Deciphering the molecular landscape of ionising radiation-induced eye damage with the help of genomic data mining.

Even at low levels, exposure to ionising radiation can lead to eye damage. However, the underlying molecular mechanisms are not yet fully understood. We aimed to address this gap with a comprehensive in silico approach to the issue. For this purpose we relied on the Comparative Toxicogenomics Database (CTD), ToppGene Suite, Cytoscape, GeneMANIA, and Metascape to identify six key regulator genes associated with radiation-induced eye damage (ATM, CRYAB, SIRT1, TGFB1, TREX1, and YAP1), all of which have physical interactions. Some of the identified molecular functions revolve around DNA repair mechanisms, while others are involved in protein binding, enzymatic activities, metabolic processes, and post-translational protein modifications. The biological processes are mostly centred on response to DNA damage, the p53 signalling pathway in particular. We identified a significant role of several miRNAs, such as hsa-miR-183 and hsamiR-589, in the mechanisms behind ionising radiation-induced eye injuries. Our study offers a valuable method for gaining deeper insights into the adverse effects of radiation exposure.

Surviving extreme radiation.

Tiny animals known as tardigrades use a combination of DNA repair machinery and a novel protein to mend their genome after intense ionizing radiation.

Low-dose ionizing radiation generates a hormetic response to modify lipid metabolism in Chlorella sorokiniana.

Algal biomass is a viable source of chemicals and metabolites for various energy, nutritional, medicinal and agricultural uses. While stresses have commonly been used to induce metabolite accumulation in microalgae in attempts to enhance high-value product yields, this is often very detrimental to growth. Therefore, understanding how to modify metabolism without deleterious consequences is highly beneficial. We demonstrate that low-doses (1-5 Gy) of ionizing radiation in the X-ray range induces a non-toxic, hormetic response in microalgae to promote metabolic activation. We identify specific radiation exposure parameters that give reproducible metabolic responses in Chlorella sorokiniana caused by transcriptional changes. This includes up-regulation of >30 lipid metabolism genes, such as genes encoding an acetyl-CoA carboxylase subunit, phosphatidic acid phosphatase, lysophosphatidic acid acyltransferase, and diacylglycerol acyltransferase. The outcome is an increased lipid yield in stationary phase cultures by 25% in just 24 hours, without any negative effects on cell viability or biomass.

Technologies for retrospective radiation dosimetry.

Radiation dosimetry is an important task for assessing the biological damages created in human being due to ionising radiation exposure. Ionising radiation being invisible and beyond the perception of human natural sensors, the dosimetry equipments/systems are the utmost requirement for its measurement. Retrospective measurement of radiation doses is a challenging task as conventional radiation dosemeters are not available at the exposure site. The material/s in close proximity of exposed individual or individuals' biological samples may be used as retrospective radiation sensor for dosimetry purpose. Environment materials such as sand, bricks, ceramics, sand stones, quartz, feldspar, glasses and electronic chips have been utilised using TL (Thermoluminescence) techniques for retrospective gamma dose (min 10 cGy) measurement. Electron Spin Resonance techniques have been employed to human biological samples such as tooth enamel, bones, nails, hair, etc. and reported for dosimetry for ~20 cGy min dose measurement. Some commercial glasses have been found sensitive enough to measure the minimum gamma doses of the order of 100 cGy using TL techniques. For internal retrospective dosimetry, the radioactivity contamination assessment in food items, water, other edible product and ambient air are the prerequisites. The radioactivity concentration vis-à-vis their consumption rate may help in controlling the internal contamination and estimation of dose absorption in human body. Defence Laboratory, Jodhpur has been working extensively on the dosimetry techniques for external dose measurement using environmental material and developed portable contamination monitoring systems for food and water radioactivity measurement in the range of 50 Bq kg-1 to 1000 kBq kg-1 in 60 s measurement time. The recent research and development in the methodologies, equipments and systems undertaken towards capacity building and self-reliance in retrospective radiation dosimetry is reported in this paper.

Multifiller-based polymer composites for shielding high energy ionising radiation.

Polydimethyl silicone rubber-based polymer composites filled with molybdenum and bismuth were fabricated using simple open mold cast technique. The physical and chemical structure and gamma shielding parameters like attenuation coefficient, half-value layer (HVL) thickness and relaxation length have been investigated for the said novel materials using X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and gamma ray spectrometer. XRD study reveals the crystalline nature of the composites. It is evident from FTIR studies that there is no chemical interaction between the polymer matrix and filler particles. The results of attenuation studies reveal that the linear attenuation coefficient increases with addition of Bi and Mo and is found to be 0.653, 1.341 and 1.017, 1.793 and 0.102, 0.152 cm-1 for 1MMB and 2MMB polymer composites at 80, 356 and 662 keV gamma rays, respectively. The HVL thickness of the materials is found to be 1.06, 0.51 and 0.68, 0.38 and 6.73, 4.532 cm for 1MMB (20Mo + 10Bi phr) and 2MMB (40Mo + 20Bi phr) at these energies, respectively. The mass attenuation coefficient of the novel composites 1MMB and 2MMB is found to be higher than the conventional materials like lead and barite for 356 keV gamma rays. In addition, the material is found to be light weight and flexible enabling to be molded in required forms, thus being a substitute for the material lead that is known to be heavy and toxic by nature.

Role of independent research at AERB for ensuring safety of nuclear facilities in India.

The mission of Atomic Energy Regulatory Board (AERB) of India is to ensure that the use of ionising radiation and nuclear energy in India does not cause unacceptable impact on the workers, members of the public and to the environment. AERB has the mandate to carry out detailed safety review for the siting, construction, commissioning, operation and decommissioning of nuclear and radiation facilities established within the country. To deliver and maintain a strong, credible and technically sound regulation, AERB has established the Safety Research Institute (SRI) at Kalpakkam with a robust technical infrastructure and wide knowledge base. This paper highlights the independent safety research activities carried out at SRI and its role to support and facilitate the decision-making process by AERB at various stages of regulatory review for ensuring safety of the nuclear facilities in India.

Magnetic-guided nanocarriers for ionizing/non-ionizing radiation synergistic treatment against triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancer (TNBC) is a subtype of breast cancer with the worst prognosis. Radiotherapy (RT) is one of the core modalities for the disease; however, the ionizing radiation of RT has severe side effects. The consistent development direction of RT is to achieve better therapeutic effect with lower radiation dose. Studies have demonstrated that synergistic effects can be achieved by combining RT with non-ionizing radiation therapies such as light and magnetic therapy, thereby achieving the goal of dose reduction and efficacy enhancement. METHODS: In this study, we applied FeCo NPs with magneto thermal function and phototherapeutic agent IR-780 to construct an ionizing and non-ionizing radiation synergistic nanoparticle (INS NPs). INS NPs are first subjected to morphology, size, colloidal stability, loading capacity, and photothermal conversion tests. Subsequently, the cell inhibitory and cellular internalization were evaluated using cell lines in vitro. Following comprehensive assessment of the NPs' in vivo biocompatibility, tumor-bearing mouse model was established to evaluate their distribution, targeted delivery, and anti-tumor effects in vivo. RESULTS: INS NPs have a saturation magnetization exceeding 72 emu/g, a hydrodynamic particle size of approximately 40 nm, a negatively charged surface, and good colloidal stability and encapsulation properties. INS NPs maintain the spectral characteristics of IR-780 at 808 nm. Under laser irradiation, the maximum temperature was 92 °C, INS NPs also achieved the effective heat temperature in vivo. Both in vivo and in vitro tests have proven that INS NPs have good biocompatibility. INS NPs remained effective for more than a week after one injection in vivo, and can also be guided and accumulated in tumors through permanent magnets. Later, the results exhibited that under low-dose RT and laser irradiation, the combined intervention group showed significant synergetic effects, and the ROS production rate was much higher than that of the RT and phototherapy-treated groups. In the mice model, 60% of the tumors were completely eradicated. CONCLUSIONS: INS NPs effectively overcome many shortcomings of RT for TNBC and provide experimental basis for the development of novel clinical treatment methods for TNBC.

Host defense alteration in Caenorhabditis elegans after evolution under ionizing radiation.

BACKGROUND: Adaptation to a stressor can lead to costs on other traits. These costs play an unavoidable role on fitness and influence the evolutionary trajectory of a population. Host defense seems highly subject to these costs, possibly because its maintenance is energetically costly but essential to the survival. When assessing the ecological risk related to pollution, it is therefore relevant to consider these costs to evaluate the evolutionary consequences of stressors on populations. However, to the best of our knowledge, the effects of evolution in irradiate environment on host defense have never been studied. Using an experimental evolution approach, we analyzed fitness across 20 transfers (about 20 generations) in Caenorhabditis elegans populations exposed to 0, 1.4, and 50.0 mGy.h- 1 of 137Cs gamma radiation. Then, populations from transfer 17 were placed in the same environmental conditions without irradiation (i.e., common garden) for about 10 generations before being exposed to the bacterial parasite Serratia marcescens and their survival was estimated to study host defense. Finally, we studied the presence of an evolutionary trade-off between fitness of irradiated populations and host defense. RESULTS: We found a lower fitness in both irradiated treatments compared to the control ones, but fitness increased over time in the 50.0 mGy.h- 1, suggesting a local adaptation of the populations. Then, the survival rate of C. elegans to S. marcescens was lower for common garden populations that had previously evolved under both irradiation treatments, indicating that evolution in gamma-irradiated environment had a cost on host defense of C. elegans. Furthermore, we showed a trade-off between standardized fitness at the end of the multigenerational experiment and survival of C. elegans to S. marcescens in the control treatment, but a positive correlation between the two traits for the two irradiated treatments. These results indicate that among irradiated populations, those most sensitive to ionizing radiation are also the most susceptible to the pathogen. On the other hand, other irradiated populations appear to have evolved cross-resistance to both stress factors. CONCLUSIONS: Our study shows that adaptation to an environmental stressor can be associated with an evolutionary cost when a new stressor appears, even several generations after the end of the first stressor. Among irradiated populations, we observed an evolution of resistance to ionizing radiation, which also appeared to provide an advantage against the pathogen. On the other hand, some of the irradiated populations seemed to accumulate sensitivities to stressors. This work provides a new argument to show the importance of considering evolutionary changes in ecotoxicology and for ecological risk assessment.

Antitumour effects of SFX-01 molecule in combination with ionizing radiation in preclinical and in vivo models of rhabdomyosarcoma.

BACKGROUND: Despite a multimodal approach including surgery, chemo- and radiotherapy, the 5-year event-free survival rate for rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in childhood, remains very poor for metastatic patients, mainly due to the selection and proliferation of tumour cells driving resistance mechanisms. Personalised medicine-based protocols using new drugs or targeted therapies in combination with conventional treatments have the potential to enhance the therapeutic effects, while minimizing damage to healthy tissues in a wide range of human malignancies, with several clinical trials being started. In this study, we analysed, for the first time, the antitumour activity of SFX-01, a complex of synthetic d, l-sulforaphane stabilised in alpha-cyclodextrin (Evgen Pharma plc, UK), used as single agent and in combination with irradiation, in four preclinical models of alveolar and embryonal RMS. Indeed, SFX-01 has shown promise in preclinical studies for its ability to modulate cellular pathways involved in inflammation and oxidative stress that are essential to be controlled in cancer treatment. METHODS: RH30, RH4 (alveolar RMS), RD and JR1 (embryonal RMS) cell lines as well as mouse xenograft models of RMS were used to evaluate the biological and molecular effects induced by SFX-01 treatment. Flow cytometry and the modulation of key markers analysed by q-PCR and Western blot were used to assess cell proliferation, apoptosis, autophagy and production of intracellular reactive oxygen species (ROS) in RMS cells exposed to SFX-01. The ability to migrate and invade was also investigated with specific assays. The possible synergistic effects between SFX-01 and ionising radiation (IR) was studied in both the in vitro and in vivo studies. Student's t-test or two-way ANOVA were used to test the statistical significance of two or more comparisons, respectively. RESULTS: SFX-01 treatment exhibited cytostatic and cytotoxic effects, mediated by G2 cell cycle arrest, apoptosis induction and suppression of autophagy. Moreover, SFX-01 was able to inhibit the formation and the proliferation of 3D tumorspheres as monotherapy and in combination with IR. Finally, SFX-01, when orally administered as single agent, displayed a pattern of efficacy at reducing the growth of tumour masses in RMS xenograft mouse models; when combined with a radiotherapy regime, it was observed to act synergistically, resulting in a more positive outcome than would be expected by adding each exposure alone. CONCLUSIONS: In summary, our results provide evidence for the antitumour properties of SFX-01 in preclinical models of RMS tumours, both as a standalone treatment and in combination with irradiation. These forthcoming findings are crucial for deeper investigations of SFX-01 molecular mechanisms against RMS and for setting up clinical trials in RMS patients in order to use the SFX-01/IR co-treatment as a promising therapeutic approach, particularly in the clinical management of aggressive RMS disease.

Comparative transcriptomics reveal a novel tardigrade-specific DNA-binding protein induced in response to ionizing radiation.

Tardigrades are microscopic animals renowned for their ability to withstand extreme conditions, including high doses of ionizing radiation (IR). To better understand their radio-resistance, we first characterized induction and repair of DNA double- and single-strand breaks after exposure to IR in the model species Hypsibius exemplaris. Importantly, we found that the rate of single-strand breaks induced was roughly equivalent to that in human cells, suggesting that DNA repair plays a predominant role in tardigrades' radio-resistance. To identify novel tardigrade-specific genes involved, we next conducted a comparative transcriptomics analysis across three different species. In all three species, many DNA repair genes were among the most strongly overexpressed genes alongside a novel tardigrade-specific gene, which we named Tardigrade DNA damage Response 1 (TDR1). We found that TDR1 protein interacts with DNA and forms aggregates at high concentration suggesting it may condensate DNA and preserve chromosome organization until DNA repair is accomplished. Remarkably, when expressed in human cells, TDR1 improved resistance to Bleomycin, a radiomimetic drug. Based on these findings, we propose that TDR1 is a novel tardigrade-specific gene conferring resistance to IR. Our study sheds light on mechanisms of DNA repair helping cope with high levels of DNA damage inflicted by IR.

Additive antitumor effect of arsenic trioxide with exposure to ionizing radiation to human acute promyelocytic leukemia HL­60 cells.

Arsenic trioxide (ATO) is expected to be a chemical drug with antitumor activity against acute promyelocytic leukemia (APL), a type of acute myeloid leukemia. In Japan, its antitumor effects were confirmed in clinical trials for APL, and it has been approved in various countries around the world. However, there have been no reports on ATO's antitumor effects on radioresistant leukemia cells, which can be developed during radiotherapy and in combination with therapeutic radiation beams. The present study sought to clarify the antitumor effect of ATO on APL cells with radiation resistance and determine its efficacy when combined with ionizing radiation (IR). The radiation­resistant HL60 (Res­HL60) cell line was generated by subjecting the native cells to 4­Gy irradiation every week for 4 weeks. The half­maximal inhibitory concentration (IC50) for cell proliferation by ATO on native cell was 0.87 µM (R2=0.67), while the IC50 for cell proliferation by ATO on Res­HL60 was 2.24 µM (R2=0.91). IR exposure increased the sub­G1 and G2/M phase ratios in both cell lines. The addition of ATO resulted in a higher population of G2/M after 24 h rather than 48 h. When the rate of change in the sub­G1 phase was examined in greater detail, the sub­G1 phase in both control cells without ATO significantly increased by exposure to IR at 24 h, but only under the condition of 2 Gy irradiation, it had continued to increase at 48 h. Res­HL60 supplemented with ATO showed a higher rate of sub­G1 change at 24 h; however, 2 Gy irradiation resulted in a decrease compared with the control. There was a significant increase in the ratio of the G2/M phase in cells after incubation with ATO for 24 h, and exposure to 2 Gy irradiation caused an even greater increase. To determine whether the inhibition of cell proliferation and cell cycle disruptions is related to reactive oxygen species (ROS) activity, intracellular ROS levels were measured with a flow cytometric assay. Although the ROS levels of Res­HL60 were higher than those of native cells in the absence of irradiation, they did not change after 0.5 or 2 Gy irradiation. Furthermore, adding ATO to Res­HL60 reduced intracellular ROS levels. These findings provide important information that radioresistant leukemia cells respond differently to the antitumor effect of ATO and the combined effect of IR.

Voltage-dependent anion channel 1 mediates mitochondrial fission and glucose metabolic reprogramming in response to ionizing radiation.

The ionizing radiation (IR) represents a formidable challenge as an environmental factor to mitochondria, leading to disrupt cellular energy metabolism and posing health risks. Although the deleterious impacts of IR on mitochondrial function are recognized, the specific molecular targets remain incompletely elucidated. In this study, HeLa cells subjected to γ-rays exhibited concomitant oxidative stress, mitochondrial structural alterations, and diminished ATP production capacity. The γ-rays induced a dose-dependent induction of mitochondrial fission, simultaneously manifested by an elevated S616/S637 phosphorylation ratio of the dynamin-related protein 1 (DRP1) and a reduction in the expression of the mitochondrial fusion protein mitofusin 2 (MFN2). Knockdown of DRP1 effectively mitigated γ-rays-induced mitochondrial network damage, implying that DRP1 phosphorylation may act as an effector of radiation-induced mitochondrial damage. The mitochondrial outer membrane protein voltage-dependent anion channel 1 (VDAC1) was identified as a crucial player in IR-induced mitochondrial damage. The VDAC1 inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), counteracts the excessive mitochondrial fission induced by γ-rays, consequently rebalancing the glycolytic and oxidative phosphorylation equilibrium. This metabolic shift was uncovered to enhance glycolytic capacity, thus fortifying cellular resilience and elevating the radiosensitivity of cancer cells. These findings elucidate the intricate regulatory mechanisms governing mitochondrial morphology under radiation response. It is anticipated that the development of targeted drugs directed against VDAC1 may hold promise in augmenting the sensitivity of tumor cells to radiotherapy and chemotherapy.

Insights into ionizing radiation-induced bone marrow hematopoietic stem cell injury.

With the widespread application of nuclear technology across various fields, ionizing radiation-induced injuries are becoming increasingly common. The bone marrow (BM) hematopoietic tissue is a primary target organ of radiation injury. Recent researches have confirmed that ionizing radiation-induced hematopoietic dysfunction mainly results from BM hematopoietic stem cells (HSCs) injury. Additionally, disrupting and reshaping BM microenvironment is a critical factor impacting both the injury and regeneration of HSCs post radiation. However, the regulatory mechanisms of ionizing radiation injury to BM HSCs and their microenvironment remain poorly understood, and prevention and treatment of radiation injury remain the focus and difficulty in radiation medicine research. In this review, we aim to summarize the effects and mechanisms of ionizing radiation-induced injury to BM HSCs and microenvironment, thereby enhancing our understanding of ionizing radiation-induced hematopoietic injury and providing insights for its prevention and treatment in the future.

Radiation Damage in Biomolecules and Cells 3.0.

Ionizing radiation is widely used in medicine, not only as a diagnostic tool but also as a therapeutic agent, since about half of cancer patients are treated with ionizing radiation, while most of them are irradiated with X-rays [...].

Combined Ionizing Radiation Exposure by Gamma Rays and Carbon-12 Nuclei Increases Neurotrophic Factor Content and Prevents Age-Associated Decreases in the Volume of the Sensorimotor Cortex in Rats.

In orbital and ground-based experiments, it has been demonstrated that ionizing radiation (IR) can stimulate the locomotor and exploratory activity of rodents, but the underlying mechanism of this phenomenon remains undisclosed. Here, we studied the effect of combined IR (0.4 Gy γ-rays and 0.14 Gy carbon-12 nuclei) on the locomotor and exploratory activity of rats, and assessed the sensorimotor cortex volume by magnetic resonance imaging-based morphometry at 1 week and 7 months post-irradiation. The sensorimotor cortex tissues were processed to determine whether the behavioral and morphologic effects were associated with changes in neurotrophin content. The irradiated rats were characterized by increased locomotor and exploratory activity, as well as novelty-seeking behavior, at 3 days post-irradiation. At the same time, only unirradiated rats experienced a significant decrease in the sensorimotor cortex volume at 7 months. While there were no significant differences at 1 week, at 7 months, the irradiated rats were characterized by higher neurotrophin-3 and neurotrophin-4 content in the sensorimotor cortex. Thus, IR prevents the age-associated decrease in the sensorimotor cortex volume, which is associated with neurotrophic and neurogenic changes. Meanwhile, IR-induced increases in locomotor activity may be the cause of the observed changes.

Biyang floral mushroom-derived exosome-like nanovesicles: characterization, absorption stability and ionizing radiation protection.

Diet-derived exosome-like nanovesicles are a class of natural active substances that have similar structures and functions to mammalian exosomes. Biyang floral mushrooms and their active extracts have been found to possess radioprotective effects and to deeply explore their novel active substances, the radioprotective effects of Biyang floral mushroom-derived exosome-like nanovesicles (BFMELNs) were investigated in this study. Results showed that these surface-negatively charged vesicles possessed an ideal size and good stability against environmental changes such as temperature and gastrointestinal digestion. Furthermore, BFMELNs could effectively be taken up by HL-7702 cells and Caco-2 cells through cellular phagocytosis mediated by clathrin and dynein. Emphatically, BFMELNs with an exosome-like morphology contained RNA, proteins, lipids, polyphenols and flavonoids to exert good antioxidant and radioprotective effects in vitro. Meanwhile, BFMELNs also exhibited good radioprotective effects by restoring peripheral blood indexes, mitigating damage to organs, and regulating the redox state in mice. Collectively, BFMELNs showed promise as novel and natural radioprotective nano-agents for preventing IR-induced oxidative stress damage.

A sperm-activating trypsin-like protease from the male reproductive tract of Spodoptera litura: Proteomic identification, sequence characterization, gene expression profile, RNAi and the effects of ionizing radiation.

Like other lepidopteran insects, males of the tobacco cutworm moth, Spodoptera litura produce two kinds of spermatozoa, eupyrene (nucleate) and apyrene (anucleate) sperm. Formed in the testis, both kinds of sperm are released into the male reproductive tract in an immature form and are stored in the duplex region of the tract. Neither type of sperm is motile at this stage. When stored apyrene sperm from the duplex are treated in vitro with an extract of the prostatic region of the male tract, or with mammalian trypsin, they become motile; activation is greater and achieved more rapidly with increasing concentration of extract or enzyme. The activating effect of prostatic extract is blocked by soybean trypsin inhibitor (SBTI), also in a dose-dependent way. These results suggest that the normal sperm-activating process is due to an endogenous trypsin-like protease produced in the prostatic region. Proteomic analysis of S. litura prostatic extracts revealed a Trypsin-Like Serine Protease, TLSP, molecular weight 27 kDa, whose 199-residue amino acid sequence is identical to that of a predicted protein from the S. litura genome and is highly similar to predicted proteins encoded by genes in the genomes of several other noctuid moth species. Surprisingly, TLSP is only distantly related to Serine Protease 2 (initiatorin) of the silkmoth, Bombyx mori, the only identified lepidopteran protein so far shown to activate sperm. TLSP has features typical of secreted proteins, probably being synthesized as an inactive precursor zymogen, which is later activated by proteolytic cleavage. cDNA was synthesized from total RNA extracted from the prostatic region and was used to examine TLSP expression using qPCR. tlsp mRNA was expressed in both the prostatic region and the accessory glands of the male tract. Injection of TLSP-specific dsRNA into adult males caused a significant reduction after 24 h in tlsp mRNA levels in both locations. The number of eggs laid by females mated to adult males that were given TLSP dsRNA in 10 % honey solution, and the fertility (% hatched) of the eggs were reduced. Injecting pupae with TLSP dsRNA caused the later activation of apyrene sperm motility by adult male prostatic extracts to be significantly reduced compared to controls. Exposure of S. litura pupae to ionizing radiation significantly reduced expression of tlsp mRNA in the prostatic part and accessory gland of irradiated males in both the irradiated generation and also in their (unirradiated) F1 progeny. The implications of these findings for the use of the inherited sterility technique for the control of S. litura and other pest Lepidoptera are discussed.

Central nervous system tumours and occupational ionising radiation exposure: a nested case-control study among the ORICAMs cohort of healthcare workers in France.

OBJECTIVE: This study aimed at investigating the relationship between occupational exposure to external ionising radiation and central nervous system (CNS) tumours mortality in healthcare workers working in France. DESIGN AND SETTING: The Occupational Radiation-Induced Cancer in Medical staff (ORICAMs) nested case-control study was conducted based on the dosimetric records of the national register of occupational dosimetry (Système d'information de la surveillance de l'exposition aux rayonnements ionisants). PARTICIPANTS AND METHODS: 33 CNS tumour deaths occurred between 2002 and 2012 among the ORICAMs cohort composed of 164 015 healthcare workers. Each case was matched to five controls alive at the time of the corresponding case's death, based on sex, year of birth, date of enrolment in the cohort and duration of follow-up. All participants were badge monitored for external radiation exposure, expressed in Hp(10). Conditional logistic regression was used to analyse the dose-response relationship between radiation dose and CNS mortality. RESULTS: Cases were exposed to a mean cumulative career radiation dose of 5.8±13.7 (max: 54.3) millisievert (mSv) compared with 4.1±15.2 (142.2) mSv for controls. No statistically significant association was found between CNS tumour mortality and cumulative whole-body career dose (OR=1.00, 95% CI 0.98 to 1.03), duration of exposure (OR=1.03; 95% CI 0.95 to 1.12) or age at first exposure (OR=0.98; 95% CI 0.91 to 1.06). CONCLUSION: We found no evidence of an association between external radiation exposure and CNS tumour risk in healthcare workers. Limitations of the study include low statistical power and short duration of follow-up.

Recent discoveries on the historical foundations of cancer risk assessment: Shedding light on the limits of LNT.

Within the past three years there has been a spate of historical discoveries by our research team on various different facets of the historical foundations of cancer risk assessment. This series of discoveries was stimulated by the creation of a 22-episode documentary of the historical foundations of cancer risk assessment by the US Health Physics Society and the need to provide documentation. This process yielded nearly two dozen distinct historical findings which have been published in numerous papers in the peer-reviewed literature. These discoveries are itemized and summarized in the present paper, along with the significance of each discovery within the historical context of ionizing radiation research and cancer risk assessment.

An Optical Reusable 2D Radiochromic Gel-Based System for Ionising Radiation Measurements in Radiotherapy.

This work describes the development of a reusable 2D detector based on radiochromic reaction for radiotherapy dosimetric measurements. It consists of a radiochromic gel dosimeter in a cuboidal plastic container, scanning with a flatbed scanner, and data processing using a dedicated software package. This tool is assessed using the example of the application of the coincidence test of radiation and mechanical isocenters for a medical accelerator. The following were examined: scanning repeatability and image homogeneity, the impact of image processing on data processing in coincidence tests, and irradiation conditions-monitor units per radiation beam and irradiation field are selected. Optimal conditions for carrying out the test are chosen: (i) the multi-leaf collimator gap should preferably be 5 mm for 2D star shot irradiation, (ii) it is recommended to apply ≥2500-≤5000 MU per beam to obtain a strong signal enabling easy data processing, (iii) Mean filter can be applied to the images to improve calculations. An approach to dosimeter reuse with the goal of reducing costs is presented; the number of reuses is related to the MUs per beam, which, in this study, is about 5-57 for 30,000-2500 MU per beam (four fields). The proposed reusable system was successfully applied to the coincidence tests, confirming its suitability as a new potential quality assurance tool in radiotherapy.