Search Results (900)

Ultraviolet B (UVB) radiation is a key factor in the overproduction of melanin in the skin. Melanocytes produce melanin through melanogenesis to protect the skin from UVB radiation-induced damage. However, excessive melanogenesis can lead to hyperpigmentation and increase the risk of malignant melanoma. Tyrosinase is the rate-limiting enzyme in melanogenesis; it catalyzes the oxidation of tyrosine to 3,4-dihydroxy-L-phenylalanine and subsequently to dopaquinone. Thus, inhibiting tyrosinase is a promising strategy for preventing melanogenesis and skin hyperpigmentation. White mulberry (Morus alba L.) is rich in antioxidants, and mulberry fruit extracts have been used as cosmetic skin-lightening agents. However, data on the capacity of mulberry fruit extracts to inhibit tyrosinase under UVB radiation-induced melanogenic conditions remain scarce, especially in an in vivo model. In this study, we evaluated the effects of a mulberry crude extract (MCE) on UVB radiation-induced melanogenesis in B16F10 melanoma cells and zebrafish embryos. The MCE significantly reduced tyrosinase activity and melanogenesis in a dose-dependent manner without inducing cytotoxicity. These effects are likely attributable to the antioxidant constituents of the extract. Our findings highlight the potential of this MCE as an effective tyrosinase inhibitor for the prevention of UVB radiation-induced skin hyperpigmentation. Full article

Objectives: To investigate how the FLASH effect modulates radiation response on multiple developmental endpoints of zebrafish embryos under normoxic and hypoxic conditions, after irradiation with proton beams at a conventional and an ultra-high dose rate (UHDR). Methods: Embryos were obtained from adult zebrafish and irradiated with a 228 MeV proton beam 24 h post-fertilization (hpf) at a dose rate of 0.6 and 317 Gy/s. For the hypoxic group, samples were kept inside a hypoxic chamber prior to irradiation, while standard incubation was adopted for the normoxic group. After irradiation, images of single embryos were acquired, and radiation effects on larval length, yolk absorption, pericardial edema, head size, eye size, and spinal curvature were assessed at specific time points. Results: Data indicate a general trend of significantly reduced toxicity after exposure to a UHDR compared to conventional regimes, which is maintained under both normoxic and hypoxic conditions. Differences are significant for the levels of pericardial edema induced by a UHDR versus conventional irradiation in normoxic conditions, and for eye and head size in hypoxic conditions. The toxicity scoring analysis shows a tendency toward a protective effect of the UHDR, which appears to be associated with a lower percentage of embryos in the high score categories. Conclusions: A radioprotective effect at a UHDR is observed both for normoxic (pericardial edema) and hypoxic (head and eye size) conditions. These results suggest that while the UHDR may preserve a potential to reduce radiation-induced damage, its protective effects are endpoint-dependent; the role of oxygenation might also be dependent on the tissue involved. Full article

One of the advantages of the EPR spectroscopy method in assessing structural defects caused by irradiation is the fact that using this method it is possible to determine not only the concentration dependences of the defect structure but to also establish their type, which is not possible with methods such as X-ray diffraction or scanning electron microscopy. Based on the data obtained, the role of variation in the ratio of components in Li₄SiO₄–Li₂TiO₃ ceramics on the processes of softening under high-dose irradiation with protons simulating the accumulation of hydrogen in the damaged layer, as well as the concentration of structural defects in the form of oxygen vacancies and radiolysis products on the processes of high-temperature degradation of ceramics, was determined. It was found that the main changes in the defect structure during the prolonged thermal exposure of irradiated samples are associated with the accumulation of oxygen vacancies, the density of which was estimated by the change in the intensity of singlet lithium, characterizing the presence of E-centers. At the same time, it was found that the formation of interphase boundaries in the structure of Li₄SiO₄–Li₂TiO₃ ceramics leads to the inhibition of high-temperature degradation processes in the case of post-radiation thermal exposure for a long time. Also, during the conducted studies, the role of thermal effects on the structural damage accumulation rate in Li₄SiO₄–Li₂TiO₃ ceramics was determined in the case when irradiation is carried out at different temperatures. During the experiments, it was determined that the main contribution of thermal action in the process of proton irradiation at a fluence of 5 × 10¹⁷ proton/cm² is an increase in the concentration of radiolysis products, described by changes in the intensities of spectral maxima, characterized by the presence of defects such as ≡Si–O, SiO₄³⁻ and Ti³⁺ defects. Full article

In this study, the neutron and gamma radiation-shielding properties of serpentinites from the Guleman ophiolite complex were investigated, and results were evaluated in comparison with rare earth element (REE) content. The linear and mass attenuation coefficients (LAC and MAC), half-value layer (HVL), mean free path (MFP), and effective atomic numbers (Z_eff) of serpentinite samples were experimentally measured in the energy range of 80.99–383.85 keV. Theoretical MAC values were calculated. Additionally, fast neutron removal cross-sections, as well as thermal and fast neutron macroscopic cross-sections, were theoretically determined. The absorbed equivalent dose rates of serpentinite samples were also measured. The radiation protection efficiency (RPE) for gamma rays and neutrons were determined. It was observed that the presence of rare earth elements within serpentinite structure has a significant impact on thermal neutron cross-sections, while crystalline water content (LOI) plays an influential role in fast neutron cross-sections. Moreover, it has been observed that the concentration of gadolinium exerts a more substantial influence on the macroscopic cross-sections of thermal neutrons than on those of fast neutrons. The research results reveal the mineralogical, geochemical, morphological and radiation-shielding properties of serpentinite rocks contribute significantly to new visions for the use of this naturally occurring rock as a geological repository for nuclear waste or as a wall-covering material in radiotherapy centers and nuclear facilities instead of concrete. Full article

This study assesses the clinical deployment of SubtlePET™, a commercial AI-based denoising algorithm, across three radiotracers—¹⁸F-FDG, ⁶⁸Ga-PSMA-11, and ¹⁸F-FDOPA—with the goal of improving image quality while reducing injected activity, technologist radiation exposure, and scan time. A retrospective analysis on a digital PET/CT system showed that SubtlePET™ enabled dose reductions exceeding 33% and time savings of over 25%. AI-enhanced images were rated interpretable in 100% of cases versus 65% for standard low-dose reconstructions. Notably, 85% of AI-enhanced scans received the maximum Likert quality score (5/5), indicating excellent diagnostic confidence and noise suppression, compared to only 50% with conventional reconstruction. The quantitative image quality improved significantly across all tracers, with SNR and CNR gains of 50–70%. Radiotracer dose reductions were particularly substantial in low-BMI patients (up to 41% for FDG), and the technologist exposure decreased for high-exposure roles. The daily patient throughput increased by an average of 4.84 cases. These findings support the robust integration of SubtlePET™ into routine clinical PET practice, offering improved efficiency, safety, and image quality without compromising lesion detectability. Full article

Background: With aging populations, the incidence of squamous cell carcinoma of the head and neck (SCCHN) among elderly patients is increasing. Although adjuvant radiotherapy or chemoradiation is a well-established component of multimodal treatment, elderly patients remain underrepresented in clinical trials. This study evaluates the feasibility of adjuvant radiotherapy and chemoradiation in patients over 70 years with SCCHN and explores the correlation between treatment feasibility and various comorbidity scores. Methods: We retrospectively analyzed patients over 70 years of age who received adjuvant radiotherapy or chemoradiation at the University Hospital Regensburg between 2004 and 2018. A total of 71 patients, with a median age of 75 years, were included. The majority were classified as UICC stage IVa. Median follow-up was 27 months. Results: Sixty-two patients completed treatment without interruption, and sixty-five received at least 95% of the prescribed radiation dose. The median total dose was 64 Gy. Acute toxicity of grade III or IV (CTC) occurred in 37 patients. Local tumor control rates were 99% at 12 months, 88% at 24 months, and 76% at 5 years. Overall survival rates were 87% at 12 months, 67% at 24 months, and 41% at 60 months, with a median overall survival of 51 months. The Elixhauser Comorbidity Score showed significant predictive value for treatment feasibility (p = 0.006). Conclusions: Adjuvant radiotherapy and chemoradiation are feasible and effective treatment options for elderly patients with SCCHN. The favorable local and locoregional control rates reported here suggest, in line with other recent reports in the literature, that age alone should not be a justification for treatment de-intensification. Full article

Background/Objectives: Non-enhanced computed tomography of the kidneys, ureters and bladder (NECT KUB) is the initial imaging modality for suspected nephroureterolithiasis. However, for alternative diagnoses, NECT may not be the ideal technique. Our institution changed the protocol for this cohort from NECT to intravenous contrast-enhanced CT (CECT) KUB. We aimed to retrospectively compare the rate of alternative diagnosis seen and the rates of calculus detection in CECT versus NECT KUB as a means of assessing performance. Our secondary aim was to compare the radiation dose between CECT and NECT KUB. Methods: Patients referred from the emergency department with suspected nephroureterolithiasis who underwent NECT and CECT KUB over two years were included. Key performance metrics included calculus detection rate, alternative findings, and negative studies. The metrics were compared between genders and age groups. Categorical variables were analysed using Chi-squared or Fisher’s Exact Test and continuous with T-testing. Results: A total of 423 patients had CT KUB imaging (209 NECT, 214 CECT). The incidence of alternative findings in the NECT group was 23% and 40% in CECT (p < 0.001). There were 48 findings (13 major, 11 moderate and 24 minor) in NECT studies and 85 findings (23 major, 43 moderate and 19 minor) in CECT (p < 0.001). Major diagnoses ranged from acute emergencies to more indolent findings, including suspicious nodules/masses. The calculus detection rate (NECT 56%, CECT 54%, p = 0.643) and negative studies (NECT 28%, CECT 22%, p = 0.168) did not significantly differ between protocols. CECT had a mean effective dose of 8.71 ± 2.58 mSv representing 2.4 times the exposure of NECT (p < 0.001). Conclusions: CECT is associated with a greater alternative diagnosis rate with similar calculus detection rates compared to NECT KUB, suggesting superior performance. However, CECT exposes patients to significantly greater levels of ionizing radiation. Full article

Thyroid nodules are a common clinical finding, with their prevalence influenced by multiple environmental and occupational factors, including exposure to ionizing radiation. Healthcare workers, particularly those operating in radiology, nuclear medicine, interventional cardiology, and radiation oncology, are potentially at increased risk due to chronic low-dose radiation exposure. This review aims to evaluate the current evidence regarding the association between occupational radiation exposure and the development of thyroid nodules among healthcare professionals. The findings suggest a higher prevalence of thyroid nodules in radiation-exposed workers compared to the general population, although data heterogeneity and methodological limitations exist. Factors such as the duration of exposure, radiation protection practices, and frequency of monitoring play critical roles in modulating the individual risk. While some studies report no significant difference in malignancy rates, the increased detection of nodules underlines the need for regular thyroid surveillance in at-risk populations. Further longitudinal and multicentric studies are warranted to clarify the causality and guide preventive strategies. This review highlights the importance of occupational health protocols, including radiation shielding and periodic thyroid evaluation, in safeguarding the long-term endocrine health of healthcare workers. Full article

Strong UV-B radiation is one of the main climatic characteristics of the Qinghai–Tibet Plateau. Plants grown on the Tibetan Plateau are exposed to high-intensity UV radiation and therefore require effective mechanisms to adapt to these stresses. However, little attention has been paid to the response of grass–endophytic fungi symbiosis to UV-B radiation in this area. In this study, we investigated the relationship between Epichloë gansuensis and the growth and antioxidant responses of Achnatherum inebrians seedlings exposed to different UV-B doses, aiming to evaluate the growth and antioxidant capacity of A. inebrians seedlings under UV-B stress. The plant height, tillers, biomass, electrical conductivity, soluble sugars, malondialdehyde (MDA), proline, hydrogen peroxide (H₂O₂), superoxide dismutase (SOD), polyphenol oxidase (POD), and catalase (CAT) of A. inebrians seedlings were determined under different intensities of UV-B radiation treatments. The results showed that, with the increase in UV-B radiation intensity, the plant height, tiller and biomass of A. inebrians seedlings showed a decreasing trend, the electrical conductivity increased, malondialdehyde content increased, soluble sugar and proline content decreased, SOD, POD, and CAT activities showed a decreasing trend, and the content of H₂O₂ increased, which means that the UV-B radiation was able to inhibit the morphogenesis and aggravate the membrane lipid peroxidation of A. inebrians seedlings. The tolerance of the A. inebrians–E. gansuensis symbiont to UV-B may enable it to have a high infection rate on the Qinghai–Tibet Plateau. Full article

Background/Objectives: Intraoperative radiotherapy (IORT) has been used for decades to improve local control in advanced and recurrent head and neck cancers by delivering a concentrated dose of radiation directly to the tumor bed during surgery. Despite its potential advantages, IORT remains controversial due to its high complication rates and logistical complexity. This systematic review aims to assess the current evidence on IORT in head and neck oncology, evaluating its indications, effectiveness, and limitations. Methods: A systematic literature review was conducted in accordance with Cochrane systematic review method and reported following PRISMA guidelines. Databases, including Medline, Embase, Cochrane, and Web of Science, were searched for studies evaluating IORT in head and neck cancer. Outcomes of interest included local control rates, overall survival, complications, and treatment logistics. Data were weighted based on patient numbers, and statistical analyses included weighted means and comparative tests. Results: Included in this review are 47 studies that included 2330 patients. The studies were highly heterogeneous, limiting definitive conclusions. IORT was mainly used in stage III/IV or recurrent tumors, with an average dose of 14.7 Gy (range: 1–40 Gy). The five-year local control was 47% to 82%. Complication rates included wound necrosis (22,3%), fistulas 34 (17.8%), and carotid blow-out (14.5%). Logistical constraints remain a major limitation. Conclusions: The heterogeneous data and logistic challenges of IORT in head and neck oncology have limited its use, and the benefits remain uncertain. Full article

Purpose: We present our single-institution experience of sarcomatous brain metastasis patients who underwent stereotactic radiosurgery (SRS) over the past 35 years. Methods: In total, 31 patients (16 males) who underwent SRS for sarcoma brain metastases were identified. Median age at presentation to SRS was 47 (range: 4–78) months. Common histopathologies included leiomyosarcoma (eight patients), osteosarcoma (six patients), alveolar sarcoma (three patients), Ewing sarcoma (three patients), and undifferentiated/unclassified sarcoma (three patients). The median Karnofsky Performance Score (KPS) was 90. Nine patients underwent pre-SRS craniotomy. The median dose prescribed was 18 Gy. The median cumulative tumor volume was 1.4 cc. Results: Median patient overall survival (OS) after SRS was 7 (range: 0–155) months. Local tumor control (LTC) was achieved in 105 out of 113 tumors, at a median time of 3 (range: 0–17) months between SRS and progression. LTC rates per patient and per tumor were 74.2% and 92.9%, respectively. Following SRS, 10 patients (32.3%) developed new tumors at a median time of 6 (range: 1–25) months. Four patients experienced adverse radiation effects (AREs). At the last follow-up, all patients died, one patient from intracranial progression, 27 from systemic disease progression, and the remaining from unrelated medical conditions. Conclusions: Given high LTC and low ARE rates, this suggests SRS as a strong candidate for the non-invasive management of sarcomatous brain metastases, which typically present late following initial presentation of the primary disease. Full article

Objective: We aimed to evaluate the feasibility, added value, and radiation dose of coronary computed tomography angiography (CCTA) and stress dynamic CT myocardial perfusion imaging (MPI) in patients with coronary artery disease (CAD) in a real-world setting. Materials and Methods: This retrospective study included 65 patients (mean age: 51.2 ± 11.5 years; 21 female) with moderate CAD, selected from the Radiological Database of our hospital between May 2022 and December 2024. All patients underwent CCTA and stress dynamic CT-MPI using a third-generation dual-source CT scanner. The shuttle-mode acquisition technique was used for CT-MPI with 60 mL of contrast (iopamidol, 370 mg iodine/mL) administered at a flow rate of 6 mL/s. The mean myocardial blood flow (MBF) and other quantitative parameters were measured for both CAD and reference segments (RSs). A 17-segment-based analysis was employed (excluding the apex). The MBF ratio, defined as the mean MBF value of CAD segments divided by that of RS, was used with a cut-off value of 0.85 to distinguish hypoperfused from non-hypoperfused segments within CAD territories. Non-parametric statistical tests were applied. Results: A total of 1040 segments were evaluated. In 62 segments, the mean MBF of CAD territories was found to have decreased. The mean MBF and myocardial blood volume (MBV) in hypoperfused CAD segments were 65.1 ± 19.8 mL/100 mL/min and 14.5 ± 2.7 mL/100 mL, respectively, both significantly lower compared to non-hypoperfused CAD segments and RSs (p < 0.001). The mean effective dose of the protocol was 6.3 ± 1.4 mSv, corresponding to an estimated individual lifetime cancer risk of approximately 0.06% per test, based on BEIR VII Phase 2 modeling. This risk is cumulative, with repeat testing over a 10-year period potentially increasing lifetime cancer risk in proportion to total radiation exposure. The mean total examination time was 26 ± 4 min. Conclusion: The combined CCTA and dynamic CT-MPI protocol is feasible in real-world clinical practice and offers a comprehensive morphological and functional assessment of moderate CAD, with a manageable radiation dose and examination time. Full article

The data on the volumetric radon activity of the Akchatau territory were systematized in the context of radioecological safety. Radon (Rn²²² and Rn²²⁰) and indoor radon (isotopes Po, Pb, and Bi) make a significant contribution to radon radiation in residential and industrial premises. Increased radon concentration in a number of areas is associated with the Akchatau tungsten–molybdenum mine. The source of radon in geological terms is acid leucocratic granites in the northwestern and southeastern parts of the studied territory. Seasonal assessment of radon radiation was carried out using modern devices “Alfarad Plus” and “Ramon-Radon”. Frequency analysis of the average annual equivalent equilibrium concentration (EEC) in 181 premises showed that only in 47.5% of the premises does the volumetric radon activity not exceed the current standards (200 Bq/m³). Differentiated values of radon concentration were obtained in cases where daily and seasonal observations were carried out. In 43.1% of premises, the effective dose varies from 6.6 mSv/year to 33 mSv/year, and for 9.4% of premises, from 33 mSv/year to 680 mSv/year. The increased radon concentration is caused by high exhalation from the soil surface, the radioactivity of building materials, and low air exchange in the surveyed premises. In the northwestern part of Akchatau, anomalous zones were found where the exposure dose rate of gamma radiation exceeds 0.6 mkSv/hour. An objective assessment of radon largely depends on a number of factors that take into account the geological, technical, atmospheric, and climatic conditions of the region. Therefore, when planning an optimal radon rehabilitation strategy, it is necessary to take the following factors into account: the design features of residential premises and socio-economic conditions. Practical recommendations are given for radiation-ecological and hygienic monitoring of radon safety levels in the environment to reduce effective doses on the population. Full article

Background/Objectives: Adjuvant radiation for gynecologic malignancies often exposes organs at risk (OARs), such as the bone marrow, bowel, rectum, and bladder, to radiation, leading to toxicities that impact treatment tolerance and patient quality of life. Scanning proton beam therapy, particularly with Individual Field Simultaneous Optimization (IFSO), may offer dosimetric and biological advantages over volumetric modulated arc therapy (VMAT). This study evaluates the clinical impact of IFSO-based proton planning in post-operative gynecologic cancer patients. Materials and Methods: Fourteen patients receiving adjuvant proton therapy to 45 Gy in 25 fractions were retrospectively analyzed. Comparison VMAT plans were generated on the same datasets. Dose–volume metrics for key OARs and normal tissue complication probabilities (NTCPs) were compared using paired statistical tests. Robustness evaluations accounted for setup and range uncertainties. Results: Proton plans significantly reduced dose to bone marrow (V10Gy: 58% vs. 86%, p < 0.00001; V20Gy: 47% vs. 58%, p < 0.00001), small bowel (V20Gy: 21% vs. 56%, p < 0.00001), and femoral heads (left femoral head mean: 11Gy vs. 13Gy, p = 0.032; right femoral head mean: 11Gy vs. 13Gy, p = 0.022). NTCP modeling predicted significantly lower rates of bowel urgency (9.4% vs. 3.3%, p < 0.001) and hematologic toxicity (10.2% vs. 4.9%, p < 0.001) with proton therapy. Plans remained robust across uncertainty scenarios. Conclusions: IFSO-based scanning proton therapy provides clinically meaningful sparing of bone marrow and bowel, with the potential to reduce hematologic and gastrointestinal toxicities. These findings support its use in patients receiving adjuvant pelvic radiotherapy, particularly those undergoing extended field treatment or chemotherapy. Full article

Background: GKRS shows a high success rate in controlling growth of vestibular schwannoma, but a small number of tumors still grow after treatment. However, only a few studies have investigated the predictive factors of this growth. Objective: Here, we aim to explore the growth determinants of vestibular schwannoma after GKRS. Methods: This paper has analyzed literature published between 2000 and 2024 from PubMed, EMBASE, and Cochrane databases. Potential determinants, including age, gender, tumor volume, radiation dose, tumor location, and imaging characteristics, have been reviewed. Conclusions: We have found that initial tumor volume, pretreatment growth rate, and imaging ADC value potentially predict growth after GKRS. These findings provide a reference for further optimizing personalized treatment in vestibular schwannoma care. Full article