Search Results (67)

In arid regions, the tritium concentration in groundwater is typically very low and often falls below the minimum detectable activity (MDA) of the conventional liquid scintillation counter (LSC). Therefore, to measure the tritium activity concentration, it is necessary to lower the detection limit so that the scintillation counter can detect it. In the present study, several methods are discussed which are effective at lowering the detectable activity of tritium. One of these methods is to enrich the tritium activity concentration by ten- to fortyfold of the initial concentration of the tritium. Twelve spiked samples with known amounts of tritium, five with high concentrations and seven with low concentrations, were enriched by the electrolysis process. The results indicated that enriching the tritium levels in groundwater lowers the MDA value. Other methods are minimizing background radiation using low-background materials for sample containers, increasing the measurement efficiency of the scintillation counter and counting time, and shielding the sample from environmental radiation using the shutter option in LSC. Moreover, reducing the number of interfering contaminants in the sample can lower the uncertainty in measuring the tritium concentration in the water sample, which is beneficial for detecting low-level tritium in water to ensure public health and safety. Full article

This work describes the creation and experimental validation of $DoseMRT$, a new software package, and its associated workflow for dose calculations in synchrotron-generated broad beam and microbeam radiation treatment fields. The $DoseMRT$ software package allows users to import CT DICOM datasets into Geant4 for Monte Carlo dose calculations. It also provides basic treatment planning capabilities, simplifying the complexity of performing Geant4 simulations and making our Monte Carlo dose calculation algorithm accessible to a broader range of users. To demonstrate the new package, dose calculations are validated against experimental measurements performed in homogeneous water tank phantoms and the anatomically complex Alderson Radiotherapy Phantom for both broad-beam and microbeam configurations. Additionally, $DoseMRT$ is successfully utilised as the primary method for patient-specific treatment prescription in an in vivo experiment involving tumour-bearing rats at the Imaging and Medical Beamline of the Australian Synchrotron. Full article

Accelerated neutron tests on silicon (Si) and silicon carbide (SiC) power MOSFETs at different temperatures and drain bias voltages were performed at the ChipIr facility (Didcot, UK). A super-junction silicon MOSFET and planar SiC MOSFETs with different technologies made by STMicroelectronics were used. Different test methods were employed to investigate the effects of temperature on neutron susceptibility in power MOSFETs. The destructive tests showed that all investigated devices failed via a single-event burnout (SEB) mechanism. Non-destructive tests conducted by using the power MOSFET as a neutron detector allowed measuring the temperature trend of the deposited charge due to neutron interactions. The results of the destructive tests, in the −50 °C–180 °C temperature range, revealed the lack of a common trend concerning the FIT temperature dependence among the investigated SiC power MOSFETs. Moreover, for some test vehicles, the FIT-temperature curves were dependent on the bias condition. The temperature dependence of the FIT values, observed in some SiC devices, is weaker with respect to that measured in the Si MOSFET. The results of the non-destructive tests showed a good correlation between the temperature trends of the deposited charge with those of FIT data, for both Si and SiC devices. Full article

Background: Stereotactic Radiotherapy (SRT) in pancreatic and biliary tract cancer (PBC) suffers from proximity to any organ(s) at risk (OARs). Some strategies to manage this issue have previously been proposed, such as Simultaneous Integrated Protection (SIP), with the aim of maintaining a biological effective dose prescription while reducing toxicities. We performed a systematic review of the literature about SRT techniques applied in patients with tumor in proximity to OARs, with the aim of testing safety and efficacy. Methods: using PRISMA guidelines, we selected studies from a pool of more than 25,000 articles published from 2010 to 30 January 2023 that explored the use of SRT to deliver targeted treatment for PBC. We then selected the ones referring to decreases in prescription doses (for SRT only) in the area of overlap between planning target volume (PTV) and OARs. Local control (LC) and toxicities being detailed were exclusion criteria for articles. Results: 9 studies were included in our review, considering 368 patients. One-year LC probability ranges between 67% and 98.3% were reported. Late G3 toxicities ranged between 0% and 5.3%, while G4-G5 late toxicities were both reported as 0.3%. Conclusion: prioritizing critical OAR constraints limits severe toxicities while preserving LC in PBC SRT. Improving in-study reporting is essential to confirm these promising results. Full article

Background: Erectile dysfunction (ED) is common after prostate cancer treatment. It has been studied for conventional radiotherapy, but associations in the hypofractionated radiotherapy context are less clear. This study aimed to determine which factors are predicted for worsening ED after highly conformal, modestly hypofractionated radiotherapy to the prostate. Methods: Two hundred and twelve patients treated with 6000 cGy in twenty fractions across four centers were included in this study. Demographic, clinical, and dosimetry factors were then evaluated for post-treatment declines in erectile function using logistic regression and an explainable machine learning-based neural network. Results: 212 patients with a median follow-up of 3.6 years were evaluated. A total of 104 (49%) patients received androgen deprivation therapy. Prior to treatment, 52 (25%) patients were on ED medication. Mean doses to the penile bulb, penile crus, and penile shaft were 2490 (IQR: 1529–3656) cGy, 2095 (1306–3036) cGy, and 444 (313–650) cGy, respectively. Fifty-nine (28%) patients had a worsening of ED after treatment. On multivariable analysis, only the mean dose to the penile shaft [OR >345 vs. ≤345: 4.47 (1.43–13.99); p = 0.010] and pretreatment use of ED medication [OR yes vs. no: 12.5 (5.7–27.5; p < 0.001)] predicted for worsening ED. The neural network confirmed that the penile shaft mean dose and pre-treatment ED medication use are the most important factors in predicting ED. Conclusions: Pre-treatment ED and penile shaft dosimetry are important predictors for ED after hypofractionated radiotherapy for prostate cancer. Full article

This study aimed to evaluate the safety of gadobutrol, a gadolinium-based contrast agent used in medical imaging, by investigating its effect on the nervous system under physiological and inflammatory conditions. Male Sprague Dawley rats were divided randomly into four groups, including gadobutrol, saline, LPS + gadobutrol, and LPS + saline, and were given intraperitoneal injections of gadobutrol (2.5 mmol/kg) or saline for 20 days. Weekly sensorimotor and cognitive behavioral tests were performed over 4 weeks, and Gd concentration in nervous tissues was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Lactate dehydrogenase (LDH) activity was measured to evaluate cytotoxicity, and electromyography (EMG) recordings from the gastrocnemius muscle were also obtained to examine signal transmission in sciatic nerves. The results indicated that gadobutrol did not induce significant behavioral changes under normal conditions. However, when administered along with LPS, the combination led to behavioral dysfunction. ICP-MS analysis revealed a higher concentration of Gd in the cerebrum and spinal cord of gadobutrol + LPS-treated rats, while peripheral nerves showed lower concentrations. In addition, there was a significant increase in LDH activity in the hippocampus of the gadobutrol group. EMG responses to electrical stimulation of the sciatic nerve demonstrated a decreased threshold of nociceptive reflexes in the gadobutrol group. Overall, while gadobutrol may be considered safe under normal physiological conditions, the findings suggest that its safety may be compromised under inflammatory conditions. Full article

We investigated the influence of modifying the voltage of an X-ray tube with a tungsten anode between 30 kV and 225 kV, and therefore its photon energy spectrum (up to 225 keV), on the Total Ionizing Dose deposited in a single-mode, phosphorus-doped optical fiber, already identified as a promising dosimeter. Simulation data, obtained using a toolchain combining SpekPy and Geant4 software, are compared to experimental results obtained on this radiosensitive optical fiber and demonstrate an increase of the deposited dose with operating voltage, at a factor of 4.5 between 30 kV and 225 kV, while keeping the same operating current of 20 mA. Analysis of simulation results shows that dose deposition in such optical fibers is mainly caused by the low-energy part of the spectrum, with 90% of the deposited energy originating from photons with an energy below 30 keV. Comparison between simulation and various experimental measurements indicates that phosphosilicate fibers are adapted for performing X-ray dosimetry at different voltages. Full article

The space radiation environment outside the protection of the Earth’s magnetosphere is severe and difficult to shield against. The cumulative effective dose to astronauts on a typical Mars mission would likely introduce risk exceeding permissible limits for carcinogenesis without innovative strategies for radiation shielding. Damaging cardiovascular and central nervous system effects are also expected in these space environments. There are many potential options for advanced shielding and risk mitigation, but magnetic shielding using superconductors offers several distinct advantages including using the conditions in space to help maintain the superconductor’s critical temperature and lower mass compared to equivalent passive shielding materials. Despite these advantages, the development of magnetic shielding technology has remained primarily in conceptual stages since the introduction of the idea in 1961. Over the last several decades, magnetic shielding has experienced periods of high and low attention by the human spaceflight community, leading to computational tools with single-use or other limitations and a non-uniform distribution of publications on the topic over time. Within the context of technology development and the surrounding space policy environment, this paper reviews and summarizes the available literature on the application of active magnetic shielding for space radiation protection, identifies challenges, and highlights areas for future research. Full article

Secondary lymphedema is caused by damage to the lymphatic system, often following an oncological tumor removal intervention, or even by an accident. The diagnosis of lymphedema is not easy, because the disease can also be confused with other clinical manifestations (for example, venous insufficiency edema), though an experienced Lymphologist is usually able to diagnose it with good accuracy. To confirm the diagnosis, it is often necessary to resort to specialist imaging tests for an anatomo-functional definition of the pathology. Among these, lymphoscintigraphy is confirmed as the “gold standard” procedure for the diagnosis of lymphedema. Lymphoscintigraphy has been included in the Italian Guidelines by the Ministry of Health. Full article

The Rothmund–Thomson syndrome (RTS) is a rare autosomal recessive disease associated with poikiloderma, telangiectasias, sun-sensitive rash, hair growth problems, juvenile cataracts and, for a subset of some RTS patients, a high risk of cancer, especially osteosarcoma. Most of the RTS cases are caused by biallelic mutations of the RECQL4 gene, coding for the RECQL4 DNA helicase that belongs to the RecQ family. Cellular and post-radiotherapy radiosensitivity was reported in RTS cells and patients since the 1980s. However, the molecular basis of this particular phenotype has not been documented to reliably link the biological and clinical responses to the ionizing radiation (IR) of cells from RTS patients. The aim of this study was therefore to document the specificities of the radiosensitivity associated with RTS by examining the radiation-induced nucleo-shuttling of ATM (RIANS) and the recognition and repair of the DNA double-strand breaks (DSB) in three skin fibroblasts cell lines derived from RTS patients and two derived from RTS patients’ parents. The results showed that the RTS fibroblasts tested were associated with moderate but significant radiosensitivity, a high yield of micronuclei, and impaired DSB recognition but normal DSB repair at 24 h likely caused by a delayed RIANS, supported by the sequestration of ATM by some RTS proteins overexpressed in the cytoplasm. To our knowledge, this report is the first radiobiological characterization of cells from RTS patients at both molecular and cellular scales. Full article

This article highlights advancements in polymeric composite/nanocomposites processes and applications for improved radiation shielding and high-rate attenuation for the spacecraft. Energetic particles, mostly electrons and protons, can annihilate or cause space craft hardware failures. The standard practice in space electronics is the utilization of aluminum as radiation safeguard and structural enclosure. In space, the materials must be lightweight and capable of withstanding extreme temperature/mechanical loads under harsh environments, so the research has focused on advanced multi-functional materials. In this regard, low-Z materials have been found effective in shielding particle radiation, but their structural properties were not sufficient for the desired space applications. As a solution, polymeric composites or nanocomposites have been produced having enhanced material properties and enough radiation shielding (gamma, cosmic, X-rays, protons, neutrons, etc.) properties along with reduced weight. Advantageously, the polymeric composites or nanocomposites can be layered to form multi-layered shields. Hence, polymer composites/nanocomposites offer promising alternatives to developing materials for efficiently attenuating photon or particle radiation. The latest technology developments for micro/nano reinforced polymer composites/nanocomposites have also been surveyed here for the radiation shielding of space crafts and aerospace structures. Moreover, the motive behind this state-of-the-art overview is to put forward recommendations for high performance design/applications of reinforced nanocomposites towards future radiation shielding technology in the spacecraft. Full article

The aim of the current work was to study natural radioactivity in soil and the correlation between ²²²Rn and ²²⁶Ra in the ground and to assess the onsite and indoor long-term excess cancer risk at the bauxite bearing area of Fongo-Tongo in Western Cameroon. ²²²Rn was measured in the ground at a depth of one meter, using Markus 10 detector. ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations were measured in soil by two techniques, in situ and laboratory gamma spectrometry. The mean values of ²²²Rn concentrations in the ground were 69 ± 18 kBqm⁻³ for Fongo-Tongo and 82 ± 34 kBq m⁻³ for the locality of Dschang, respectively. The mean values of ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations obtained with in situ gamma spectrometry were 129 ± 22, 205 ± 61, and 224 ± 39 Bq kg⁻¹ for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively, and those obtained by laboratory gamma spectrometry were 129 ± 23, 184 ± 54, and 237 ± 44 Bq kg⁻¹, respectively. A strong correlation between ²²²Rn and ²²⁶Ra activity concentrations determined by in situ and laboratory measurements (R² = 0.86 and 0.88, respectively) was found. In addition, it is shown that the total excess cancer risk has a maximum value of 8.6 × 10⁻³ at T = 0 year and decreases progressively in the long term. It is also shown that ²²⁶Ra makes a major contribution, i.e., above 70%, to the total excess cancer risk. Full article

Cardiovascular diseases represent one of the most frequent diseases worldwide; among these, lower limb ischemia is a threatening condition, which can lead to permanent disability if not promptly and correctly diagnosed and treated. A patient’s clinical evaluation and diagnostic imaging (e.g., color-Doppler ultrasound, computed tomography angiography (CTA), and magnetic resonance imaging (MRI)) are mandatory to carefully assess arterial lesion extension and severity. Digital subtraction angiography (DSA) is a minimally invasive technique that represents the gold standard for percutaneous revascularization treatment of symptomatic patients who are refractory to medical management. However, when dealing with patients with lower limb terminal ischemia, the correct interpretation of diagnostic DSA findings is mandatory for treatment re-planning and to effectively evaluate post-treatment results and complications. The purpose of this review is to provide interventional radiologists and endovascular practitioners with an up-to-date practical guide to diagnostic angiography of the lower limbs, which is mandatory to address correct treatment decisions and post-treatment evaluation. Full article

In order to test the theory of Brizhik et al. about the dynamic allocation of acupuncture meridians on human body and their role as hydric paths for solitons, we tested the effect of both acupuncture and exposure to extremely low frequencies (ELF) tuned with suitable ion cyclotron frequencies. The similarity of the effects, inducing variations of body impedance measured in well-known acupuncture points, up to the interchangeability and the synergy of the two treatments, the mechanic and the electromagnetic ones, turns to be evidence of the validity of the theory. Resistance and reactance variations have been detected in a group of 31 healthy volunteers before and after stimulation with a standard sequence of cyclotron frequencies, emitted from an innovative electromagnetic therapy (EMT) device. These variations were then compared with the variations produced by the well-known percutaneous stimuli of mechanical and piezoelectric nature, and, in particular in this work, acupuncture. Our results show that the observed variations can be considered as significant in both groups: cyclotron and acupuncture. The greater variations brought about by the cyclotron treatment stand out clearly. Full article