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One of the most recent and promising developments in radiotherapy dosimetry was the introduction of 3D radiationsensitive gels. These gels present tissue equivalent composition and density, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some gels are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gel). In this work Fricke gel dosimeters produced with a matrix of poly-vinyl alcohol (PVA) cross-linked with glutaraldehyde (GTA) were analyzed with magnetic resonance imaging (MRI). This work focused on the analysis of the temporal diffusion of ferric ions through PVA-GTA gel dosimeters. PVA-GTA gel samples, partly exposed with 6 MV X-rays in order to create an initial steep gradient, were mapped using magnetic resonance imaging on a 7T MRI scanner for small animals. The results obtained with PVA-GTA gels were compared with those achieved with agarose gels, which is a standard dosimetric gel formulation. The analysis showed that the diffusion process is much slower (more than five times) for PVA-GTA gels than for agarose ones. Furthermore, MRI was performed on the PVA-GTA gels at 1.5 T with a clinical scanner in order to optimize the acquisition parameters and obtain high contrast between irradiated and non-irradiated samples. The PVA gels were found to offer good linearity in the range of 0-10 Gy and a stable signal for several hours after irradiation. The sensitivity was about 40% higher compared to gels produced with agarose as gelling agent. The effect of xylenol orange (XO) on the MRI signal was also investigated: gel dosimeters made without XO show higher sensitivity to x-rays than those made with XO. The dosimetric accuracy of the 3D gels was investigated by comparing their MRI response to percentage depth dose and transversal dose profile measurements made with an ionization chamber in a water phantom. The comparison of PVA-GTA gels with and without XO showed that the chelating agent reduces the MRI sensitivity of the gels. Depthdose and transversal dose profiles acquired by PVA-GTA gels without XO are more accurate and consistent with the ionization chamber data.

Fricke Xylenol Gel (FXG) dosimetric system is based on the radiation induced oxidation of ferrous (Fe2+) to ferric (Fe3+) ions. The application of Fricke gels for ionizing radiation dosimetry is continuously increasing worldwide due to their many favorable properties. However, one of their shortcomings is that ferrous and ferric ions diffuse in the gel matrix. To maintain the spatial integrity of the dose distribution, Fricke gels must be undergoing measurement within a few hours of their irradiation, so that ferric ions remain close to their point of production. Thus, the spatial integrity of the dose distribution in the Fricke gel is maintained. The gel matrix also contributes to the oxidation of ferrous ions during irradiation, increasing the chemical yield of ferric ions in aqueous solution and increasing the sensitivity of the dosimeter. The oxidation of ferrous ions also causes a reduction of the longitudinal nuclear magnetic relaxation time T1 which can be measured by means of Nuclear Magnetic Resonance Relaxometry (NMR) and Magnetic Resonance Imaging (MRI). The results presented are related to an experimental investigation conducted on Fricke Gels characterized by gelatinous matrix of Agarose or PVA. The dose calibration curves are reported and discussed from the point of view of the dosimeter use in clinical radiotherapy. This work has highlighted that the optimization of additives inside gel matrix is fundamental for optimizing photon sensitivity of these detectors. We can conclude that FXG dosimeters with optimal ferrous ammonium sulfate content can be regarded as a valuable dosimetric tool to achieve fast information on spatial dose distribution.

Fricke Xylenol Gel (FXG) dosimetric system is based on the radiation induced oxidation of ferrous (Fe2+) to ferric (Fe3+) ions. The application of Fricke gels for ionizing radiation dosimetry is continuously increasing worldwide due to their many favorable properties. However, one of their shortcomings is that ferrous and ferric ions diffuse in the gel matrix. To maintain the spatial integrity of the dose distribution, Fricke gels must be undergoing measurement within a few hours of their irradiation, so that ferric ions remain close to their point of production. Thus, the spatial integrity of the dose distribution in the Fricke gel is maintained. The gel matrix also contributes to the oxidation of ferrous ions during irradiation, increasing the chemical yield of ferric ions in aqueous solution and increasing the sensitivity of the dosimeter. The oxidation of ferrous ions also causes a reduction of the longitudinal nuclear magnetic relaxation time T1 which can be measured by means of Nuclear Magnetic Resonance Relaxometry (NMR) and Magnetic Resonance Imaging (MRI). The results presented are related to an experimental investigation conducted on Fricke Gels characterized by gelatinous matrix of Agarose or PVA. We performed NMR relaxometry investigations which allow for direct measurements of the relaxation times in samples exposed to clinical photon beams. The main dosimetric features of the NMR signal were investigated. The gels were irradiated in the clinical dose range between 0 and 20 Gy. In order to assess the photon sensitivitywe analyzed the dependence of NMR relaxation time on radiation dose with varying ferrous ammonium sulfate content inside FXGs. Furthermore, signal stability was followed for several days after irradiation. These measurements were preliminary to MRI analysis which can permit 3D dose mapping. In order to optimized the MRI response a systematic study was performed to optimize acquisition sequences and parameters. In particular, we analyzed for inversion recovery sequences the dependence of MRI signal on the repetition time TR and on the inversion time TI . The dose calibration curves are reported and discussed from the point of view of the dosimeter use in clinical radiotherapy. This work has highlighted that the optimization of additives inside gel matrix is fundamental for optimizing photon sensitivity of these POSTERS 355 detectors. We can conclude that FXG dosimeters with optimal ferrous ammonium sulfate content can be regarded as a valuable dosimetric tool to achieve fast information on spatial dose distribution.

An integrated analytical approach can be useful to study the effectiveness of preservation treatment for Carrara marble surfaces, carried out for testing commercial products which are based on nano-structured silica oxides. Variation in hydrophobic properties, porosity distribution, and chemical composition of treated surfaces have been studied. With this aim, contact angle evaluation, NMR, XRF measurements have been used. Changes of above mentioned physical and chemical characteristics have been evaluated before and after aging in saline chamber of the treated and untreated samples. Moreover, the effectiveness of ultrasonic treatment in “safe” removal of the products from treated surfaces has been evaluated by XRF measurements, studying results by the PC analysis. Results show that some of tested products enhanced the required properties, while some other do not, hence their use should be avoided in the field of CH. Regarding the analysed stone sample, a “safe” removal of product from treated surfaces is possible by using ultrasound probe.

The use of nanoproducts in the Cultural Heritage (CH) field requires great sensitivity and responsibility and, above all, analytical research and studies evaluating effectively their potential use. In order to evaluate the capability of nanostructured protective in the CH field, limestone materials of historical-artistic interest were treated and then studied. The study focuses on the non-invasive evaluation of samples stone, of interest in the CH field, their surface has been tested with nanostructured products. In particular, samples of limestone of Favara (Sicily) have been studied, before and after artificial aging. The analytical methodology involved X-ray fluorescence measurements, in order to evaluate the elemental composition differences between treated and untreated samples; spectrophotometric measurements to determine the colour changes due to the protective application, contact angle estimations on the untreated/treated surfaces and, finally, evaluation of the amount of the absorbed water by capillarity. The samples were, also, artificially aged inside a microclimate chamber, in order to evaluate how the waterproofer properties of the nanostructured products are affected by temperature and humidity. The investigation, repeated after saline chamber, allowed to evaluate the treatments effectiveness and, in particular, their persistence after aging through Si presence/absence, selected as a XRF marker of nanostructured protective layer.

The evaluation of long–term heavy metal concentrations in the Gulf of Palermo was carried out in this study. Measurements of Cr, Cu, Hg, Pb and Zn concentrations were performed by atomic absorption spectrophotometry (AAS) on dated fractions of a sediment core, dated by the 210Pbex method. They are found to cover a time period from 1951 to 2004. The constant sedimentation rate model was used for dating. Specific activities of 137Cs have also been measured in the sediment core sections as a check of the time scale derived by the 210Pbex method. A time-series analysis based on temporal decomposition was used in order to investigate the presence of heavy metal pollution trend. The additive component model, widely used to estimate seasonal and long–term behavior, was chosen for the temporal analysis. Results showed the presence of a specific heavy metal concentration trend. Residual time–autocorrelation has also been taken into account in order to investigate their stochastic properties. Concentrations of some metals (Cu, Hg, and Zn) have been found increasing until the beginning of the 1970s. A peak around the beginning of the 1980s has been found for Cr and Pb. Heavy metal concentration in the sediment core show a significant decreasing after these years. Our results for the concentration time trends are in good agreement with other surveys performed in different areas of the world, and they can be explained in terms of the reduction of anthropogenic contribution to atmospheric emissions. Further investigations on time properties and spatial distributions, are also planned.

This work presents experimental results regarding a new ammonium tartrate blend for ESR dosimetry, with a higher sensitivity and a lower lowest detectable dose (LDD) to 60 Co -rays than the recently used pure ammonium tartrate. The blend composed by ammonium tartrate and gadolinium-oxide (Gd2 O3 ) shows a greater sensitivity (∼2 times) and a smaller LDD than ammonium tartrate. The increased sensitivity was mainly attributed to the great atomic number (Z = 64) of gadolinium, that increases the effective atomic number of the blend; the interaction probability with photons and consequently the radical yield is therefore enhanced. Moreover ammonium tartrate with Gd2 O3 has a linear dose response in the investigated dose range (1–50 Gy). We find this blend suitable for use in ESR dosimetry.

Gold nanorods (AuNRs) can combine therapeutic hyperthermia with diagnostic features, representing a smart choice to address personalized cancer treatments. In this regard, a crucial quest is the selection of the right biocompatible coating agent able to stabilize them in the physiological environment, further endowing the possibility to load bioactive molecules and/or targeting moieties. Therefore, AuNRs optical properties can be successfully merged with advantageous materials features to obtain selective photothermal therapy (PTT) systems. Here, the natural materials lipoic acid (LA) and the polysaccharide gellan gum (GG) were chosen to prepare three types of stabilized gold nanorods, using LA (AuNRs/LA), a layered coating of LA and GG (AuNRs/LA,GG) or a newly synthesized covalent derivative of LA and GG (AuNRs/GG-LA). The samples displayed diverse stability and dispersibility. Hydrodynamic diameters and surface potential analyses confirmed the nanometric size (100&ndash, 200 nm) and showed surface charges ranging from +19.5 to &minus, 25.6 mV. Particular attention was thus paid to analyze the differences between hyperthermia properties exhibited after near-infrared (NIR) laser irradiation. Furthermore, the cytocompatibility and photothermal effect were tested on HCT116 human colon cancer cell line. Collected data have finally allowed selecting AuNRs/LA,GG as the best candidate for possible use in PTT of cancer.