Assessment of image quality in digital radiology using the CDRAD contrast-detail phantom in pediatrics / Evaluación de la calidad de la imagen en radiología digital utilizando el fantoma de detalle de contraste CDRAD en pediatría

ABSTRACT The transition from analog to digital radiology has expanded the capabilities of radiological imaging but has also made it possible to increase the radiation dose received by patients. Image quality in radiology is determined by factors such as radiographic techniques (kVp and mAs), which directly impact the dose and image quality. This study focuses on pediatric radiological exams considering their greater radiosensitivity and longer life expectancy. The study aimed to investigate the correlation between image quality and applied radiographic techniques using the CDRAD contrast-detail phantom. The results showed a direct linear relationship between the increase in kVp and the corresponding increase in image quality. Nonetheless, there was a significant variation in image quality between current-time products ranging from 0.5 to 2.5 mAs, in contrast to the nearly linear relationship observed within the 2.5 and 10 mAs range

RESUMEN La transición de la radiología analógica a la digital ha ampliado las capacidades de las imágenes radiológicas, pero ha también permitió aumentar la dosis de radiación que reciben los pacientes. La calidad de la imagen en radiología está determinada por factores como las técnicas radiográficas (kVp y mAs), que impactan directamente en la dosis y la calidad de la imagen. Este estudio se centra en exámenes radiológicos pediátricos considerando su mayor radiosensibilidad y mayor espe ranza de vida. El estudio está dirigido a investigar la correlación entre la calidad de la imagen y las técnicas radiográficas aplicadas utilizando el detalle de contraste CDRAD fantasma. Los resultados mostraron una relación lineal directa entre el aumento de kVp y el correspondiente aumento de calidad de la imagen. No obstante, hubo una variación significativa en la calidad de la imagen entre los productos actuales que van desde 0,5 a 2,5 mAs, en contraste con la relación casi lineal observada dentro del rango de 2,5 y 10 mAs.

Development of a teledentistry system for the elderly in the context of the covid-19 pandemic: 3d diagnostic models integration in a web platform / Desarrollo de un sistema de teleodontología para adultos mayores en el contexto de la pandemia de covid-19: integración de modelos de diagnóstico 3d en una plataforma web

Objective: To recognize the usefulness of incorporating Three-Dimensional models of standardized humans in electronic health records, in the context of the development of a teledentistry web platform designed for the attention of the elderly population in COVID-19 pandemic context. Material and Methods: A teledentistry web platform designed with different modules for clinical records. Through a new user-computer interface with a standardized virtual 3D phantom, an extraoral physical examination, an intraoral examination section was modeled. A label-associated marker is allowed to record descriptive aspects of the findings. A 3D odontogram represents multiple patient's conditions for each of the 32 dental positions. Results: From a total of 135 patients registered on the platform, 51 markers and 33 photographs associated with the surface of the virtual 3D phantoms were recorded. For the Location parameter: Hard palate 27.6%, inserted gingiva 15.7%, tongue 15.6%. For the Type of lesion parameter (according to the information entered in the pathology selector): unidentified 35.3%, sub-prosthetic stomatitis 23.5%, irritative fibroma 9.8%. Through the registration of the exact location of the finding in the virtual phantom by a 3D marker, the 3D modeling of the oral pathologies contributed to a better diagnosis, improving the remote communication between the attending dentist and specialists. Conclusion: The combination of the 3D modeling and anatomical-referencing in a teledentistry platform can become a powerful tool for the dental practice, due to their utility and specificity.

Objetivo: Reconocer la utilidad de incorporar modelos tridimensionales de humanos estandarizados en registros electrónicos de salud, en el contexto del desarrollo de una plataforma web de teleodontología diseñada para la atención de la población adulta mayor en contexto de pandemia por COVID-19. Material y Métodos: Una plataforma web de teleodontología diseñada con diferentes módulos para historias clínicas. A través de una nueva interfaz usuario-computadora con un fantoma 3D virtual estandarizado, se modeló un examen físico extraoral, una sección de examen intraoral. Se permite un marcador asociado a la etiqueta para registrar aspectos descriptivos de los hallazgos. Un odontograma 3D representa múltiples condiciones del paciente para cada una de las 32 posiciones dentales.Resultados: De un total de 135 pacientes registrados en la plataforma, se registraron 51 marcadores y 33 fotografías asociadas a la superficie de los fantomas virtuales 3D. Para el parámetro Ubicación: Paladar duro 27,6%, encía insertada 15,7%, lengua 15,6%. Para el parámetro Tipo de lesión (según la información ingresada en el selector de patología): no identificado 35,3%, estomatitis subprotésica 23,5%, fibroma irritativo 9,8%. A través del registro de la ubicación exacta del hallazgo en el fantoma virtual mediante un marcador 3D, el modelado 3D de las patologías orales contribuyó a un mejor diagnóstico, mejorando la comunicación remota entre el odontólogo tratante y los especialistas. Conclusión: La combinación del modelado 3D y la referenciación anatómica en una plataforma de teleodontología puede convertirse en una poderosa herramienta para la práctica odontológica, debido a su utilidad y especificidad.

Comportamiento dosimétrico de un sistema de planificación mediante curvas de calibración de densidades electrónicas relativas / Dosimetric behaviour of a planning system through calibration curves of relative electron density

En esta investigación se planteó como objetivo la verificación del comportamiento dosimétrico del Sistema de Planificación de Tratamiento (TPS) de Radioterapia mediante las curvas de calibración de Densidades Electrónicas Relativas (DER). Este estudio se realizó en el Hospital de la Sociedad de Lucha Contra el Cáncer (SOLCA) Núcleo Loja, usando un fantoma antropomorfo CIRS 062M y un tomógrafo Toshiba Activion 16. Para determinar la nueva curva de calibración DER se tomaron los valores de densidades electrónicas especificadas en el manual del fantoma y las Unidades Hounsfield de la imagen tomográfica. Se realizó controles de calidad dosimétricos y verificación dosimétrica en tres casos clínicos: tórax, pelvis y cráneo; para realizar las pruebas dosimétricas se utilizó un acelerador CLINAC CX, cámara de ionización PTW tipo Farmer con volumen sensible de 0,6 cm3 y un electrómetro PTW UNIDOS E. Los resultados mostraron que las medidas para cada inserto del fantoma en ningún caso excedieron los límites establecidos de ± 20 UH, para el tomógrafo y el TPS; las pruebas de control de calidad no superaron el límite máximo de desviaciones en el cálculo de dosis absorbida por el TPS y la obtenida por medición de ± 4 % establecida por la IAEA y las verificaciones dosimétricas en tórax, pelvis y cráneo, determinaron que las desviaciones en el cálculo de la dosis absorbida por el TPS y la obtenida por medición no superaban la tolerancia del ± 5 % establecida por la ICRU.

In this research, the aim was to verify the dosimetric behavior of the Radiotherapy Treatment Planning System (TPS) using the Relative Electron Density (DER) calibration curves. This study was carried out at the SOLCA (Society of Fight Against Cancer) hospital in Loja, using an CIRS model 062M anthropomorphic phantom and a Toshiba Activion 16 tomograph. To determine the new DER calibration curve, the values of the electron densities specified in the manual of the phantom and the Hounsfield Units of the tomographic image were taken. Dosimetric quality controls were made in the location of three clinical cases: thorax pelvis and skull; used a CLINAC CX accelerator was used to perform the dosimetric tests, PTW ionization chamber type Farmer with sensitive volume of 0.6 cm3 and a PTW UNIDOS E electrometer. The results showed that the measurements for each insert of the phantom in no case exceeded the established limits of ± 20 UH, for the tomograph and the TPS; the quality control tests did not exceed the maximum limit of deviations in the calculation of dose absorbed by the TPS and the one obtained by measurement of ± 4% established by the IAEA and the clinical planning in the thorax, pelvis and skull, determine that the deviations in the calculation of the dose absorbed by the TPS and that obtained by measurement, they do not exceed the tolerance of ± 5% established by the ICR.

The development of a free radiological anatomy software teaching tool / Desarrollo de un software libre de anatomia radiológica como una herramienta de enseñanza

SUMMARY: The purpose of this research was to develop a free radiological anatomy software for radiologic anatomy education to assist students and professionals in health science. The study was divided into two phases: image acquisition and software development. The first phase was to obtain plain radiographic images and computed tomographic (CT) scans of an anthropomorphic phantom of head and neck. In addition, plain radiographic images of an anthropomorphic phantom of the chest were obtained. The second phase was the development of the anatomy software as an ImageJ macro. The software was developed through the insertion of the radiologic anatomy landmarks into the images that were obtained and application of multiple choice questions. The software was then tested for usability by getting the professors to answer the multiple choice questions. The software presented radiologic anatomy from 1) Head projections: Waters view, Towne view, Caldwell view, Lateral view, Submentovertex, PA view; 2) Thoracic Spine projections: AP and Lateral View and 3) Chest: PA view, Lateral and Oblique. Tomographic imaging presented one hundred radiologic landmarks of head. In total, there were 354 questions. A final report containing the score of correct answers, as well as the user ID, Date and Time of the test were showed. The test were available in three languages (Spanish, English and Portuguese). A user-friendly and inexpensive software was developed and presented. Students and professionals from several countries are able to practice, repeatedly, the recognition of radiologic anatomical landmarks.

RESUMEN: El propósito de esta investigación fue desarrollar un software gratuito de anatomía radiológica para la educación de anatomía radiológica para ayudar a estudiantes y profesionales de ciencias de la salud. El estudio se dividió en dos fases: adquisición de imágenes y desarrollo de software. La primera fase consistió en obtener imágenes radiográficas simples y tomografías computarizadas (TC) de un fantasma antropomórfico de cabeza y cuello. Además, se obtuvieron imágenes radiográficas simples de un fantasma antropomórfico del tórax. La segunda fase fue el desarrollo del software de anatomía como una macro ImageJ. El software se desarrolló a través de la inserción de los puntos de referencia de la anatomía radiológica en las imágenes que se obtuvieron y la aplicación de preguntas de opción múltiple. Luego, se probó la usabilidad del software haciendo que los profesores respondieran las preguntas de opción múltiple. El software presentó la anatomía radiológica de 1) Proyecciones de la cabeza: vista de aguas, vista de Towne, vista de Caldwell, vista lateral, Submentovertex, vista de PA; 2) proyecciones de la columna torácica: vista AP y lateral y 3) Cofre: vista de PA, lateral y oblicua. Las imágenes tomográficas presentaron cien puntos de referencia radiológica de la cabeza. En total, hubo 354 preguntas. Se mostró un informe final con la puntuación de las respuestas correctas, así como la identificación del usuario, la fecha y la hora de la prueba. Las pruebas estaban disponibles en tres idiomas (español, inglés y portugués). Se desarrolló y presentó un software fácil de usar y de bajo costo. Estudiantes y profesionales de varios países pueden practicar, repetidamente, el reconocimiento de puntos de referencia anatómicos radiológicos.

Construcción, reparación y mantenimiento de simuladores de paciente (fantomas) de ecografía / Construction, Repair and Maintenance of Ultrasound Fantoms

El uso de simuladores "fantomas" o fantoms ha demostrado ser de utilidad para la enseñanza de ultrasonido y particularmente para la enseñanza de técnicas de intervencionismo guiado por ecografía. Los fantomas se pueden conseguir comercialmente, aunque son costosos, o se pueden construir utilizando gelatina, lo cual es más económico. Construimos fantomas de gelatina para la instrucción de técnicas de intervencionismo y, como es natural, estos se deterioraron ostensiblemente con el uso debido a la falta de experiencia de los estudiantes. Por lo tanto, desarrollamos técnicas de reparación para rupturas grandes de la superficie, para el deterioro por el uso de agujas en repetidas ocasiones y finalmente para el deterioro ocasionado por crecimiento de microorganismos.

Ultrasound phantoms are useful for teaching ultrasound and particularly in the instruction of ultrasound guided techniques. They are commercially available, being expensive, or they can be inexpensively built using gelatin. We built gelatin phantoms for the instruction of ultrasound guided techniques and during the practice they deteriorated due to the apprentices lack of experience. We developed repair techniques for gross ruptures in the surface, for small dents resulting from multiple punctures and finally for the growth of microorganisms.

Preclinical molecular imaging: development of instrumentation for translational research with small laboratory animals / Imagem molecular pré-clínica: desenvolvimento de instrumentação para pesquisa translacional com pequenos animais

ABSTRACT Objective: To present the result of upgrading a clinical gamma-camera to be used to obtain in vivo tomographic images of small animal organs, and its application to register cardiac, renal and neurological images. Methods: An updated version of the miniSPECT upgrading device was built, which is composed of mechanical, electronic and software subsystems. The device was attached to a Discovery VH (General Electric Healthcare) gamma-camera, which was retired from the clinical service and installed at the Centro de Imagem Pré-Clínica of the Hospital Israelita Albert Einstein. The combined system was characterized, determining operational parameters, such as spatial resolution, magnification, maximum acceptable target size, number of projections, and acquisition and reconstruction times. Results: Images were obtained with 0.5mm spatial resolution, with acquisition and reconstruction times between 30 and 45 minutes, using iterative reconstruction with 10 to 20 iterations and 4 projection subsets. The system was validated acquiring in vivo tomographic images of the heart, kidneys and brain of normal animals (mice and adult rats), using the radiopharmaceuticals technetium-labeled hexakis-2-methoxy-isobutyl isonitrile (99mTc-Sestamibi), technetium-labeled dimercaptosuccinic acid (99mTc-DMSA) and technetium-labeled hexamethyl propyleneamine oxime (99mTc-HMPAO). Conclusion: This kind of application, which consists in the adaptation for an alternative objective of already existing instrumentation, resulted in a low-cost infrastructure option, allowing to carry out large scale in vivo studies with enhanced quality in several areas, such as neurology, nephrology, cardiology, among others.

RESUMO Objetivo: Apresentar o resultado da adaptação de uma gama câmara clínica para uso dedicado na obtenção de imagens tomográficas in vivo de órgãos de pequenos animais de experimentação, e de sua aplicação na obtenção de imagens cardíacas, renais e neurológicas. Métodos: Foi construída uma versão atualizada do dispositivo de adaptação miniSPECT, composto por três subsistemas: mecânico, eletrônico e de software. O dispositivo foi montado em uma câmara Discovery VH da General Electric Healthcare, retirada do serviço clínico e instalada no Centro de Imagem Pré-Clínica do Hospital Israelita Albert Einstein. O sistema combinado foi caracterizado, determinando parâmetros de funcionamento como resolução espacial, magnificação, limites de tamanho dos alvos de estudo, número de projeções, tempo de registro e tempo de reconstrução das imagens tomográficas. Resultados: Foram obtidas imagens com resolução espacial de até 0,5mm, com tempos de registro e reconstrução de 30 a 45 minutos, utilizando reconstrução iterativa com 10 a 20 iterações e 4 subconjuntos de projeções. O sistema foi validado obtendo imagens tomográficas in vivo do coração, dos rins e do cérebro de animais normais (camundongos e ratos adultos), utilizando os radiofármacos hexaquis-2-metoxi-isobutil-isonitrila marcado com 99mTc (Sestamibi-99mTc), ácido dimercaptosuccínico marcado com 99mTc (DMSA-99mTc) e hexametil-propileno-amina-oxima marcada com 99mTc (HMPAO-99mTc). Conclusão: Este tipo de aplicação, que consiste na adaptação para um objetivo alternativo de instrumentação já existente, constituiu-se em uma opção de infraestrutura de baixo custo, que permite realizar estudos in vivo em larga escala, com qualidade aprimorada, em áreas diversas, como neurologia, nefrologia, cardiologia, entre outras.

Using an abdominal phantom to teach urology residents ultrasound-guided percutaneous needle placement

ABSTRACT Introduction: To assess the effect of a hands-on ultrasound training session to teach urologic trainees ultrasound-guided percutaneous needle placement. Materials and methods: University of California, San Francisco (UCSF) urology residents completed a time trial, placing a needle into a phantom model target under ultrasound guidance. Participants were randomized into three educational exposure groups: Group 1's time trial occurred prior to any teaching intervention, group 2's after experiencing a hands-on training module, and group 3's after exposure to both the training module and one-on-one attending feedback. Needle placement speed and accuracy as well as trainees' perceived confidence in utilizing ultrasound were measured. Results: The study cohort consisted of 15 resident trainees. Seven were randomized to group 1, three to group 2, and five to group 3. All residents reported minimal prior ultrasound experience. Their confidence in using ultrasound improved significantly after completing the training module with the most significant improvement seen among junior residents. Time to needle placement was fastest after receiving attending feedback (46.6sec in group 3 vs. 82.7sec in groups 1 and 2, p<0.01). Accuracy also improved with attending feedback, though the number of repositioning attempts did not differ significantly between groups. Conclusions: A hands-on training module and use of an abdominal phantom trainer increased resident confidence and skill in their use of ultrasound to guide percutaneous needle positioning. Attending feedback is critical for improving accuracy in needle guidance toward a target. Ultrasound-guided needle positioning is a teachable skill and can be applicable to multiple urologic procedures.

Accuracy of magnetic resonance imaging for measuring maturing cartilage: A phantom study

OBJECTIVES: To evaluate the accuracy of magnetic resonance imaging measurements of cartilage tissue-mimicking phantoms and to determine a combination of magnetic resonance imaging parameters to optimize accuracy while minimizing scan time. METHOD: Edge dimensions from 4 rectangular agar phantoms ranging from 10.5 to 14.5 mm in length and 1.25 to 5.5 mm in width were independently measured by two readers using a steel ruler. Coronal T1 spin echo (T1 SE), fast spoiled gradient-recalled echo (FSPGR) and multiplanar gradient-recalled echo (GRE MPGR) sequences were used to obtain phantom images on a 1.5-T scanner. RESULTS: Inter- and intra-reader reliability were high for both direct measurements and for magnetic resonance imaging measurements of phantoms. Statistically significant differences were noted between the mean direct measurements and the mean magnetic resonance imaging measurements for phantom 1 when using a GRE MPGR sequence (512x512 pixels, 1.5-mm slice thickness, 5:49 min scan time), while borderline differences were noted for T1 SE sequences with the following parameters: 320x320 pixels, 1.5-mm slice thickness, 6:11 min scan time; 320x320 pixels, 4-mm slice thickness, 6:11 min scan time; and 512x512 pixels, 1.5-mm slice thickness, 9:48 min scan time. Borderline differences were also noted when using a FSPGR sequence with 512x512 pixels, a 1.5-mm slice thickness and a 3:36 min scan time. CONCLUSIONS: FSPGR sequences, regardless of the magnetic resonance imaging parameter combination used, provided accurate measurements. The GRE MPGR sequence using 512x512 pixels, a 1.5-mm slice thickness and a 5:49 min scan time and, to a lesser degree, all tested T1 SE sequences produced suboptimal accuracy when measuring the widest phantom.

Corrección de índice de dosis en tomografía computarizada por parámetro de diámetro efectivo según reporte 204 de la Asociación Americana de Físicos Médicos / Computed tomography dose index correction by effective diameter according to report 204 by the American Association of Physicists in Medicine

Abstract. In order to have a more accurate estimation of the dose delivered for computed tomography (CT) studies, and given that the current dose estimates do not include the size of the patient, a retrospective study was conducted on a sample of 388 patients from the radiology department of a general hospital, to make a better assessment of the dose delivered for CT scans of the chest, abdomen and pelvis in adult and paediatric patients. A comparison was made between the volume computed tomography dose index (CTDIvol) delivered by the scanner and CTDIvol value corrected by the incorporation of the effective patient diameter according to the report 204 of the American Association of Physicists in Medicine (AAPM). It was found that the values of CTDIvol vary in all cases when the patient size parameter is included, with this variation being greater as sizes go to extremes.

Resumen. Con el objetivo de tener una estimación de dosis más exacta entregada por los estudios de tomografía computarizada (TC) y dado que los estimadores de dosis actuales no incluyen el tamaño del paciente en la estimación, se realizó un estudio retrospectivo en una muestra de 388 pacientes de un servicio de radiología de un hospital general, para calcular las dosis entregadas en exámenes de TC de tórax, abdomen y pelvis en pacientes adultos y pediátricos. Se elaboró y realizó una comparación entre el índice de dosis de TC (CTDI VOL) entregado por el equipo y el CTDI VOL corregido mediante la incorporación del parámetro del diámetro efectivo del paciente según el reporte 204 de la Asociación Americana de Físicos Médicos (AAPM). Se pudo comprobar que los valores de CTDI VOL varían en la totalidad de los casos al ingresar el parámetro de tamaño del paciente y que esta variación es mayor a medida que los tamaños se van a los extremos.

Efectos del voltaje de tubo en la dosis de radiación y calidad de imagen en fantoma en tomografía computarizada multicorte pediátrica / Effect of tube voltage on radiation dose and image quality in paediatric MSCT

Abstract. The use of CT has continued to increase in the last few years, making it the largest contributor to the collective world dose. Children are not exempt from this, with a potentially increasing risk. The effect of tube voltage as a tool for dose reduction has been studied with the aim of investigating methods for optimisation in MSCT, including assessing its effect on image quality. It has been observed that when using the same kV values, the CTDIw is higher by a factor of 2 for the paediatric phantom compared to the adult phantom. A significant reduction in CTDIw was corroborated when lowering the kV, with fewer effects on noise in the paediatric image. On the other hand, a kV reduction allows better contrast when imaging bony structures and using contrast media.

El incremento en el uso de la TC es sostenido en los últimos años, llegando a ser la mayor contribución a la dosis colectiva mundial. Los niños no están exentos de ello, con un riesgo potencialmente creciente. Con el objetivo de estudiar métodos de optimización en TCMC se investigó el efecto del voltaje de tubo como herramienta de reducción de dosis gracias al uso de fantomas representativos, evaluando paralelamente su efecto sobre la calidad de imagen. Se observó que para el fantoma pediátrico el CTDIw es mayor en un factor de 2 con respecto a su símil adulto para iguales valores de kV. Se constató que una reducción en el kV permite una notoria disminución de CTDIw, con menores efectos sobre el ruido en la imagen pediátrica. Por otro lado, una reducción de kV permite mejorar el contraste de estructuras óseas y con medio de contraste yodado.

Densidad ósea volumétrica vertebral obtenida sin fantoma en estudios de rutina de tomografía computarizada de abdomen: correlación con los valores medidos por densitometría ósea areal por rayos X / Phantom-less volumetric vertebral density obtained from routine abdominal ct studies: correlation with data obtained by DXA

La densidad mineral ósea (DMO) por tomografía computarizada cuantitativa (QCT) mide con exactitud y precisión de corto plazo la densidad volumétrica (DMOv) de secciones axiales de los cuerpos vertebrales lumbares valiéndose de un fantoma de calibración. Existe evidencia de que la densitometría por TC sin fantoma convirtiendo las unidades Hounsfield en g/cm3 aplicando un coeficiente específico para cada equipo, presenta muy alta correlación con la DMO por QCT y que es confiable para evaluar la densidad ósea vertebral. Apoyándonos en ello, correlacionamos DMO y CMO estimados a partir de estudios de TC con los obtenidos por DXA. Se incluyeron 28 mujeres (edad: 63,4±10,3 años, rango: 37-85) que habían realizado una TC de abdomen y previamente una DMO en un lapso previo no mayor de 6 meses. Se midieron: 1) TC: DMOv promedio integral (trabecular + cortical) en un corte axial medio vertebral de 10 mm de espesor y el área en cm2 . Se multiplicó la densidad por el área, obteniendo un valor equivalente al CMO de la sección (CMO-TC) y 2) DXA: se consideraron la DMOa y CMO en una RI de 10 mm de altura a nivel del centro de la vértebra L3. Las correlaciones entre los parámetros homólogos obtenidos por ambos métodos fueron significativas: resultó superior para CMO [DMOv vs. DMOa r: 0,67 (p=0,005) y CMO-TC vs. CMO-DXA r: 0,75 (p=0,00063)]. El estudio complementa los ya existentes y abre la posibilidad de utilizar estudios de rutina de TC de abdomen para evaluar la densidad ósea, para lo cual deberán establecerse valores de referencia sexo y edad específicos. (AU)

Conventional quantitative computed tomography (QCT) uses a calibration phantom scanned simultaneously with the anatomical region of interest and measures bone density accurately and with short-term high precision. Evidence supports that phantom-less volumetric BMD highly correlates with QCT BMD and is a reliable method for assessing bone density of vertebral bodies. Assessment of BMD in routine abdominal CT scans has been investigated in recent years. The aim of the study was to correlate BMD and bone mineral content (BMC) obtained from CT studies with data obtained by DXA. Twenty eight women (age 63.4±10.3 years old, range: 37-85) who underwent abdominal CT for different reasons and DXA measurements within 6 months were included. A simple manual region of interest (RI) which delineated the edge of the vertebral body was applied to L3. We measured 1) CT: Volumetric integral density (BMDv) -trabecular and cortical bone- of the axial section and area (A) in cm2 . Density was multiplied by area to obtain a value equivalent to BMC. 2) DXA: BMD and BMC in a RI of 10 mm height in the middle of L3. All parameters obtained by CT correlated significantly with the corresponding to DXA : BMDv vs BMDa r: 0.67 (p=0.005) y BMC-CT vs BMC-DXA: r: 0.75 (p=0.00063). This study complements previous reports and opens the possibility of using routine abdominal CT studies to assess bone density. For that purpose reference values (age and gender) must be established. (AU)

Analysis of the reproducibility of the gray values and noise of a direct digital radiography system

The aim of this study was to evaluate the reproducibility of the gray values and noise of a direct digital radiography system (Visualix eHD) for various exposure times and analyzed regions. To obtain radiographic images in a standardized manner, the digital sensor of the system and a stepwedge were positioned in a phantom at a focus-film distance of 30 cm in a dental device at 70 kV, 7 mA and 2.2 mm filtration. Ten consecutive repetitions of X-ray imaging were performed at each exposure time (0.05, 0.07, 0.09 and 0.13 s). Gray values were analyzed using ImageJ software in five regions of interest (ROIs): alveolar bone (AB), soft tissue (ST) and three steps of the stepwedge (S1, S2 and S3). The results showed that both the variability of the gray values and the noise were statistically greater (p < 0.05) in the most radiolucent region (ST). Only the noise was affected by the exposure time. In conclusion, the reproducibility of the gray values and the noise of the Visualix eHD system can vary in specific areas with different radiolucency.

Avaliação de protocolo para redução da distorção em estereotaxia para ressonância magnética de três tesla / A method for geometric distortion correction for stereotaxic neurosurgery on three tesla

Introdução: o presente estudo demonstra a aplicação de um algoritmo para correção de distorções em imagens de RM em 3T. Métodos: foi utilizado um Modelo Tridimensional com Alvos (MTA) de acrílico (Micromar, São Paulo, Brasil) montado em uma plataforma com as dimensões e características de um arco estereotáctico. O MTA foi submetido à aquisição de imagens em uma bobina de crânio utilizando o aparelho Philips 3T Magnetom Sigma LX(TM) (Philips Medical Systems, Eindhoven, Netherlands). Para cada aquisição duas imagens foram obtidas, a normal e a reversa (nRM e rRM, respectivamente). Foi aplicado o protocolo de correção com gradiente reverso para produzir coordenadas x, y e z corrigidas. Após ter sido determinada a acurácia dos alvos, foram submetidos 20 pacientes ao mesmo protocolo para determinar a validade em indivíduos. Resultados: a análise dos dados demonstrou que as diferenças entre observadores não foram estatisticamente significantes. Além disso, os pontos obtidos após o processo de retificação das coordenadas no MTA revelou uma distorção média de 1,05 mm. Nos pacientes, a distorção pré correção variava de 0 a 5,6 mm; após a correção variou entre 0 e 3,5 mm. Conclusão: o presente estudo examinou uma técnica de retificação das distorções geométricas encontradas em imagens de RM. Esta mostrou-se bem sucedida em produzir resultados consistentemente acurados para registro de alvos estereotácticos. A técnica pode ser aplicada de maneira universal a todas as imagens de RM adquiridas em protocolo spin-echo e corrige as distorções geométricas presentes.

The present work presents an application of a image distortion correction algorithm for 3T MR images. Methods: We used a phantom head model (Micromar, São Paulo, Brazil) mounted on a plataform with the dimensions and features of a stereotactic frame. The phantom was scanned within the head coil of a Philips 3T Magnetom Sigma LX(TM) (Philips Medical Systems, Eindhoven, Netherlands). For each scan, 2 images were obtained - the normal and the reversed image (nMR and rMR, respectively). We applied the inverted gradient correction protocol to produce a corrected x, y and z coordinate. After we ensure target accuracy we submitted 20 patients to the same protocol to exactitude evaluation in human subjects. Results: For all the analyzed data, the differences among the observers were not statistically significant. Moreover, the data rectification proved to be effective as the average distortion on phantom, after correction, was 1.05 mm. On patients the pre-correction distortion varied between 0 and 5.6mm, after correction it varied between 0 mm and 3.5 mm. Conclusion: This study examined a rectifying technique for correcting geometric distortions encountered in the MR images, and the technique proved to be highly successful in producing consistently accurate stereotactic target registration. The technique is universally applicable to all routinely employed spin-echo MR images, and corrects for geometric distortions.

Cáncer gástrico en una zona con alto potencial para la cultura apícola y su aplicación en la prevención de las lesiones gástricas premalignas y malignas / Gastric cancer in an area of high potential for beekiping culture and its application in the prevention of premalignat and malignat gastric lesion

El cáncer gástrico es la principal causa de muerte por cáncer del estado Táchira - Venezuela. Con una particular elevada tasa de mortalidad en los estados andinos. Los esfuerzos realizados en la detección temprana basados en estudios radiológicos y endoscópicos no han permitido cubrir gran parte de la población. La identificación de lesiones pre malignas y cáncer asociadas a la infección por Helicobacter pylori han obligado al desarrollo de proyectos epidemiológicos de prevención primaria que tiendan a incidir sobre estilos de vida y factores dietéticos. La erradicación de H. pylori con el uso de terapia antimicrobiana convencional ha dado resultados controvertidos en diferentes latitudes, con los mismos esquemas terapéuticos. La capacidad antimicrobiana de diferentes tipos de propóleos ante el H. pylori, ya ha sido evaluada, siendo el principal responsable los flavonoides: pinocembrina, galangina y crisina. La alta prevalencia de H. pylori en la Aldea Potrero de las Casas, Táchira, Venezuela, aunado al potencial y cultura apícola de la zona promueven estudios de intervención con productos de la colmena que son accesibles y de bajo costo

Gastric Cancer is the leading cause of cancer death in Táchira State - Venezuela with a high mortality rate especially in the Andean States. Efforts at early gastric cancer detection based on radiological and endoscopic studies have failed to cover all the population. The identification of premalignant gastric lesion and gastric cancer associated with Helicobacter Pylori infection have led to the development of epidemiological primary prevention projects that led to influence on dietary and life style factors Helicobacter Pylori eradication using conventional therapy has been controversial results in differents latitudes with the same therapeutics regimens. The antimicrobial activity of different types of propolis against Helicobacter Pylori has been evaluated, the main responsibility are flavonoids,pinocembrin, galactin and chrysin. The high prevalence of Helicobacter Pylori in the village of Potrero de las Casas, Táchira Venezuela together with the potential of the area in the bee culture induce to think about to promote intervention studies with bee products that are accessible and low cost

Vibroacoustography for the assessment of total hip arthroplasty

OBJECTIVES: This paper proposes imaging with 3-dimensional vibroacoustography for postoperatively assessing the uncovered cup area after total hip arthroplasty as a quantitative criterion to evaluate implant fixation. METHODS: A phantom with a bone-like structure covered by a tissue-mimicking material was used to simulate a total hip arthroplasty case. Vibroacoustography images of the uncovered cup region were generated using a two-element confocal ultrasound transducer and a hydrophone inside a water tank. Topological correction based on the geometry of the implant was performed to generate a 3-dimensional representation of the vibroacoustography image and to accurately evaluate the surface. The 3-dimensional area obtained by the vibroacoustography approach was compared to the area evaluated by a 3-dimensional motion capture system. RESULTS: The vibroacoustography technique provided high-resolution, high-contrast, and speckle-free images with less sensitivity to the beam incidence. Using a 3-dimensional-topology correction of the image, we accurately estimated the uncovered area of the implant with a relative error of 8.1% in comparison with the motion capture system measurements. CONCLUSION: Measurement of the cup coverage after total hip arthroplasty has not been well established; however, the covered surface area of the acetabular component is one of the most important prognostic factors. The preliminary results of this study show that vibroacoustography is a 3-dimensional approach that can be used to postoperatively evaluate total hip arthroplasty. The favorable results also provide an impetus for exploring vibroacoustography in other bone or implant surface imaging applications. .

Gray scale inversion in digital image for measurement of tooth length

The aim of this study was to assess the applicability of gray scale inversion in performing digital linear endodontic measurements. Standardized digital images were taken of 40 extracted human permanent single-rooted teeth with K-files size 15 placed at different lengths in the root canal, using the CDR Wireless® digital system. All images were treated with Positive, a digital tool that inverts the grayscale value. Eight radiologists measured the distance between the lower limit of the rubber stop and the tip of the file on both original and positive images. After 15 days, they repeated this procedure in 50% of the image samples. The intra- and inter-examiner agreement was analyzed by intraclass correlation test, and the comparison between the two image groups and the actual lengths by the Student's t-test (α=0.05). Intra- and inter-examiner evaluation showed high reproducibility (r>0.95) of both original and positive images. No statistically significant differences (p>0.05) were found between measurements performed on original and positive images, but both differed significantly from the actual lengths (p<0.05). Gray scale inversion has low applicability in measuring endodontic files, since it did not improve the accuracy of measurements.

O objetivo deste estudo foi avaliar a aplicabilidade da inversão da escala de cinza na realização de mensurações endodônticas lineares digitais. Quarenta dentes unirradiculares humanos extraídos foram radiografados com limas K tamanho 15 posicionadas no canal radicular em diferentes comprimentos, usando o sistema digital CDR Wireless®. Todas as imagens foram tratadas com Positive, uma ferramenta digital que inverte os valores da escala de cinza. Oito radiologistas mediram a distância entre o limite inferior do stop de borracha e a ponta da lima endodôntica nas imagens originais e positivas. Após quinze dias, eles repetiram esse procedimento em 50% da amostra. A concordância intra- e interobservador foi analisada pelo teste de correlação intraclasse e a comparação entre os dois grupos de imagem e os valores reais, pelo teste t-Student (α=0,05). A análise intra- e interobservador apresentou elevada reprodutibilidade (r>0,95) das imagens original e Positive. Não foi encontrada diferença (p>0,05) entre as medidas realizadas nas imagens original e positiva, mas ambas diferiram dos valores reais (p<0,05). A inversão da escala de cinza tem baixa aplicabilidade na realização de mensuração endodôntica, considerando que as medidas não se apresentaram mais acuradas.

Influência das características mamárias na cintilografia miocárdica pelo método Monte Carlo / Influence of breast characteristics in myocardial scintigraphy through the Monte Carlo method / Influência das características mamárias na cintilografia miocárdica pelo método Monte Carlo

FUNDAMENTO: Pela redução da especificidade associada à perda de informação, a influência da atenuação das mamas é de fundamental importância em estudos de perfusão do miocárdio. Entretanto, apesar de vários estudos terem sido realizados ao longo dos últimos anos, pouco se tem evoluído para determinar com acurácia a influência das características das mamas sobre a qualidade da cintilografia miocárdica, evitando exposições adicionais de radiação às pacientes. OBJETIVO: O objetivo deste estudo é quantificar a atenuação de fótons pelas mamas, em estudos de perfusão do miocárdio com 99mTc, de acordo com diferentes tamanhos e composições. MÉTODOS: Cada mama foi assumida como sendo um cubo composto de tecido adiposo e fibroglandular. Os dados referentes aos fótons de 99mTc foram analisados em um modelo de Monte Carlo. Variamos a espessura e a composição das mamas e analisamos as interferências na atenuação. Foi empregado o software EGS 4 para as simulações. RESULTADOS: Fixando a espessura de uma mama, a variação da sua composição acarreta um acréscimo máximo de 2,3 por cento no número de fótons atenuados. Em contrapartida, mantendo-se uma composição do tecido mamário fixa, a diferença na atenuação de fótons foi de 45,0 por cento, sendo em média de 6,0 por cento para cada acréscimo de centímetro na espessura da mama. CONCLUSÃO: A simulação por Monte Carlo demonstrou que a influência das espessuras das mamas na atenuação de fótons em cintilografias do miocárdio com 99mTc é muito maior do que a influência das suas composições.

BACKGROUND: By reducing the specificity associated with loss of information, the influence of attenuation of the breasts is very important in myocardial perfusion studies. However, although several studies have been conducted over the past years, little has been developed to determine accurately the influence of the characteristics of the breasts on the quality of myocardial scintigraphy, avoiding additional exposure to radiation. OBJECTIVE: The purpose of this study is to quantify the attenuation of photons by the breasts, in myocardial perfusion studies with 99mTc according to different sizes and compositions. METHODS: Each breast was assumed to be a cube composed of fibroglandular and adipose tissue. The data related to 99mTc photons were analyzed in a Monte Carlo model. We varied the thickness and composition of breasts and analyzed the interference in attenuation. The EGS 4 software was used in the simulations. RESULTS: Setting the thickness of a breast, the variation of its composition causes a maximum increase of 2.3 percent in the number of photons attenuated. By contrast, maintaining a fixed composition of breast tissue, the difference in photon attenuation was 45.0 percent, averaging 6.0 percent for each additional centimeter in the breast thickness. CONCLUSION: Monte Carlo simulation showed that the influence of the thickness of the breasts in the attenuation of photons in myocardial scintigraphy with 99mTc is much greater than the influence of their compositions.

FUNDAMENTO: Por la reducción de la especificidad asociada a la pérdida de información, la influencia de la atenuación de las mamas es de fundamental importancia en estudios de perfusión del miocardio. Entre tanto, a pesar de que varios estudios han sido realizados a lo largo de los últimos años, poco se ha evolucionado para determinar con precisión la influencia de las características de las mamas sobre la calidad de la cámara gamma miocárdica, evitando exposiciones adicionales de radiación a las pacientes. OBJETIVO: El objetivo de este estudio es cuantificar la atenuación de fotones por las mamas, en estudios de perfusión del miocardio con 99mTc, de acuerdo con diferentes tamaños y composiciones. MÉTODOS: Cada mama fue asumida como siendo un cubo compuesto de tejido adiposo y fibroglandular. Los datos referentes a los fotones de99mTc fueron analizados en un modelo de Monte Carlo. Variamos el espesor y la composición de las mamas y analizamos las interferencias en la atenuación. Fue empleado el software EGS 4 para las simulaciones. RESULTADOS: Fijando el espesor de una mama, la variación de su composición acarrea un aumento máximo de 2,3 por ciento en el número de fotones atenuados. En contrapartida, manteniéndose una composición del tejido mamario fija, la diferencia en la atenuación de fotones fue de 45,0 por ciento, siendo en media de 6,0 por ciento para cada aumento de centímetro en el espesor de la mama. CONCLUSIÓN: La simulación por Monte Carlo demostró que la influencia de los espesores de las mamas en la atenuación de fotones en cámara gamma del miocardio con 99mTc es mucho mayor que la influencia de sus composiciones.

A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target’s three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology.

Influencia del movimiento respiratorio sobre el contraste de las lesiones en estudios de perfusión pulmonar: simulación mediante el uso de un fantoma virtual / Respiratory motion on the contrast of pulmonary lesions in lung perfusion scintigraphy: a simulation study with a virtual phantom

El movimiento respiratorio (MR) constituye un factor de degradación de las imágenes con potencial influencia sobre la capacidad de detección de lesiones tromboembólicas en estudios de perfusión pulmonar. El objetivo fue investigar la influencia del MR sobre el contraste de lesiones pulmonares, por medio de simulación con un fantoma virtual. Mediante un fantoma N-CAT se generó un modelo de perfusión pulmonar con SPECT; el modelo fue reconstruido produciendo cortes tomográficos y reproyección de los mismos en tres situaciones: sin MR, simulando MR con desplazamiento diafragmático de 2 cm, y con desplazamiento de 4 cm. Se instalaron en el modelo 7 "lesiones" hipocaptantes simulando la situación del tromboembolismo pulmonar (TEP) en situación superior, media y basal y se calculó el contraste de las lesiones en las 3 situaciones descriptas. Los resultados muestran que el contraste de las lesiones es menor con el MR, que se deteriora más cuanto mayor es la magnitud del MR, y que el MR afecta en mayor grado el contraste de las lesiones de ubicación basal. La corrección de MR podría mejorar la detectabilidad de algunos defectos de perfusión, especialmente los de ubicación basal, incrementando la sensibilidad de la técnica para el diagnóstico de TEP.

Respiratory motion (RM) represents a major factor of image degradation with potential impact on the detection of embolic lesions in lung perfusion scintigraphy. The aim was to investigate the influence of RM on the contrast of pulmonary lesions through a simulation study with a virtual phantom. Using a N-CAT phantom, a SPECT lung perfusion model was generated; the model was reconstructed producing three sets of tomographic slices and image reprojection under different conditions: without RM, RM simulation with 2 cm diaphragmatic displacement, and RM simulation with 4 cm diaphragmatic displacement. Seven "cold" lesions were placed in the model resembling a typical pulmonary embolism (PE) situation in superior, medial and basal locations and image contrast was calculated. Results showed a decrease in lesion contrast proportional to the degree of RM, which was more pronounced for basal lesions. Motion correction could improve the detectability of some perfusión defects, especially those in basal locations, thus incrementing the sensitivity of the technique for the diagnosis of PE.

Comparative evaluation among different materials to replace soft tissue in oral radiology studies

OBJECTIVE: The aim of this study was to establish which materials afford better simulation of soft tissues in Oral Radiology studies. MATERIAL AND METHODS: The sample was composed of four materials in eleven different thicknesses to simulate the soft tissues of the face. The mean values of the relative amounts of radiographic contrast of the materials were determined and compared to a gold standard value, which was obtained from 20 patients who were referred to have periapical radiographs taken of the left mandibular molars. Data were subjected to statistical analysis with Dunnett's test (p<0.05). RESULTS: The mean value of the relative amounts of contrast encountered in the patients was 0.47, with a range between 0.36 and 0.64 for all 44 material/thickness combinations. The majority of the tested materials showed values close to those of the patients' tissues, without statistically signifcant differences among them. The values of only three materials/thickness combinations differed statistically from those of the patients' tissues. CONCLUSIONS: Based on the results of the present study, it may be concluded that except for utility wax (4 mm and 8 mm) and water (4 mm), all materials tested at different thickness could be used as soft tissue substitute materials in Oral Radiology studies.