Radiation and Environmental Biophysics最新文献

Radon therapy alleviates the symptoms of autoimmune diseases by enhancing antioxidant and anti-inflammatory effects. Although radon inhalation normalizes serum cytokine concentrations modulated by lipopolysaccharide (LPS) administration, it also increases pulmonary oxidative stress. Hence, its effects on lungs must be comprehensively evaluated; however, no study has reported the effects of short-term radon inhalation or the associated proteomic changes. In this study, we aimed to evaluate the state of protein expression in the lungs after radon inhalation and LPS administration and identified biomarkers that could be particularly affected. We performed shotgun proteomics and multivariate analyses and evaluated myeloperoxidase (MPO) activity. On examining the control, LPS-administration, and radon inhalation plus LPS-administered groups, the expression levels of cilia- and flagella-associated protein 61, segment polarity protein dishevelled homolog DVL-1, histone-lysine N-methyltransferase 2 A, and heat shock protein beta-1 varied and were identified as characteristic indicators. However, radon inhalation did not suppress MPO activity indicating an absence of anti-inflammatory effect in the lungs. Thus, although the combination of short-term continuous radon pre-inhalation and LPS administration cannot yet be considered effective against lung inflammation, we identified four key indicators for assessing the associated effects. Despite not clarifying the biological significance of these proteins, our findings provide useful information for applying radon therapy in systemic inflammation.

Bone metastases are a major clinical problem, mainly in breast and prostate cancers, which comprise the majority of cancer cases. With technological advances that improve precision and efficacy, radiotherapy is an essential palliative solution. In this study, two radiotherapy planning techniques were evaluated, the longitudinal isocenter (LONI), and the three-isocenters (3ISO) that combine the lateral isocenters for pelvis and longitudinal isocenters for lumbar metastases, using the Halcyon^TM2.0 machine with the volumetric modulated arc therapy (VMAT) technique. Dosimetric parameters such as conformity index (CI), homogeneity index (HI), (dose coverage (D_95%), dose max (D_MAX), monitor units (MUs), and conformation number (CN) were analyzed. No significant difference in dose conformity between the two studied techniques was observed. However, remarkable results in terms of dose homogeneity were achieved in the application of the 3ISO modality, with an improvement of 42.8%. Additionally, D_95% for 3ISO was 96.26% against 92.71% for LONI. Regarding CN, which considers both dose coverage and healthy tissue optimization, 3ISO technique resulted in an improvement of 12.3%. It is noted, however, that 3ISO requires more time and accurate patient positioning to guarantee optimal outcomes.

Paediatric patients are particularly sensitive to ionizing radiation, and accurate surface dose estimation is crucial in diagnostic X-ray imaging. Standard homogeneous phantoms inadequately reproduce tissue heterogeneity, leading to errors in backscatter evaluation. This study aimed to characterize backscatter factors (BSFs) in a heterogeneous, tissue-equivalent paediatric head phantom under conventional radiography conditions. An in-house epoxy-based heterogeneous phantom was fabricated with five inserts simulating bone, brain, cerebrospinal fluid, eye lens and air cavities. Entrance surface dose (ESD) and BSF measurements were performed using an ionization chamber and a Fujifilm digital X-ray system (40-150 kVp, field sizes: 10 × 10, 20 × 20, 25 × 25 cm²). Additional aluminium filtrations of 2.5 mm and 3.0 mm were applied to evaluate beam hardening effects. Measured ESD increased from 0.82 mGy at 40 kVp to 18.93 mGy at 150 kVp (no filtration, 25 × 25 cm²). Applying 3.0 mm Al filtration reduced ESD by up to 57% at 60 kVp. Experimental BSFs ranged from 1.1 to 2.1, increasing with tube potential and reaching a maximum under small field size and hardened beam (120 kVp, 10 × 10 cm², 3.0 mm Al), reflecting enhanced cumulative backscatter energy from heterogeneous tissue interfaces. Compared with IAEA TRS-457 reference data, the heterogeneous phantom yielded higher BSFs than PMMA or water for 10 × 10 cm² fields, demonstrating enhanced scatter from realistic tissue interfaces, while lower BSFs were observed for larger fields. The study confirms that homogeneous phantoms may underestimate paediatric backscatter under specific conditions, while heterogeneous phantoms provide more representative dosimetric references, improving BSF estimation and dose optimization.

Epidemiological studies have shown a statistically significant increase in lung cancer risk from prolonged exposure to indoor radon. While current radiation protection efforts address the general population, including workers in radon-prone areas, pregnant individuals represent a vulnerable subgroup that requires specific consideration. Prenatal exposure to ionizing radiation, including radon and its progeny, raises concerns not only for maternal health but also for potential in-utero tissue reactions and/or cancer development in other life stages in the offspring. This study aimed to develop a comprehensive biokinetic model for radon to evaluate fetal uptake following maternal exposure through inhalation. The model was based on the latest ICRP age- and sex-specific biokinetic model for radon, adapted to include pregnancy-specific compartments such as the uterus, placenta, arterial and venous cord blood, and key fetal organs (lungs, brain, kidneys, thyroid, bone surface, liver, and adipose). Transfer rates were calculated using Fick's law of passive diffusion. Maternal and fetal physiological changes throughout pregnancy, including tissue masses and blood flows, were incorporated. Model simulations show that, despite radon gas being predominantly exhaled after inhalation, a fraction crosses the placenta, reaching fetal tissues-particularly those with higher fat content. Additionally, due to the chemical affinity of radon and fatty tissues, fetal adipose tissue receives a significant proportion of radon, resulting in the highest predicted uptake among fetal tissues. This biokinetic model provides an approach to estimate fetal uptake of radon from maternal exposures, supporting more accurate assessments for radiation protection of pregnant individuals and their developing fetuses.