RODRIGO TEIXEIRA DE ABREU

RODRIGO TEIXEIRA DE ABREU

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Anisotropy function of a new 192-Ir brachytherapy source
2021 - ABREU, R.T.; ANGELOCCI, L.V.; NOGUEIRA, B.R.; SANTOS, H.N.; ZEITUNI, C.A.; ROSTELATO, M.E.C.M.
Brachytherapy is a type of radiotherapy that uses radioactive sources (seeds, wires, among others) close to the tumor. Is important to provide a detailed description of seed dosimetry, so only the tumor will be irradiated avoiding unnecessary dose on adjacent organs and structures. To evaluate the dosimetric parameter of the anisotropy function for a new brachytherapy source, this work proposes the use of microcube TLD-100 dosimeters to find the dose rate using the AAPM Task Group 43 protocol (TG-43). The anisotropy function represents dose distribution around the source and has a major role for characterization of a new iridium source being implemented in Brazil. The value of D(r,θ) was measured using Solid Water phantoms, r value being the distance from the geometric center of the source to the position of the dosimeter on the phantom, and θ being the angle formed between the longitudinal axis of the source and the line connecting the geometric center to the TLD. Monte Carlo calculations were performed to evaluate the anisotropy function to validate the experimental measurements. For each distance value (r), an anisotropy function was plotted (1.0, 2.0, 3.0, 4.0, 5.0, and 10.0 cm). The results obtained with Monte Carlo calculations agreed ±2% with the experimental values for r greater than 3.0 cm, so these results show a good distribution of dose around the seed considering the high energy of 192-Ir (average of 380 KeV) and encapsulation thickness.
End-weld thickness variation effects on dose rate for a new ir-192 brachytherapy source
2019 - ANGELOCCI, LUCAS V.; NOGUEIRA, BEATRIZ R.; ABREU, RODRIGO T.; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
Brachytherapy is a form of radiation therapy that uses small sealed sources close to the tumor to deliver a high dose to target while keeping dose on neighboring healthy tissues as low as possible. A wide variety of radionuclides and different sources are available for brachytherapy, each with his own unique geometry. The Laboratory of Sources Production for Radiotherapy (IPEN/CNEN) developed a new Ir-192 seed for eye tumor treatment that is currently under dosimetric definition. This work is part of a larger project that aims the full dosimetry of this new source, but rather than calculate the usual parameters proposed by the American Association of Physicists in Medicine, the specific contribution to the dose rate of a usually not considered factor was investigated under a statistical approach: end-weld thickness variation, which is important due to this source being welded by an in-house method. Its effects were investigated using the Monte Carlo radiation transport code MCNP4C and an in-house routine programmed with MATLAB® to analyze the data. Final results are presented as a mean value for dose rate at different points of interest and their associated standard deviations. The results are discussed based on the influence of said parameter on different points around the source.
Anisotropy function of a new 192-Ir brachytherapy source
2019 - ABREU, RODRIGO T.; ANGELOCCI, LUCAS V.; NOGUEIRA, BEATRIZ R.; SANTOS, HAMONA N. dos; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
Brachytherapy is a type of radiotherapy that uses radioactive sources (seeds, wires, among others) close to the tumor. Is important to provide a detailed description of seed dosimetry, so only the tumor will be irradiated avoiding unnecessary dose on adjacent organs and structures. To evaluate the dosimetric parameter of the anisotropy function for a new brachytherapy source, this work proposes the use of microcube TLD-100 dosimeters to find the dose rate using the AAPM Task Group 43 protocol (TG-43). The anisotropy function represents dose distribution around the source and has a major role for characterization of a new iridium source being implemented in Brazil. The value of D(r,θ) was measured using Solid Water phantoms, r value being the distance from the geometric center of the source to the position of the dosimeter on the phantom, and θ being the angle formed between the longitudinal axis of the source and the line connecting the geometric center to the TLD. Monte Carlo calculations were performed to evaluate the anisotropy function to validate the experimental measurements. For each distance value (r), an anisotropy function was plotted (1.0, 2.0, 3.0, 4.0, 5.0, and 10.0 cm). The results obtained with Monte Carlo calculations agreed ±2% with the experimental values for r greater than 3.0 cm, so these results show a good distribution of dose around the seed considering the high energy of 192-Ir (average of 380 KeV) and encapsulation thickness.
Dose-rate constant evaluation of a new 192-Ir brachytherapy source using Monte-Carlo and experimental parameters
2019 - ABREU, R.T.; ANGELOCCI, L.V.; NOGUEIRA, B.R.; SANTOS, H.N.; ZEITUNI, C.A.; ROSTELATO, M.E.C.M.
Study and methodologies for fixing epoxy resin in radioactive sources used for brachytherapy
2017 - RODRIGUES, BRUNA T.; ROSTELATO, MARIA E.C.M.; SOUZA, CARLA D.; TOZETTI, CINTIA A.; ZEITUNI, CARLOS A.; NOGUEIRA, BEATRIZ R.; SILVA, JOSE T.; K. JUNIOR, DIB; FERNANDES, VAGNER; SOUZA, RAQUEL V.; ABREU, RODRIGO T.
The World Health Organization (WHO) estimates that the number of new cancer cases worldwide will reach 15 million by 2020. The disease is already the second leading cause of death worldwide, being behind only cardiovascular disease. It is unquestionable that it is a public health problem, especially among developing countries. Prostate cancer is the most common among men, approximately 28.6%. The choice of type of treatment for prostate cancer should consider several factors such as: tumor size and extent, apparent aggressiveness (pathological characteristics), age, health. Among the methods applied, brachytherapy has been used in the initial and intermediate stages of the disease. Brachytherapy is a safe and effective treatment for localized prostate cancer. Brachytherapy is a form of radiotherapy in which radioactive seeds are placed in contact with or within the organ being treated. This technique allows a large dose of radiation to be released only on the target tumor that protects healthy surrounding tissues. Sources may have different shapes and sizes, but the one used for prostate cancer is usually 4.5 mm in length and 0.8 mm in diameter. About 80 to 120 seeds can be used per patient. Iodine-125 is the radioisotope most used in brachytherapy of the prostate, it emits 35,49keV X-rays in 100% of the decays, with average energy of 29 keV. The treatment of prostate cancer with permanent implantation of iodine-125 seeds has grown dramatically in the world in recent years. Most patients can return to normal life within three days with little or no pain.
Brazil radioactive sources production for cancer treatment
2016 - ROSTELATO, MARIA E.; SOUZA, CARLA D.; ZEITUNI, CARLOS A.; MOURA, JOAO A.; MARQUES, JOSE R.O.; COSTA, OSVALDO L.; FEHER, ANSELMO; RODRIGUES, BRUNA T.; SOUZA, DAIANE C.B. de; PELEIAS JUNIOR, FERNANDO S.; SORGATTI, ANDERSON; MOSCA, RODRIGO; MOURA, EDUARDO S. de; ABREU, RODRIGO T.; SOUZA, RAQUEL V. DE; NOGUEIRA, BEATRIZ R.
The modality, known as brachytherapy, was performed in Brazil by only a hand full of hospitals at an extremely high cost. For producing new sources, five major areas must be considered: 1) source production: nuclear activation and/or radiochemical reaction; 2) welding; 3) Quality control: leakage tests; 4) Dosimetry and metrology; 5) Operational procedures; 6) validation studies. To perform all steps, a multidisciplinary team works together to overcome difficulties. - Iridium-192 pellets: In Brazil there are 140 machines with pellets that replacement every 5 years. Our new production line has assembly, welding and quality control hot cells. - Iridium-192 wires: Produced since 1999. The wire is activated at IPENs IEA-R1 reactor for 30 hours with 5x1013 n/cm-2.s-1 neutron flux resulting in 192 mCi maximum activity. - Iridium-192 seed: New seed for ophthalmic cancer treatment. The irradiation device presented 90% activity homogeneity. We are still testing in-vivo. - Iodine-125 seeds: Largely used in low dose brachytherapy. I-125 binding yield achieved with our new reaction was 80%; Laser welding presented 70% efficiency. Approved in all leakage tests. - Other ongoing projects: Veterinary brachytherapy, Waste management, Radionecrosis healing with laser, calibrations sources production, linear accelerator calculations for hospitals, sources with polymeric matrix Our Iodine-125 seeds will be available in 2018. All other projects are advancing. We will continue to develop new products hoping to help the Brazilian population fight against cancer. For producing new sources, five major areas must be considered: 1) source production: nuclear activation and/or radiochemical reaction; 2) welding; 3) Quality control:eakage tests; 4) Dosimetry and metrology; 5) Operational procedures; 6) validation studies. To perform all steps, a multidisciplinary team works together to overcome difficulties