Fletcher, E. M., Ballester, F., Beaulieu, L., Morrison, H., Poher, A., Rivard, M. J., et al. (2024). Generation and comparison of 3D dosimetric reference datasets for COMS eye plaque brachytherapy using model-based dose calculations. Med. Phys., 51, 694–706.
Abstract: PurposeA joint Working Group of the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) was created to aid in the transition from the AAPM TG-43 dose calculation formalism, the current standard, to model-based dose calculations. This work establishes the first test cases for low-energy photon-emitting brachytherapy using model-based dose calculation algorithms (MBDCAs).Acquisition and Validation MethodsFive test cases are developed: (1) a single model 6711 125I brachytherapy seed in water, 13 seeds (2) individually and (3) in combination in water, (4) the full Collaborative Ocular Melanoma Study (COMS) 16-mm eye plaque in water, and (5) the full plaque in a realistic eye phantom. Calculations are done with four Monte Carlo (MC) codes and a research version of a commercial treatment planning system (TPS). For all test cases, local agreement of MC codes was within & SIM;2.5% and global agreement was & SIM;2% (4% for test case 5). MC agreement was within expected uncertainties. Local agreement of TPS with MC was within 5% for test case 1 and & SIM;20% for test cases 4 and 5, and global agreement was within 0.4% for test case 1 and 10% for test cases 4 and 5.Data Format and Usage NotesDose distributions for each set of MC and TPS calculations are available online () along with input files and all other information necessary to repeat the calculations.Potential ApplicationsThese data can be used to support commissioning of MBDCAs for low-energy brachytherapy as recommended by TGs 186 and 221 and AAPM Report 372. This work additionally lays out a sample framework for the development of test cases that can be extended to other applications beyond eye plaque brachytherapy.
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Vijande, J., Valcarce, A., Carames, T. F., & Richard, J. M. (2014). Multiquark Systems. Few-Body Syst., 55(8-10), 675–681.
Abstract: In this talk we tackle the description of hadron spectroscopy in terms of the constituent quark model. We focus on the mesonic charm sector, where several of the new reported resonances seem to defy their classification as simple quark-antiquark states. We pay special attention to higher order Fock space components in describing excited states of the meson spectra in close connection with the hadron-hadron interaction. The main goal of the present study is a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.
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Hueso-Gonzalez, F., Ballester, F., Perez-Calatayud, J., Siebert, F. A., & Vijande, J. (2017). Towards clinical application of RayStretch for heterogeneity corrections in LDR permanent I-125 prostate brachytherapy. Brachytherapy, 16(3), 616–623.
Abstract: PURPOSE: RayStretch is a simple algorithm proposed for heterogeneity corrections in low-dose-rate brachytherapy. It is built on top of TG-43 consensus data, and it has been validated with Monte Carlo (MC) simulations. In this study, we take a real clinical prostate implant with 71 1251 seeds as reference and we apply RayStretch to analyze its performance in worst-case scenarios. METHODS AND MATERIALS: To do so, we design two cases where large calcifications are located in the prostate lobules. RayStretch resilience under various calcification density values is also explored. Comparisons against MC calculations are performed. RESULTS: Dose volume histogram related parameters like prostate D-90, rectum D-2cc, or urethra D-10 obtained with RayStretch agree within a few percent with the detailed MC results for all cases considered. CONCLUSIONS: The robustness and compatibility of RayStretch with commercial treatment planning systems indicate its applicability in clinical practice for dosimetric corrections in prostate calcifications. Its use during intraoperative ultrasound planning is foreseen.
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Quintero-Quintero, A., Patiño-Camargo, G., Soriano, A., Palma, J. D., Vilar-Palop, J., Pujades, M. C., et al. (2018). Calibration of a thermoluminescent dosimeter worn over lead aprons in fluoroscopy guided procedures. J. Radiol. Prot., 38(2), 549–563.
Abstract: Fluoroscopy guided interventional procedures provide remarkable benefits to patients. However, medical staff working near the scattered radiation field may be exposed to high cumulative equivalent doses, thus requiring shielding devices such as lead aprons and thyroid collars. In this situation, it remains an acceptable practice to derive equivalent doses to the eye lenses or other unprotected soft tissues with a dosimeter placed above these protective devices. Nevertheless, the radiation backscattered by the lead shield differs from that generated during dosimeter calibration with a water phantom. In this study, a passive personal thermoluminescent dosimeter (TLD) was modelled by means of the Monte Carlo (MC) code Penelope. The results obtained were validated against measurements performed in reference conditions in a secondary standard dosimetry laboratory. Next, the MC model was used to evaluate the backscatter correction factor needed for the case where the dosimeter is worn over a lead shield to estimate the personal equivalent dose H-p(0.07) to unprotected soft tissues. For this purpose, the TLD was irradiated over a water slab phantom with a photon beam representative of the result of a fluoroscopy beam scattered by a patient. Incident beam angles of 0 degrees and 60 degrees, and lead thicknesses between the TLD and phantom of 0.25 and 0.5 mm Pb were considered. A backscatter correction factor of 1.23 (independent of lead thickness) was calculated comparing the results with those faced in reference conditions (i.e., without lead shield and with an angular incidence of 0 degrees). The corrected dose algorithm was validated in laboratory conditions with dosi-meters irradiated over a thyroid collar and angular incidences of 0 degrees, 40 degrees and 60 degrees, as well as with dosimeters worn by interventional radiologists and cardiologists. The corrected dose algorithm provides a better approach to estimate the equivalent dose to unprotected soft tissues such as eye lenses. Dosimeters that are not shielded from backscatter radiation might underestimate personal equivalent doses when worn over a lead apron and, therefore, should be specifically characterized for this purpose.
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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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