Study of Alternative Imaging Methods for In Vivo Boron Neutron Capture Therapy.

Boron Neutron Capture Therapy (BNCT) is an innovative and highly selective treatment against cancer. Nowadays, in vivo boron dosimetry is an important method to carry out such therapy in clinical environments. In this work, different imaging methods were tested for dosimetry and tumor monitoring in BNCT based on a Compton camera detector. A dedicated dataset was generated through Monte Carlo tools to study the imaging capabilities. We first applied the Maximum Likelihood Expectation Maximization (MLEM) iterative method to study dosimetry tomography. As well, two methods based on morphological filtering and deep learning techniques with Convolutional Neural Networks (CNN), respectively, were studied for tumor monitoring. Furthermore, clinical aspects such as the dependence on the boron concentration ratio in image reconstruction and the stretching effect along the detector position axis were analyzed. A simulated spherical gamma source was studied in several conditions (different detector distances and boron concentration ratios) using MLEM. This approach proved the possibility of monitoring the boron dose. Tumor monitoring using the CNN method shows promising results that could be enhanced by increasing the training dataset.

Heavy metals concentration, pollution indexes, and health risk assessment of urban road dust in the historical center of Havana, Cuba.

In recent years, the historical center of Old Havana has been under a serious restoration movement which could increase the heavy metal concentrations in street dusts and thus severely impact humans in the area. Therefore, the aim of this work is to study the heavy metal concentrations, pollution indexes, and health risk assessment of urban road dusts from the city in order to assess if this restoration movement is harmful to the citizens and visitors. Street road dust samples were collected at 33 stations for the determination of some heavy metals (Co, Ni, Cu, Zn, and Pb) concentrations using an X-ray fluorescence (XRF) instrument. The mean concentration values of the elements Co, Ni, Cu, Zn, and Pb were 7.0 mg.kg-1, 60.6 mg.kg-1, 73.6 mg.kg-1, 548.7 mg.kg-1, and 60.8 mg.kg-1, respectively. Zn and Pb showed higher values of the background. The study of the enrichment factor (EF), the pollution index (IP), and the integral pollution index (IPI) showed some stations with high values of contamination near construction places. Zn was identified as the major pollutant and correlated to the biggest construction places of the municipality at that moment. However, the hazard index (HI) and carcinogenic risk (CR) values do not show the risk of getting non-carcinogenic or carcinogenic diseases associated with the analyzed pollutants. Therefore, it was safely concluded that the big reconstruction movement does not represent a health problem.