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In the present work we report dating procedure of these shells by using the electron paramagnetic resonance. The first step of the analysis was the definition of the optimal procedure for sample preparation. At this aim the analysis of the sample composition was carried out by X-ray fluorescence (XRF) measurements and an accurate analysis was study on the effect of the chemical etching with varying typology and concentration of acid to be used for removing the external layer of shells which are affected by alpha particles.

Purpose: To evaluate the position stability of a phakic intraocular lens (Cachet pIOL; Alcon, Laboratories, Inc., Fort Worth, TX) in the anterior chamber (AC) during a 6-months follow-up. Methods: Thirty eyes of 16 subjects underwent a Cachet pIOL implantation for the correction of high myopia from -6.50 to -16.00 D with plano targeted refraction. The position stability of the Cachet pIOL was evaluated using an Anterior Segment-OCT (AS-OCT, Carl Zeiss AG, Oberkochen, Germany) at 1- and 6-months postoperatively. Three measurements have been taken into account: 1) the minimum distance between the anterior surface of the Cachet pIOL optic disk and the central corneal endothelium; 2) the minimum distance between the optic disk’s edges of the pIOL and the endothelium; 3) the minimum distance between the posterior surface of the pIOL optic disk and the anterior surface of the crystalline lens. The endothelial cell density (ECD) was also recorded. Results: No statistically significant changes of the Cachet pIOL position in the AC were found during follow-up. The average changes were ≤0.1 mm between 1- and 6-months postoperatively (P>0.05). At the end of follow-up, The mean ECD loss was 0.7 % (from 2794 ± 337 cell/mm2 to 2776 ± 388 cell/mm2; P>0.05). Conclusion: A high position stability of the Cachet pIOL in the anterior chamber was shown during a 6-months follow-up.

This study focused on the battlements of the Tower of Palazzo Alliata Pietratagliata in Palermo, which is one of the most important examples of late medieval civil architecture in Sicily. The battlements are made by biocalcarenite and currently affected by a strong desegregation. In order to first characterize the stone some tests have been carried out on small samples collected in situ: chemical and morphological analysis through X-ray diffractometry, scanning electron microscopy (SEM), optical polarized light microscopy (PLM), determination of total soluble salt content by measuring the conductivity and dosage of the anions and determination of the dimensional distribution of the pores. The second step was the testing of nanostructured products for the consolidation. Indeed, since for this purpose it was not possible to take the necessary amount of samples directly from the tower, the study proceeded on the limestone of Marsala, intended as the lithotype with structural and textural characteristics similar to the one used in the battlements of the tower. On these stone samples other analyses were performed: determination of bulk (MVA) and real (MVR) density through helium picnometer, water open porosity measurement through the method of the hydrostatic balance, x-ray diffractometry, porosimetry through nuclear magnetic resonance (NMR) relaxometry and scanning electron microscopy (SEM). Moreover, after an induced aging of the specimens for simulating the desegregation of the stone, two nanostructured products for the consolidation, both based on nanosilica, have been applied. Then, two more cycles of diagnostics have been performed in order to understand the effect of the products on the stone. The results obtained through these various experimental techniques are reported and extensively discussed.

In this work we report some preliminary results regarding the analysis of electron paramagnetic resonance (EPR) response of alanine pellets and alanine pellets added with gadolinium used for dosimetry at the TRIGA research reactor in Mainz, Germany. Two set-ups were evaluated: irradiation inside PMMA phantom and irradiation inside boric acid phantom. We observed that the presence of Gd2O3 inside alanine pellets increases the EPR signal by a factor of 3.45 and 1.24 in case of PMMA and boric acid phantoms, respectively. We can conclude that in the case of neutron beam with a predominant thermal neutron component the addition of gadolinium oxide can significantly improve neutron sensitivity of alanine pellets. Monte Carlo (MC) simulations of both response of alanine and Gd-added alanine pellets with FLUKA code were performed and a good agreement was achieved for pure alanine dosimeters. For Gd2O3-alanine deviations between MC simulations and experimental data were observed and discussed.

PURPOSE To estimate the influence of corneal properties on intraocular pressure (IOP) differences between an air-puff tonometer (NT530P; Nidek) and the Goldmann applanation tonometer (Haag-Streit). PATIENTS AND METHODS The influence of central corneal thickness (CCT), keratometry, and Ocular Response Analyzer (Reichert) measurements of corneal viscoelasticity [corneal hysteresis (CH) and corneal resistance factor (CRF)] on IOP differences between tonometers was evaluated. RESULTS The CRF was calculated to be the best predictor of the differences in IOP readings between tonometers (r2=0.23; P

To examine levels of serum homocysteine (Hcy), vitamin B12 and folic acid in patients with pseudoexfoliation glaucoma (PEXG), primary open-angle glaucoma (POAG), and healthy control subjects. This study included 36 patients with PEXG, 40 with POAG, and 40 age-matched healthy subjects. Fasting plasma Hcy concentrations and levels of serum vitamin B12 and folic acid were measured using competitive chemiluminescent enzyme immunoassay; values exceeding 14 μm/l were considered elevated. Mean plasma Hcy was significantly higher in PEXG (16.55 ± 7.23 μm/l) compared with POAG (13.91 ± 3.61 μm/l) and controls (13.12 ± 5.13 μm/l) (p = 0.03 and p = 0.0007 respectively). There were no statistical differences in serum vitamin B12 and folic acid levels among PEXG, POAG and control subjects (p > 0.05). A moderate, although statistically significant, relationship between Hcy and folic acid levels was found in the PEXG group (R2 = 0.23, p = 0.003). Hcy levels were found not to be related with folic acid or vitamin B12 in either POAG or control subjects. In this study, plasma Hcy is significantly higher in PEXG group than the POAG and control groups. Hyper-Hcy might play a role in the pathogenesis of PEXG. Hyper-Hcy may be an independent factor stressing vasculopathy in addition to pseudoexfoliation, so might be a modifiable risk factor for PEXG.

The formation of the coastal plain of the Brazilian sea is mainly due to the fluctuation of relative sea level in the past. Armacao dos Buzios or simply Buzios is a municipality in the microregion of lakes, in the state of Rio de Janeiro. In this region there is a lowland area about two meters above current sea level. This lowland area is also known as coastal plain of Una River. It is expected that during the Holocene period the sea level reached a maximum about 2.5 meters above the current level. During that time billions of mollusks lived and proliferated in the shallow waters around the coastal plain of the Una River. As they died their shells formed a layer in the soil including Malhada Marsh that belongs to the Una River plain. In this study, shells were collected from this region and dated using the techniques of Electronic Paramagnetic Resonance (EPR). Ages from 2480±130 to 4490±270 years were obtained. Radiocarbon dating were performed at the Beta Analytic Lab, USA for comparison with the EPR results. Shells ages obtained are compatible with geological data from the Holocene period relative to past sea level fluctuations.

This article describes Electron Spin Resonance (ESR) response measurements of Kodak BioMax alanine films exposed to low-energy X-rays from a Cu-target tube operating at 20 kV. Commercial alanine detectors were used to ensure maximum reproducibility of the results, while the choice of a film was due the low penetration of the soft X-rays. X-ray energy spectra and fluences were determined with an innovative digital semiconductor detector system. These data were used to quantify the irradiation of the alanine films in terms of absorbed dose to water. The alanine films were found to present a stable response, highly linear with dose. To our knowledge, these data have not been previously reported and they may be extremely relevant, e.g., when mapping the high-gradient treatment fields used in microbeam radiation therapy (MRT) with synchrotron radiation.

Fricke Gel (FXGs) dosimetric system is based on the radiation induced oxidation of ferrous to ferric 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 (Schreiner, 2015). 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) (Marrale, 2014). The results here presented are related to an experimental investigation conducted on Fricke Gels characterized by gelatinous matrix of Polyvinyl alcohol (PVA) cross-linked with a Glutaraldehyde (GTA) (Marini, 2016). 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 sensitivity we analyzed the dependence of NMR relaxation times 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 maximize 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 maximizing 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.

In questo lavoro sono presentate le misure effettuate tramite rilassometria NMR su campioni costituiti da una matrice gelatinosa drogata con ioni ferrosi comunemente chiamati dosimetri gel di tipo Fricke (FXG). La dosimetria con gel Fricke si basa sulla ossidazione degli ioni ferrosi (Fe2+) in ioni ferrici (Fe3+) all’interno di una matrice gelatinosa a seguito di irraggiamento (Schreiner, 2004). Tale processo è fortemente dipendente dalla dose somministrata (Marrale, 2014a). I dosimetri di Fricke sono tessuto-equivalenti, rispondono ad ogni tipo di radiazione ionizzante ed, assumendo la forma del contenitore in cui avviene la gelificazione, possono essere utilizzati per studiare l’effetto delle radiazioni su fantocci antropomorfi da essi costituiti. Inoltre, la matrice di gel rallenta la diffusione degli ioni ferrosi (Fe2+) e ferrici (Fe3+) in modo che, se il gel viene analizzato entro un paio di ore dall’irraggiamento, gli ioni ferrici rimangono prossimi al loro punto di produzione. Inoltre, il gel favorisce l’ossidazione degli ioni ferrosi durante l'irraggiamento, in modo da aumentare la resa chimica degli ioni ferrici e quindi la sensibilità dei dosimetri. Lo scopo di questo lavoro è l'analisi tramite risonanza magnetica nucleare (NMR) delle proprietà di rilassamento protonico dei gel dosimetrici da noi preparati al variare della concentrazione dei centri paramagnetici (Fe3+) prodotti al variare della dose di irraggiamento. I gel Fricke sono stati irradiati con fasci di fotoni (LINAC) nel range clinico tra 0 e 20 Gy. Le analisi NMR sono state affiancate da acquisizioni di imaging a Risonanza Magnetica Nucleare (MRI) utilizzata in ambito ospedaliero (Galante, 2008). Per valutare la sensibilità a fotoni, abbiamo studiato la dipendenza dei tempi di rilassamento nucleari dalla dose, dalla concentrazione di solfato di ammonio ferroso contenuto all’interno dei gel e dalla presenza di indicatori ottici degli ioni metallici. Inoltre, è stata monitorata la stabilità del segnale per diversi giorni dopo l'irraggiamento. Le acquisizioni MRI sono state finalizzate alla mappatura 3D della dose su fantocci estesi. Vengono presentati e discussi i risultati ottenuti in relazione ad applicazioni dei dosimetri gel Fricke in ambito radioterapico. Questo lavoro evidenzia come valutazioni dosimetriche non possono prescindere dall’ottimizzazione della concentrazione degli additivi.

Negli ultimi anni è cresciuto il rischio di esposizioni radiologiche non controllate della popolazione, sia a causa di incidenti associati ad applicazioni industriali e mediche delle radiazioni ionizzanti sia in seguito ad incidenti legati all’abbandono o alla dismissione di sorgenti ma anche ad un uso criminale di materiale radioattivo [1–3]. Gli effetti biologici prodotti dalle radiazioni ionizzanti dipendono fortemente dalla quantità di energia impartita per unità di massa (dose assorbita) [4]. Pertanto, nell’ambito di un incidente radiologico, disporre di procedure di ricostruzione della dose assorbita da un individuo può contribuire oltre che ad identificare i membri della popolazione eventualmente coinvolti anche a stimare la gravità del danno subito. Inoltre per prevedere i possibili effetti a lungo termine e programmare un corretto trattamento terapeutico può essere altresì importante conoscere la distribuzione di dose al corpo [5, 6]. Poiché la popolazione comune non indossa dosimetri individuali specifici, diviene indispensabile la ricerca di dosimetri di emergenza tra i materiali facilmente reperibili sulla persona esposta o sul luogo dell’evento. I dosimetri fortuiti devono essere di facile acquisizione, semplici da preparare per le misure ed è auspicabile che l’intera procedura per la ricostruzione della dose in condizioni di emergenza sia rapida e non invasiva. É importante, inoltre, che la loro lettura sia sufficientemente sensibile da permettere la misura di dosi clinicamente significative (sicuramente inferiori ai 10 Gy) e la differenziazione tra valori di dose appartenenti ai diversi intervalli di dose di interesse per la dosimetria in caso di emergenza radiologica [7, 8]. L’insieme delle misure finalizzate alla ricostruzione della dose ricevuta in un passato recente o lontano vengono descritte collettivamente come dosimetria retrospettiva [6]. Si parla di dosimetria retrospettiva accidentale qualora le valutazioni siano mirate a ricostruire dosi ricevute in seno ad incidenti ai quali è associata emissione di radiazioni ionizzanti. Spesso le esposizioni accidentali dei membri della popolazione sono localizzate o comunque molto eterogenee. In tal caso, può essere utile adottare come dosimetri accidentali oggetti prossimi a diverse parti del corpo così da poter ricostruire la distribuzione di dose al corpo stesso. Per tale motivo vari tipi di materiali organici ed inorganici, prelevabili direttamente dagli individui o da oggetti in loro stretta prossimità, sono stati sottoposti ad esperimenti, anche con più tecniche sperimentali, per studiarne le potenzialità come dosimetri individuali fortuiti. Sono state prese in considerazione tecniche di dosimetria biologica e di dosimetria fisica. Queste ultime, in particolare, consentono una misura indiretta della dose tramite valutazione degli effetti fisici indotti dalle radiazioni ionizzanti. Tra le varie tecniche di dosimetria fisica, la spettroscopia di risonanza di spin elettronico (ESR) permette la valutazione quantitativa della concentrazione delle specie paramagnetiche radioindotte che è strettamente legata alla dose assorbita. Invece, la termoluminescenza (TL) fornisce informazioni sulla dose di irraggiamento tramite la misura della concentrazione di elettroni indotti dalla radiazione ionizzante nelle trappole della struttura di materiali isolanti o semiconduttori. L’obiettivo di questo lavoro è l'analisi delle proprietà dosimetriche campioni di vetro minerale, quale quello presente sui quadranti degli orologi da polso, irradiati con fasci di fotoni tramite spettroscopia EPR e tecnica TL.

La radioattività delle famiglie di radionuclidi naturali contenuti nei materiali da costruzione è responsabile in una certa misura dell'equivalente di dose riferibile al fondo naturale delle radiazioni. Tale radioattività contribuisce a due fattori di dose: la dose gamma esterna e la dose alfa interna legata all'introduzione e all'accumulo del radon nonché ad un contributo dovuto all’inalazione di polveri nelle quali le concentrazioni dei capostipiti naturali sono alte. I materiali da costruzione sono la sorgente principale del rateo di dose gamma nelle abitazioni. Tutti gli edifici in pietra contengono nuclei radioattivi come 226Ra, 232Th e 40K. É noto che i livelli di radon sono legati al radio intrappolato nei grani del materiale lapideo. Negli edifici con alti livelli di radio l'esalazione di radon può diventare di grande importanza. La conoscenza dei livelli di radioattività nei materiali da costruzione è perciò importante nel definire il rischio radiologico per la salute umana. La Sicilia è un'isola con caratteristiche geologiche e litologiche specifiche. Ogni litologia presenta diverse concentrazioni di radionuclidi. Questo diventa importante sia nel caso di costruzioni in pietra che di materiali ottenuti da malte e cementi ottenuti da miscelazione dei materiali provenienti da diverse cave.

Studies on the optical absorbance spectra of Fricke xylenol orange gel dosimeters were performed, in the wavelength range from 300 nm to 800 nm, in order to highlight some particular characteristics that can affect the achievable precision. The spectra are different mainly due to the different types of xylenol orange that was used and to a lower extent due to the different gelling agents (agarose or gelatine). The characteristic of variation of absorbance spectra versus dose, however, are similar in the various cases and can explain some peculiarities, as apparent effects of dose threshold. Changes of spectral shapes appear over the time after irradiation. Magnetic resonance measurements performed at various times after irradiation only reveal the slow changes due to the auto-oxidation effect, proving therefore that the modality of chelation of ferric ions by xylenol orange can affect the observed changes in the optical absorbance spectra.

Sono stati analizzati tramite rilassometria NMR ed acquisizioni MRI dosimetri gel di tipo Fricke realizzati utilizzando un'innovativa matrice gel sintetica e tessuto equivalente: Polyvinyl alcohol (PVA) attivando chimicamente il processo di gelificazione tramite l'aggiunta di Glutaraldehyde (GTA). Questi gel sono stati irradiati con fasci di fotoni (LINAC) nel range 0--20 Gy. Per valutare la sensibilità a fotoni è stata studiata la dipendenza dei tempi di rilassamento nucleari dalla dose e dalla concentrazione di ferro nei gel. Inoltre è stata monitorata la stabilità del segnale dopo l'irraggiamento. Acquisizioni preliminari MRI con uno scanner MRI da 7 T sono state affiancate alle misure NMR. Questo lavoro evidenzia come le valutazioni dosimetriche non possono prescindere dall'ottimizzazione della concentrazione degli additivi.

The aminoacid L-a-alanine has attracted considerable interest for use in radiation ESR dosimetry and has been formally accepted as a secondary standard for high-dose (kGy) and transfer dosimetry . The accuracy of the method is quite high, largely due to the low dependence of the alanine response on various irradiation parameters (photon energies above 100 keV, dose rate, temperature, etc.). Furthermore, this system presents alinear response to dose, fairly high sensitivity, tissue equivalence, absence of fading, small dimensions, ruggedn ess, and non-destructive readout. In this work, we examined the energy dependence of alanine ESR dosimeters in the low energy X-photon energy range between 1 keV and 40 keV, which was not previously described. Furthermore, we analyzed the response enhancement of alanine loaded with gadolinium oxide. The ESR measurements were complemented by the information provided by a reference ionization chamber and a by semiconductor detection systems.

Fricke gel dosimeters are ideal candidates to provide 3D maps of dose distributions and are particularly useful in the plann ing and verification phase of radiotherapy treatments. One of the most effective experimental techniques to reconstruct dose maps is magnetic resonance imaging (MRI). This measures th e nuclear relaxation times variations induced by irradiation. In this work, we analyzed Fricke gels with and without Xylenol Orange by means of a single side-NMR relaxometer (which is abl e to provide information on both relaxation relaxation times T1 and T2 and is mainly used in the field of diagnostics for Cultural Heritage [1-2] to perform porosimetry meaurements). Our goal was to perform a more basic investigation on the MR relaxation features of these gels with and without xylenol orange in order to achieve a deeper understanding of the physical properties of these gels from the relaxation times.

Introduction: Fricke Xylenol Gel (FXG) dosimetric system is based on the radiation induced oxidation of ferrous to ferric ions. In this kind of gels it can occur that ferrous and ferric ions diffuse in the gel matrix. To preserve the spatial distribution of the dose from diffusion, Fricke gels must be undergoing measurement within a few hours of their irradiation. Thus, the spatial integrity of the dose distribution in the Fricke gel is maintained. The oxidation of ferrous ions also causes a reduction of the longitudinal nuclear magnetic relaxation time which can be measured by means of nuclear magnetic resonance (NMR) instrumentation. In this work we performed NMR relaxometry and MR imaging investigations of Fricke Xylenol Gel characterized by gelatinous matrix of Agarose for possible applications in clinical photon beams used for radiation therapy. Materials and Methods: NMR relaxometry measurements were performed using an mq-ProFiler single-side relaxometer (Bruker Biospin). MRI imaging was realized on a 1.5 T Achieva scanner (Philips) with an eight channel head coil. The gels were irradiated in the clinical dose range (0– 20 Gy) with a Siemens Primus Low linear accelerator. Results: The main dosimetric features of the NMR signal were investigated. The linearity of the response with dose was observed. In order to assess the photon sensitivity we analyzed the dependence of NMR relaxation time on radiation dose with varying ferrous ammonium sulfate content inside FXG. The ferrous ammonium sulfate content which maximizes sensitivity is 1.75 mM. Furthermore, signal stability was followed for several days after irradiation. Aldo for MRI analysis the dose calibration curves were obtained also with MRI scanner. Moreover, a depth dose profile was reconstructed. Conclusions: 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.

Introduction Fricke gel dosimeters allow measurements of 3D dose distributions and can be an effective tool for dosimetry verifications in radiotherapy. Various authors have reported drawbacks of the gels affecting the accuracy in case of low dose measurements. Purpose This study aims at investigating such drawbacks and at establishing the conditions for an optimal use of the gels. Materials and methods Our dosimeters consist of gels infused with a Fricke ferrous sulphate solution combined with xylenol orange (XO). Two kinds of xylenol orange (XO) and two different gelling agents (gelatin from porcine skin and Agarose) were utilized. Gels are red out by light absorption techniques: images of absorbance in two wavelength regions (around 430 nm and 585 nm) are acquired with a CCD camera. Absorbance spectrum measurements were done with a compact spectrometry based on optical fibres. Magnetic resonance (MR) measurements of Longitudinal Relaxation Time (T1) were also performed. Results Different trends characterized the absorbance spectra of dosimeters obtained with different gelling agents or different XOs. Moreover, the trends were different for different absorbed doses and varied over a few hours after irradiation. Conclusion The variation of the absorbance spectra is consistent with various previously unexplained effects reported in literature and may explain them. The results are a valid aid for a better use of these dosimeters and warrant further studies of the changes in the Fricke gel matrices after irradiation. Disclosure Authors declare no relationship that may bias the presentation.

The glow curves of thermoluminescent dosimeters (TLD600, TLD700 and MCP), exposed to a mixed field of thermal neutrons and gamma photons are analysed. The fluence values of thermal neutrons used, comparable with those used in radiotherapy, allow one to define the reliability of the TLDs, in particular the most sensitive MCP, in this radiation field and to get information on the dose absorbed values. The glow curves obtained have been deconvoluted using general order kinetics and the observed differences for the different LET components have been analysed. In particular, the ratio of the n(0) parameter of two different peaks seems to allow to discriminate the different contributions of neutrons and gamma photons in the beam.

An extensive study of sediment cores in the Palermo Bay has been carried during the last two years. Main goal of the research was to study the environmental pollution of the area, using foraminifers as an environmental indicator.