Abstract: Purpose or Objective: Brachytherapy sources for ocular melanoma usually contain Co-60, I-125, Pd-103 or Ru/Rh-106 as radionuclides. Ir-192 is not a preconized radioactive material for this purpose, although it is used for other brachytherapy applications. Higher mean energy from Ir-192 emission (ca. 380 keV) may be a reason for the preference of I-125 (35 keV) or Pd-103 (21 keV) over it, since low penetration is desired on the small structures of the human eye. This is not, however, an excluding criterion, considering Co-60 and Ru/Rh-106 have even higher mean energies. The demand in Brazil for lower-cost seeds to treat ocular melanoma lead to the development of an Ir-192 seed to make treatment more accessible, but since it is not used as an ophthalmic brachytherapy source, before its dosimetry is considered, one should care about the possibility of using it over more stablished materials. Considering this, the aim of this work is to assess the possibility of using Ir-192 seeds as ophthalmic brachytherapy sources by comparing some dosimetric parameters of a new seed model with the most stablished I-125 seed in literature, OncoSeed 6711. Material and Methods: As an initial study on the topic, this work relies only on Monte-Carlo simulations using MCNP4C transport code. Parameters analyzed are air-kerma strength, dose-rate constant and depth-dose curve, attention given to points within the human eye dimensions. The medium considered was homogeneous water, as it is a good approximation to the eye tissues in terms of composition and density and allows for future comparisons with TG-43 based calculations. OncoSeed 6711 is not produced anymore, but its long term as the reference source for dosimetry was considered. A 20 mm COMS ophthalmic applicator was also modeled and considered to be fully loaded with each seed model to compare the same parameters at a realistically clinical approach. Results: As expected, due to the higher energy of the Ir-192 emission spectrum, dose fall-off on the transversal axis of the seeds is less pronounced for the new seed model. The steeper dose gradient for I-125 is also visible on the doserate constant value. The effect of using a COMS applicator only strengthens this characteristic. Depth-dose curves were calculated up to the distance of 5 cm, both for a single seed and for an applicator fully loaded with 24 seeds. All the eye components relevant for dosimetry are located within this range, like the cells of the crystallin and the optical nerve. Conclusion: If one expects to use Ir-192 as an alternative to I-125 in ophthalmic cancer treatment, at least the dosimetry following TG-43 protocol should be carried with utmost attention, as undesirable dose to healthy nearby tissues is unavoidable. Crafting a different applicator most suited for this radionuclide is a possibility that can be taken into account. Another recommendation is to go beyond TG-43 water-based protocol and actually estimate dose to relevant eye components.

ANGELOCCI, L.; NOGUEIRA, B.R.; SOUZA, C.D. de; ZEITUNI, C.A.; ROSTELATO, M.E.C.M. Assessing Ir-192 as an alternative to I-125 in ophthalmic treatment. Radiotherapy and Oncology, v. 152, p. S735-S736, 2020. Supplement 1, DOI: 10.1016/S0167-8140(21)01402-X. Disponível em: http://repositorio.ipen.br/handle/123456789/32695. Acesso em: $DATA.

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Abstract: Purpose: A great challenge in the brachytherapy sources production is to fulfill the Good Manufacturing Practices (GMPs) requirements, involving the process validation and of all supporting activities such as cleaning and sanitization. The increasingly strict requirements for quality assurance system, with several norms, normative resolutions and rules that must follow both medical products and radiochemical requirements, has led to a constant validation concerns. The main goal of GMP is to reduce inherent risks such as product contamination with microorganisms and cross-contamination. Methods: In the Laboratory for Brachytherapy Sources Production it was established a cleaning program for cleanrooms and hot cells using a hydrogen peroxide solution (6%). This work aims to assess the effectiveness of this cleaning agent in reducing and/or eliminating microbial load into the cleanrooms and equipments to acceptable levels in accordance with the current legislation. Results: The analysis was conducted using the results of the environmental monitoring program with settling contact plates in cleanrooms after the cleaning procedures. Furthermore, it was possible to evaluate the action of the sanitizing agent on the microbial population at the equipment and cleanrooms’ surfaces. It was also evaluated the best way to accomplish the cleaning program considering the dosimetry factor in each production process, hence the importance of radiological contamination. All the following environmental monitoring procedures presented satisfactory results, showing that the cleaning procedures was able to reduce and maintain the acceptable levels of viable and non-viable particles for the cleanroom classification (ISO 5 and ISO 7). The cleaning process with this sanitizer (hydrogen peroxide) can be performed quickly right before the production; allowing the production of brachytherapy sources without after use residues. Conclusion: This data will help the production of a clean and reliable product.

Palavras-Chave: radiopharmaceutical; isotope production; cleaning; equipment; clean rooms; pollution sources; contamination; hydrogen peroxide

BAPTISTA, T.; ROSTELATO, M.C.M.; ZEITUNI, C.; PERINI, E.A.; SOUZA, C.D. de; MARQUES, J. de O.; NOGUEIRA, B.R.; ANGELOCCI, L.V. Efficiancy of hydrogen peroxide for cleaning production areas and equipments in the Laboratory for Brachyterapy Sources Production. Medical Physics, v. 44, n. 6, p. 2828-2828, 2017. DOI: 10.1002/mp.12304. Disponível em: http://repositorio.ipen.br/handle/123456789/31132. Acesso em: $DATA.

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Abstract: Purpose: This study aims to present a solid waste management plan for the laboratory of radioactive sources production (LPFR), iodine-125 brachytherapy seeds, located at the Energy and Nuclear Research Institute (IPEN). After the implementation, it is expected to meet a demand of 8000 seeds per month. Methods: Waste from the production of Iodine-125 sources is classified as “Very Low Level Waste Disposal” (T1/2 ≤ 100 days) in the IAEA regulations. Despite that, they have levels of activity above the limits established in standard (CNEN 8.01) needing adequate management in order to guarantee the safety of the installation, operators and environment. The solid waste is generated in Glove box 1, were the fixation reaction (iodine-125 – core) takes place. The wastes from this production are absorbent papers and filters used in surface and air decontamination processes; glass vials, syringes and needles, used in the fixation reaction. Measures of mass, volume and values of activities generated over 5 years of production were performed for each glove box by estimating different scenarios throughout production (supplier switching, variation in activity by radioactive source, etc.). The concentration of activity was also determined in order to meet the criteria established in the standard for safe release of the waste. Results: The final volumes and activities calculated indicated that the laboratory has enough space for temporary storage until the release to the environment (thus not requiring treatment, transport, and another place for management). The data collected proved that a secure management system for radioactive waste within the facility is possible. Conclusion: The management proposed by this work was able to safely contemplate all stages of waste management. This data is indispensable for the construction and licensing of the laboratory.

Palavras-Chave: radioactive waste management; solid wastes; iodine 125; brachytherapy; regulations; waste disposal

SOUZA, D.B. de; ROSTELATO, M.C.M.; VICENTE, R.; ZEITUNI, C.; SOUZA, C.D. de; RODRIGUES, B.T.; MARQUES, J. de O.; CARVALHO, V.; BARBOSA, N. Measurement of Iodine-125 radioactive solid waste derived from sources production laboratory for brachytherapy. Medical Physics, v. 44, n. 6, p. 2974-2975, 2017. DOI: 10.1002/mp.12304. Disponível em: http://repositorio.ipen.br/handle/123456789/31133. Acesso em: $DATA.

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Abstract: Purpose: Cancer is one of the most complex public health problems. Prostate cancer is the second most common among men. In prostate brachytherapy use Iodine-125, which is fixated on a silver substrate, then inserted and sealed in a titanium capsule. This work proposes a new source configuration using epoxy resin substrate. Methods: Comparation and analysis methods were used to define the methodology for combining iodine-125 in polymers. The parameters were immersion time, reaction type, concentration of the adsorption solution, specific activity of the radioactive solution, need for carrier and chemical form of radioactive iodine. Results: The methodology developed with an epoxy resin was very good. The final radioactive intake on the resin was higher than 80%. The immobilization of the radioactive solution occurred in the matrix, without any loss or deposition of undesirable materials on its surface, as evidenced by the smear test. The material maintains its integrity when autoclaved at 140 °C. The curing process of the resin was 40 minutes. With the value of the initial activity of the Iodine solution by mass (774.2 lCi/g), it was possible to calculate the immobilization efficiency Average of 680 lCi/g. The immersion test in distilled water at room temperature did not exceed the limit allowed by ISO 9978, which is 5 nCi (185 Bq), proof of no leakage. In a computational simulation by the Monte Carlo Method, PENELOPE, the simulations were consistent with the values adopted by the literature for the GE Healthcare model 6711, which shows the value of the dose rate constant as 0, 965 cGy.U-1.h-1. Conclusion: The effective method for combining iodine-125 in epoxy resin was determinated. The major advantage was the high efficiency percentage fixation, around 82,1 3,2%, and the simplicity and safety of the process.

Palavras-Chave: neoplasms; prostate; iodine 125; polymers; epoxides; resins

RODRIGUES, B.T.; ROSTELATO, M.C.M.; SOUZA, C.D. de; ZEITUNI, C.; MOURA, E.S. de; SOUZA, D.B. de; TOZETTI, C.; RODRIGUES, B. New core configuration for producing Iodine 125 seeds. Medical Physics, v. 44, n. 6, p. 2828-2829, 2017. DOI: 10.1002/mp.12304. Disponível em: http://repositorio.ipen.br/handle/123456789/31135. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

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