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Vijande, J., Granero, D., Perez-Calatayud, J., & Ballester, F. (2013). Monte Carlo dosimetric study of the medium dose rate CSM40 source. Appl. Radiat. Isot., 82, 283–288.
Abstract: The Cs-137 medium dose rate (MDR) CSM40 source model (Eckert & Ziegler BEBIG, Germany) is in clinical use but no dosimetric dataset has been published. This study aims to obtain dosimetric data for the CSM40 source for its use in clinical practice as required by the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO). Penelope2008 and Geant4 Monte Carlo codes were used to characterize this source dosimetrically. It was located in an unbounded water phantom with composition and mass density as recommended by AAPM and ESTRO. Due to the low photon energies of Cs-137, absorbed dose was approximated by collisional kerma. Additional simulations were performed to obtain the air-kerma strength, sic. Mass-energy absorption coefficients in water and air were consistently derived and used to calculate collisional kerma. Results performed with both radiation transport codes showed agreement typically within 0.05%. Dose rate constant, radial dose function and anisotropy function are provided for the CSM40 and compared with published data for other commercially available Cs-137 sources. An uncertainty analysis has been performed. The data provided by this study can be used as input data and verification in the treatment planning systems. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Brachytherapy; Cs-137 seed; TG-43 based dosimetry; Monte Carlo
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Gimenez-Alventosa, V., Ballester, F., & Vijande, J. (2016). VoxelMages: a general-purpose graphical interface for designing geometries and processing DICOM images for PENELOPE. Appl. Radiat. Isot., 118, 251–257.
Abstract: The design and construction of geometries for Monte Carlo calculations is an error-prone, time-consuming, and complex step in simulations describing particle interactions and transport in the field of medical physics. The software VoxelMages has been developed to help the user in this task. It allows to design complex geometries and to process DICOM image files for simulations with the general-purpose Monte Carlo code PENELOPE in an easy and straightforward way. VoxelMages also allows to import DICOM-RT structure contour information as delivered by a treatment planning system. Its main characteristics, usage and performance benchmarking are described in detail.
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Oliver, S., Vijande, J., Tejedor-Aguilar, N., Miro, R., Rovira-Escutia, J. J., Ballester, F., et al. (2023). Monte Carlo flattening filter design to high energy intraoperative electron beam homogenization. Radiat. Phys. Chem., 212, 111102–6pp.
Abstract: Intraoperative radiotherapy using mobile linear accelerators is used for a wide variety of malignancies. However, when large fields are used in combination with high energies, a deterioration of the flatness dose profile is measured with respect to smaller fields and lower energies. Indeed, for the LIAC HWL of Sordina, this deterioration is observed for the 12 MeV beam combined with 10 cm (or larger) diameter applicator. Aimed to solve this problem, a flattening filter has been designed and validated evaluating the feasibility of its usage at the upper part of the applicator. The design of the filter was based on Monte Carlo simulations because of its accuracy in modeling components of clinical devices, among other purposes. The LIAC 10 cm diameter applicator was modeled and simulated independently by two different research groups using two different MC codes, reproducing the heterogeneity of the 12 MeV energy beam. Then, an iterative process of filter design was carried out. Finally, the MC designed conical filter with the optimal size and height to obtain the desired flattened beam was built in-house using a 3D printer. During the experimental validation of the applicator-filter, percentage depth dose, beam profiles, absolute and peripheral dose measurements were performed to demonstrate the effectiveness of the filter addition in the applicator. These measurements conclude that the beam has been flattened, from 5.9% with the standard configuration to 1.6% for the configuration with the filter, without significant increase of the peripheral dose. Consequently, the new filter-applicator LIAC configuration can be used also in a conventional surgery room. A reduction of 16% of the output dose and a reduction of 1.1 mm in the D50 of the percentage depth dose was measured with respect to the original configuration. This work is a proof-of-concept that demonstrates that it is possible to add a filter able to flatten the beam delivered by the Sordina LIAC HWL. Future studies will focus on more refined technical solutions fully compatible with the integrity of the applicator, including its sterilization, to be safely introduced in the clinical practice.
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Otal, A., Celada, F., Chimeno, J., Vijande, J., Pellejero, S., Perez-Calatayud, M. J., et al. (2022). Review on Treatment Planning Systems for Cervix Brachytherapy (Interventional Radiotherapy): Some Desirable and Convenient Practical Aspects to Be Implemented from Radiation Oncologist and Medical Physics Perspectives. Cancers, 14(14), 3467–15pp.
Abstract: Simple Summary There are no brachytherapy treatment planning systems (TPS) exclusively for the treatment of cervical tumours, so general-purpose TPSs are used. However, these treatments have some particular features concerning the treatment of other pathologies, especially in the case of exclusive use of MRI as an imaging modality and the presence of gynaecological applicators in combination with an interstitial part. That is why it is essential to review the latest versions of commercial TPSs to find the potential features to improve with the help of a group of experimented medical physicists and radiation oncologists. Furthermore, after reviewing the recent literature for advances applicable to cervical brachytherapy and through his own clinical experience, possible improvements are proposed to software providers for the development of new tools. Intracavitary brachytherapy (BT, Interventional Radiotherapy, IRT), plays an essential role in the curative intent of locally advanced cervical cancer, for which the conventional approach involves external beam radiotherapy with concurrent chemotherapy followed by BT. This work aims to review the different methodologies used by commercially available treatment planning systems (TPSs) in exclusive magnetic resonance imaging-based (MRI) cervix BT with interstitial component treatments. Practical aspects and improvements to be implemented into the TPSs are discussed. This review is based on the clinical expertise of a group of radiation oncologists and medical physicists and on interactive demos provided by the software manufacturers. The TPS versions considered include all the new tools currently in development for future commercial releases. The specialists from the supplier companies were asked to propose solutions to some of the challenges often encountered in a clinical environment through a questionnaire. The results include not only such answers but also comments by the authors that, in their opinion, could help solve the challenges covered in these questions. This study summarizes the possibilities offered nowadays by commercial TPSs, highlighting the absence of some useful tools that would notably improve the planning of MR-based interstitial component cervix brachytherapy.
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Oliver-Canamas, L., Vijande, J., Candela-Juan, C., Gimeno-Olmos, J., Pujades-Claumarchirant, M. C., Rovira-Escutia, J. J., et al. (2023). A User-Friendly System for Mailed Dosimetric Audits of Ir-192 or Co-60 HDR Brachytherapy Sources. Cancers, 15(9), 2484–14pp.
Abstract: Nowadays, the options available to perform external dosimetric audits of the high dose rate (HDR) brachytherapy treatment process are limited. In this work, we present a methodology that allows for performing dosimetric audits in this field. A phantom was designed and manufactured for this purpose. The criteria for its design, together with the in-house measurements for its characterization, are presented. The result is a user-friendly system that can be mailed to perform dosimetric audits in HDR brachytherapy on-site for systems using either Iridium-192 (Ir-192) or Cobalt-60 (Co-60) sources. Objectives: The main goal of this work is to design and characterize a user-friendly methodology to perform mailed dosimetric audits in high dose rate (HDR) brachytherapy for systems using either Iridium-192 (Ir-192) or Cobalt-60 (Co-60) sources. Methods: A solid phantom was designed and manufactured with four catheters and a central slot to place one dosimeter. Irradiations with an Elekta MicroSelectron V2 for Ir-192, and with a BEBIG Multisource for Co-60 were performed for its characterization. For the dose measurements, nanoDots, a type of optically stimulated luminescent dosimeters (OSLDs), were characterized. Monte Carlo (MC) simulations were performed to evaluate the scatter conditions of the irradiation set-up and to study differences in the photon spectra of different Ir-192 sources (Microselectron V2, Flexisource, BEBIG Ir2.A85-2 and Varisource VS2000) reaching the dosimeter in the irradiation set-up. Results: MC simulations indicate that the surface material on which the phantom is supported during the irradiations does not affect the absorbed dose in the nanoDot. Generally, differences below 5% were found in the photon spectra reaching the detector when comparing the Microselectron V2, the Flexisource and the BEBIG models. However, differences up to 20% are observed between the V2 and the Varisource VS2000 models. The calibration coefficients and the uncertainty in the dose measurement were evaluated. Conclusions: The system described here is able to perform dosimetric audits in HDR brachytherapy for systems using either Ir-192 or Co-60 sources. No significant differences are observed between the photon spectra reaching the detector for the MicroSelectron V2, the Flexisource and the BEBIG Ir-192 sources. For the Varisource VS2000, a higher uncertainty is considered in the dose measurement to allow for the nanoDot response.
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