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The manufacturing industry's focus on achieving surfaces with advanced mechanical performance is driven by objectives of competitiveness, sustainability, and efficiency. This study explores the use of Directed Energy Deposition-Laser Beam (DED-LB) process to create Metal Matrix Composites (MMCs) coatings with high mechanical properties, consisting of a nickel-based alloy (Colmonoy 227-F) reinforced with WC-Co-Cr particles, deposited on a 316 L steel substrate. The specific aims of this research are to optimize the DED-LB process parameters and investigate the effect of different reinforcement percentages on the mechanical properties of MMC coatings. The objectives include evaluating the microstructural integrity, hardness, and material distribution of coatings with varying WC-Co-Cr reinforcement levels. The DED-LB technique offers advantages such as localized heat input, rapid cooling rates for finer microstructures, and controlled bonding between substrate and coating. Particularly, it allows for the creation of MMCs, including ceramic-reinforced ones, known for their enhanced mechanical properties. However, managing the dissolution of ceramic reinforcement within the metal matrix remains a challenge. In this research, two reinforcement percentages (10 % and 40 % WC-Co-Cr) were investigated to optimize the process parameters and enhance mechanical properties. Microstructural analysis showed that coatings with 10 % reinforcement maintained a spherical morphology, while 40 % exhibited a slight dispersion of individual carbide grains within the matrix. Vickers hardness tests indicated hardness values of 375 ± 15 HV for 10 % and 490 ± 10 HV for 40 %, with the pure matrix hardness measured at 325 ± 10 HV. This demonstrates the reinforcement effect in both composite coatings. Chemical composition analysis confirmed proper distribution of elements. The study demonstrates that MMC coatings produced through laser deposition with optimized parameters exhibit favorable microstructures, increased hardness, and correct material distribution. The scientific novelty of this work lies in demonstrating that a high level of reinforcement (40 %) can be incorporated without metallurgical defects, enhancing the mechanical properties significantly beyond typical reinforcement levels. These findings are essential for improving mechanical performance and wear resistance in high abrasive load applications. The research contributes valuable insights into optimizing DED-LB processes for advanced MMC coatings, crucial for sustainable and efficient manufacturing practices. • Enhanced MMC coatings via DED-LB: achieved advanced mechanical properties. • Optimal process parameters identified for 10 % and 40 % reinforcement. • Microstructural analysis: no reinforcement melting observed. • Hardness increase observed: 375 ± 15 HV (10 %), 490 ± 10 HV (40 %). • XRD confirmed no W 2 C or Cr compounds, ensuring coating integrity. [ABSTRACT FROM AUTHOR]

Purpose Statistical process control (SPC) is a tool widely used in industrial engineering to monitor and improve processes, allowing early detection and prevention of problems. We retrospectively applied SPC methods on daily Tomotherapy output check in order to assess the possibility to use it as predictive maintenance tool. Methods and materials From January 2014 to September 2017 a total of 1916 daily output check have been performed in static (958) and dynamic (958) modality, using the "cheese" phantom and a ionization chamber inserted into it. In the first case, a static field of 5 cm × 40 cm has been used, while an optimized IMRT plan was considered in the second case. All collected data have been organized per year, and for each year in subgroup of 30 data, representing approximately a month of output checks. Individual (I) and exponentially weighted moving average (EWMA) charts have been used to monitoring the long and short term data variability, respectively. The process performance was evaluated by means of capability indices using the Chan method. Results For each year considered in the study, the I- and EWMA-charts have shown the presence of out of control situation referable to specialist interventions. In particular, as reported in the figure below, the EWMA-charts have shown the presence of out of control situations before the interventions. Even if the tolerance suggested by AAPM TG 148 have been respected in the considered period of time, the process performance were in agreement with the scenario considered: the higher the interventions, the worst the results. Conclusion SPC methods are able to effectively detect variation in Tomotherapy output checks. Further investigation will consider on-line daily results. [ABSTRACT FROM AUTHOR]

Purpose Radiometabolic treatment with 177Lu-PSMA (prostate-specific membrane-antigen) have shown to be a promising option for progressive prostate cancer patients with metastatic disease. Main organ toxicity limiting maximum injectable activity were kidneys(KDs), parotid glands(PGs) and red marrow(RM). We evaluated the delivered dose to healthy tissues(KDs, PGs, RM) for177Lu-PSMA treatments in combination with mannitol intra-venous infusion and iron mineral glutamate oral administration(via candy) combined with ice external application in order to reduce KDs and PGs uptake, respectively. Methods and materials Six patients were enrolled (Table 1). Post injection whole body(WB) planar scans and blood samples were acquired at different timing (1 h, 16–24 h, 36–48 h, 120 h post-injection). ROIs for whole body, KDs and PGs were contoured on the first image and transferred to all others(Xeleris software,GE). KDs and PGs mean counts were normalized to initial whole body activity and (corrected for background, scatter, physical decay and patient's thickness) used to generate biological time-activity curves. Blood samples measurements (High-Purity Germanium detector) were used for RM uptake activity and biological time-activity curve estimation. Dose calculations in terms of mGy/MBq were performed following MIRD formalism(OLINDA/EXM software). Obtained results were compared to previous studies [1,2] with unpaired T-test. Results No statistically significant difference was found for whole body (median[range]:0.04[0.02–0.05] vs 0.05[0.01–0.10] mGy/MBq, p-value = 0.37) or RM (0.04[0.001–0.08] vs 0.03[0.01–0.06], p-value = 0.85) absorbed dose (Figure1). Absorbed dose to kidneys was lower for our patient cohort (0.20[0.11–0.31]) compared to data[1,2](0.86[0.20–1.90]), with statistically significance (p-value = 0.001). Parotid glands absorbed dose was not statistically significant different considering all patients(0.79[0.33–1.24] vs 1.73[0.30–9.50], p-value = 0.24), but the difference increased considering only patients that received iron mineral candy administration (0.40[.33–0.47] vs 1.73[0.30–9.50], p-value = 0.09). Conclusions The possibility to reduce kidneys and parotid gland absorbed dose in 177Lu-PMSA treatments with the administration of combined therapies was shown. The increased of therapeutic index (i.e. same injected activity vs lower dose to main limiting healthy tissues) may provide the possibility to perform injected activity escalation of 177Lu-radioisotope linked to PSMA, compared to previous ligand. [ABSTRACT FROM AUTHOR]

Purpose Air monitoring systems are mandatory in all areas potentially contaminated with airborne radioactivity, such as hot laboratories, treatment rooms, and radioactive waste storage areas. The calibration of such systems may be practically complicated or require the application of correction factors, obtained by means of approximated analytical calculations. Monte Carlo techniques provide an effective way to check the calibration and the impact of the approximations used in the calculation. Methods The present work compares two different systems: a continuous air monitoring system, composed by a NaI detector located inside a chimney, and an air pumping system that measures the sample activity in a Marinelli beaker geometry, equipped with NaI detector. This setup allows to calibrate the continuous air monitoring system using the measurements provided by the Marinelli beaker system. A self-absorption correction factor, applied in the calibration of the Marinelli beaker system, is derived for gamma and beta+ radiation and compared with approximated analytical calculation available for gamma [1]. The cross-calibration of the two systems is complicated by the presence of F18 that sticks to the duct's walls, producing a background that continuously increases during the air flow, therefore the calibration constants are checked using an approximate analytical calculation and a Geant4 simulation. Results Calibration factors are computed for ducts of different sizes and lengths, and validated using the IRST monitoring system. These coefficients represent a useful estimate in the calibration of continuous air monitoring systems in all cases where the cross-calibration of two systems is not possible. Conclusions Monte Carlo techniques help in overcome challenging aspects in the calibration of air monitoring systems, providing reliable results that can be used to cross-check the calibration constants of the system in case of large experimental uncertainties. [ABSTRACT FROM AUTHOR]

Purpose To present our results regarding the commissioning of the RayStation TPS and to compare its dosimetric accuracy with the clinical Pinnacle TPS. Methods A 6 MV beam quality of an Elekta Synergy was considered for modeling in RayStation. The dose calculation accuracy was tested in several situations. Firstly, measured PDD and profiles were compared with calculations using the 1D-gamma analysis. Secondly, using the test fields from the ESTRO booklet No. 7, absolute point doses were measured in a water phantom and compared with calculated values. Then, IMRT and VMAT techniques were tested performing pre-treatment verifications with the PTW-Octavius4D system. For this purpose, the AAPM TG-119 test cases as well as 20 clinical patients with various treatment sites were considered. The agreement between measurements and calculations was assessed with 3D-gamma analysis. Finally, 10 VMAT clinical cases optimized with Pinnacle were recalculated in RayStation. Dose distributions from both TPSs were compared with measurements. Results maximum values of 1D-gamma confidence-level were 0.6 for PDDs (2%-2 mm, local normalization, Table 1) and 0.75 for profiles (3%-2 mm, local normalization). Absolute point dose measurements agreed with calculated values within 1.5%. 3D-gamma pass-rates for the TG-119 cases and patient-specific verifications were within the ranges [97.2%-99.7%] and [89.0%-97.5%] for 3%-3 mm global and local normalization, espectively. Absolute differences between average gamma pass-rates of patient-specific verifications were 0.1% (3%-3 mm, global normalization) and 1.1% (3%-3 mm, local normalization). These differences were not statistically significant (minimum p-value for a Wilcoxon-signed-rank test was 0.51, Fig. 1). Conclusions RayStation was commissioned for a 6 MV beam quality of an Elekta Synergy. The dosimetric accuracy was tested in several situations, including standard international protocols. The agreement between measurements and calculations was clinically acceptable. Furthermore, RayStation accuracy was comparable with the clinically established Pinnacle TPS. [ABSTRACT FROM AUTHOR]

Focused ultrasound are recently introduced as alternative therapy for pain palliation caused by bone metastases. The heat absorption and propagation in the soft tissues and in the bones strongly depends on the correct focalization of the ultrasonic beam through the interfaces. The real-time thermal map provided by the MRI gives to the interventional radiologist the feedback for the online treatment planning. The present work is focused on the verification of planning therapy system of a MRgFUs system giving a verification of the propagation and the accumulation of the temperature in bones in particular for the pelvic bone. In this work it has been studied the Philips Sonalleve HIFU installed on Ingenia 3T. The thermal maps has been studied on a multi-interface phantom with albumin-agarose gel volumetric detector. The planned volume ablation temperature has been compared with the T2 imaging modification on the phantom. A dedicated software has been developed for the extraction of the thermal image maps from the system and for the evaluation of the cumulative thermal dose. A first approach has been proposed for the evaluation of the plan in term of DVH (dose/volume histogram). High impedance interfaces create local depositions of energy along the sonicated surfaces. The plan cumulative dose verification gives constraints to the physicians on sonication cells positioning. The MRgFUs feedback planning gives partial information of the heat deposition. The bone phantom is used to evaluate the real cells volume. The de-focalization created by bones demonstrate the needs of preplanning system dedicated to bones treatments. [ABSTRACT FROM AUTHOR]

Marinelli beaker systems are used to monitor the activity of radioactive samples. These systems are usually calibrated with water solutions and the determination of the activity in gases requires correction coefficients accounting for the different mass-thickness of the sample. For beta+ radionuclides the different distribution of the positrons annihilation points should be also considered. In this work a Monte Carlo simulation based on Geant4 is used to compute correction coefficients for the measurement of the activity of air samples. [ABSTRACT FROM AUTHOR]

Based on a large body of evidence asbestos minerals have been classified as carcinogens. Despite the Italian ban on asbestos in 1992 and the subsequent remediation activities, latent sources of contamination may still represent a hazard where asbestos were particularly used. Using wild rats as sentinel animals, this study aimed at uncovering sites with the greatest potential for non-occupational exposure to asbestos in the city of Casale Monferrato (Piedmont Region, Italy), where the largest Italian manufacturing plant of asbestos-cement had been active. During the study period (2013–2015) a total of 40 wild rats were captured from 16 sampling capture points. The lungs of wild rats have been investigated by using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The SEM-EDS detected the presence of asbestos fibers (tremolite/actinolite, amosite, and chrysotile) in rats' lungs from 11 sampling points. The hypothetical rats' home-range and the observed site-specific concentration of asbestos fibers per gram of dry lung tissue were used to identify areas to be targeted by additional search of latent sources of asbestos. In conclusion, our results showed that the use of wild rats as sentinel animals may effectively integrate the strategies currently in use to reduce the exposure to asbestos. Unlabeled Image • Wild rats were used as sentinels of asbestos latent sources contamination. • Measurement of the lung asbestos fiber burden was conducted by SEM-EDS. • Different asbestos fibers species were found in rats' lungs living in an Italian city. • The concentration of fibers was spatially associated with the rats' capture points. • Based on the home-range of rats, we suggest a hot-spot of latent sources of asbestos. [ABSTRACT FROM AUTHOR]

Radionuclides handled in nuclear medicine departments are often characterized by high volatility and short half-life. It is generally difficult to monitor directly the intake of these short-lived radionuclides in hospital staff: this makes measuring air contamination of utmost interest. The aim of the present work is to provide a method for the evaluation of internal doses to workers in nuclear medicine, by means of an air activity sampling detector, to ensure that the limits prescribed by the relevant legislation are respected. A continuous air sampling system measures isotope concentration with a Nal(TI) detector. Energy efficiency of the system was assessed with GEANT4 and with known activities of 18 F. Air is sampled in a number of areas of the nuclear medicine department of the IRST-IRCCS hospital (Meldola- Italy). To evaluate committed doses to hospital staff involved (doctors, technicians, nurses) different exposure situations (rooms, times, radionuclides etc) were considered. After estimating the intake, the committed effective dose has been evaluated, for the different radionuclides, using the dose coefficients mandated by the Italian legislation. Error propagation for the estimated intake and personal dose has been evaluated, starting from measurement statistics. [ABSTRACT FROM AUTHOR]