Vocal Load of University Professors: Preliminary Results

Purpose: To describe the acoustic characteristics of a classroom, voice quality, fatigue, and vocal load of university professors. Methods: Exploratory, observational, longitudinal, and descriptive study with a single group of participants, including vocal monitoring data over two weeks. Acoustic characterization of the classroom, perceptual-auditory evaluation, and acoustic analysis of voice samples were conducted before and after classes. Vocal dosimetry was performed during classes, and the Vocal Fatigue Index (VFI) was assessed at the beginning of each week. Descriptive analysis of the findings was conducted, and randomization test was performed to verify the internal reliability of the judge. Results: All participants reported speaking loudly in the classroom, with the majority reporting vocal changes in the past six months, and only one participant reported a current vocal change. The classroom had acoustical measures and estimations that deviated from established standards. The professors used high vocal intensities during classes. After the classes, an increase in the absolute values of the aggregated data for CAPE-V, jitter, and fundamental frequency was found, varying within the range of normality. Furthermore, there was an observed increase in both post-lesson intensity and VFI when comparing the two-week period. Conclusions: Vocal intensities and VFI were possibly impacted by the acoustics of the classroom. The increase in average VFI between the weeks may be attributed to a cumulative fatigue sensation. Further research with a larger number of participants and in acoustically conditioned classrooms is suggested in order to evaluate collective intervention proposals aimed at reducing the vocal load on teachers.

Objetivo: Describir las características acústicas, calidad vocal, fatiga y carga vocal de profesores universitarios. Métodos: Estudio exploratorio, observacional, longitudinal, descriptivo con un solo grupo de participantes y datos de monitoreo vocal durante dos semanas. Se realizó caracterización acústica de la sala, evaluación auditiva-perceptiva y acústica de muestras de voz antes y después de las clases. Se realizó dosimetría vocal durante las clases y se verificó el Índice de Fatiga Vocal (IFV) en dos semanas. Se realizó un análisis descriptivo de los hallazgos y una prueba de aleatorización para verificar la confiabilidad interna del juez. Resultados: Todos los participantes informaron hablar en voz alta en clase, la mayoría informó cambios vocales en los últimos seis meses y solo uno informó cambios vocales actuales. La sala presentó mediciones y estimaciones acústicas fuera de las normas establecidas. Los profesores utilizaron intensidades vocales altas durante las clases. Hubo un aumento en los valores absolutos de los datos agrupados para CAPE-V, jitter y frecuencia fundamental, variando dentro de los límites normales, después de las clases. La intensidad después de las clases y el IFV, en la comparación entre las dos semanas, mostraron un aumento. Conclusiones: La dosis vocal y el IFV posiblemente se vieron afectados por la acústica del aula. El aumento del IFV medio entre semanas pudo deberse a la sensación de cansancio acumulada. Se sugieren nuevas investigaciones con un mayor número de participantes y que se realicen en la sala acondicionada acústicamente para evaluar propuestas de intervención colectiva, con el objetivo de reducir la carga vocal de los docentes.

Vocal Demand Response to the Educational Setting Based Communication Scenarios: A Single Subject Study

Objectives: This was a single-subject study, aimed to demonstrate different vocal demand situations that are typical for primary school and teacher's vocal demand response under two acoustical conditions, with and without voice amplification, during five working days. Methods: The long-term voice dosimetry with Vocal Holter Med (PR.O. Voice Srl) was carried out on a 49-year-old female teacher with voice disorders during daily teaching activities. A sound field amplification system (SFAS) PentaClass Runa was installed in the classroom. Voice dosimetry was provided under two different acoustical conditions: without SFAS (2 days) and with SFAS (3 days). Results: Phonation time percentage, sound pressure level (SPL), SPL SD, fundamental frequency (F0), F0 SD, cycle, and distance doses were investigated in seven communication scenarios (lessons, group/individual classes, sports lessons in the gym and schoolyard, breaks, lunch breaks, and other activities). The median scores of all voice parameters differed significantly between different vocal demand contexts. The significant statistical difference in the vocal demand response was in the communication situations with and without SFAS. In addition, the number of children, reverberation time, and ambient air relative humidity impacted voice SPL and the cycle dose. Conclusions: Lessons, sports lessons held in the gym or schoolyard, breaks, and lunch breaks were considered as high vocal demand communication situations requiring higher voice intensity and fundamental frequency, higher phonation time percentage, cycle, and distance doses. Group/individual work and other teacher activities during the day, unrelated to direct work with students, were categorized as low vocal demand communication scenarios.

Objetivos: Este fue un estudio de sujeto único, cuyo objetivo fue demostrar diferentes situaciones de demanda vocal típicas de la escuela primaria y la respuesta vocal de los docentes bajo dos condiciones acústicas, con y sin amplificación de voz, durante cinco días laborables. Métodos: Se llevó a cabo dosimetría vocal a largo plazo con Vocal Holter Med (PR.O. Voice Srl) durante las actividades diarias de enseñanza en una docente de 49 años con trastornos de la voz. Se instaló un sistema de amplificación de campo sonoro (SFAS) PentaClass Runa en el aula. La dosimetría vocal se realizó bajo dos condiciones acústicas diferentes: sin SFAS (2 días) y con SFAS (3 días). Resultados: Se investigaron el porcentaje de tiempo de fonación, el nivel de presión sonora (SPL), SPL SD, la frecuencia fundamental (F0), F0 SD, ciclos y dosis de distancia en siete escenarios de comunicación diferentes (clases, clases grupales/individuales, clases de educación física en el gimnasio y el patio de la escuela, recreos, almuerzos y otras actividades). Las puntuaciones medias de todos los parámetros vocales diferían significativamente entre los diferentes contextos de demanda vocal. La diferencia estadísticamente significativa en la respuesta a la demanda vocal se observó en las situaciones de comunicación con y sin SFAS. Además, el número de niños, el tiempo de reverberación y la humedad relativa del aire ambiente afectaron al SPL de la voz y la dosis de ciclo. Conclusiones: Las lecciones, las clases de educación física en el gimnasio o el patio de la escuela, los recreos y los almuerzos se consideraron situaciones de comunicación de alta demanda vocal, que requerían una mayor intensidad y frecuencia fundamental de la voz, un mayor porcentaje de tiempo de fonación y dosis de ciclo y distancia más altas. El trabajo grupal/individual y otras actividades del profesor durante el día no relacionadas con el trabajo directo con los estudiantes se categorizaron como escenarios de comunicación de baja demanda vocal.

Validation of automated image co-registration integrated into in-house software for voxel-based internal dosimetry on single-photon emission computed tomography images / Validação do corregistro automático de imagem integrado a software de análise de dosimetria interna baseada em voxel para tomografia computadorizada de emissão de fóton único

Abstract Objective: To develop an automated co-registration system and test its performance, with and without a fiducial marker, on single-photon emission computed tomography (SPECT) images. Materials and Methods: Three SPECT/CT scans were acquired for each rotation of a Jaszczak phantom (to 0°, 5°, and 10° in relation to the bed axis), with and without a fiducial marker. Two rigid co-registration software packages-SPM12 and NMDose-coreg-were employed, and the percent root mean square error (%RMSE) was calculated in order to assess the quality of the co-registrations. Uniformity, contrast, and resolution were measured before and after co-registration. The NMDose-coreg software was employed to calculate the renal doses in 12 patients treated with 177Lu-DOTATATE, and we compared those with the values obtained with the Organ Level INternal Dose Assessment for EXponential Modeling (OLINDA/EXM) software. Results: The use of a fiducial marker had no significant effect on the quality of co-registration on SPECT images, as measured by %RMSE (p = 0.40). After co-registration, uniformity, contrast, and resolution did not differ between the images acquired with fiducial markers and those acquired without. Preliminary clinical application showed mean total processing times of 9 ± 3 min/patient for NMDose-coreg and 64 ± 10 min/patient for OLINDA/EXM, with a strong correlation between the two, despite the lower renal doses obtained with NMDose-coreg. Conclusion: The use of NMDose-coreg allows fast co-registration of SPECT images, with no loss of uniformity, contrast, or resolution. The use of a fiducial marker does not appear to increase the accuracy of co-registration on phantoms.

Resumo Objetivo: Desenvolver corregistro automático e testar seu desempenho com ou sem marcador fiducial em imagens de tomografia computadorizada de emissão de fóton único (SPECT). Materiais e Métodos: Três SPECT/CTs foram adquiridas para cada rotação de um simulador de Jaszczak em relação ao eixo da maca (0°, 5° e 10°), com e sem fiducial. Dois métodos de corregistro inelástico foram aplicados - SPM12 e NMDose-coreg -, e a porcentagem do erro quadrático médio (%RMSE) foi usada para analisar a qualidade do corregistro. Uniformidade, contraste e resolução foram medidos antes e após o corregistro. NMDose com corregistro automático foi usado para calcular a dose renal de 12 pacientes tratados com 177Lu-DOTATATE e comparado com OLINDA/EXM. Resultados: A marcação fiducial não modificou a qualidade do corregistro das imagens SPECT, medida pela %RMSE (p = 0,40). Não houve impacto na uniformidade, contraste e resolução após o corregistro de imagens adquiridas com ou sem fiduciais. Aplicação clínica preliminar mostrou tempo total de processamento de 9 ± 3 min/paciente para NMDose e 64 ± 10 min/paciente para OLINDA/EXM, com alta correlação entre ambos, apesar de menor dose renal em NMDose. Conclusão: NMDose-coreg permite o corregistro rápido de imagens SPECT, sem perda de uniformidade, contraste ou resolução. O uso da marcação fiducial não aumentou a precisão do corregistro em fantomas.

Inicio de la Dosimetría Biológica en Costa Rica y su importancia en la atención de poblaciones sobreexpuestas a radiaciones / Beginning of Biological Dosimetry in Costa Rica and its importance in the care of populations overexposed to ionizing radiation

Resumen Introducción: el laboratorio de citogenética del Instituto de Investigaciones en Salud (INISA) de la Universidad de Costa Rica estableció un Servicio de Dosimetría Biológica en enero del 2020 utilizando biomarcadores citogenéticos de exposición a radiaciones ionizantes. Es el primero de su tipo en la región centroamericana. Objetivo: establecer un servicio de dosimetría biológica para Costa Rica, elaborando una curva de calibración dosis-efecto para rayos gamma. Metodología: para la realización de la curva de calibración se irradiaron muestras de sangre periférica in vitro con rayos gamma de dos voluntarios, uno femenino y otro masculino, en 11 puntos de dosis en el rango de 0 a 5 Gy. Se cultivó la sangre acorde a los protocolos internacionales durante 48 horas y se registraron las aberraciones inducidas. Los programas Dose Estimate V5.2 y R versión 4.03 se utilizaron para el cálculo de los coeficientes de la curva de calibración que correlaciona la frecuencia de cromosomas dicéntricos con la dosis. Resultados: los coeficientes de la curva son α: 0.02737±0.00658, ß: 0,05938±0,00450 y C: 0.00129±0.00084. Estos coeficientes tienen valores similares a los reportados internacionalmente. La curva se validó calculando dos dosis incógnitas, en la primera incógnita la dosis suministrada fue de 1,5 Gy y la dosis estimada fue 1,47 Gy y en la segunda la dosis suministrada fue de 4 Gy y la dosis estimada fue 3,616 Gy, para ambos casos no existen diferencias estadísticamente significativas entre las dosis suministradas y las estimadas. Conclusiones: actualmente El Servicio de Dosimetría Biológica del INISA puede estimar dosis absorbida en personas que se sospecha de una sobre exposición a rayos gamma en personal ocupacionalmente expuesto o personas involucradas en un accidente radiológico.

Abstract Introduction. The cytogenetics laboratory of the Health Research Institute (INISA) of the University of Costa Rica established a Biological Dosimetry Service in January 2020 using cytogenetic biomarkers of exposure to ionizing radiation. It is the first of its kind in the Central American region. Objective: establish a biological dosimetry service for Costa Rica, developing a dose-effect calibration curve for gamma rays. Methodology: to carry out the calibration curve, peripheral blood samples from two volunteers, one female and the other male, were irradiated in vitro with gamma rays, at 11 dose points in the range of 0 to 5 Gy. Blood was cultured according to international protocols for 48 hours and induced aberrations were recorded. The Dose Estimate V5.2 and R version 4.03 programs were used to calculate the coefficients of the calibration curve that correlates the frequency of dicentric chromosomes with the dose. Results: the coefficients of the curve are α: 0.02737 ± 0.00658, ß: 0.05938 ± 0.00450 and C: 0.00129 ± 0.00084. These coefficients have values similar to those reported internationally. The curve was validated by calculating two unknown doses, in the first unknown case the delivered dose was 1.5 Gy and the estimated dose was 1.47 Gy and in the second case the delivered dose was 4 Gy and the estimated dose was 3.616 Gy. for both cases there are no statistically significant differences between the delivered and estimated doses. Conclusions: the Biological Dosimetry Service of the INISA can estimate absorbed dose in persons suspected of overexposure to gamma rays in occupationally exposed personnel or persons involved in a radiological accident.Health is loaded with symbolisms and practical manifestations that differ according to social groups and sociocultural contexts. In order to make everyday life and needs visible, the Theoretical Paradigm of Social Representations provides the theoretical-methodological bases necessary to understand the common sense knowledge associated with health among the Nicaraguan migrant population in Costa Rica. Methodology: Qualitative study with ethnographic approach that aimed to identify the social representation of health, through the process of objectification, present among Nicaraguan migrants living in Costa Rica. Data collected through semi-structured interviews, participant observation, and field diaries. Processing according to Content Analysis. Results: The social representation of health found behaves analogously to a formula; where, the search for peaceful environments is added to the achievement of financial stability to result in two interdependent representations: 1) Health as physical-mental strength; and 2) Health as a future and abstract sensation of well-being, happiness and transcendence. The socio-political antecedents in Nicaragua, the migratory process, and the adaptation to Costa Rica play a preponderant role in shaping the representation on health. Conclusion: Social representations about health have direct practical implications on the ways of life and needs of migrant groups. Understanding their common sense knowledge allows to move towards more contextualized public policies. More integration of the thoughts, opinions and feelings of migrants in decision-making platforms is recommended.

Description of the methodology for dosimetric quantification in treatments with 177Lu-DOTATATE. / Descripción de la metodología para la cuantificación dosimétrica en tratamientos con 177Lu-DOTATATE.

Implementation of dosimetry calculations in the daily practice of Nuclear Medicine Departments is, at this time, a controversial issue, partly due to the lack of a standardized methodology that is accepted by all interested parties (patients, nuclear medicine physicians and medical physicists). However, since the publication of RD 601/2019 there is a legal obligation to implement it, despite the fact that it is a complex and high resource consumption procedure. The aim of this article is to review the theoretical bases of in vivo dosimetry in treatments with 177Lu-DOTATATE. The exposed methodology is the one proposed by the MIRD Committee (Medical Internal Radiation Dose) of the SNMMI (Society of Nuclear Medicine & Molecular Imaging). According to this method, the absorbed dose is obtained as the product of 2factors: the time-integrated activity of the radiopharmaceutical present in a source region and a geometrical factor S. This approach, which a priori seems simple, in practice requires several SPECT/CT acquisitions, several measurements of the whole body activity and taking several blood samples, as well as hours of image processing and computation. The systematic implementation of these calculations, in all the patients we treat, will allow us to obtain homogeneous data to correlate the absorbed doses in the lesions with the biological effect of the treatment. The final purpose of the dosimetry calculations is to be able to maximize the therapeutic effect in the lesions, controlling the radiotoxicity in the organs at risk.

Amplificador de voz: efeitos na dose e na intensidade vocal de professoras sem disfonia / Voice amplifier: effects on dose and vocal intensity of teachers without dysphonia

RESUMO Objetivo Analisar a interferência do uso do amplificador de voz na dose vocal de professoras não disfônicas. Método Trata-se de um estudo experimental, comparativo intrassujeitos, composto por 20 professoras do ensino fundamental da Rede Municipal de Ensino de Belo Horizonte/MG. Após o consentimento as participantes, foram solicitadas a responder o questionário de Escala de Sintomas Vocais - ESV e posteriormente participaram de dois momentos do estudo, selecionados aleatoriamente. No primeiro momento as participantes utilizaram somente o dosímetro vocal e no segundo momento utilizaram o dosímetro vocal e o amplificador de voz. As medições foram registradas pelo aparelho durante 1h40m, na sala de aula que as professoras lecionavam. O espaço entre as duas medições foi de uma semana, sendo mantidas a mesma sala, mesmo horário e mesma disciplina lecionada, em ambos os momentos. Resultados O parâmetro intensidade foi o único que apresentou diferença com o uso de amplificação de voz. Conclusão O uso da amplificação de voz durante a docência de professoras não disfônicas não interfere nos parâmetros acústicos de frequência fundamental, e nas medidas de dose vocal. A intensidade da voz é menor quando o professor faz uso de amplificação vocal.

ABSTRACT Purpose Analyze the interference of using the voice amplifier in vocal dose of non-dysphonic teachers. Methods This is an experimental study comparing people from the same ambience compound for 20 teachers from municipal elementary school in Belo Horizonte/MG. After consent, the participants were requested to answer the vocal symptom scale questionnaire (ESV) and later participated in two different moments of the study, for which they randomly selected. In the first moment, the participants used only the vocal dosimeter and in the second, they used the vocal dosimeter and the voice amplifier. The measurements were recorded by the device for 1h40m, in the classroom that the teachers taught. The time between the two measurements was one week, with the same room, the same time and the same discipline being taught, at both times. Results The intensity parameter was the only one that showed difference with the use of the voice amplifier. Conclusion Use voice amplification while non-dysphonic teachers are teaching doesn't affect the fundamental frequency and vocal dose measure in the acoustics parameters. The vocal intensity is smaller when teacher uses the vocal amplification.

Análise da dose vocal em pessoas cisgênero: resultados preliminares / Analysis of vocal dose in cisgender people: preliminary results

RESUMO Objetivo Verificar a diferença das medidas de frequência fundamental, intensidade e de dose vocal entre mulheres e homens cisgêneros, em situações de mesma demanda de voz. Métodos Trata-se de uma pesquisa observacional transversal. Participaram do Grupo 1 cinco homens cisgêneros, com idade entre 21 e 24 anos, e do Grupo 2, cinco mulheres cisgêneras, com idade entre 22 e 25 anos, todos sem queixas vocais e estudantes do curso de Fonoaudiologia. Os indivíduos foram pareados por demanda vocal, sendo que todos estavam matriculados nas mesmas disciplinas do curso de graduação. Todos os participantes se autodefiniram como cisgêneros, ou seja, identificaram-se com o sexo designado ao nascer. A coleta foi realizada de forma simultânea aos pares (um participante do G1 e um do G2), por um período contínuo de dez horas. Para a coleta de dados, utilizaram-se dois dosímetros da marca VoxLogⓇ. Para comparação das medidas entre os grupos utilizou-se o teste t de Student, com nível de confiança de 95%. Resultados Observou-se que as mulheres cisgêneras apresentaram maiores valores de frequência fundamental (p=0,001), porcentagem de fonação (p=0,037), dose cíclica (p=0,002) e dose de distância (p=0,008). A intensidade da voz de ambos os grupos foi semelhante no período avaliado. Conclusão Mulheres cisgêneras apresentam maiores valores de frequência fundamental, porcentagem de fonação, dose cíclica e dose de distância, do que homens cisgêneros. Avaliar a dose vocal entre os gêneros é importante para a melhor compreensão dos fatores etiológicos das disfonias comportamentais e para definir uma reabilitação vocal mais personalizada.

ABSTRACT Purpose The purpose of this study is to verify the difference in fundamental frequency, intensity and vocal dose measurements between male and female cisgender people, in same voice demand situations. Methods This is a cross-sectional observational case study. Group 1 participated with five male people, aged between 21 and 24 years old and Group 2 with five female people, aged between 22 and 25 years old, both without vocal complaints, students of the Speech-language pathology course. The individuals were paired by vocal demand, and all were enrolled in the same activists of the undergraduate course. All participants defined themselves as cisgender, that is, they identified themselves with the gender designated at birth. The data was carried out at the same time, for a period of 10 hours, while the participants carried out their daily activities for that period. For data collection, two dosimeters of VoxLogⓇ, were used. Student's t test was used to compare measures between groups. The 95% confidence level was considered. Results It was observed that women have higher values of fundamental frequency (p=0,001), percentage of phonation (p=0,037), cyclic dose (p=0,002) and distance dose (p=0,008). The voice intensity of both groups was similar in the period evaluated. Conclusion cisgender women have higher values ​​of fundamental frequency, percentage of phonation, cyclic dose and distance dose than cisgender men. Assessing the vocal dose between genders is important for a better understanding of the etiological factors of behavioral dysphonia and to define a more personalized vocal rehabilitation.

Application of computed tomography dose index as dosimetric parameter in dental tomography / Aplicação do índice de dose em tomografia computadorizada como parâmetro dosimétrico em tomografia odontológica

ABSTRACT Objective Quantify the CTDI from a reference beam, correcting this value for several beam widths from the ratio of CTDI100 values measured in the air, and verifying the underestimation of the dose comparing CTDI100 and CTDI300, applied to dental CBCT. Methods i-CAT and Prexion 3D tomographs, 100mm pencil ionization chamber, electrometer. Firstly for beam above 40 mm, CTDIW,NT from CTDIW,Ref, multiplied by the ratio of CTDIAR measurements to N.T widths and reference, was estimated. In second, CTDI100 and CTDI300 are obtained by displacing the ionization chamber along the beam with spacing intervals equal to 100 mm to cover sufficiently large integration intervals for CBCT protocols, and a comparison is made through the modified efficiency. Results CTDIAR,100,Ref averaged 53% higher than CTDIW,Ref, due to attenuation of the beam by the simulator object, and the ratio between CTDIAR,100,Ref and CTDIW,Ref is greater than 1, being this constant relationship and validating the method for dosimetry in quality control tests. For the second method, CTDI100 greatly underestimates the dose deposited on the central axis, where CTDI300 covers all beam sizes and stands out in relation to CTDI100 to more accurately quantify the radiation levels emitted. Conclusions The IEC method is applicable to quality control, facilitating practice, and optimizing time and resources. CTDI300 is a better dose descriptor than CTDI100, and should be implemented for CBCT modalities when used.

RESUMO Objetivo Quantificar o CTDI a partir de um feixe de referência, corrigindo este valor para diversas larguras de feixe a partir da razão dos valores CTDI100 medidos no ar e verificar a subestimação da dose comparando o CTDI100 e CTDI300, aplicados à CBCT odontológica. Métodos Tomógrafos i-CAT e Prexion 3D, câmara de ionização de 100mm tipo lápis, eletrômetro. Primeiramente para feixes acima de 40mm, estimou-se o CTDIW,NT a partir do CTDIW,Ref, multiplicado pela razão das medidas do CTDIAR para larguras N.T e referência. Em segundo, CTDI100 e CTDI300 são obtidos deslocando-se a câmara de ionização ao longo do feixe com intervalos de espaçamento igual a 100 mm para cobrir intervalos de integração suficientemente grandes para protocolos CBCT e uma comparação é realizada através da eficiência modificada. Resultados O CTDIAR,100,Ref foi em média 53% maior que o CTDIW,Ref, devido a este atenuar o feixe pelo objeto simulador, e a razão entre o CTDIAR,100,Ref e CTDIW,Ref é maior que 1, sendo essa relação constante e validando o método para dosimetria em testes de controle de qualidade. Para o segundo método, o CTDI100 subestima muito a dose depositada no eixo central, onde o CTDI300 abrange todos os tamanhos de feixe e se destaca em relação ao CTDI100 para quantificar com maior exatidão os níveis de radiação emitidos. Conclusão O método IEC é aplicável para controle de qualidade, facilitando a prática, e otimizando tempo e recursos. O CTDI300 é um melhor descritor de dose que o CTDI100, e deve ser implementado para modalidades CBCT quando usados.

Caracterización dosimétrica de equipos para radioterapia superficial con rayos X / Dosimetric characterization of X-ray Surface Radiotherapy Equipments

RESUMEN Introducción: en Cuba, en el 2018, fueron diagnosticados un total de 12 070 nuevos casos de cáncer de piel, de los cuales se estima que 11 587 corresponden a la variante no melanómica. La radioterapia con rayos x está considerada como la primera opción de tratamiento en muchos de estos casos. Recientemente, el sistema nacional de salud, adquirió cuatro equipos de la marca SENSUS SRT-100TM para el tratamiento del NMSC. Objetivo: desarrollar una metodología estandarizada para la caracterización dosimétrica de los equipos de radioterapia superficial con rayos X instalados en Cuba. Métodos: se caracterizaron cuatro equipos de radioterapia SENSUS SRT-100TM para cada una de sus calidades radiológicas, en términos de linealidad, estabilidad, capa hemirreductora, tasas de dosis de referencia, perfiles de dosis, factores de cono y porcentaje de dosis en profundidad. Se emplearon para ello, las recomendaciones de la AAPM TG-61 y el IAEA-TRS 398. Resultados: lo promedios de las HVLs (mm Al) y sus respectivos coeficientes de variación (CV) fueron de 5,526 - 5,2 %; 1,130 - 2,1 % y 2,007 - 2,1 % para 50,70 y 100 kV respectivamente. Los rendimientos presentaron poca variabilidad entre máquinas (CV < 3%) y fueron muy similares por los métodos "en agua" y "en aire" (discrepancia. < 0,5 %). Conclusiones: los equipos muestran una excelente estabilidad, y características dosimétricas muy similares entre ellos, lo cual permite establecer valores de referencia para eventuales auditorías externas y re-ajustes de los haces ulteriormente a los mantenimientos o reparaciones que impliquen al generador de rayos X.

ABSTRACT Introduction: in Cuba, in 2018, a total of 12 070 new cases of skin cancer were diagnosed, from which it is estimated that 11 587 correspond to the non-melanoma type. Radiation therapy with X-rays is considered the first-line treatment in many of these cases. Recently, the national healthcare system acquired four SENSUS SRT-100TM units for treating Non-Melanoma Skin Cancer (NMSC). Objective: to develop a standardized methodology for the dosimetric characterization of the equipments of surface radiotherapy with X-rays installed in Cuba. Methods: four SENSUS SRT-100TM radiotherapy equipments were characterized for each of their radiological qualities, in terms of linearity, stability, hemi-reductive layer, reference dose rates, dose profiles, cone factors and percentage of dose in depth. The recommendations of the AAPM TG-61 and the IAEA-TRS 398 were applied for this purpose. Results: the averages of HVLs (mm Al) and their respective coefficients of variation (CV) were 5,526 - 5,2 %; 1,130 - 2,1 % and 2,007 - 2,1 % for 50, 70 and 100 kV respectively. The yields presented little variability between machines (CV < 3%) and were very similar by the methods "in water" and "in air" (discrepancy < 0,5 %). Conclusions: the equipments show excellent stability and very similar dosimetric characteristics among them, which allows establishing reference values for eventual external audits and beam readjustments after the maintenance or repairs involving the X-ray generator.

Descripción de elementos de radioprotección y dosimetría en unidades de cardiología intervencionista sudamericanas: un estudio piloto / Radioprotection and dosimetry in Interventional cardiology units in South America. a pilot study

ANTECEDENTES: Las unidades de Cardiología intervencional han evidenciado un número creciente de procedimientos, cada vez más variados y complejos, lo cual podría eventualmente generar daños a los profesionales ocupacionalmente expuestos a radiaciones ionizantes (POEs) de no contar con los adecuados elementos de radioprotección y un uso correcto de ellos. OBJETIVO: Caracterizar la disponibilidad y utilización de los elementos de radioprotección y dosimetría de unidades de cardiología intervencionista de centros Sudamericanos. MATERIAL Y MÉTODOS: Se realizó una encuesta autoaplicada a 139 POEs, de ambos sexos de 7 países, a través de una plataforma on-line, se les consultó sobre características demográficas, dosimétricas y de radioprotección. RESULTADOS: Los elementos de radioprotección más tradicionales; delantales y cuellos plomados se utilizaron un 99,5 % y 98,4 % respectivamente, aquellos elementos más recientes como gafas, gorros y paños plomados solo alcanzaron un 36,8 %, 6,8 % y 34,2%, de utilización respectivamente, en cuanto a la utilización de los dosímetros, solo un 7,9 % lo hace apegado a las normas de la Organización Internacional de Energía Atómica (OIEA). CONCLUSIÓN: Se constató en la muestra analizada una falta de elementos de radioprotección y un uso inadecuado de ellos, urge realizar intervenciones educativas y técnicas para mejorar estos datos.

BACKGROUND: Due to the increasing number of interventional cardiology procedures currently performed, health professionals (POE) are exposed to ionizing radiation unless adequate protective elements are used. AIM: to describe the use of radioprotection elements and dosimetry in interventional cardiology laboratories in South America. METHODS: A self-administered survey was performed on 139 POE of both sexes and 7 countries using an online platform. Demographic data, dosimetry and characteristics of radioprotection analyzed. RESULTS: Commonly used radioprotective elements (lead aprons and collars) were used in 99.5% and 98% respectively. Recently introduced protection elements like lead goggles, caps and drapery were used in 36.8, 6.8 and 34.2% , respectively. Dosimetry according to the International Atomic Energy Commission (OIAE) was performed in only 7.9% of the procedures. CONCLUSION: there is a severe lack of adequate radioprotection during interventional cardiology procedures. Urgent measures, including technical implementation and educational interventions are needed to improve radioprotection in interventional cardiology.

A prospective comparative study of two methods of individual calculation of 131I activity in the treatment of hyperthyroidism. / Estudio prospectivo comparativo de dos métodos de cálculo individual de la actividad de 131I en el tratamiento del hipertiroidismo.

OBJECTIVE: Radioiodine (131I) is an established modality of definitive treatment of hyperthyroidism. In spite of the vast experience available, there are still several aspects to be clarified, such as whether fixed or calculated doses should be used. The aim of this study was to assess whether efficacy of this treatment could be improved by implementing a simple dosimetric calculation method including ultrasonographic estimation of thyroid volume and a single measurement of 24-hour 131I thyroid uptake. METHODS: A prospective non-inferiority study was designed to compare two procedures to calculate radioiodine activity: the «semi-fixed¼ dose method (A), and the «calculated¼ dose method (B). The first consisted of activity escalation (185MBq steps) based on etiology of hyperthyroidism, 131I uptake, and treatment objective. The second method was based on the «dosimetric compromise¼ concept, considering 24-hour uptake and thyroid volume as the only factors and using a standard half-life of 5.5 days. The target absorbed dose was 150Gy, but after a preliminary analysis (first 100 cases) it was increased to 200Gy in diffuse toxic goiters (DTGs). RESULTS: A total of 212 patients were included. MethodB was at least as effective in terms of final and functional outcome, with a trend to more success and less hypothyroidism. In addition, activities administered were significantly lower. CONCLUSION: In radioiodine therapy of hyperthyroidism, a simple dosimetric method that provided results at least equal to those of a fixed dose-based method, with lower administered activities, could be implemented.

CPHR: 35 años al Servicio de la Protección Radiológica, la Salud y el Medio Ambiente / CPHR: 35 years at the Service of Radiological Protection, Health and the Environment

Resumen El Centro de Protección e Higiene de las Radiaciones fue fundado en 1985 para sustentar la aplicación segura de las tecnologías nucleares en Cuba. En la actualidad la institución es considerada como una referencia nacional y regional en materia de seguridad radiológica, gracias a una sólida estrategia institucional que aporta de manera sostenida soluciones a problemas prioritarios del país. Este trabajo presenta una reseña de los principales resultados del centro hasta la fecha.

Abstract The Center for Radiation Protection and Hygiene was founded in 1985 to support the safe application of nuclear technologies in Cuba. Nowdays, the institution is considered as a national and regional reference for radiation protection , thanks to the comprehensive institutional strategy that support the solutions of the problems with priority in the country. The paper presents the overview about the main results of the center up today.

Dose efetiva de radiação nos exames de tomografia computadorizada: um estudo retrospectivo e descritivo / Effective dose of radiation in exams of computed tomography: one retrospective and descriptive study

Contexto: A tomografia computadorizada revolucionou os estudos radiológicos convencionais. Porém, tal avanço se deu associado com o aumento das doses de radiação ionizante. A tomografia computadorizada representa 15% de todos os exames de imagem e contribui com 75% de radiação para a população. Objetivo: Estimar a dose efetiva de radiação imprimida aos pacientes durante os exames de tomografia computadorizada. Desenho e local: Estudo retrospectivo e descritivo em instituição hospitalar de nível terciário no Rio de Janeiro. Métodos: Foram selecionados 1.476 pacientes que realizaram exames de tomografia computadorizada de crânio, tórax e abdome/pelve, sem contraste endovenoso, no serviço de radiodiagnóstico do hospital no período de 1 de janeiro a 31 de março de 2018 para os exames de tórax, e no período de 1 de janeiro a 28 de fevereiro de 2018 para os exames de crânio e de abdome/pelve. Os dados foram coletados a partir do Picture Archivingand Communication System (PACS) da instituição para avaliar a dose de radiação utilizada por cada tipo de exame, por meio do cálculo das doses efetivas médias em cada tipo de exame. Resultados: As médias das doses efetivas encontradas foram de 1,57 mSv, 8,37 mSv e 12,28 mSv para os exames de crânio, tórax e abdome/pelve, respectivamente. Conclusão: O estudo verificou que os exames de crânio e abdome/pelve foram realizados com as médias das doses efetivas dentro dos valores típicos preconizados, enquanto nos exames de tórax as doses efetivas estavam acima da faixa fornecida pela Associação Americana de Física Médica (American Association of Physicists in Medicine, AAPM) (relatório # 96).

Resultados finales del programa cubano con niños de territorios afectados por el accidente de Chernóbil / Final results of the Cuban program for children from areas affected by the Chernobyl accident

RESUMEN Cuba organizó y desarrolló desde 1990 hasta 2011 un programa de atención médica integral masivo y gratuito destinado a niños de áreas afectadas por el accidente de Chernóbil. Este trabajo recoge los resultados finales de este programa, al cual estuvieron vinculados cientos de trabajadores de la salud y la ciencia en Cuba y que permitió, durante más de 21 años, que se trataran y rehabilitaran en la isla un total de 26 114 pacientes, el 84 % de los cuales eran niños, procedentes fundamentalmente de Ucrania, Rusia y Bielorrusia. Se presentan también otros aspectos de la colaboración médica desarrollada en territorio ucraniano, así como los resultados esenciales de la evaluación del impacto radiológico del accidente en los niños que recibieron asistencia médica en nuestro país.

ABSTRACT From 1990 till 2011, a free health care program for children from areas affected by the Chernobyl accident was organized and implemented by the Cuban Government.. A significant number of qualified personal in medicine and science collaborated with this program. The information gathered for more than 21 years and the conclusive results obtained in the program are presented here. During this time, 26 114 patients, 84 % children, mostly from Ukraine, Russia and Belarus were treated in the mentioned program. Other aspects of the Cuban medical assistance in Ukraine and the main results obtained in the radiological impact evaluation of the accident on the children treated in Cuba are also included.

Estimación de las desviaciones volumétricas de dosis entregada vs. planificada durante el tratamiento de hipertiroidismo con 131I: resultados preliminares / Estimation of volumetric dose distribution delivery deviations vs. dose planned in 131I hyperthyroidism treatment: preliminary results

Resumen En 2013, la Asociación Europea de Medicina Nuclear (AEMN) recomendó un "Procedimiento estándar" para desarrollar la dosimetría individual pretratamiento del Hipertiroidismo con 131I basada en la captación y en cinética tiroidea del paciente. Para estimar las desviaciones en la distribución de dosis entregada vs planificada al volumen tiroideo bajo este procedimiento, se desarrolló y verificó una aplicación en Matlab. Esta aplicación desarrolla el ajuste de la farmacocinética tiroidea, los cálculos de actividad acumulada, la estimación de la masa funcional tiroidea, el cálculo de la actividad a administrar para garantizar la dosis prescrita por el médico, y estimar el mapa tridimensional (3D) de dosis y los parámetros estadísticos relacionados que la caracterizan. La aplicación desarrollada se verificó empleando una imagen-maniquí y 6 farmacocinéticas conocidas. Además, se estimaron y verificaron los parámetros dosimétricos de planificación en 6 pacientes con dosis prescritas entre 150-400 Gy (promedio 241,67 Gy). Las distribuciones de actividad acumulada y de dosis absorbida fueron marcadamente heterogéneas. La distribución de dosis 3D mostró desviaciones estándar entre 18,01-27,08 % de la dosis prescrita. Las diferencias entre la dosis máxima y mínima por voxel/MBq de actividad administrada fue de 74-129 %. De acuerdo a los resultados, sólo entre el 50,2 % y 71,4 % de volumen tiroideo se tratará con la dosis prescrita ±20 %. Conclusiones: la dosis administrada al tejido tiroideo es no-homogénea y discrepa significativamente de la prescrita en algunas regiones, situación que requiere estudios posteriores más profundos con el objetivo de optimizar el tratamiento y sus resultados.

Abstract In 2013, the European Association of Nuclear Medicine Dosimetry Committee recommends a "Standard Operational Procedures for Hyperthyroidism Pre-Therapeutic Dosimetry" based on the assessment of the individual 131I uptake and kinetics. To estimate the 3D dose delivery deviations from prescribed dose during patient specific application of this SOP, a computer Matlab application was developed and verified. It was design to execute: radiopharmaceutical curve fitting, cumulated activity calculations, functional thyroid mass estimation, obtain the therapeutic planning activity to warranty the prescribed dose and produce the 3D planning dose map and related dosimetry parameters. 6 patients with 150-400Gy prescribed dose data planning (average 241,67Gy) were analysed using the developed application. The developed system was verify successfully using a test image phantom and 6 known pharmacokinetics data. The tridimensional thyroid volume cumulated activity and dose distributions were heterogeneous. 3D dose distribution showed standard deviations between 18.01-27.08 % of prescribed dose. The differences between maximum and minimum dose value per voxel/MBq were 74-129%. According to the result, between 50,2 % and 71,4 % of patient's thyroid will be treat with a dose of DP±20 % of planned dose, the rest will be overdose or sub dose. Conclusions: the 3D treatment planning dose distribution were completely no-homogenous, the significant difference observed should be study in the future more deeply in order to optimized the hyperthyroidism iodine treatment.

The association of dosimetric quantities from computed tomography with operational factors: basis for optimization strategies / Asociación de magnitudes dosimétricas de tomografía computarizada con factores operacionales: bases para estrategias de optimización

Abstract Clinical Computed Tomography (CT) imaging is supported by a patient - technology - observers system. Such system involves dosimetric quantities associated with image quality descriptors, where operational factors are predictors. Knowledge of quantitative association between CT dosimetric and image quality quantities with systemic factors, provides the basis to devise scanner-specific optimization strategies. Kerma indexes were measured with a pencil ionization chamber free in air C a,100 and in phantom C pmma,x (x changes into c and p for center and periphery respectively). Polymethyl Methacrylate (PMMA) standard phantoms were used (diameters of 16 and 32 cm). Several operational factors of a Siemens Sensation 64 Cardiac were considered: estimated spectrums, tube potential F 8 (80 - 140 kV), tube current x time product F 1 (40 - 350 mAs) and total collimation at isocenter F 3 (2,7 - 19,2 mm). The water equivalent radius R w , an important factor for patient Size Specific Dose Estimators (SSDE), was estimated by taking into account the spectrums in each phantom. Average pixel noise was measured from Regions of Interest (ROIs) in water phantoms with radius of 2,5; 3; 6; 8 and 11,5 cm. A linear association was found between C pmma,p and C pmma,c . A dose reduction of C pmma,c = 2 mGy per tube rotation can be obtained from data analysis (head mode), with F 1 = 50 mAs, F 3 = 19,2 mm, resulting in average pixel noise of 20 Hounsfield Units (HU). Knowledge of noise association with C pmma,c provides a straightforward tool for quantitative optimization, considering a systemic approach, which includes patient - technology - observer factors.

Resumen La tomografía computarizada (TC) clínica se basa en un sistema paciente - tecnología - observador. Dicho sistema incluye magnitudes dosimétricas asociadas a descriptores de calidad, donde los factores operacionales son predictores. Conocer la asociación cuantitativa entre magnitudes dosimétricas y de calidad de imagen con factores sistémicos, provee la base para concebir estrategias de optimización específicas por tomógrafo. Se midieron índices de kerma en aire C a,100 y en maniquí C pmma,x (x cambia a c y p para centro y periferia respectivamente) con una cámara de ionización tipo lápiz. Se utilizaron maniquíes de Polimetil Metacrilato (PMMA) con diámetros de 16 y 32 cm. Se consideraron factores operacionales de un equipo Siemens Sensation 64 Cardiac: espectros estimados, tensión del tubo F 8 (80 - 140 kV), producto corriente x tiempo de exposición F 1 (40 - 350 mAs) y colimación total en isocentro F 3 (2,7 - 19,2 mm). El radio agua-equivalente R w es un factor importante para Estimadores de Dosis Específicos del paciente (SSDE), se estimó teniendo en cuenta el espectro en cada maniquí. El ruido promedio de píxel se midió en regiones de interés (ROIs) de imágenes de maniquíes de agua con radios de 2,5; 3; 6; 8 y 11,5 cm. Se encontró una asociación lineal entre C pmma,p y C pmma,c . Se describe una reducción de dosis a C pmma,c = 2 mGy por rotación del tubo mediante el análisis de datos (modo cabeza), con F 1 = 50 mAs, F 3 = 19,2 mm, resultando en un ruido promedio de píxel de 20 Unidades Hounsfield (UH).

In vivo dosimetry in total body irradiation / Dosimetría in vivo en irradiación corporal total

Abstract Total Body Irradiation (TBI) is a radiotherapy technique that consists of irradiating homogeneously the whole patient's body and it is characterized by an extended source to surface distances and the use of large irradiation fields. The limitations of the available input data and inherent problems with the calculation procedures make it very difficult to accurately determine the dose distributions in TBI. For these reasons, it is highly recommended to use In Vivo Dosimetry (IVD), to guarantee the quality of TBI treatments as a direct measurement of the delivered dose. An IVD QA system was implemented based on semiconductor diodes and radiochromic films. For the commissioning of the system, both detector types were calibrated independently, using as reference an ionization chamber with a valid certificate in terms of absorbed dose to water (Dw). This guarantees the traceability of the measurements. An experiment was carried out to simulate a clinical TBI procedure to a phantom. In this way, the calibration of the dosimetry system was confirmed.

Resumen La irradiación total del cuerpo (TBI) es una técnica de radioterapia que consiste en irradiar de manera homogénea todo el cuerpo del paciente y se caracteriza por una fuente extendida a distancias superficiales y el uso de grandes campos de irradiación. Las limitaciones de los datos de entrada disponibles y los problemas inherentes con los procedimientos de cálculo hacen que sea muy difícil determinar con precisión las distribuciones de dosis en TBI. Por estos motivos, es altamente recomendable utilizar la dosimetría in vivo (IVD), para garantizar la calidad de los tratamientos de TBI como una medida directa de la dosis administrada. Se implementó un sistema IVD QA basado en diodos semiconductores y películas radiocromáticas. Para la puesta en marcha del sistema, ambos tipos de detectores se calibraron de forma independiente, utilizando como referencia una cámara de ionización con un certificado válido en términos de dosis absorbida en agua (Dw). Esto garantiza la trazabilidad de las mediciones. Se llevó a cabo un experimento para simular un procedimiento clínico de TBI a un fantasma. De esta forma, se confirmó la calibración del sistema de dosimetría.

Verificación de niveles de atenuación de protectores auditivos tipo copa en trabajadores del sector Hidrocarburos / Verifying the attenuation levels of earmuff hearing protectors in Oil & Gas workers / Verificando os níveis de atenuação dos protetores auditivos de abafador em trabalhadores de petróleo e gás

RESUMEN Objetivo Verificar los niveles de atenuación de dos tipos de protectores auditivos de copa bajo condiciones reales de operación. Métodos Se realizó un diseño experimental de medidas repetidas de los niveles de presión sonora al interior y exterior de los protectores auditivos, realizando mediciones de ruido bajo circunstancias habituales de trabajo para operadores de una planta de hidrocarburos. Posteriormente, se determinaron las diferencias entre los niveles de atenuación establecidos por el fabricante, los niveles de atenuación ajustados bajo el método recomendado por NIOSH y los niveles de atenuación obtenidos experimentalmente. Resultados Los valores de atenuación ofrecidos por los fabricantes difieren de los obtenidos experimentalmente, siendo estos últimos, menores en todos los casos del estudio. Los valores de atenuación de los protectores auditivos ajustados bajo el método NIOSH alcanzaron valores más cercanos a los experimentales. Conclusiones La variabilidad entre los valores de atenuación teóricos y experimentales, permiten establecer que las estimaciones de los niveles de atenuación obtenidos en condiciones controladas no consideran aspectos que en condiciones reales de uso afectan la eficiencia del protector auditivo. Este estudio plantea la necesidad de implementar programas integrales de protección auditiva, que permitan considerar variables asociadas a la eficacia del dispositivo en condiciones de uso, a través de la aplicación de pruebas de ajuste o en su defecto a través de la aplicación de los factores de ajuste sugeridos por NIOSH, con el fin de realizar una adecuada selección que permita alcanzar un control efectivo para el ruido.

ABSTRACT Objective To verify the attenuation levels of two types of earmuffs under real operating conditions. Materials and Methods A study with experimental design was carried out to obtain repeated measurements of the sound pressure levels inside and outside hearing protectors in a sample of workers of an oil and gas company working under normal process and exposure conditions. The results allowed determining differences between the attenuation levels established by the manufacturer, the adjusted attenuation levels under the NIOSH method, and the attenuation levels obtained experimentally. Results The attenuation values established by the manufacturers are lower than those ones obtained under actual use conditions in all cases evaluated. Likewise, the attenuation values of the hearing protectors, once adjusted under the NIOSH method, reached values much closer to those obtained experimentally. Conclusions The variability between theoretical attenuation values and experimental values allows concluding that the attenuation levels obtained under controlled laboratory conditions do not take into account certain characteristics that, based on their use, affect the efficiency of the hearing protection device. This study encourages the implementation of comprehensive hearing protection programs that consider variables such as hearing protection effectiveness, under real use conditions, by applying fit tests or other adjustment factors like the one suggested by NIOSH. This would ensure an adequate selection that aims at achieving an effective control of this risk factor.

RESUMO Objetivo Verifique os níveis de atenuação de dois tipos de protetores auriculares em condições reais de operação. Métodos Foi realizado um projeto experimental de medições repetidas dos níveis de pressão sonora dentro e fora dos protetores auditivos, fazendo medições de ruído em condições normais de trabalho para operadores de uma usina de hidrocarbonetos. Posteriormente, foram determinadas as diferenças entre os níveis de atenuação estabelecidos pelo fabricante, os níveis de atenuação ajustados pelo método recomendado pelo NIOSH e os níveis de atenuação obtidos experimentalmente. Resultados Os valores de atenuação oferecidos pelos fabricantes diferem daqueles obtidos experimentalmente, sendo este último menor em todos os casos do estudo. Os valores de atenuação dos protetores auditivos ajustados pelo método NIOSH atingiram valores mais próximos aos experimentais. Conclusões A variabilidade entre os valores de atenuação teórica e experimental permite estabelecer que as estimativas dos níveis de atenuação obtidos em condições controladas não consideram aspectos que, em condições reais de uso, afetam a eficiência do protetor auditivo. Este estudo levanta a necessidade de implementar programas abrangentes de proteção auditiva que permitam considerar variáveis associadas à efetividade do dispositivo em condições de uso, através da aplicação de testes de adaptação ou, na sua falta, através da aplicação de ajuste sugerido pelo NIOSH, a fim de fazer uma seleção adequada para obter um controle eficaz do ruído.(AU)

Comparación de la dosis recibida por personal ocupacionalmente expuesto en intervencionismo / Comparison of the received dose by occupationally exposed personnel in interventionism

El objetivo de esta investigación fue determinar la relación entre la dosis de radiación recibida y la práctica en intervención médica. Se estudiaron estadísticamente los reportes dosimétricos de profesionales que han laborado en intervencionismo con un Arco en C en el Hospital José Carrasco Arteaga de la ciudad de Cuenca, Ecuador. Estos informes se basan en lecturas bimensuales de los dosímetros TLD utilizados por el personal para seguridad radiológica. En total, se analizaron 124 personas que trabajaron en el período de noviembre de 2013 a marzo de 2018, es decir, 24 informes. La dosis promedio anual para las enfermeras de quirófanos es de 1,32 mSv, 1,59 mSv para el personal de Urología, 1,74 mSv para el personal de Gastroenterología, 1,78 mSv para el personal de Hemodinamia y 2,33 mSv para el personal de Traumatología. Se concluyó que la dosis promedio para cada práctica no excede la dosis de restricción de 1/3 de la dosis permitida para trabajadores ocupacionalmente expuestos. Intervencionismo en Traumatología resulta ser la práctica con mayor dosis recibida y la más baja perteneció al personal de Enfermería de Quirófanos. Estos resultados son de gran utilidad para saber qué nivel va acorde con cada práctica médica.

The objective of this research was to determine the relationship between the radiation dose received and the practice in medical intervention. The dosimetric reports of professionals who have worked in intervention with a C-Arm at the José Carrasco Arteaga Hospital in the city of Cuenca, Ecuador, were studied statistically. These reports are based on bi-monthly readings of the TLD dosimeters used by the staff for radiological safety. In total, 124 professionals who worked in the period from November 2013 to March 2018 were analyzed, that is, 24 reports. The average annual dose for operating room nurses is 1.32 mSv, 1.59 mSv for urology staff, 1.74 mSv for gastroenterology staff, 1.78 mSv for hemodynamic staff and 2.33 mSv for trauma staff. It is concluded that the average dose for each practice does not exceed the restriction dose of 1/3 of the dose allowed for occupationally exposed workers. Traumatology is the practice with the highest dose received and the lowest belongs to the operating room nursing staff. These results are very useful to know which level is consistent with each medical practice.

Dosimetria in vivo 2D por retroprojeção utilizando EPID em pacientes de próstata / [2D in vivo dosimetry by rear projection using EPID in patients with prostate]

Este trabalho avaliou a viabilidade de se realizar dosimetria in vivo 2D por retroprojeção em pacientes com câncer de próstata utilizando um dispositivo eletrônico de imagem portal (EPID) combinado a um método previamente validado para cálculo de dose no isocentro, e verificar se esta nova metodologia seria capaz de detectar variações significativas na entrega de dose. Fluências transmitidas pelo paciente durante o tratamento foram coletadas de 9 pacientes. Todos os tratamentos e imagens foram realizados em um acelerador linear Trilogy equipado com um detector de silicone amorfo modelo aS500-II e um On-Board Imager (OBI). Juntamente com uma tomografia Cone Beam (CBCT) adquirida no mesmo dia de tratamento e as fluências irradiadas diretamente no portal para a verificação prétratamento, um modelo previamente validado de cálculo de dose 1D foi utilizado para se calcular a distribuição 2D de dose no plano do isocentro. Desvios entre a dose esperada e a dose medida foram avaliados utilizando uma análise gamma (5%, 3 mm). Um conjunto de dados com 456 campos adquiridos em 68 datas de aquisição foi avaliado. A aprovação média da análise gamma para todos os campos foi de 95,4% e 79% dos campos tiveram aprovação superior a 90%. Ao considerar sessões de tratamento, 84% destas tiveram aprovações médias superiores a 90%. Uma revisão detalhada nos dados das sessões com aprovação média inferior a 90% demonstrou que variações no volume e conteúdo do reto era uma fonte frequente de variações na entrega de dose. A adaptação proposta neste trabalho demonstrou a viabilidade de se utilizar uma rotina automatizada por meio de scripts em Matlab. Grandes alterações na entrega de dose não foram identificadas, embora a metodologia tenha demonstrado sensibilidade suficiente para detectar alterações na entrega de dose devido à variabilidade no volume do reto dos pacientes.

This work assess the viability of performing 2D in vivo back-projection dosimetry for prostate cancer patients using an Electronic Portal Imaging Device (EPID) combined with a previously validated method for isocenter dose calculation, and verify whether this methodology could identify deviations in dose delivery. Transmitted field fluencies were collected using an EPID during treatment sessions of ten prostate cancer patients. All treatments and images were performed using a Trilogy linear accelerator equipped with an amorphous silicon EPID model aS500-II and On-Board Imager (OBI). Together with a Cone Beam Computer Tomography (CBCT) acquired at the same day as treatment and the fluencies directly irradiated over the EPID for the treatment plan quality assurance, a 1D previously validated mathematical model was utilized to calculate the 2D dose distribution of each field orthogonal plane that contains the isocenter. Deviations between the delivered and planned doses were evaluated utilizing a gamma analysis (5%, 3mm). A dataset of 476 fields acquired from 73 acquisition dates was evaluated. Gamma analysis mean approval rate of all fields was 95.0±8.2%, and 78% of the fields had approval rates superior to 90%. When considering treatment sessions, 82.8% of the acquisition dates had mean field approval superior to 90%. A detailed inspection on the acquisition dates whose mean approval rate was inferior to 90% revealed that a common source of error was differences on patients' rectum volume. The proposed adaptation of a previously implemented method for 1D in vivo back-projected dosimetry to a 2D approach through a streamline workflow of Matlab scripts was successfully achieved. No major dose delivery changes were observed in the utilized dataset. Nevertheless, the methodology showed enough sensitivity to detect changes in dose delivery, especially those related to volume changes in patients rectum.