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Pedro-Borja Aguilar-Redondo

Bio: Pedro-Borja Aguilar-Redondo is an academic researcher from University of Navarra. The author has contributed to research in topics: CPU time & Multileaf collimator. The author has an hindex of 1, co-authored 3 publications receiving 1 citations.

Papers
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Journal ArticleDOI
TL;DR: A set of optimized Geant4 physics options of general use for radiotherapy simulation are proposed and the CPU time is optimized using several of the optimization techniques that GAMOS offers.
Abstract: We have studied each of the physics options that Geant4 offers to simulate an X-ray radiotherapy treatment with the aim of obtaining those that provide the best possible match to the experimental data of dose profiles and at the same time reduce the CPU time. The procedure has been repeated for two linac setups: an ELEKTA Versa HD with an Agility Multileaf Collimator using two nominal energies, 6 MV and 10 MV, both without flattening filter. After combining the results with those of a previous similar study of a 6 MV VARIAN Clinac 2100 C/D linac with flattening filter, we can propose a set of optimized Geant4 physics options of general use for radiotherapy simulation. Together with this, we have optimized the CPU time using several of the optimization techniques that GAMOS offers, reaching a reduction of several hundred times for each setup.

7 citations

Journal ArticleDOI
TL;DR: A new procedure for the comparison of two dose matrices by means of a statistical test based on the square difference between the experimental and expected gamma matrix results, which gives the same statistical significance as 90% of gamma-pass rate.
Abstract: In this study, we present a new procedure for the comparison of two dose matrices by means of a statistical test. A statistical distance is proposed to decide whether the difference between the two matrices is statistically significant. This statistical test is based on the square difference between the experimental and expected gamma matrix results. The expected gamma matrix is calculated by simulating the measurement process. For comparison purposes, the significance level of the test was chosen to give the same statistical significance as 90% of gamma-pass rate. The performance of the statistical distance is checked against 53 VMAT. The power of the presented test was compared using simulations with the 90% gamma-pass rate criteria for two cases in which intentional errors are introduced. In both cases, the test is uniformly more powerful. According to the test, two of the measured plans have a significant difference with calculated matrices, although the gamma pass rate measured was always greater than 90%.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: Among the available methods for the comparison of two dose distributions, the γ-analysis (gamma analysis) has been widely adopted as the gold standard in verification procedures and the development of a better metric taking into account both statistical and in clinical parameters is required.

12 citations

Book ChapterDOI
28 Jan 2022
TL;DR: In this paper , the authors present some applications for radiotherapy procedures with use, specifically, megavoltage x-rays and electrons beams, in scenarios with homogeneous and anatomical phantoms for determining dose, dose distribution, as well dosimetric parameters through the PENELOPE and TOPAS code.
Abstract: Monte Carlo simulations have been applied to determine and study different parameters that are challenged in experimental measurements, due to its capability in simulating the radiation transport with a probability distribution to interact with electrosferic electrons and some cases with the nucleus from an arbitrary material, which such particle track or history can carry out physical quantities providing data from a studied or investigating quantities. For this reason, simulation codes, based on Monte Carlo, have been proposed. The codes currently available are MNCP, EGSnrc, Geant, FLUKA, PENELOPE, as well as GAMOS and TOPAS. These simulation codes have become a tool for dose and dose distributions, essentially, but also for other applications such as design clinical, tool for commissioning of an accelerator linear, shielding, radiation protection, some radiobiologic aspect, treatment planning systems, prediction of data from results of simulation scenarios. In this chapter will be present some applications for radiotherapy procedures with use, specifically, megavoltage x-rays and electrons beams, in scenarios with homogeneous and anatomical phantoms for determining dose, dose distribution, as well dosimetric parameters through the PENELOPE and TOPAS code.

1 citations

Journal ArticleDOI
TL;DR: SPHINX in conjunction with next-generation linear accelerators has the potential to achieve substantially higher dose rates than conventional MLC based delivery, with delivery of an intensity modulated 100×100 mm2 field achievable in 0.9 to 10.6 s depending on the beamlet widths used.
Abstract: PURPOSE In radiation therapy, X-ray dose must be precisely sculpted to the tumor, whilst simultaneously avoiding surrounding organs at risk. This requires modulation of X-ray intensity in space and/or time. Typically, this is achieved using a Multi Leaf Collimator (MLC) - a complex mechatronic device comprising over one hundred individually powered tungsten 'leaves' that move in or out of the radiation field as required. Here, an all-electronic X-ray collimation concept with no moving parts is presented, termed "SPHINX": Scanning Pencil-beam High-speed Intensity-modulated X-ray source. SPHINX utilizes a spatially distributed bremsstrahlung target and collimator array in conjunction with magnetic scanning of a high energy electron beam to generate a plurality of small X-ray "beamlets". METHODS A simulation framework was developed in Topas Monte Carlo incorporating a phase space electron source, transport through user defined magnetic fields, bremsstrahlung X-ray production, transport through a SPHINX collimator, and dose in water. This framework was completely parametric, meaning a simulation could be built and run for any supplied geometric parameters. This functionality was coupled with Bayesian optimization to find the best parameter set based on an objective function which included terms to maximize dose rate for a user defined beamlet width while constraining inter-channel cross talk and electron contamination. Designs for beamlet widths of 5, 7, and 10 mm2 were generated. Each optimization was run for 300 iterations and took approximately 40 hours on a 24 core computer. For the optimized seven-mm model, a simulation of all beamlets in water was carried out including a linear scanning magnet calibration simulation. Finally, a back-of-envelope dose rate formalism was developed and used to estimate dose rate under various conditions. RESULTS The optimized five-mm, seven-mm, and ten-mm models had beamlet widths of 5.1 mm, 7.2 mm, and 10.1 mm2 and dose rates of 3574 Gy/C, 6351 Gy/C and 10015 Gy/C respectively. The reduction in dose rate for smaller beamlet widths is a result of both increased collimation and source occlusion. For the simulation of all beamlets in water, the scanning magnet calibration reduced the offset between the collimator channels and beam centroids from 2.9+-1.9 mm to 0.01 +- 0.03mm. A slight reduction in dose rate of approximately 2% per degree of scanning angle was observed. Based on a back-of-envelope dose rate formalism, SPHINX in conjunction with next-generation linear accelerators has the potential to achieve substantially higher dose rates than conventional MLC based delivery, with delivery of an intensity modulated 100×100 mm2 field achievable in 0.9 to 10.6 s depending on the beamlet widths used. CONCLUSIONS Bayesian optimization was coupled with Monte Carlo modelling to generate SPHINX geometries for various beamlet widths. A complete Monte Carlo simulation for one of these designs was developed, including electron beam transport of all beamlets through scanning magnets, X-ray production and collimation, and dose in water. These results demonstrate that SPHINX is a promising candidate for sculpting radiation dose with no moving parts, and has the potential to vastly improve both the speed and robustness of radiotherapy delivery. This article is protected by copyright. All rights reserved.

1 citations