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106 results on '"Irazola, L."'

13. External photon radiation treatment for prostate cancer: Uncomplicated and cancer-free control probability assessment of 36 plans

Author

Pontificia Universidad Católica de Chile, Banco Santander, Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Comisión Nacional de Investigación Científica y Tecnológica (Chile), Sánchez-Nieto, B., Romero-Expósito, M., Terrón, José Antonio, Irazola, L., García-Hernández, M. T., Mateos, Juan C., Roselló, J., Planes, D., Paiusco, M., Sánchez-Doblado, F., Pontificia Universidad Católica de Chile, Banco Santander, Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Comisión Nacional de Investigación Científica y Tecnológica (Chile), Sánchez-Nieto, B., Romero-Expósito, M., Terrón, José Antonio, Irazola, L., García-Hernández, M. T., Mateos, Juan C., Roselló, J., Planes, D., Paiusco, M., and Sánchez-Doblado, F.

Abstract

[Purpose] To perform a systematic and thorough assessment, using the Uncomplicated and Cancer-Free Control Probability (UCFCP) function, of a broad range of photon prostate cancer RT treatments, on the same scenario (a unique pelvic CT set). UCFCP considers, together with the probabilities of local tumour control (TCP) and deterministic (late) sequelae (NTCP), the second primary cancer risk (SPCR) due to photon and neutron peripheral doses., [Methods and materials] Thirty-six radiotherapy plans were produced for the same CT. 6, 10, 15 and 18 MV 3DCRT, IMRT and VMAT (77.4 Gy in 43 fractions) and 6 and 10 MV SBRT (36.25 Gy in 5 fractions with flattened and FFF beams) for Elekta, Siemens and Varian Linacs plans were included. DVH and peripheral organ dosimetry were used to compute TCP, NTCP, and SPCR (the competition and LNT models) for further plan ranking., [Results] Biological models (and parameters) used predicted an outcome which is in agreement with epidemiological findings. SBRT plans showed the lowest SPCR and a below average NTCPrectal. High energy plans did not rank worse than the low energy ones. Intensity modulated plans were ranked above the 3D conformal techniques., [Conclusions] According to UCFCP, the best plans were the10 MV SBRTs. SPCR rates were low and did not show a substantial impact on plan ranking. High energy intensity-modulated plans did not increase in excess the average of SPCR. Even more, they ranked among the best, provided that MU were efficiently managed.

Published
2019

14. 10-MV SBRT FFF irradiation technique is associated to the lowest peripheral dose: the outcome of 142 treatment plans for the 10 most common tumour locations

Author

Irazola, L., Sánchez-Nieto, B., García-Hernández, M. T., Terrón, José Antonio, Roselló, J., Ortiz-Seidel, M., Béjar, M. J., Linares, R., Velázquez, S., Sánchez-Doblado, F., Irazola, L., Sánchez-Nieto, B., García-Hernández, M. T., Terrón, José Antonio, Roselló, J., Ortiz-Seidel, M., Béjar, M. J., Linares, R., Velázquez, S., and Sánchez-Doblado, F.

Abstract

There is a growing interest in the combined use of Stereotactic Body Radiation Therapy (SBRT) with Flattening Filter Free (FFF) due to the high local control rates and reduced treatment times, compared to conventionally fractionated treatments. It has been suggested that they may also provide a better radiation protection to radiotherapy patients as a consequence of the expected decrease in peripheral doses. This work aims to determine this reduction in unattended out-of-field regions, where no CT information is available but an important percentage of second primary cancers occur. For that purpose, ten different cases suitable for SBRT were chosen. Thus, 142 different treatment plans including SBRT, as well as 3D‐CRT, IMRT and VMAT (with standard fractionation) in low and high energies for Varian (FF and FFF), Siemens and Elekta machines were created. Then, photon and neutron peripheral dose in 14 organs were assessed and compared using two analytical models. For the prostate case, uncomplicated and cancer free control probability estimation was also carried out. As a general behavior, SBRT plans led to the lowest peripheral doses followed by 3D-CRT, VMAT and IMRT, in this order. Unflattened beams proved to be the most effective in reducing peripheral doses, especially for 10 MV. The obtained results suggest that FFF beams for SBRT with 10 MV represent the best compromise between dose delivery efficiency and peripheral dose reduction.

Published
2019

23. Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes

Author

Junta de Andalucía, Ministerio de Economía y Competitividad (España), Consejo de Seguridad Nuclear (España), Campus de Excelencia Internacional BioTic (España), Irazola, L., Praena, Javier, Fernández-Martínez, Begoña, Macías-Montero, M., Arias de Saavedra, Fernando, Porras, Ignacio, Junta de Andalucía, Ministerio de Economía y Competitividad (España), Consejo de Seguridad Nuclear (España), Campus de Excelencia Internacional BioTic (España), Irazola, L., Praena, Javier, Fernández-Martínez, Begoña, Macías-Montero, M., Arias de Saavedra, Fernando, and Porras, Ignacio

Abstract

Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days.

Published
2016

45. Peripheral dose assessment after IMRT and VMAT vs CFRT

Author

Sánchez-Nieto, B., primary, El-far, R., additional, Expósito, M.R., additional, Lagares, J.I., additional, Mateo, J.C., additional, Terrón, J.A., additional, Zeladas, G., additional, Irazola, L., additional, and Doblado, F. Sánchez, additional

Published
2014
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47. Developing and implementing a mentoring and enabling programme within EFOMP.

Author

Lopez Medina A, Polycarpou I, Tzoumi N, Irazola L, and Koutsouveli E

Subjects
Europe, Program Development, Humans, Mentors, Societies, Scientific, Mentoring
Abstract

To ensure the continued advancement of the medical physics profession, the European Federation of Organisations for Medical Physics (EFOMP) has designed a mentorship programme. This programme aims to support Early Career Medical Physicists by providing them with the guidance needed for both professional and personal development to meet the continually evolving demands of the medical physics field within their working environments. The EFOMP mentorship programme is an important step forward in supporting the next generation of medical physicists. This article provides an overview of the history, framework, goals, and implementation strategy of this programme. The programme will have two main orientations: mentoring, which will help mentees to improve their scientific, professional and soft skills, and enabling, which aims to prepare a sufficient number of early career professionals to get involved within EFOMP's activities, join the EFOMP structures and represent the European Medical Physics community to National and International Organisations. Each year a survey from mentors and mentees will be conducted and analysed by the European and International Matters Committee and the Early Career Special Interest Group to identify areas for improvement and to evaluate the degree of satisfaction and achievements of the participants. By providing structured mentoring, fostering professional development, and promoting sustainability, EFOMP aims to ensure that early career medical physicists are well-prepared to meet the challenges of the future and continue to advance the field of medical physics as a community., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Published
2024
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49. Performance evaluation of a preclinical SPECT/CT system for multi-animal and multi-isotope quantitative experiments.

Author

Prieto E, Irazola L, Collantes M, Ecay M, Cuenca T, Martí-Climent JM, and Peñuelas I

Subjects
Animals, Rats, Mice, Phantoms, Imaging, Radionuclide Imaging, Isotopes, Image Processing, Computer-Assisted, Tomography, X-Ray Computed, Tomography, Emission-Computed, Single-Photon methods
Abstract

The aim was to study the performance of the U-SPECT 6 /CT E-class system for preclinical imaging, to later demonstrate the viability of simultaneous multi-animal and multi-isotope imaging with reliable quantitative accuracy. The performance of the SPECT was evaluated for two collimators dedicated for mouse (UHS-M) and rat imaging (UHR-RM) in terms of sensitivity, energy resolution, uniformity and spatial resolution. Point sources, hot‑rod and uniform phantoms were scanned, and additional tests were carried out to evaluate singular settings such as simultaneous multi-isotope acquisition and imaging with a multi-bed system. For in-vivo evaluation, simultaneous triple-isotope and multi-animal studies were performed on mice. Sensitivity for 99m Tc was 2370 cps/MBq for the UHS-M collimator and 493 cps/MBq for the UHR-RM. Rods of 0.6 mm and 0.9 mm were discernible with the UHS-M and UHR-RM collimators respectively, with optimized reconstruction. Uniformity in low counting conditions has proven to be poor (> 75%). Multi-isotope and multi-bed phantom acquisitions demonstrated accurate quantification. In mice, simultaneous multi-isotope imaging provided the separate distribution of 3 tracers and image quality of the multi-mouse bone scan was adequate. The U-SPECT 6 /CT E-class has shown good sensitivity and spatial resolution. This system provides quantitative images with suitable image quality for multi-mouse and multi-isotope acquisitions., (© 2022. The Author(s).)

Published
2022
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50. Peripheral Organ Equivalent Dose Estimation Procedure in Proton Therapy.

Author

Domingo C, Lagares JI, Romero-Expósito M, Sánchez-Nieto B, Nieto-Camero JJ, Terrón JA, Irazola L, Dasu A, and Sánchez-Doblado F

Abstract

The aim of this work is to present a reproducible methodology for the evaluation of total equivalent doses in organs during proton therapy facilities. The methodology is based on measuring the dose equivalent in representative locations inside an anthropomorphic phantom where photon and neutron dosimeters were inserted. The Monte Carlo simulation was needed for obtaining neutron energy distribution inside the phantom. The methodology was implemented for a head irradiation case in the passive proton beam of iThemba Labs (South Africa). Thermoluminescent dosimeter (TLD)-600 and TLD-700 pairs were used as dosimeters inside the phantom and GEANT code for simulations. In addition, Bonner sphere spectrometry was performed inside the treatment room to obtain the neutron spectra, some relevant neutron dosimetric quantities per treatment Gy, and a percentual distribution of neutron fluence and ambient dose equivalent in four energy groups, at two locations. The neutron spectrum at one of those locations was also simulated so that a reasonable agreement between simulation and measurement allowed a validation of the simulation. Results showed that the total out-of-field dose equivalent inside the phantom ranged from 1.4 to 0.28 mSv/Gy, mainly due to the neutron contribution and with a small contribution from photons, 10% on average. The order of magnitude of the equivalent dose in organs was similar, displaying a slow reduction in values as the organ is farther from the target volume. These values were in agreement with those found by other authors in other passive beam facilities under similar irradiation and measurement conditions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Domingo, Lagares, Romero-Expósito, Sánchez-Nieto, Nieto-Camero, Terrón, Irazola, Dasu and Sánchez-Doblado.)

Published
2022
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