Assessment of the neutron radiation field with activation foils and intermittent irradiations around a PETtrace biomedical cyclotron.

This work aimed at assessing the neutron radiation field with activation foils around of the PETtrace biomedical cyclotron. Activation foils of gold, gold covered with cadmium, indium and nickel was used to evaluate the thermal, epithermal and fast neutron contributions, respectively. The irradiations of the activation foils were performed using the intermittent irradiation method to conciliate the measurements with the routine 18F production. The evaluated points showed the contributions of the thermal, epithermal and fast neutrons due to interaction with the vault room, cyclotron accelerator and main cyclotron components.

EXPERIMENTAL EVALUATION OF NEUTRON SHIELDING MATERIALS.

A new proposed design of neutron shielding material-based on the commercial material Borotron UH050 with an addition of Al(OH)3-is evaluated in order to determine if its neutron and gamma shielding properties match those of a reference material, NS4FR. Neutron and gamma dosimetry measurements are performed, as well as neutron spectrometry measurements and Monte Carlo simulations. Negligible differences are found between the materials for neutron shielding, while significant differences are found for gamma shielding. The effect of Al(OH)3 addition to Borotron UH050 is to reduce neutron shielding properties while increasing gamma shielding properties. The resulting material is as efficient as NS4FR for neutron shielding but less efficient for gamma shielding-thicknesses 20% higher are required to match gamma shielding properties of NS4FR. Monte Carlo models of the materials are validated based on the performed measurements of neutron spectra and neutron and gamma ambient dose equivalent.

Índice de normalidade da distância atlantoaxial dorsal em cães / Normal index of dorsal atlantoaxial distance in dogs

Foram utilizados 30 cães neurologicamente saudáveis e realizadas radiografias da coluna cervical, sendo mensurada a menor distância atlantoaxial dorsal e outros parâmetros anatômicos vertebrais. Esses dados foram avaliados por meio do coeficiente de correlação de Pearson. Após detecção do melhor parâmetro de correlação, utilizou-se a fórmula de coeficiente de correlação dimensional (CCD). Na segunda etapa desta pesquisa, foram utilizadas imagens radiográficas de 33 cães com subluxação atlantoaxial (SAA) e aplicou-se a fórmula CCD. Todas as imagens atlantoaxiais normais e subluxadas foram distribuídas aleatoriamente e submetidas à análise subjetiva. Observou-se que o parâmetro anatômico de maior correlação foi o comprimento do processo espinhoso do áxis, obtendo-se valor de índice médio de 0,056 e desvio-padrão de 0,019. O valor de índice médio obtido em cães com SAA foi de 0,287, e o desvio-padrão de 0,123. A análise subjetiva revelou acerto de 88,89% a 95,24%, enquanto a avaliação por meio da fórmula CCD demonstrou ser 100% eficiente no diagnóstico da SAA. Sugeriu-se a utilização da fórmula CCD para obtenção do índice de normalidade da distância atlantoaxial com valor de normalidade médio de 0,056 e limite máximo de 0,098, sendo esse índice eficaz no diagnóstico da subluxação entre o atlas e o áxis.(AU)

Thirty healthy dogs had their cervical spines radiographed, and the dorsal atlantoaxial distance and others vertebral anatomical parameters were measured. These data were assessed using the Pearson correlation coefficient. After detection of the best correlation parameter, we used the dimensional correlation coefficient of formula (CCD). In the second stage of the study, radiographs of the 33 dogs with atlantoaxial subluxation (SAA) were used. In each radiographic image, the CCD formula was applied. All normal and subluxation radiographic images were randomized, and submitted to subjective analysis. It was observed that the anatomical parameter with the highest correlation is the length of the spinous process of the axis, obtaining a mean value of 0.056 index and 0.019 standard deviation. Index mean value obtained in dogs with the disease of 0.287 and standard deviation of 0.123. The subjective analysis revealed 88.89% to 95.24% agreement, while the result obtained by the CCD formula was shown to be 100% effective in the diagnosis of SAA. We suggest the use of the CCD formula to obtain the index of normality of the atlantoaxial distance with a mean value of 0.056 and maximum of 0.098, and it is concluded that the index is highly effective in the diagnosis of subluxation between the atlas and the axis.(AU)

Ramos do arco aórtico e da aorta torácica em bicho-preguiça (Bradypus variegatus) / Branches of the aortic arch and thoracic aorta of the sloth (Bradypus variegatus)

As preguiças são mamíferos arborícolas, bem específicos quanto aos hábitos e à morfofisiologia. Essa condição faz delas ainda mais vulneráveis aos impactos ambientais. Com o objetivo de fornecer informações que auxiliem na clínica médico-cirúrgica desses Xenarthras, realizou-se um estudo do arco aórtico e da artéria aorta torácica, a fim de se identificarem seus principais ramos. Foram utilizados 10 animais da espécie Bradypus variegatus, sendo uma fêmea e três machos submetidos a dissecação, por meio da qual foram obtidas medidas de diâmetro e comprimento dos vasos, enquanto três fêmeas e três machos destinaram-se à técnica de radiografia digital com contraste. Constatou-se uma sintopia uniforme do arco, bem como da porção descendente da artéria aorta no tórax. No entanto, a topografia difere consideravelmente. Com base nos ramos, percebeu-se, independentemente do sexo, uma maior variação naqueles originados do arco e dos que emergem da artéria aorta torácica e irrigam estruturas medianas e do antímero direito do tórax. Foram obtidos valores maiores para o diâmetro das artérias na fêmea do que nos machos e, para o comprimento da artéria aorta torácica, foram encontrados valores correspondentes em ambos. Toda essa variação dos bradipodídeos apresenta diferenças em relação a outros mamíferos.(AU)

Sloths are arboreal mammals, very specific, regarding their habits and morphology. This condition makes them even more vulnerable to environmental impacts. In order to provide information to assist in the medical and surgical assistance to these Xenarthras, a study of the aortic arch and thoracic portion of the descending aorta was carried out with the purpose of identify its main branches. Ten animals of the Bradypus variegatus species were used. One female and three males were submitted to dissection, where measurements of vessel diameter and length were obtained, while three females and three males were submitted to the digital contrast x-ray technique. There was a uniform syntopy of the arch, as well as of the descending portion of the aorta in the thorax. However, the topography differs considerably. Based on the branches, regardless of gender, a greater variation was observed in those originating from the arch, and those that emerge from the thoracic aorta and irrigate medial structures and the right antimere of the thorax. Greater values were obtained for the diameter of the arteries in the female than in the males and corresponding values for the length of the thoracic aorta in both. All this variation is possibly related to the adaptive processes of Bradipodidae over time.(AU)

Neutron spectra due (13)N production in a PET cyclotron.

Monte Carlo and experimental methods have been used to characterize the neutron radiation field around PET (Positron Emission Tomography) cyclotrons. In this work, the Monte Carlo code MCNPX was used to estimate the neutron spectra, the neutron fluence rates and the ambient dose equivalent (H*(10)) in seven locations around a PET cyclotron during (13)N production. In order to validate these calculations, H*(10) was measured in three sites and were compared with the calculated doses. All the spectra have two peaks, one above 0.1MeV due to the evaporation neutrons and another in the thermal region due to the room-return effects. Despite the relatively large difference between the measured and calculated H*(10) for one point, the agreement was considered good, compared with that obtained for (18)F production in a previous work.

Use of the MCNPX to calculate the neutron spectra around the GE-PETtrace 8 cyclotron of the CDTN/CNEN, Brazil.

The Monte Carlo code MCNPX was used to calculate the neutron spectra in 4 points around the targets of the CDTN/CNEN cyclotron, Belo Horizonte, Brazil, during the production of the (18)FDG. Simulated data were compared with experimental data obtained with a Bonner multisphere spectrometry system (BSS) using TLD-600 and TLD-700 and the unfolding codes BUNKIUT, BUMS and NSDUAZ. In general, simulated spectra disagreed with those obtained by experimental means by a factor as high as 14. Measurements performed with a doserate meter in other 3 more shielded points, showed also an overestimation of the ambient dose equivalent rate by a factor as high as 20 in comparison with simulated results. Results are not conclusive and a more refined study is necessary. However, neutron emission rate of the source-term of radiation must be investigated and an special caution must be taken in the experimental measurements, by discriminating of the target selected for the irradiations and utilizing a matrix response suitable for the passive detectors (e.g. TLD) utilized in the experiments, instead of a matrix response (e.g. UTA4) developed for scintillation detectors.

Use of a TLD-based multisphere spectrometry system to measure the neutron spectra around a not-self-shielded PET cyclotron: Preliminary results.

In the present work, we utilized the BSS system with TLD-600 and TLD-700 to measure the neutron spectra around the GE-PETtrace 8 cyclotron of the Development Centre of Nuclear Technology (CDTN/CNEN) in Belo Horizonte, Brazil. The cyclotron is capable of accelerating protons up to 16.5 MeV, to production of fluorine-18. Four points inside the bunker of the cyclotron were studied. Two points in front of the primary radiation beam and other two opposed to the primary radiation beam. The measurements were unfolded with the BUMS and the NSDUAZ computer codes. The dosimetric quantities obtained were in agreement with the other published data and were coherent with the expected from theoretical estimates obtained from source term informed by the manufacturer of the cyclotron.

Farmacodermia em um cão após administração de antibióticos do grupo betalactâmico: relato de caso / Pharmacodermia in a dog after administration of beta-lactam antibiotics: case report

A severe cutaneous reaction in a female dog after administration of penicillin and cephalexin is described, in which the main signs presented by the patient were fever, lack of appetite, and detachment of epidermis in the dorsal region of body.The established treatment was surgical debridement of the region, topical application of Aloe Vera with sugar, and systemic antibiotic therapy with ciprofloxacin, resulting in the recovery and wound closure in approximately 45 days.