An Approach to Establishing Diagnostic Reference Levels in Interventional Pediatric Cardiology from Different Regions of Brazil.

Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma-area product-PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups.

Raman and Fluorescence Profiles Modifications of Muscular and Adipose Tissues Exposed to Low Energy X-ray Beams.

This work aims to investigate changes induced by low-energy radiation in adipose and muscular tissues employing autofluorescence and Raman spectroscopic techniques. X-ray beams expositions with 25 and 35 kV at 0.11, 1.1, and 2.1 Gy radiation dose levels were applied. Changes in Raman line intensities at specific bands assigned to collagen, proteins, and lipids were observed. Autofluorescent analysis exhibit variations in the collagen and nicotinamide adenine dinucleotide emission (NADH), resulting from the structural modifications, variations on the reduced/oxidized fluorophores equilibrium followed by radiation exposure. Results show that Raman and fluorescence spectroscopy are suitable techniques to evaluate radiation effects on biomolecules even at low radiation doses and energies.

OSL and TL techniques combined in a beryllium oxide detector to evaluate simultaneously accumulated and single doses.

Optically stimulated luminescence (OSL) and thermoluminescence (TL) are similar techniques widely used in radiation dosimetry. The main difference between these techniques is the stimulus to induce luminescence emission: TL technique uses thermal stimulation, whereas OSL uses optical stimulation. One of the main intrinsic characteristics of the OSL technique is the possibility of reading several times the dosimetric materials with a negligible loss of signal. In the case of BeO, recent studies have shown that TL stimulation up to 250°C does not affect its OSL signal. Taking the advantages of dosimetric characteristics of BeO combined with both techniques, in this study, we demonstrated the possibility of measuring accumulated and single doses in the same BeO-based detector in order to use it to improve individual monitoring of radiation workers exposed to X-ray or gamma-ray fields. Single doses were measured using TL technique by heating the detector up to 250°C, whereas accumulated doses were estimated using OSL technique in the same detector in a relatively short time of optical stimulation. The detectors were exposed to two energies: 28keV X-rays and 1.25MeV Co-60 gamma rays. The doses estimated by OSL and TL of BeO (Thermalox 995) were compared with those obtained with LiF (TLD-100) and recorded with a calibrated ionization chamber. The results indicate that combined OSL and TL signals of BeO detectors can provide additional information of accumulated dose, with additional exploration of the advantages of both techniques, such as speed in readouts with OSL, and double-check the doses using TL and OSL intensities from BeO.

Diagnostic reference levels for the most frequent radiological examinations carried out in Brazil.

OBJECTIVES: A large-scale survey of doses to patients undergoing the most frequent radiological examinations was carried out in health services in São Paulo (347 radiological examinations per 1 000 inhabitants), the most populous Brazilian state. METHODS: A postal dosimetric kit with thermoluminescence dosimeters was used to evaluate the entrance surface dose (ESD) to patients. A stratified sampling technique applied to the national health database furnished important data on the distribution of equipment and the annual number of examinations. Chest, head (skull and sinus), and spine (cervical, thoracic, and lumbar) examinations were included in the trial. A total of 83 rooms and 868 patients were included, and 1 415 values of ESD were measured. RESULTS: The data show large coefficients of variation in tube charge, giving rise to large variations in ESD values. Also, a series of high ESD values associated with unnecessary localizing fluoroscopy were detected. Diagnostic reference levels were determined, based on the 75th percentile (third quartile) of the ESD distributions. For adult patients, the diagnostic reference levels achieved are very similar to those obtained in international surveys. However, the situation is different for pediatric patients: the ESD values found in this survey are twice as large as the international recommendations for chest radiographs of children. CONCLUSIONS: Despite the reduced number of ESD values and rooms for the pediatric patient group, it is recommended that practices in chest examinations be revised and that specific national reference doses and image quality be established after a broader survey is carried out.

Diagnostic reference levels for the most frequent radiological examinations carried out in Brazil / Niveles de referencia diagnósticos para los exámenes radiológicos más frecuentes realizados en Brasil

OBJECTIVES: A large-scale survey of doses to patients undergoing the most frequent radiological examinations was carried out in health services in São Paulo (347 radiological exami nations per 1 000 inhabitants), the most populous Brazilian state. METHODS: A postal dosimetric kit with thermoluminescence dosimeters was used to evalu ate the entrance surface dose (ESD) to patients. A stratified sampling technique applied to the national health database furnished important data on the distribution of equipment and the an nual number of examinations. Chest, head (skull and sinus), and spine (cervical, thoracic, and lumbar) examinations were included in the trial. A total of 83 rooms and 868 patients were in cluded, and 1 415 values of ESD were measured. RESULTS: The data show large coefficients of variation in tube charge, giving rise to large variations in ESD values. Also, a series of high ESD values associated with unnecessary lo calizing fluoroscopy were detected. Diagnostic reference levels were determined, based on the 75th percentile (third quartile) of the ESD distributions. For adult patients, the diagnostic ref erence levels achieved are very similar to those obtained in international surveys. However, the situation is different for pediatric patients: the ESD values found in this survey are twice as large as the international recommendations for chest radiographs of children. CONCLUSIONS: Despite the reduced number of ESD values and rooms for the pediatric pa tient group, it is recommended that practices in chest examinations be revised and that specific national reference doses and image quality be established after a broader survey is carried out.

OBJETIVOS: Estudio a gran escala de las dosis aplicadas a pacientes sometidos a los exámenes radiológicos más frecuentes realizados en los servicios de salud de São Paulo (347 exámenes radiológicos por 1 000 habitantes), el estado más poblado de Brasil. MÉTODOS: Se empleó un sistema dosimétrico postal con dosímetros termoluminiscentes para evaluar la dosis en la superficie de entrada (DSE) de los pacientes. Se realizó un muestreo estratificado de la base de datos nacional de salud que aportó información importante sobre la distribución del equipamiento y el número de pruebas realizadas anualmente. El estudio abarcó los exámenes de tórax, cabeza (cráneo y senos paranasales) y columna vertebral (cervical, dorsal y lumbar). Se incluyeron 83 instalaciones y 868 pacientes; se obtuvieron 1 415 mediciones de DSE. RESULTADOS: Los resultados mostraron grandes coeficientes de variación en la carga del tubo, lo que originó variaciones considerables en las DSE. Además, se detectaron valores elevados de DSE asociados con fluoroscopias de localización innecesarias. Los niveles de referencia diagnósticos se determinaron a partir del percentil 75 (tres cuartiles) de las distribuciones de las DSE. Para pacientes adultos, los niveles de referencia diagnósticos alcanzados fueron muy similares a los obtenidos en estudios internacionales. No obstante, la situación fue diferente en los pacientes pediátricos: los valores de DSE obtenidos en este estudio fueron dos veces mayores que los recomendados internacionalmente para radiografías de tórax en niños. CONCLUSIONES: A pesar del reducido número de valores de DSE e instalaciones en el grupo de pacientes pediátricos, se recomienda revisar la práctica de estudios radiológicos de tórax y establecer referencias nacionales específicas para las dosis y la calidad de las imágenes, después de realizar un estudio más amplio.