Specific spectral sub-images for machine learning evaluation of optical differences between carbon ion and X ray radiation effects.

Advances in radiotherapy, particularly the exploration of alternative radiation types such as carbon ions have updated our understanding of its effects and applicability on chondrosarcoma cells. Here we compare the optical effects produced by carbon ions (CI) and X-rays (XR) radiations on chondrosarcoma cells nuclei and set an automated method for evaluating the radiation-induced alterations without the need of chemical marking. Hyperspectral images (HSI) of SW1353 chondrosarcoma line carry detectable optical changes of the cells irradiated either with CI or XR compared to non-irradiated ones (REF). The differences between the spectral profiles of CI, XR and REF nuclei classes led to partitioning the HSIs into spectral sub-images. The changes are detected by support vector machine (SVM) classifiers whose performances are evaluated by the most used point metrics: sensitivity (SEN), accuracy (ACC), and precision (PREC), applied on spatial feature values. Specific interaction mechanisms by radiation type reveal distinct subintervals where HSIs changes are more prominent, and the classifiers perform at best. For CI the best classifiers are obtained for sub-images in the interval (424-436 nm), while for XR the best classifiers are obtained for sub-images in the interval (436-445 nm). The classifiers work better with texture features than roughness features in both cases. The classifier with the best SEN point metric in the testing phase is the most suitable to measure the irradiation efficiency irrespective of the radiation type. The altered nuclei are easier to discriminate when irradiated with CI than with XR. The study proves that SVM with optical data offers a rapid, automated, and label-free method for evaluating radiation-induced alterations in chondrosarcoma nuclei, thereby enabling effective analysis of extensive data.

RadPhysBio: A Radiobiological Database for the Prediction of Cell Survival upon Exposure to Ionizing Radiation.

Based on the need for radiobiological databases, in this work, we mined experimental ionizing radiation data of human cells treated with X-rays, γ-rays, carbon ions, protons and α-particles, by manually searching the relevant literature in PubMed from 1980 until 2024. In order to calculate normal and tumor cell survival α and ß coefficients of the linear quadratic (LQ) established model, as well as the initial values of the double-strand breaks (DSBs) in DNA, we used WebPlotDigitizer and Python programming language. We also produced complex DNA damage results through the fast Monte Carlo code MCDS in order to complete any missing data. The calculated α/ß values are in good agreement with those valued reported in the literature, where α shows a relatively good association with linear energy transfer (LET), but not ß. In general, a positive correlation between DSBs and LET was observed as far as the experimental values are concerned. Furthermore, we developed a biophysical prediction model by using machine learning, which showed a good performance for α, while it underscored LET as the most important feature for its prediction. In this study, we designed and developed the novel radiobiological 'RadPhysBio' database for the prediction of irradiated cell survival (α and ß coefficients of the LQ model). The incorporation of machine learning and repair models increases the applicability of our results and the spectrum of potential users.

Seed Priming by Low-Dose Radiation Improves Growth of Lactuca sativa and Valerianella locusta.

Valerian salad and lettuce are edible species that are easy to grow rapidly, and have traits useful for commercial purposes. The consumption of these species is increasing worldwide for their nutritional properties. Seed germination and seedling development are critical stages in the life cycle of plants. Seed priming, including the use of high-energy radiation, is a set of techniques based on the idea that low stress levels stimulate plant responses, thereby improving seed germination and plant growth. In this study, we evaluated in hydroponic culture (i) the germination performance; (ii) morphological traits; and (iii) antioxidant and phenol contents at different endpoints in Lactuca sativa and Valerianella locusta that were developed from seeds exposed to X-rays (1 Gy and 10 Gy doses). Under radiation, biomass production increased in both species, especially in lettuce, where also a reduction in the mean germination time occurred. Radiation increased the level of phenols during the first growth weeks, under both doses for lettuce, and only 1 Gy was required for valerian salad. The species-specific responses observed in this research suggest that the use of radiations in seed priming needs to be customized to the species.

Externally Applied Electromagnetic Fields and Hyperthermia Irreversibly Damage Cancer Cells.

At present, the applications and efficacy of non-ionizing radiations (NIR) in oncotherapy are limited. In terms of potential combinations, the use of biocompatible magnetic nanoparticles as heat mediators has been extensively investigated. Nevertheless, developing more efficient heat nanomediators that may exhibit high specific absorption rates is still an unsolved problem. Our aim was to investigate if externally applied magnetic fields and a heat-inducing NIR affect tumor cell viability. To this end, under in vitro conditions, different human cancer cells (A2058 melanoma, AsPC1 pancreas carcinoma, MDA-MB-231 breast carcinoma) were treated with the combination of electromagnetic fields (EMFs, using solenoids) and hyperthermia (HT, using a thermostated bath). The effect of NIR was also studied in combination with standard chemotherapy and targeted therapy. An experimental device combining EMFs and high-intensity focused ultrasounds (HIFU)-induced HT was tested in vivo. EMFs (25 µT, 4 h) or HT (52 °C, 40 min) showed a limited effect on cancer cell viability in vitro. However, their combination decreased viability to approximately 16%, 50%, and 21% of control values in A2058, AsPC1, and MDA-MB-231 cells, respectively. Increased lysosomal permeability, release of cathepsins into the cytosol, and mitochondria-dependent activation of cell death are the underlying mechanisms. Cancer cells could be completely eliminated by combining EMFs, HT, and standard chemotherapy or EMFs, HT, and anti-Hsp70-targeted therapy. As a proof of concept, in vivo experiments performed in AsPC1 xenografts showed that a combination of EMFs, HIFU-induced HT, standard chemotherapy, and a lysosomal permeabilizer induces a complete cancer regression.

The role of non-ionizing electromagnetic radiation on female fertility: A review.

With increasing technological developments, exposure to non-ionizing radiations has become unavoidable as people cannot escape from electromagnetic field sources, such as Wi-Fi, electric wires, microwave oven, radio, telecommunication, bluetooth devices, etc. These radiations can be associated with increased health problems of the users. This review aims to determine the effects of non-ionizing electromagnetic radiations on female fertility. To date, several in vitro and in vivo studies unveiled that exposure to non-ionizing radiations brings about harmful effects on oocytes, ovarian follicles, endometrial tissue, estrous cycle, reproductive endocrine hormones, developing embryo, and fetal development in animal models. Non-ionizing radiation also upsurges the free radical load in the uterus and ovary, which leads to inhibition of cell growth and DNA disruptions. In conclusion, non-ionizing electromagnetic radiations can cause alterations in both germ cells as well as in their nourishing environment and also affect other female reproductive parameters that might lead to infertility.

Combination of natural polyphenols with a precursor of NAD+ and a TLR2/6 ligand lipopeptide protects mice against lethal γ radiation.

INTRODUCTION: Effective agents that could confer long-term protection against ionizing radiation in vivo would have applications in medicine, biotechnology, and in air and space travel. However, at present, drugs that can effectively protect against lethal ionizing radiations are still an unmet need. OBJECTIVE: To investigate if combinations of natural polyphenols, known for their antioxidant potential, could protect against ionizing radiations. METHODS: Plant-derived polyphenols were screened for their potential ability to confer radioprotection to mice given a lethal whole-body γ radiation (137Cs) dose expected to kill 50% of the animals in 30 days. Telomere and centromere staining, Q-FISH and comet assays were used to investigate chromosomal aberration, micronuclei formation and DNA breaks. Molecular oxidations were investigated by enzyme immunoassays and UPLC-MS/MS. RT-PCR, western blotting and siRNA-induced gene silencing were used to study signaling mechanisms and molecular interactions. RESULTS: The combination of pterostilbene (PT) and silibinin (SIL) was the most effective against γ-irradiation, resulting in 100% of the mice surviving at 30 days and 20% survival at one year. Treatment post γ-irradiation with two potential radiomitigators nicotinamide riboside (NR, a vitamin B3 derivative), and/or fibroblast-stimulating lipoprotein 1 (FSL1, a toll-like receptor 2/6 agonist), did not extend survival. However, the combination of PT, SIL, NR and FSL1 achieved a 90% survival one year post γ-irradiation. The mechanism involves induction of the Nrf2-dependent cellular antioxidant defense, reduction of NF-kB signaling, upregulation of the PGC-1α/sirtuins 1 and 3 axis, PARP1-dependent DNA repair, and stimulation of hematopoietic cell recovery. The pathway linking Nrf2, sirtuin 3 and SOD2 is key to radioprotection. Importantly, this combination did not interfere with X-ray mediated killing of different tumor cells in vivo. CONCLUSION: The combination of the radioprotectors PT and SIL with the radiomitigators NR and FSL1 confer effective, long-term protection against γ radiation in vivo. This strategy is potentially capable of protecting mammals against ionizing radiations.

Routine first-line detection of breast cancer therapy-related cardiotoxicity by serial, fast and ultra-low-dose equilibrium radionuclide angiography.

BACKGROUND: This study assesses a first-line left ventricular ejection fraction (LVEF) monitoring provided by an ultra-low-dose equilibrium radionuclide angiography (ERNA) in breast cancer women treated with potentially cardiotoxic drugs and analyzes patient outcome based on the ERNA results. METHODS: Breast cancer women treated with anthracyclines, followed or not by trastuzumab, were monitored using ERNA with a high-sensitivity CZT-camera. Calibrated LVEF measurements were obtained with an almost threefold reduction of radiation doses and 10-min recording times. RESULTS: During a mean 24 ± 6 months follow-up, 552 ERNAs with a mean effective dose of 2.3 ± 0.6 mSv were performed in 195 women, among whom 22 (11%) presented both ERNA criteria of cardiotoxicity (LVEF < 50% and > 10% drop from baseline; Tox + group), 35 (18%) only one criterion (Tox ± group), and 138 (71%) neither (Tox - group). This ERNA-based classification correlated with trastuzumab-anthracycline treatment (p = 0.001), prior cardiovascular disease (p = 0.018), and cardiac outcome, with a 30-month survival with no cardiotoxicity-driven drug regimen changes of 97 ± 2% in Tox -, 60 ± 13% in Tox ± and 36 ± 13% in Tox + (p < 0.001) groups. CONCLUSION: First-line detection of breast cancer therapy-related cardiotoxicity by ultra-low-dose ERNA provides consistent results, confirming the excellent cardiac outcome for the greatest majority of women with no ERNA cardiotoxicity criteria.

Effects of certain physical stresses on the composition of the membrane of bacteria implicated in food and environmental contamination.

Bacterial membranes are implicated in the adaptation process of bacteria to numerous environmental conditions. In this context, our aim was to explain the consequences of a few physical stressor factors, like UV radiations and magnetic fields underlying the structural adaptation of cellular membranes to physical factors. The goal was also to review the state of the art about the link between membrane composition and bacterial resistance. According to comparative studies between ionizing γ-radiation, non-ionizing UVc radiations and Static Magnetic Field SMF, the response of some Gram negative bacteria appears to be generalized and was manifested by a membrane unsaturation, because of a production peak of unsaturated fatty acids. However, disturbances found inside the membrane, after UVB and Pulsed Electric Field (PEF) exposure were marked by a lower unsaturated fatty acids rate. This result is not concordant to disturbance seen after UVC treatment, even if the treatment is by UV radiation.

Retrospective audit of CT scans performed at a hospital for surgical patients.

Introduction: Easy accessibility, high sensitivity and specificity of CT scans have markedly increased its usage in developed countries. Its importance is undeniably considered integral for the diagnosis of various pathologies. However, sometimes this costly resource is wasted when used unnecessary. This paper is an audit on CT scans performed to look for surgical pathologies between July 2018 and April 2019 recapitulating the numbers of CT scan's abnormal and normal findings. Methodology: Anonymized record of all the patients seen by the surgical team in the emergency department was reviewed. Retrospective data of every patient who had the CT scan was taken through Mckesson Radiology software of an Irish Hospital. Analysis was done using SPSS. Findings of 102 CT scans was broken down in to three different groups depending at which departmental level CT was performed, namely:Emergency department, Inpatient and Outpatient. Results: 102 CT Scans were performed of which 51 (50%) patients out of all the three groups had unremarkable. Conclusions: Adequate history, proper clinical examination and strong clinical knowledge may bring down the number of unnecessary CT scans.

Thyroid parameters variations in healthcare workers and students exposed to low-dose ionizing radiations.

SUMMARY: Background. Ionizing Radiations (IR) are an important occupational risk factor for the potential damage that can cause to workers' health and for their presence in numerous professional settings. Health care workers (HCW) can be exposed to IR from various sources, in particular from x-rays using radiological equipment, and represent the largest group of workers occupationally at risk, despite increased regulation and protection which caused exposure to low dose radiations. The thyroid gland is one of the most sensitive organs to damage and an important target of IR, leading to functional and organic diseases. The aim of this study is to assess the variations in thyroid hormones, in a population of HCW exposed to low-dose IR. Methods. 121 individuals of the Teaching Hospital Policlinico Umberto I in Rome exposed to low-dose of IR (78 HCW, 17 Residents and 26 Radiology Technicians Students) were observed assessing serum levels of different thyroid function parameters as free triiodothyronine, free thyroxine and thyroid stimulating hormone at T1, T2 and DeltaT. Age, gender, history of thyroid diseases, BMI and smoke were analyzed as possible influencing factors using linear and multiple logistic regression analysis. Results. Analyzing TSH, fT3 and fT4 serum levels, in two different measurement (T1 and T2) and considering Delta between them, adjusting for different confounding factors, data showed no variation of TSH levels related to occupational exposure, a decrease of fT3 hormone values in HCW and residents, and an increase of fT4 in HCW. Discussion. The analysis of our results revealed that hospital occupation has an impact on thyroid hormones variations, with an increase of fT4 and a decrease of fT3 and no variations of TSH. These results are in conflict with previous studies evidences, in which both free hormones decreased with a concomitant increase of TSH. Conclusion. Exposure to low dose IR influences levels of free thyroid hormones, with no variation in TSH, which could result in a functional or organic disease. For this reason it is recommended continuous surveillance through a periodic check of all the thyroid hormones for an overall view of each HCW. However, further studies are necessary to confirm hormones trend and assess any related thyroid diseases.

Radioprotective Role of Natural Polyphenols: From Sources to Mechanisms.

The identification and development of radioprotective agents have emerged as a subject matter of research during recent years due to the growing usage of ionizing radiation in different areas of human life. Previous work on synthetic radioprotectors has achieved limited progress because of the numerous issues associated with toxicity. Compounds extracted from plants have the potential to serve as lead candidates for developing ideal radioprotectors due to their low cost, safety, and selectivity. Polyphenols are the most abundant and commonly dispersed group of biologically active molecules possessing a broad range of pharmacological activities. Polyphenols have displayed efficacy for radioprotection during various investigations and can be administered at high doses with lesser toxicity. Detoxification of free radicals, modulating inflammatory responses, DNA repair, stimulation of hematopoietic recovery, and immune functions are the main mechanisms for radiation protection with polyphenols. Epicatechin, epigallocatechin-3-gallate, apigenin, caffeic acid phenylethylester, and silibinin provide cytoprotection together with the suppression of many pro-inflammatory cytokines owing to their free radical scavenging, anti-oxidant, and anti-inflammatory properties. Curcumin, resveratrol, quercetin, gallic acid, and rutin's radioprotective properties are regulated primarily by the direct or indirect decline in cellular stress. Thus, polyphenols may serve as potential candidates for radioprotection in the near future; however, extensive investigations are still required to better understand their protection mechanisms.

REV1 Inhibition Enhances Radioresistance and Autophagy.

Cancer therapy resistance is a persistent clinical challenge. Recently, inhibition of the mutagenic translesion synthesis (TLS) protein REV1 was shown to enhance tumor cell response to chemotherapy by triggering senescence hallmarks. These observations suggest REV1's important role in determining cancer cell response to chemotherapy. Whether REV1 inhibition would similarly sensitize cancer cells to radiation treatment is unknown. This study reports a lack of radiosensitization in response to REV1 inhibition by small molecule inhibitors in ionizing radiation-exposed cancer cells. Instead, REV1 inhibition unexpectedly triggers autophagy, which is a known biomarker of radioresistance. We report a possible role of the REV1 TLS protein in determining cancer treatment outcomes depending upon the type of DNA damage inflicted. Furthermore, we discover that REV1 inhibition directly triggers autophagy, an uncharacterized REV1 phenotype, with a significant bearing on cancer treatment regimens.

Association of Caspase 3 Activation and H2AX γ Phosphorylation in the Aging Brain: Studies on Untreated and Irradiated Mice.

Phosphorylation of H2AX is a response to DNA damage, but γH2AX also associates with mitosis and/or apoptosis. We examined the effects of X-rays on DNA integrity to shed more light on the significance of H2AX phosphorylation and its relationship with activation of caspase 3 (CASP3), the main apoptotic effector. After administration of the S phase marker BrdU, brains were collected from untreated and irradiated (10 Gray) 24-month-old mice surviving 15 or 30 min after irradiation. After paraffin embedding, brain sections were single- or double-stained with antibodies against γH2AX, p53-binding protein 1 (53BP1) (which is recruited during the DNA damage response (DDR)), active CASP3 (cCASP3), 5-Bromo-2-deoxyuridine (BrdU), and phosphorylated histone H3 (pHH3) (which labels proliferating cells). After statistical analysis, we demonstrated that irradiation not only induced a robust DDR with the appearance of γH2AX and upregulation of 53BP1 but also that cells with damaged DNA attempted to synthesize new genetic material from the rise in BrdU immunostaining, with increased expression of cCASP3. Association of γH2AX, 53BP1, and cCASP3 was also evident in normal nonirradiated mice, where DNA synthesis appeared to be linked to disturbances in DNA repair mechanisms rather than true mitotic activity.

Effects of Combination Treatments with Astaxanthin-Loaded Microparticles and Pentoxifylline on Intracellular ROS and Radiosensitivity of J774A.1 Macrophages.

Radiation-induced fibrosis (RIF) is a serious, yet incurable, complication of external beam radiation therapy for the treatment of cancer. Macrophages are key cellular actors in RIF because of their ability to produce reactive oxidants, such as reactive oxygen species (ROS) and inflammatory cytokines that, in turn, are the drivers of pro-fibrotic pathways. In a previous work, we showed that phagocytosis could be exploited to deliver the potent natural antioxidant astaxanthin specifically to macrophages. For this purpose, astaxanthin encapsulated into µm-sized protein particles could specifically target macrophages that can uptake the particles by phagocytosis. In these cells, astaxanthin microparticles significantly reduced intracellular ROS levels and the secretion of bioactive TGFß and increased cell survival after radiation treatments. Here we show that pentoxifylline, a drug currently used for the treatment of muscle pain resulting from peripheral artery disease, amplifies the effects of astaxanthin microparticles on J774A.1 macrophages. Combination treatments with pentoxifylline and encapsulated astaxanthin might reduce the risk of RIF in cancer patients.

[Assessment of the practices and knowledge among cardiologists regarding radiation protection in Tunisia]. / Évaluation des pratiques et connaissances en radioprotection des cardiologues en Tunisie.

INTRODUCTION: interventional cardiology procedures have become complex and expensive in time with a higher risk of exposure to ionizing radiations. The purpose of our study was to assess radiation protection knowledge and practices among Tunisian cardiologists exposed to X-rays. METHODS: we conducted a descriptive, analytical study in October 2019. An anonymous survey on the knowledge and practices regarding radiation protection was sent to all Tunisian cardiologists exposed to X-rays. RESULTS: among 126 cardiologists exposed to X-rays and having received the survey, 58 physicians responded to the survey (48%), with a male predominance (72%, n=42). Thirty-eight physicians (65%) were public sector workers. Average years of working experience were 12.02 years (SD 6.88 years). Half of doctors had a knowledge score of less than 50%. The average practice score was 43.83 (SD 13.95%). Wearing a lead apron, thyroid shield, dosimeter, lead glasses, lead cap accounted for 100% (n=58), 86.2% (n=50), 30.7% (n=18), 12.1% (n=7) and 1.7% (n=1) respectively. There was no correlation between scores and doctor's age as well as the length of working experience. There was no statistical differences between knowledge scores of males and females (p=0.06) or between public sector and private sector (p=0.9). Practice score was significantly higher among men (0.007) and interventional cardiologists compared to rhythmologists and pediatric cardiologists (p<0.001). CONCLUSION: the level of knowledge and practices among Tunisian cardiologists regarding radiation protection is generally insufficient. Then, health authorities should implement regular training programs.

Inclusion of ionizing radiation in a mathematical model for photosynthesis.

Ionizing radiation of astrophysical origin might have played an important role in biological evolution during the long course of Earth's evolution. Several phenomena might have induced intense fluctuations in background ionizing radiation, such as highly energetic stellar explosions. There might also be anthropogenic causes for environmental radiation fluctuations, resulting from nuclear industry activities. The inclusion of these effects in a mathematical model for photosynthesis provides a useful tool to account for the damages of the above-mentioned phenomena in vegetal life. Mathematical models for photosynthesis typically only consider ultraviolet radiation and photosynthetically active radiation, as they have been a ubiquitous physical factor in the settlement of vegetal life. In this work a mathematical model for aquatic photosynthesis is modified, from first principles, to include the action of particulate ionizing radiation on the photosynthetic process. After assuming an ansatz allowing to separate damage/repair kinetics of ultraviolet and ionizing radiations, a treatable mathematical expression of the model is obtained. This generalized model is presented as a function of radiometric and photometric magnitudes, making it prone to calibration and useful to apply to aquatic ecosystems under radiational stress due to gamma-ray bursts, cosmic ray bursts, solar storms, or other sources of ionizing radiations.

Can a causal relationship be established between acoustic neuroma and occupational exposure to non-ionizing radiations from mobile devices? Comparison between scientific literature data and medico-legal methodology.

BACKGROUND: Over the process of establishing the causal relation-ship, medical and legal methodologies may be at variance over the definitional standards and terminologies applied, which can hinder the activities of expert witnesses. OBJECTIVES: The article's authors have set out to assess whether, and under what conditions, a causal relationship can be established between acoustic neuroma and exposure to non-ionizing radiation from mobile communication devices. METHODS: The study design is a Systematic Review. The authors have drawn upon a 2020 Turin Court of Appeals ruling which found such a causal relationship in a somewhat peculiar case: rare tumor and exposure to non-ionizing radiation of unusually long and regular dura-tion. The case presents several peculiarities, herein analyzed in light of a) scientific evidence relative to the etiopathogenesis of the neuroma; b) available medico-legal literature defining causality evaluation criteria, and lastly c) court filings in regard to the probability standards applied to prove causal relationship. RESULTS: A direct tie cannot be proven, not even in cases of sub-stantially intense and lengthy exposure, if the medico-legal standards applied are not consistent enough to prove that nexus is more likely than not. DISCUSSION: Several elements suggest a causal relationship is unlikely: a) a dearth of evidence on humans; b) rats exposed to such radiation have developed cardiac tumors, not in their ears; c) exposure has caused no tumors in mice; d) the length of exposure is incompat-ible with tumor size and type. That fourth point only concerns the case herein explored, whereas the first three have a general scope of validity. The main limitation of the present study design is the heterogeneity among the included studies. Retrospective and prospective studies have been included, which may be a source of bias.

Radiofrequency radiation: A possible threat to male fertility.

Radiofrequency exposure from man-made sources has increased drastically with the era of advanced technology. People could not escape from such RF radiations as they have become the essential part of our routine life such as Wi-Fi, microwave ovens, TV, mobile phones, etc. Although non-ionizing radiations are less damaging than ionizing radiations but its long term exposure effect cannot be avoided. For fertility to be affected, either there is an alteration in germ cell, or its nourishing environment, and RF affects both the parameters subsequently, leading to infertility. This review with the help of in vitro and in vivo studies shows that RF could change the morphology and physiology of germ cells with affected spermatogenesis, motility and reduced concentration of male gametes. RF also results in genetic and hormonal changes. In addition, the contribution of oxidative stress and protein kinase complex after RFR exposure is also summarized which could also be the possible mechanism for reduction in sperm parameters. Further, some preventative measures are described which could help in reverting the radiofrequency effects on germ cells.

G-quadruplex DNA structures and their relevance in radioprotection.

BACKGROUND: DNA, the genetic material of most of the organisms, is the crucial element of life. Integrity of DNA needs to be maintained for transmission of genetic material from one generation to another. All organisms are constantly challenged by the environmental conditions which can lead to the induction of DNA damage. Ionizing radiation (IR) has been known to induce DNA damage and IR sensitivity varies among different organisms. The causes for differential radiosensitivity among various organisms have not been studied in great detail. SCOPE OF REVIEW: We discuss DNA secondary structure formation, GC content of the genome, role of G-quadruplex formation, and its relationship with radiosensitivity of the genome. MAJOR CONCLUSION: In Deinococcus radiodurans, the bacterium that exhibits maximum radio resistance, multiple G-quadruplex forming motifs are reported. In human cells, G-quadruplex formation led to differential radiosensitivity. In this article, we have discussed, the role of secondary DNA structure formation like G-quadruplex in shielding the genome from radiation and its implications in understanding evolution of radio protective effect of an organism. We also discuss role of GC content and its correlation with radio resistance. GENERAL SIGNIFICANCE: This review provides an insight into the role of G-quadruplexes in providing differential radiosensitivity at different site of the genome and in different organisms. It further discusses the possibility of higher GC content contributing towards reduced radiosensitivity in different organisms, evolution of radiosensitivity, and regulation of multiple cellular processes.