The Brazilian Journal of Medical Physics (RBFM) is a scientific journal published by the Brazilian Association of Medical Physics (ABFM). The RBFM publishes original scientific research articles, technical communications and review articles in the field of Medical Physics, which include the areas of Radiotherapy, Nuclear Medicine, Diagnostic Radiology, Radiological Protection and Radiation Dosimetry, diagnosis and therapy modalities with ionizing and non-ionizing radiation, as well as Teaching and Instrumentation in Medical Physics. RBFM also publishes reviews of theses and dissertations in the area of Medical Physics. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Editors-in-Chief Dra. Juliana Fernandes Pavoni Dra. Renata Ferranti Leoni ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Publishing Model Continuous flow, open access with no cost for publication ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 45 days Submission to first decision
The submission of original articles to the Brazilian Journal of Medical Physics implies the transfer, by the authors, of the rights of print and digital publication. Copyright for published articles remains with the author, with journal rights on first publication. Authors may only use the same results in other publications by clearly indicating this journal as the original publisher. As we are an open access journal, free use of articles in educational, scientific, non-commercial applications is allowed, as long as the source is cited. The Brazilian Journal of Medical Physics is under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).
Comparative Study of Patient Dose Indicators in Cardiology Procedures Using Angiography Systems with Different Technologies
Interventional radiology plays a key role in hemodynamic procedures by enabling minimally invasive diagnoses and treatments. However, exposure to ionizing radiation remains a concern for both patients and healthcare professionals. This study aims to compare typical values of dose indicators—cumulative air kerma (Ka) and kerma-area product (PKA)—and fluoroscopy time, in association with the anthropometric characteristics of patients undergoing cardiac procedures using angiography systems with different technologies, installed in the hemodynamics unit of a large hospital. Retrospective data from 509 clinical procedures performed on angiography systems of different technological generations were analyzed, including two modern systems (manufactured in 2023) and one older system (manufactured in 2011), all using flat-panel detectors. Dose indicators were obtained from equipment reports and institutional records, along with patient body mass index (BMI) and fluoroscopy time. Among all cases, coronary angiography accounted for 55%, elective angioplasty for 22%, and combined angiography with angioplasty for 15%. The results show that, despite similar patient profiles (BMI) and comparable fluoroscopy times across the rooms, dose indicator values varied significantly among systems with different technologies, with the oldest angiograph delivering considerably higher radiation doses. This study highlights the importance of routinely monitoring dose indicators and exposure parameters in interventional radiology procedures and underscores the impact that technological modernization can have on reducing patient radiation exposure.
Copyright (c) 2025 Raphael Souza, Mariana França, Antônio Daud, Rennan Rocha, Adriano Caixeta, Regina Medeiros, Marcelo Freitas https://creativecommons.org/licenses/by-nc-nd/4.0
Determination of the sensitive volume of the PTW N23361 ionization chamber by micro-computed tomography
The determination of the sensitive volume of ionization chambers is essential to ensure the best possible accuracy in dosimetric procedures, especially in the context of radiotherapy and radiation protection. This work presents a geometric analysis of the ionization chamber manufactured by PTW, model N23361, whose nominal volume is 30 cm³ as declared by the manufacturer. The three-dimensional reconstruction was performed using images obtained through micro-computed tomography (micro-CT) with the Baker Hughes GE Phoenix V|tome|x M300 system, enabling detailed internal visualization and precise segmentation of the sensitive cavity, with the complete exclusion of the central electrode. The determined volume was 30.7 cm³, revealing a difference of +0.7 cm³ (+2.3%) in relation to the value provided by the manufacturer. The use of micro-CT proved to be an effective metrological tool for the non-destructive evaluation of ionizing radiation measurement devices, allowing for more accurate analyses than conventional methods. This study is part of a broader initiative aimed at implementing a primary air-kerma standard at the Department of Radiological Sciences (DCR).
Copyright (c) 2025 Vanessa Mondaini de Castro, Carlos Eduardo de Almeira, Olga Maria Oliveira de Araújo, Ricardo Lopes Tadeu, Carla Lemos Mota https://creativecommons.org/licenses/by-nc-nd/4.0
Efficiency evaluation of a Commercial Software for Breast Cancer plus Lymph Nodes Radiotherapy Planning
The emergence of automation tools to assist in the routine tasks of Radiation Therapy centers has become increasingly prominent in recent years, particularly in sites with a high incidence of cancer. Various commercial software solutions are available for automated treatment planning; among these, EZFluence from Radformation Inc. (New York, USA) stands out as a tool used for achieving dose homogeneity within the target tissue by generating sliding window or Field-in-Field Beams. Therefore, the objective of this study is to assess the efficiency gains associated with the implementation of the EZFluence tool in clinical practice. Two experienced physicists retrospectively manually planned treatment for ten patients, with breast cancer and eight patients with breast cancer and lymph node involvement. The time taken to create clinically acceptable plans was recorded. Additionally, the time taken to generate plans using EZFluence was documented. The treatment protocol adopted for this study consists of hypofractionation, with 40.05 Gy delivered in 15 fractions. The mean time required to generate treatment plans decreased from 15 minutes and 57 seconds ± 4 minutes and 11 seconds to 8 minutes and 40 seconds ± 2 minutes and 48 seconds for plans generated using EZFluence for breast cancer patients without lymph node involvement (p-value < 0.01) and from 23 minutes and 52 seconds ± 4 minutes and 47 seconds for manual planning to 15 minutes and 56 seconds ± 1 minute and 26 seconds for plans generated using EZFluence for breast cancer patients with lymph node involvement (p-value < 0.01). Furthermore, the dosimetric quality of the plans was found to be comparable, once all the manual and automatic plans were adjusted to meet clinical acceptability criteria. The use of EZFluence has been demonstrated to enhance planning efficiency while upholding the dosimetric quality of treatment plans.
Copyright (c) 2025 Giulianne Rivelli Rodrigues Zaratim, Ricardo Gomes dos Reis, Luis Felipe Oliveira e Silva https://creativecommons.org/licenses/by-nc-nd/4.0
Construction of a low-cost simulator for evaluating doppler ultrasound image quality
The doppler ultrasound technique is widely used in medicine, being essential for cardiac function assessment and other applications. Understanding the physical principles that underpin each diagnostic examination modality and applying them in simulators (phantoms) allows for the analysis of image formation and the identification of quality parameters required by health regulations. This study aims to describe the construction of a low-cost doppler simulator prototype for evaluating image quality parameters in doppler ultrasound devices. The methodology was developed in stages that included: study and development of the base material and ducts simulating biological tissues, construction of the electronic system for pumping and monitoring flow, assembly of the simulator, acquisition of static and dynamic images, and qualitative and quantitative analysis of the results. The analyses indicate that the device satisfactorily reproduces the similarity to biological tissues, blood vessels, and flow, in addition to demonstrating the doppler phenomenon in flow variation in both directions. The simulator also proved useful for the calibration of ultrasound equipment, with a sensitivity of 83% in the assessment of blood flow velocity.
Copyright (c) 2025 Francisco Gomes, Fabio Rolemberg Silva https://creativecommons.org/licenses/by-nc-nd/4.0
Evaluation of Image Quality in Digital Breast Tomosynthesis
The most widely used imaging modality for early detection of breast cancer is mammography. However, it has limitations, since it obtains two-dimensional images of a three-dimensional structure, generating tissue overlap. The implementation of digital breast tomosynthesis (DBT) makes it possible to minimize this condition, allowing for more accurate diagnoses. However, to ensure that images with diagnostic quality are acquired, it is important to perform periodic evaluations on the equipment. In Brazil, there are few studies on quality control in DBT, and specific limits have not yet been established in national standards. Therefore, the tests performed in this study were based on international protocols, such as the Protocol of the Spanish Society of Medical Physics (SEFM), the Protocol for Quality Control of the physical and technical aspects of digital Breast Tomosynthesis systems of the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services (EUREF) and those used by the National Health Service Breast Screening Programme (NHSBSP), in order to establish a local baseline. Quantitative evaluations were performed by calculating the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and qualitative evaluations were performed by visually inspecting for artifacts and inhomogeneities; and by assessing the system's ability to identify groups of microcalcifications, masses, and fibers using the Phantom ACR (American College of Radiology). The results indicate good agreement in the qualitative and quantitative tests, with homogeneous images throughout the reconstructed volume. A reduction in the CNR was observed in the reconstructed volumes compared to the raw data, possibly attributed to the reconstruction algorithm. The CNR varied satisfactorily, remaining below the 20% limit, demonstrating the equipment's ability to handle different dense areas. In the repeatability and DGM tests, the results were below the reference limits, and the performance in the ACR simulator remained within the manufacturer's specifications.
Copyright (c) 2025 Bianca Franciele Santana dos Santos, Marcela Costa Alcântara Estácio, Karoline Ferreira Batista, Márcia Regina Pereira Attie https://creativecommons.org/licenses/by-nc-nd/4.0
Computed Tomography is a widely used diagnostic tool, performed on various types of patients. However, when it comes to the pediatric population, conducting the exam can present specific challenges, especially regarding the child’s cooperation during the procedure. Due to the need for high-quality images and the equipment’s sensitivity to movement, sedation often becomes indispensable to ensure a successful exam. Nonetheless, this approach involves several risks and limitations, such as image degradation caused by sedation devices, the clinical risks associated with sedation itself, reliance on the availability of a specialized anesthesiologist, and the need for post-exam care. Because of these factors, many institutions choose, whenever possible, to avoid sedation and allow the presence of a caregiver in the exam room as an alternative to promote containment and comfort for the child. This caregiver assumes the role of reassuring and containing the child; however, this practice introduces a new concern regarding radiation protection, since the individual present in the room is potentially exposed to scattered radiation emitted by the child. Therefore, this study aimed to evaluate, based on the annual dose limits for members of the public established by the Brazilian National Nuclear Energy Commission (CNEN), the levels of scattered radiation to which caregivers are exposed during pediatric computed tomography procedures. The results showed that without the use of personal protective equipment (PPE), the effective dose to caregivers for pediatric head, mastoid, and abdomen (without contrast) protocols was approximately 38, 19, and 12 µSv, respectively. Additionally, a 94% reduction in scattered radiation dose was observed for the same protocols with the use of PPE.
Copyright (c) 2025 José Ravel Campos Lima, Cássio Costa Ferreira, Matheus Bastos Reis, Victoria Beatryz Alves de Andrade https://creativecommons.org/licenses/by-nc-nd/4.0
Lattice Radiotherapy: A Comparative Feasibility Study of IMRT with VMAT
The comparative study included ten neoplasia cases planned with IMRT, contrasted with VMAT plans previously studied in the institution. The Lattice Spatially Fractionated Radiation Therapy technique was applied in the initial fraction, prescribing 5 Gy to the target volume and 14 Gy to spheres within the GTV, followed by four additional fractions of 5 Gy homogeneous in the target. The study revealed greater difficulty in conforming the prescribed dose to peaks, evidenced by the conformity index variation, averaging 1.85 ± 0.27 for IMRT and 1.19 ± 0.24 for VMAT. The analysis indicated a +4.1% discrepancy in the average dose at peaks and a 3.7 ratio in MUs. Although both met quality criteria in gamma evaluation, IMRT's beam-on time was 3.6 times longer than VMAT. The analysis of OAR doses suggests comparability between approaches. This study emphasizes the potential equivalence between SFRT with the Lattice technique using IMRT versus VMAT. It concludes that both have peculiarities, with the choice based on clinical needs, treatment efficiency, and technology availability. The increase in MUs and beam-on time were IMRT's main limitations, but its efficacy in preserving critical organs was highlighted, reinforcing the safety and personalization of radiotherapeutic treatment with IMRT in the application of the Lattice technique.
Copyright (c) 2025 JHEFERSON SALVADOR DA SILVA GOMES, Marina de Arruda Botelho, Maira Ribeiro dos Santos, Julia Martini Fontana, Joel Marques Xavier Filho https://creativecommons.org/licenses/by-nc-nd/4.0
Clinical implementation of Total Body Irradiation with Tomotherapy: from imaging to dose delivery
Total Body Irradiation (TBI) has been used as part of conditioning regimens pre-bone marrow transplantation for several years. With technology advances, IMRT started to be applied to this purpose, aiming potentially less toxicity by allowing OAR sparing and more homogeneous dose distribution. Tomotherapy® equipment has been used for modulated TBI and represents a sophisticated, safe and high quality method for this purpose. The main purpose of this paper is to present a methodology to clinically implement TBI treatments using Tomotherapy and to provide metrics of dose distribution based in our clinical experience. The presented methodology includes in a description of the immobilization accessories used and presenting a detailed workflow for treatment planning and delivery. Results of 20 patients showed good uniformity and target coverage, registration offsets averages inferior to 5 mm and in-vivo dosimetry with good agreement with the prescribed dose. The provided metrics could be used as a guide for those institutions that are willing to implement TBI with Tomotherapy.
Copyright (c) 2025 Pedro Henrique Bonfim Cardoso, Gabriela Reis dos Santos de Jesus, Daniela Piai Groppo https://creativecommons.org/licenses/by-nc-nd/4.0
Quantitative Analysis of the Uniformity of Ultrasound Images: An Approach Based on the Horssen Method
Introduction: Ultrasound (US) imaging is widely used in medical procedures. RDC No. 611/2022 and IN No. 96/2021 establish quality control (QC) criteria for US systems in Brazil, including the uniformity test, which is often based on visual and subjective analyses. Objectives: To evaluate the computational analysis of images from linear transducers based on the method of Horssen et al. (2017) for the uniformity test, considering the effect of acquisition mode and equipment gain. Materials and Methods: Images were acquired at the Hospital de Clínicas de Porto Alegre and Clínica Sidi using a Konex UN-US simulator. The tested variables included transducer pressure and tilt, with images evaluated for uniformity and gain sensitivity according to Horssen et al. (2017) and IN 96. The analysis in Python applied statistical parameters such as covariance, skewness, and minimum value. Results and Conclusions: The method effectively identified and quantified image uniformity, showing high covariance averages (22.48) and low Ulow values (-0.43), indicating lower uniformity. Extreme tilt angles negatively impacted uniformity, recommending 90°. Pressure variations had minimal influence. The method proved effective in assessing US image uniformity.
Copyright (c) 2025 Ester Azeredo da Silva Lima, Thatiane Alves Pianoschi Alva, Rochelle Lykawka, Alexandre Bacelar, Viviane Rodrigues Botelho https://creativecommons.org/licenses/by-nc-nd/4.0
Yesterday’s bunkers, today’s technologies: how to expand the modulated workload without structural renovations?
The incorporation of modulated techniques in radiotherapy has raised new challenges for shielding adequacy in radiotherapy treatment bunkers, originally designed for conventional workloads. Renovating these structures is often impractical, and traditional reassessment methods, such as those from NCRP Report No. 151, show practical limitations for operating facilities. This study presents a practical analytical model based on direct dose rate measurements and an inverse calculation approach to quickly and safely estimate the maximum permissible workload, while complying with CNEN regulatory standards. We evaluated five Brazilian institutions, using real clinical profiles and bunker characteristics. The results showed that most facilities could increase the use of modulated techniques up to 100% without requiring structural modifications. Additionally, response surface modeling confirmed the mathematical consistency and operational reliability of the method. Compared to existing approaches, our model offers greater simplicity, faster application, and better alignment with actual construction features. This work provides a practical tool for expanding the use of advanced techniques and optimizing treatment capacity in radiotherapy centers, without compromising radiation protection, representing a strategic advancement for the management of oncology services.
Copyright (c) 2025 Andre Gonçalves Prospero, Lucas Radicchi, Leandro Baptista, Beatriz Tomazzi, Herminiane Vasconcelos, Cristina Giolo, Flávio da Silva Guimarães, Thales Hilario Hungaro, Amanda Meletti, Fernanda Belletti, Taís Peron, José Carlos da Cruz https://creativecommons.org/licenses/by-nc-nd/4.0
Energy Deposition and DNA Damage Analysis of Protons and Alpha Particles simulated with FLUKA applied to a cellular model
Microdosimetry is a crucial research area in the development of radiotherapy that aims to understand dose variations at the subcellular level. This work addresses microdosimetry with proton and ion beams, focusing on energy deposition in a cellular geometric model implemented using the Monte Carlo method via FLUKA software. Scenarios were simulated where a proton beam or an alpha particle beam, with energies ranging from 1 to 20 keV, interacted with a simplified cellular model. Detectors were set up to record fluence and energy density in the medium during simulations. The results showed that more particles reached the nucleus as beam energy increased, especially for alpha particles. Energy density analysis revealed that the depth of maximum deposition increases with kinetic energy and was higher for alpha particles. Subsequently, using MCDS (Monte Carlo Damage Simulation) software, dose data from simulations were used to calculate the probability of various DNA damage types—base lesions (BD), single-strand breaks (SSB), and more complex breaks. This study confirmed the effectiveness of the model in simulating microdosimetric effects, highlighting differences in energy deposition and DNA damage between protons and alpha particles. These findings contribute to a better understanding of radiation interactions and the improvement of radiotherapy.
Copyright (c) 2025 Victória Raposo, Joel Mesa Hormaza https://creativecommons.org/licenses/by-nc-nd/4.0
Characterization Of Optically Stimulated Luminescent Dosimeters Used For Dosimetry In Mammography
Mammography is currently the most effective method for detecting breast cancer early. As it is an exam that uses ionizing radiation, it is necessary to monitor and optimize the doses received by patients, to guarantee high quality images with the lowest dose. One method of monitoring dose to the breast is by measuring skin entry kerma using dosimeters and calculating the mean glandular dose (MGD). There are several dosimeters that can be used for this, such as thermoluminescent dosimeters (TLD) and optically stimulated dosimeters (OSLDs). However, as the response of the OSL dosimeter differs depending on the energy used, to guarantee the use of this type of dosimeter, there is a need to characterize its limits, reproducibility, precision and evaluate the energy dependence. The objective of this work is to characterize the OSLDs for the energy range used in mammography and evaluate results of measurements carried out in mammography services in the country between the years 2020 and 2022 using this type of dosimetry. For this, the lower limit of detection (DLID), reproducibility, statistical precision, sensitivity factor and calibration factors were determined. As a result, DLID = 18.5035 ± 0.0009 µGy, sensitivity factors between 0.91 and 1.07 and calibration factors between 0.248916 and 0.294323 µGy/Reading were found. It was concluded that the lower limit of detection of OSLDs is capable of detecting values close to 98% lower than the minimum dose used in mammography exams and that the sensitivity factors determined improve the reproducibility of dosimeters when using large batches.
Copyright (c) 2025 Stella Mainoth, Claudio Almeida, João Emílio Peixoto https://creativecommons.org/licenses/by-nc-nd/4.0
Development of a Hand Phantom for Teaching in Medical Radiology
The primary objective of the present study was the development and validation of a three-dimensional (3D) anatomical model of a pediatric hand (phantom) using 3D printing technology. The initial stage involved 3D printing of the mimicked bone structures using ABS (Acrylonitrile Butadiene Styrene) filament, followed by the fabrication of a silicone mold, which was then filled with a transparent polymer to simulate soft tissues. The phantom was validated through radiographic imaging and computed tomography (CT). Radiographic images revealed a strong correlation between the anatomical structures of the phantom and those of a human hand, demonstrating the accuracy of the bone features. Based on CT analysis, the density values in Hounsfield Units (HU) for cortical bone (734.4 ± 75.2 HU) and trabecular bone (235.5 ± 43.9 HU) showed agreement with clinical data and relevant literature, confirming the reliability of additive manufacturing in replicating the radiological properties of bone tissue. However, the soft tissue covering (-160.4 ± 21.7 HU) suggested a predominantly adipose and aerated composition of the material used, indicating a potential area for future refinement to improve the representation of soft tissues. The developed phantom represents a cost reduction of over 95% compared to commercial models, without compromising the quality of bone tissue representation, further validating its application in both clinical practice and research contexts.
Copyright (c) 2025 Bárbara Bohrer, Lu´´´´isa Cassol, Valnir De paula, Jonas Teloeken, Marion Silva da Silva, Thiago Victorino Claus https://creativecommons.org/licenses/by-nc-nd/4.0
Optimization of Patient Care Flow in a Radiotherapy Service using the PDCA Cycle
This study explored the application of the PDCA Cycle (Plan, Do, Check, Act) to optimize the patient care workflow in a radiotherapy service, focusing on efficient scheduling and execution of sessions on linear accelerators. Prior to the study, the service faced workload overload issues with significant delays, especially in the afternoon and evening periods. The methodology included the standardization of routines, definition of performance indicators, and restructuring of the schedule based on the actual capacity of the equipment, adjusting the average times by type of treatment. In the implementation of the PDCA Cycle, quality management tools were used, i.e., brainstorming, 5 Whys, Ishikawa diagram, and control charts. The results showed a significant reduction (p<0.05) in delays without compromising service capacity. The reorganization of time slots enabled an optimal distribution of workload with more efficient use of resources, resulting in punctual sessions and shorter waiting times. Patient satisfaction analysis after the intervention revealed a reduction in complaints related to delays and an improved perception of efficiency in care. The application of the PDCA Cycle proved effective in optimizing the care workflow through schedule and slot adjustments. The continuous adoption of the PDCA Cycle has shown to be a resilient and adaptable strategy, promoting quality, efficiency, and safety in radiotherapy care.
Copyright (c) 2025 Rogério Sanches Santos, Carlos Eduardo Ribeiro, Carlos Eduardo Gonçalves de Oliveira, Emerson Nobuyuki Itikawa https://creativecommons.org/licenses/by-nc-nd/4.0
Environmental Monitoring Program: Methodologies and Air Kerma Assessments at the Regional Center for Nuclear Sciences of the Midwest
This work presents an analysis of the Environmental Monitoring Program (PMA) of CRCN-CO, with a focus on air kerma measurements. The PMA is essential to ensure the containment of radioactive waste resulting from the Goiânia accident, as well as to guarantee compliance with the regulations of the National Nuclear Energy Commission (CNEN) and international standards. Additionally, it ensures adherence to the safety guidelines established by CNEN and international radiological protection standards.
Copyright (c) 2025 Laísa Vieira dos Santos, Daniel Anderson Rodrigues, Rugles César Barbosa https://creativecommons.org/licenses/by-nc-nd/4.0
Assessment of intrafractional motion in lung SBRT treatment
The global impact of cancer on public health is alarming, leading to a significant increase in incidence and mortality, including in Brazil, where an increase to approximately 704 thousand new cases between 2023 and 2025 is projected. Lung cancer is one of the most common forms of the disease, affecting both men and women. Radiotherapy plays a crucial role in the treatment of lung cancer, harnessing technological advancements to improve precision and minimize side effects. The technique of Stereotactic Body Radiotherapy (SBRT) has emerged as an effective approach, especially for patients who are not candidates for surgery. However, respiratory motion can compromise the accuracy of radiation delivery, requiring the use of respiratory management techniques and 4DCT imaging to ensure treatment accuracy. Cone-Beam Computed Tomography (CBCT) plays a fundamental role in error correction during the treatment process. At the National Cancer Institute (INCA), SBRT has been applied since 2014, with rigorous verification protocols before each radiotherapy session. Recent studies have focused on intrafraction target motion during lung SBRT, aiming to enhance treatment effectiveness and reduce adverse effects. A prospective analysis of the total treatment time of six patients undergoing lung SBRT highlighted the importance of immobility during the procedure. The results revealed small patient displacements, which did not have a significant impact on dose distribution, as the displacements were within the adopted margin and without radiation dosimetric impairments. Although the current 5 mm PTV margin used at INCA is considered appropriate, further research is needed to determine whether a reduction of this margin can further improve outcomes for patients.
Copyright (c) 2025 Valquiria Guimarães Pereir https://creativecommons.org/licenses/by-nc-nd/4.0
Study of the Feasibility of Optimizing the Skull Computed Tomography Protocol Using Figure of Merit
Computerized tomography medical examinations are an imaging diagnostic method that employs high doses of radiation, compared to other diagnostic modalities. According to Resolution RDC 611/2022, medical exposures of patients must be optimized to the minimum value necessary to obtain the radiological objective, as well as being compatible with acceptable image quality standards. The objective of this work is to present the evaluation of a process to optimize the skull computed tomography examination protocol using the figure of merit (FOM) method, evaluating image acquisition parameters, dose and quality of image. FOM was calculated using contrast-to-noise ratio (CNR) and volumetric computed tomography dose index (CTDIvol). The tomographic image quality assessment simulator of the tomography equipment itself was used to calculate the CNR and CTDIvol indicated by the equipment for each evaluated protocol. The criterion established to indicate the most optimized protocol was the one that obtained the highest FOM value. 10 protocols were evaluated, varying the current, tube rotation time and iDose, in addition to the routine protocol currently used. Among the protocols evaluated, two protocols showed better performance, Protocol 08 and Protocol 09, promoting an increase in FOM of 34.47% and 31.61% and a dose reduction of 50.29% and 50.10% respectively, in relation to the routine protocol currently used.
Copyright (c) 2025 Danillo Menezes Oliveira, Fábio Alessandro Rolemberg Silva, João Vinícius Batista Valença, Marcelo Motta Garcia, Claudio Lucindo Rodrigues Junior https://creativecommons.org/licenses/by-nc-nd/4.0
Risk Analysis Based on Failure Modes and Effect Analysis for the IGRT Process
Image-Guided Radiation Therapy is a positioning technique that enables precise verification of the region to be irradiated based on images obtained in the treatment room prior to the radiotherapy procedure and compared to reference images. Therefore, it is a highly recommended technique and it is necessary to guarantee its safe applicability. For this safety, the Failure Modes and Effect Analysis (FMEA) tool was used to perform the risk analysis in two centers. With the analysis, it was possible to perceive the importance of identifying the Failure Modes with the highest Risk Priority Number (RPN) and severity values ​​so that interventions could be proposed in order to obtain a mitigation of possible errors, in addition to the broad participation of the multidisciplinary team. The results obtained with the FMEA proved useful for the identification of the most probable errors in each of the institutions, being favorable for the quality assurance related to the IGRT process. However, it is of fundamental significance that its use is thoroughly understood in order to identify all the possible errors that may be involved and, in this way, deliver radiotherapy treatment with greater quality and efficiency.
Copyright (c) 2025 Gabriela Alves Costa, Victor Augusto Bertotti Ribeiro, Laura Furnari, Caroline Castilhano Bueno https://creativecommons.org/licenses/by-nc-nd/4.0
Quality Assessment of Commercial Contouring Software based on Convolutional Neural Networks: Implications for Clinical Practice
The treatment planning for radiotherapy, particularly the delineation of pelvic structures, is a complex and time-consuming task, demanding considerable expertise from physicians. The development of automation tools for these procedures could potentially reduce the workload and improve treatment planning efficiency. The goal of this study is to evaluate the efficacy of the AutoContour software, a commercial auto-segmentation tool utilizing convolutional neural networks, in delineating organs at risk during cervical cancer radiotherapy. We evaluated the performance of the AutoContour software on fifteen pelvic CT scans from cervical cancer patients previously treated at our institution. This study compared the automatically generated structures with those manually delineated by two experienced radiation oncologists. The comparison employed the Dice Similarity Coefficient (DSC) to assess the quality of structures, and we also measured the time savings achieved by using the auto-segmentation tool. The study found that most of the structures delineated by the AutoContour software closely matched those contoured by the radiation oncologists, with DSC values greater than 0.80, indicating high similarity. However, the bowel bag showed lower similarity, which could be attributed to interobserver variability among the physicians themselves. The use of AutoContour resulted in a reduction of up to 25.86 minutes in the time required per patient for structure delineation, demonstrating substantial efficiency gains without compromising the quality of the contours. The AutoContour software streamlines the delineation process in cervical cancer radiotherapy planning, maintaining high-quality output with minimal need for adjustments. These results suggest that the integration of this auto-segmentation tool could considerably decrease the specialized workload, enhancing the overall efficiency of clinical workflows in radiation oncology departments. This automation not only saves time but also reduces the potential for human error, promising more consistent and reliable treatment planning.
Copyright (c) 2025 RICARDO GOMES DOS REIS, Otacílio P. L. Frota, Wenzel C. de Abreu, Giullianne Rivelli R. Zaratim, Thyago F. Mangueira, Luis Felipe Oliveira e Silva https://creativecommons.org/licenses/by-nc-nd/4.0
Avaliação da ecogenicidade e ecotextura de tecidos moles da cavidade abdominal de Pets por meio da técnico de histograma em escala cinza
Ultrasound is an imaging technique used in veterinary medicine to evaluate different organs and tissues. It is a non-invasive, safe, and cost-effective procedure that enables real-time visualization, making it valuable for assessing organs and monitoring potential pathologies. However, certain challenges are encountered in this practice, either due to reliance on the operational aspects of the equipment or the need for proper interpretation by the operator. This reliance is linked to the necessity of comparing the echogenic characteristics of organs with similar features. To address these limitations, this study aimed to correlate the qualitative and quantitative evaluation of the echogenicity and echotexture of soft tissues in the abdominal cavity of animals using the grayscale histogram (HEC) technique. For this purpose, abdominal ultrasounds of 16 different dogs were analyzed as part of the clinical routine of a veterinarian. All images were examined following a standardized measurement protocol. Subsequently, histograms with superimposed curves were created for organs with multiple ultrasound images, compiling them into a single graph for each organ of each animal. The images studied were qualitatively classified according to the condition of the organ. The grayscale histogram technique proved to be effective, demonstrating consistency between quantitative and qualitative analyses in assessing the echogenicity and echotexture of soft tissues in the abdominal cavity of animals. This method enables a more precise and objective diagnostic report while also presenting numerical patterns that can assist in the characterization and conclusion of such reports.
Copyright (c) 2025 Maryane Ferreira, Mateus Hilário de Lima, Carlos Henrique Souza Santos https://creativecommons.org/licenses/by-nc-nd/4.0
Metodologia para Validação de Equipamento de Proteção Individual Ocular Para Uso Com Laser em Procedimentos Médicos
Laser beams are widely used in health institutions and require proper protection to operator and patient. International standards provide counseling on how to exert this protection, specially with respect to the eye which is very sensible to optical radiation. Googles must provide enough shielding to specific wavelengths of the laser beam used in the procedure. In this work we present a protocol on how to determine whether a google is adequate to a specific laser emitter. Real values were used in the calculations and must be adapted for each situation.
Copyright (c) 2025 Cássio Moura, Maiara Cecchin, Rochelle Lykawka, Alexandre Bacelar https://creativecommons.org/licenses/by-nc-nd/4.0
Development of an Automated Image Segmentation Platform for Cell Migration Assays Based on Artificial Intelligence
Biomedical image analysis has significantly benefited from advances in artificial intelligence, particularly through the application of convolutional neural networks (CNNs) for cellular structure segmentation. This study proposed the development of a web-based computer vision tool to automate the analysis of cell migration assays (wound healing), replacing the traditional manual method performed using ImageJ. A total of 716 images were collected, converted, normalized, resized, and expanded through data augmentation techniques, resulting in 4,160 images used for training. Segmentation annotations were performed using Roboflow with the Smart Polygon tool and the Segment Anything Model 2 (SAM2). The final tool was made available through an interactive interface on the Hugging Face Spaces platform, enabling users to upload and automatically analyze images with graphical overlay of the results. The effectiveness of the tool was evaluated by comparing manual and automated analyses across datasets reviewed by three independent operators. The Roboflow fast model demonstrated superior performance compared to YOLOv11 fast (mAP@50 = 94.9; precision = 99.6%; recall = 87.7%) and improved inter-operator consistency, reducing the variability observed in the traditional manual method. These results demonstrate that the automated solution significantly reduces analysis time, eliminates subjectivity, and enhances reproducibility, establishing itself as an efficient, standardized, and accessible alternative for cell migration studies.
Copyright (c) 2025 Nycolas Mariotto, Geovana Andrade dos Santos, Geovana Ramos Fioschi, Andria Cristini Marata Higino, Luís Fernando Pereira Passeti, Thainá Omia Bueno Pereira, Gabriela Morelli Zampieri, Valéria Cristina Sandrim, Allan Felipe Fattori Alves https://creativecommons.org/licenses/by-nc-nd/4.0
Bases Metodológicas para Cálculo de Blindagens em Medicina Nuclear
In Brazil, every Nuclear Medicine Service must submit a shielding memorandum to regulatory bodies before construction and the start of its activities. The premises of radiative facilities must have sufficient shielding to keep the doses received by the public and Occupationally Exposed Individuals within the reference levels established by the resolutions of the National Nuclear Energy Commission. Shielding consists of adding physical barriers to existing structures to attenuate ionizing radiation from sources within the facilities. This requires complex calculations due to the many variables involved, as nuclear medicine uses unsealed sources of ionizing radiation, and the patients themselves become radioactive sources. Few documents have been published on this subject, and to date, we have not found a publication in the literature that clearly brings together all the necessary information and guidelines for performing shielding calculations for nuclear medicine facilities. The aim of this work is to provide a guide with methodological bases and a logical reasoning process for performing shielding calculations in nuclear medicine in Brazil, compiling the definitions and considerations found in the literature.
Copyright (c) 2025 Paula Duarte Correia, Walter Siqueira Paes, Ana Paula Perini, Lucio Pereira Neves https://creativecommons.org/licenses/by-nc-nd/4.0
Unraveling the Mechanisms of Radiotherapy: Biological Pathways and Therapeutic Innovations
Radiotherapy (RT) plays a pivotal role in oncology as a treatment modality for various malignancies, leveraging physical principles such as ionizing radiation to damage cancer cells and inhibit tumor growth. Recent advancements in RT technologies, such as proton therapy, carbon ion radiotherapy (CIRT), and adaptive radiation therapy (ART) have significantly enhanced the precision and effectiveness of radiation delivery. Despite these technological advancements, RT is still limited by factors such as tumor heterogeneity, normal tissue toxicity, and radioresistance, which can significantly impact treatment outcomes. The biological effects of radiation, including DNA damage, cell cycle arrest, and apoptosis, are influenced by the tumor microenvironment (TME) and mechanisms like hypoxia, which contribute to increased resistance. Nanoparticles, with their multifunctional capabilities, have emerged as a promising tool to overcome these limitations. They enable precise targeting, enhance local radiation deposition, and modulate the TME, potentially improving the efficacy of RT. However, concerns regarding their biocompatibility and potential toxicity, particularly with prolonged exposure, must be addressed. Furthermore, the integration of artificial intelligence (AI) and machine learning (ML) into radiotherapy planning is revolutionizing treatment strategies. These technologies allow for more accurate tumor delineation, personalized treatment planning, and optimization of radiation doses, improving therapeutic outcomes. To overcome radioresistance, innovative combination therapies that target both tumor cells and the TME, along with advancements in nanotechnology and AI, are promising avenues to enhance RT efficacy and improve patient survival.
Copyright (c) 2025 Silvina Odete Bustos, Renata Saito, Wagner Henrique Marques, Mara de Souza Junqueira, Roger Chammas https://creativecommons.org/licenses/by-nc-nd/4.0
A Critical Analysis of the Overall Uncertainties in the Radiotherapy Treatment Process
The integration of all the steps involved in the treatment process is quite complex, as it involves the correct knowledge of the dose-response curves developed in laboratory experiments, the translation of these results to the clinic, the adequate delineation of the tumor, the appropriate dose prescribed for each type of tumor and delivered daily to the patient. For example, the correct assessment of the dose administered to a patient strongly depends on an interconnected chain of steps executed harmoniously, as the demand for accuracy of a given dosimetry procedure is very high. In this case, the measurement results must be represented the best possible reported values with their typical uncertainties to allow clinical results to be achieved and comparable with those of other institutions. The robustness of the chain of events is often fragile, with uncertainties at each stage sometimes not considered or sometimes difficult to estimate, requiring different conceptual and statistical approaches at various times in the decision-making process. As a result, as the additive sequence of uncertainties is generally not fully considered, and the clinical outcome may not be as anticipated. The objective of this review is to critically and constructively highlight the weak points observed in the interrelationship of all steps that lead to better tumor control and ultimately, to provoke a reflection on the theme.
Copyright (c) 2025 Carlos Eduardo de Almeida https://creativecommons.org/licenses/by-nc-nd/4.0