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Vijande, J., Ballester, F., Ouhib, Z., Granero, D., Pujades-Claumarchirant, M. C., & Perez-Calatayud, J. (2012). Dosimetry comparison between TG-43 and Monte Carlo calculations using the Freiburg flap for skin high-dose-rate brachytherapy. Brachytherapy, 11(6), 528–535.
Abstract: PURPOSE: The purpose of this work was to evaluate whether the delivered dose to the skin surface and at the prescription depth when using a Freiburg flap applicator is in agreement with the one predicted by the treatment planning system (TPS) using the TG-43 dose-calculation formalism. METHODS AND MATERIALS: Monte Carlo (MC) simulations and radiochromic film measurements have been performed to obtain dose distributions with the source located at the center of one of the spheres and between two spheres. Primary and scatter dose contributions were evaluated to understand the role played by the scatter component. A standard treatment plan was generated using MC- and TG-43-based TPS applying the superposition principle. RESULTS: The MC model has been validated by performing additional simulations in the same conditions but transforming air and Freiburg flap materials into water to match TG-43 parameters. Both dose distributions differ less than 1%. Scatter defect compared with TG-43 data is up to 15% when the source is located at the center of the sphere and up to 25% when the source is between two spheres. Maximum deviations between TPS- and MC-based distributions are of 5%. CONCLUSIONS: The deviations in the TG-43-based dose distributions for a standard treatment plan with respect to the MC dose distribution calculated taking into account the composition and shape of the applicator and the surrounding air are lower than 5%. Therefore, this study supports the validity of the TPS used in clinical practice. (C) 2012 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
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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.
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Vijande, J., Tedgren, A. C., Ballester, F., Baltas, D., Papagiannis, P., Rivard, M. J., et al. (2021). Source strength determination in iridium-192 and cobalt-60 brachytherapy: A European survey on the level of agreement between clinical measurements and manufacturer certificates. Phys. Imag. Radiat. Oncol., 19, 108–111.
Abstract: Background and purpose: Brachytherapy treatment outcomes depend on the accuracy of the delivered dose distribution, which is proportional to the reference air-kerma rate (RAKR). Current societal recommendations require the medical physicist to compare the measured RAKR values to the manufacturer source calibration certificate. The purpose of this work was to report agreement observed in current clinical practice in the European Union. Materials and methods: A European survey was performed for high- and pulsed-dose-rate (HDR and PDR) highenergy sources (Ir-192 and Co-60), to quantify observed RAKR differences. Medical physicists at eighteen hospitals from eight European countries were contacted, providing 1,032 data points from 2001 to 2020. Results: Over the survey period, 77% of the Ir-192 measurements used a well chamber instead of the older Krieger phantom method. Mean differences with the manufacturer calibration certificate were 0.01% +/- 1.15% for Ir-192 and -0.1% +/- 1.3% for Co-60. Over 95% of RAKR measurements in the clinic were within 3% of the manufacturer calibration certificate. Conclusions: This study showed that the agreement level was generally better than that reflected in prior societal recommendations positing 5%. Future recommendations on high-energy HDR and PDR source calibrations in the clinic may consider tightened agreements levels.
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