MURILLO BELLEZZO
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Resumo IPEN-doc 28461 MAASTRO applicator, a novel rectal applicator for contact brachytherapy with 192Ir HDR sources2020 - BELLEZZO, M.; FONSECA, G.P.; VONCKEN, R.; VERRIJSSEN, A.; VAN BEVEREN, C.; ROELOFS, E.; YORIYAZ, H.; RENIERS, B.; VAN LIMBERGEN, E.J.; BARBEE, M.; VERHAEGEN, F.Purpose or Objective: The standard care for rectal cancer includes surgery, which may be avoided if complete response is achieved, e.g. with chemoradiotherapy (EBCRT) or external beam radiotherapy EBRT, adopting a watch and wait strategy. Studies report a local regrowth reduction from 30% (EBCRT alone) to 11% when EBCRT is associated with a radiation boost using 50 kV x-rays (CXB), technique that allows a high dose delivery to a highly selective volume, allowing preservation of organs at risk (OAR) and low toxicity. However, CXB is not widely adopted due to its low costeffectiveness. Hence, the MAASTRO applicator was developed to deliver a dose distribution similar to those generated by CXB devices, but using HDR 192Ir sources, as a cost-effective alternative to CXB, with possibility of integration to treatment planning systems (TPS). Material and Methods: Fig 1-a shows the applicator design, a cylindrical applicator with 5 channels and a slanted edge, using its tip. Results: Due to the applicator geometry, the most distal position of the source in each channel doesn’t reach the sharp edge of the applicator, resulting in an effective treatment surface (high dose region shown in Fig 1 a and b) of approximately 20 x 20 mm2, which is smaller than the contact surface. The resulting dose falloff is steeper than the one resulting from the P50 with a 22 mm applicator. With the dose falloff normalized at 2mm, the relative dose values delivered at depths of 0, 2, 5 and 10 mm are, respectively, 130, 100, 70 and 43% for the P50 and 140, 100, 67 and 38% for the applicator. The time required to deliver an average dose of 32 Gy to the treatment surface of the applicator is 5m30s for a 40700 U source (new source) and 8m30s for a 20350 U source (source to be replaced), including the time required to perform obstruction verification before irradiation. The applicator delivers a high dose to a small target volume while the lateral shielding spares normal tissues in all directions other than the contact surface. Conclusion: The MAASTRO applicator was designed to deliver dose distributions similar to those of CXB devices using 192Ir HDR sources. The applicator has the advantage of TPS integration, increasing the degrees of freedom to modulate the dose distribution.Artigo IPEN-doc 27125 Advanced design, simulation, and dosimetry of a novel rectal applicator for contact brachytherapy with a conventional HDR 192Ir source2020 - BELLEZZO, MURILLO; FONSECA, GABRIEL P.; VONCKEN, ROBERT; VERRIJSSEN, AN-SOFIE; VAN BEVEREN, CELINE; ROELOFS, ERIK; YORIYAZ, HELIO; RENIERS, BRIGITTE; VAN LIMBERGEN, EVERT J.; BERB EE, MAAIKE; VERHAEGEN, FRANKPURPOSE: Dose escalation yields higher complete response to rectal tumors, which may enable the omission of surgery. Dose escalation using 50 kVp contact x-ray brachytherapy (CXB) allow the treatment of a selective volume, resulting in low toxicity and organs-at-risk preservation. However, the use of CXB devices is limited because of its high cost and lack of treatment planning tools. Hence, the MAASTRO applicator (for HDR 192Ir sources) was developed and characterized by measurements and Monte Carlo simulations to be a cost-effective alternative to CXB devices. METHODS AND MATERIALS: A cylindrical applicator with lateral shielding was designed to be used with a rectoscope using its tip as treatment surface. Both the applicator and the rectoscope have a slanted edge to potentially allow easier placement against tumors. The applicator design was achieved by Monte Carlo modeling and validated experimentally with film dosimetry, using the Papillon 50 (P50) device as reference. RESULTS: The applicator delivers CXB doses in less than 9 min using a 20375 U source for a treatment area of approximately 20 20 mm2 at 2 mm depth. Normalized at 2 mm, the dose falloff for depths of 0 mm, 5 mm, and 10 mm are 130%, 70%, and 43% for the P50 and 140%, 67%, and 38% for the MAASTRO applicator, respectively. CONCLUSIONS: The MAASTRO applicator was designed to use HDR 192Ir sources to deliver a dose distribution similar to those of CXB devices. The applicator may provide a cost-effective solution for endoluminal boosting with clinical treatment planning system integration.Artigo IPEN-doc 26506 Sistemas de planejamento em radioterapia2019 - FONSECA, GABRIEL P.; BELLEZZO, MURILLO; YORIYAZ, HELIOEste artigo apresenta uma breve descrição do histórico do desenvolvimento de sistemas de planejamento, seguida da descrição dos atuais sistemas comerciais utilizados nos centros de radioterapia no país e no mundo. É apresentado também um novo sistema de planejamento denominado A Medical Image-based Graphical platfOrm (AMIGO). Esse software foi desenvolvido em parceria com o Instituto de Pesquisas Energéticas e Nucleares, a Universidade de São Paulo e a Universidade de Maastricht. A primeira versão do software foi desenvolvida para simular tratamentos braquiterápicos por meio de uma interface gráfica com recursos similares aos sistemas de planejamento comerciais. Uma nova versão está sendo desenvolvida para uso em teleterapia, como uma alternativa aos softwares comercias, e permitirá a análise de diversos detalhes do tratamento, além da validação dos cálculos realizados pelos sistemas comerciais.Artigo IPEN-doc 26471 Mechanical evaluation of the Bravos afterloader system for HDR brachytherapy2019 - BELLEZZO, MURILLO; BAEZA, JOSE A.; VONCKEN, ROBERT; RENIERS, BRIGITTE; VERHAEGEN, FRANK; FONSECA, GABRIEL P.PURPOSE: The Bravos afterloader system was released by Varian Medical Systems in October of 2018 for high-dose-rate brachytherapy with 192Ir sources, containing new features such as the CamScale (a new device for daily quality assurance and system recalibration), channel length verification, and different settings for rigid and flexible applicators. This study mechanically evaluated the Bravos system precision and accuracy for clinically relevant scenarios, using dummy sources. METHODS AND MATERIALS: The system was evaluated after three sets of experiments: (1) The CamScale was used to verify inter- and intra-channel dwelling variability and system calibration; (2) A high-speed camera was used to verify the source simulation cable movement inside a transparent quality assurance device, where dwell positions, dwell times, transit times, speed profiles, and accelerations were measured; (3) The source movement inside clinical applicators was captured with an imaging panel while being exposed to an external kV source. Measured and planned dwell positions and times were compared. RESULTS: Maximum deviations between planned and measured dwell positions and times for the source cable were 0.4 mm for the CamScale measurements and 0.07 seconds for the high-speed camera measurements. Mean dwell position deviations inside clinical applicators were below 1.2 mm for all applicators except the ring that required an offset correction of 1 mm to achieve a mean deviation of 0.4 mm. CONCLUSIONS: Features of the Bravos afterloader system provide a robust and precise treatment delivery. All measurements were within manufacturer specifications.Artigo IPEN-doc 25706 A systematic review comparing radiation toxicity after various endorectal techniques2019 - VERRIJSSEN, AN-SOFIE; OPBROEK, THIRZA; BELLEZZO, MURILLO; FONSECA, GABRIEL P.; VERHAEGEN, FRANK; GERARD, JEAN-PIERRE; MYINT, ARTHUR S.; LIMBERGEN, EVERT J.V.; BERBEE, MAAIKEPURPOSE: A clinical complete response is seen after neoadjuvant chemoradiation for rectal tumors in 15%e20% of patients. These patients can potentially be spared mutilating total mesorectal excision surgery through a watch-and-wait policy. Recent studies show that dose escalation by a radiation boost increases the clinical complete response rate. The boost dose to the tumor can be administered through external beam radiotherapy or through internal radiotherapy using techniques like contact therapy, low-dose-rate or high-dose-rate brachytherapy (BT). However, limited information is available concerning treatment-related toxicity of these techniques. With this systematic review, we aim to summarize and compare published data concerning acute and late toxicity after contact X-ray therapy (CXT) and BT for rectal cancer. METHODS AND MATERIALS/RESULTS: Thirty-eight studies reporting toxicity after endorectal radiation techniques for rectal cancer were included, resulting in 3682 patients for analysis. Direct comparison of toxicity by the different radiation modes was hampered by various combinations of endorectal techniques, a lack of clear reporting of toxicity scores, dose prescription, technique used, and treated volumes. $ Grade 3 rectal toxicity was reported in 2.9% of patients having received only CXT; 6.3% of patients who received only BT had Grade 3 rectal toxicity, and BT also caused Grade 3 urinary toxicity in 1 patient. CONCLUSION: All techniques reported some$Grade 3 toxicity. Toxicity after CXTwas confined to the rectum, whereas after BT, urogenital toxicity and skin toxicity were seen as well. Unfortunately, few specific conclusions could be drawn regarding the dose-related risk of toxicity for the various techniques due to nonuniform reporting strategies and missing information. To enable future comparisons and improvements, the endorectal radiation field urgently needs consensus guidelines on dose reporting, dose prescription, treatment volume specification, and toxicity reporting. 2018 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.Artigo IPEN-doc 25053 A novel rectal applicator for contact radiotherapy with HDR 192Ir sources2018 - BELLEZZO, MURILLO; FONSECA, GABRIEL P.; VERRIJSSEN, AN-SOFIE; VONCKEN, ROBERT; BOSCH, MICHIEL R.V. den; YORIYAZ, HELIO; RENIERS, BRIGITTE; BERBEE, MAAIKE; LIMBERGEN, EVERT J.V.; VERHAEGEN, FRANKPURPOSE: Dose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate 192Ir BT sources. METHODS AND MATERIALS: A cylindrical multichannel BT applicator with lateral shielding was designed by Monte Carlo modeling, validated experimentally with film dosimetry and compared with results found in the literature for the Papillon 50 (P50) contact x-ray radiotherapy device regarding rectoscope dimensions, radiation beam shape, dose fall-off, and treatment time. RESULTS: The multichannel applicator designed is able to deliver 30 Gy under 13 min with a 20350 U (5 Ci) source. The use of multiple channels and lateral shielding provide a uniform circular treatment surface with 22 mm in diameter. The resulting dose fall-off is slightly steeper (maximum difference of 5%) than the one generated by the P50 device with the 22 mm applicator. CONCLUSIONS: A novel multichannel rectal applicator for contact radiotherapy with high-doserate 192Ir sources that can be integrated with commercially available treatment planning systems was designed to produce a dose distribution similar to the one obtained by the P50 device.Artigo IPEN-doc 20608 A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phanton2014 - BELLEZZO, MURILLO; NASCIMENTO, EDUARDO do; YORIYAZ, HELIOArtigo IPEN-doc 20236 A medical image-based graphical platform-Features, applications and relevance for brachytherapy2014 - FONSECA, GABRIEL P.; RENIERS, BRIGITTE; LANDRY, GUILLAUME; WHITE, SHANE; BELLEZZO, MURILLO; ANTUNES, PAULA C.G.; SALES, CAMILA P. de; WELTEMAN, EDUARDO; YORIYAZ, HELIO; VERHAEGEN, FRANKDissertação IPEN-doc 20160 Desenvolvimento de um software de Monte Carlo para transporte de fótons em estruturas de voxels usando unidades de processamento gráfico2014 - BELLEZZO, MURILLOSendo o método mais preciso para estimar a dose absorvida em radioterapia, o Método de Monte Carlo (MMC) tem sido amplamente utilizado no planejamento de tratamento radioterápico. No entanto, a sua eciência pode ser melhorada para aplicações clínicas de rotina. Nesta dissertação é apresentado o código CUBMC, um código de Monte Carlo que simula o transporte de fótons para cálculo de dose, desenvolvido na plataforma CUDA (Compute Unified Device Architecture). A simulação de eventos físicos é baseada no algoritmo presente no código PENELOPE, e as tabelas de seção de choque utilizadas são geradas pela rotina MATERIAL, também presente no código PENELOPE. Os fótons são transportados em objetos simuladores descritos por voxels. Existem duas abordagens distintas utilizadas para a simulação. A primeira delas obriga o fóton a realizar uma parada toda vez que cruza a fronteira de um voxel, a segunda e pelo Método de Woodcock, onde o fóton ignora a existência de fronteiras e é transportado em um meio homogêneo fictício. O código CUBMC tem como objetivo ser uma opção de código simulador que, ao utilizar a capacidade de processamento paralelo de unidades de processamento gráfico (GPU), apresente alto desempenho em máquinas compactas e de baixo custo, podendo assim ser aplicado em casos clínicos e incorporado a sistemas de planejamento de tratamento em radioterapia.