layers where drift and multiplication stages (WELL type) alternate in the structure. The signals from each multiplication stage can be read out from any external readout boards through the capacitive couplings, providing a signal with a gain of 104–105. The main advantage of this new device is the improvement of the timing provided by the competition of the ionization processes in the different drift regions, which can be exploited for fast timing at the high luminosity accelerators (e.g. HL-LHC upgrade) as well as for applications like medical imaging.
Josephson junctions, in appropriate configurations, can be excellent candidates for detection of single photons in the microwave frequency band. Such possibility has been recently addressed in the ...framework of galactic axion detection. Here are reported recent developments in the modelling and simulation of dynamic behaviour of a Josephson junction single microwave photon detector. For a Josephson junction to be enough sensitive, small critical currents and operating temperatures of the order of ten of mK are necessary. Thermal and quantum tunnelling out of the zero-voltage state can also mask the detection process. Axion detection would require dark count rates in the order of 0.001 Hz. It is, therefore, is of paramount importance to identify proper device fabrication parameters and junction operation point.
On the space resolution of the μ-RWELL Bencivenni, G.; Capoccia, C.; Cibinetto, G. ...
Journal of instrumentation,
08/2021, Volume:
16, Issue:
8
Journal Article
The aim of this study was to investigate the dosimetric characteristics of the electron beams generated by the light intraoperative accelerator, Liac® (SORDINA, Italy), using Monte Carlo (MC) ...calculations. Moreover we investigated the possibility of characterizing the Liac® dosimetry with a minimal set of dosimetric data. In fact accelerator commissioning requires measurements of both percentage depth doses (PDDs) and off-axis profiles for all the possible combinations of energy, applicator diameter and bevelled angle. The Liac® geometry and water phantom were simulated in a typical measurement setup, using the MC code EGSnrc/BEAMnrc. A simulated annealing optimization algorithm was used in order to find the optimal non-monoenergetic spectrum of the initial electron beam that minimizes the differences between calculated and measured PDDs. We have concluded that, for each investigated nominal energy beam, only the PDDs of applicators with diameters of 30, 70 and 100 mm and the PDD without an applicator were needed to find the optimal spectra. Finally, the output factors of the entire set of applicator diameters/bevelled angles were calculated. The differences between calculated and experimental output factors were better than 2%, with the exception of the smallest applicator which gave differences between 3% and 4% for all energies. The code turned out to be useful for checking the experimental data from various Liac® beams and will be the basis for developing a tool based on MC simulation to support the medical physicist in the commissioning phase.
The FLASH effect is a radiobiological phenomenon that has garnered considerable interest in the clinical field. Pre-clinical experimental studies have highlighted its potential to reduce side effects ...on healthy tissues while maintaining isoeffectiveness on tumor tissues, thus widening the therapeutic window and enhancing the effectiveness of radiotherapy. The FLASH effect is achieved through the administration of the complete therapeutic radiation dose within a brief time frame, shorter than 200 milliseconds, and, therefore, utilizing remarkably high average dose rates above at least 40 Gy/s. Despite its potential in radiotherapy, the radiobiological mechanisms governing this effect and its quantitative relationship with temporal parameters of the radiation beam, such as dose-rate, dose-per-pulse, and average dose-rate within the pulse, remain inadequately elucidated. A more profound comprehension of these underlying mechanisms is imperative to optimize the clinical application and translation of the FLASH effect into routine practice. Due to the aforementioned factors, the undertaking of quantitative radiobiological investigations becomes imperative, necessitating the utilization of sophisticated and adaptable apparatus capable of generating radiation beams with exceedingly high dose-rates and dose-per-pulse characteristics. This study presents a comprehensive account of the design and operational capabilities of a Linear Accelerator (LINAC) explicitly tailored for FLASH radiotherapy research purposes. Termed the “ElectronFlash” (EF) LINAC, this specialized system employs a low-energy configuration (7 and 9 MeV) and incorporates a triode gun. The EF LINAC is currently operational at the Centro Pisano FLASH Radiotherapy (CPFR) facility located in Pisa, Italy. Lastly, this study presents specific instances exemplifying the LINAC’s adaptability, enabling the execution of hitherto unprecedented experiments. By enabling independent variations of the temporal parameters of the radiation beam implicated in the FLASH effect, these experiments facilitate the acquisition of quantitative data concerning the effect’s dependence on these specific parameters. This novel approach hopefully contributes to a more comprehensive understanding of the FLASH effect, shedding light on its intricate radiobiological behavior and offering valuable insights for optimizing its clinical implementation.
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