Range Of Radiation Doses Research Articles

Retrospective Review of Patients With Cardiac Implantable Electronic Devices Treated With Spot Scanning Proton Therapy

There is limited data on the effects of intensity modulated proton therapy (IMPT) on cardiac implantable electronic devices (CIEDs) such as pacemakers or defibrillators. Neutron scatter could affect CIED function and great caution needs to be taken when treating patients (pts) with CIEDs with IMPT. The purpose of this retrospective study was to review our experience treating CIED pts with IMPT.We retrospectively reviewed 50 pts age ≥18 years with CIEDs underwent IMPT for esophageal (11), H&N (10), other GI (7), NSCLC (6), prostate (6), brain (3), and breast (2) cancers, 4 pts with sarcomas and 1 pt with metastatic disease to bone between June 2015 and July 2020 at our institution on this IRB approved study. Thirty-seven pts were male and the average age (range) was 74 years (25-91). CIED manufacturers were Medtronic (21), Boston Scientific (15), Abbott (10), Biotronik (3) and Sorin (1). Forty-three pts had pacemakers and 7 had defibrillators. Eight pts were pacemaker dependent. Prior to treating the first CIED pt with IMPT, a multidisciplinary team including radiation oncology, cardiology, anesthesiology and nursing was established to develop guidelines for safe treatment and monitoring before, during and after IMPT. We implemented a risk-based decision tree for monitoring during treatment based on CIED dependence and underlying heart rate. We report with descriptive statistics pt demographics, cancer diagnosis, dose and distance from CIED, and CIED events and outcomes (CIED malfunctions, resets, battery depletion).Thirteen pts had intensive monitoring of their CIED during IMPT and the remaining 37 pts had reduced monitoring. Overall, 619 fractions were analyzed. The median prescribed proton dose (range) of radiation was 50 GyRBE1.1 in 25 fractions (25-75 GyRBE1.1). 46 pts had zero proton dose to the CIED. Those who had dose to the CIED had an average dose of 0.85 GyRBE1.1 (range of 0.03-2.18 GyRBE1.1). The average distance from CIED was 16.4cm (range: 2.4- > 50cm). There were no major CIED events related to the IMPT. There were three pts who had pacemaker programming resets to manufacturer settings, and all three of these pts had Biotronik CIEDs. These three pts had 6, 1 and 3 resets, and their CIED were 4cm, 7cm and 9cm from the 80% isodose line, respectively. No clinical cardiac events were related to these resets, and the CIEDS were reprogrammed to original settings uneventfully. Routine CIED battery depletion occurred in 2 pts, one of whom underwent CIED replacement during treatment. Projected CIED battery longevity decreased by 1-4 yrs in five pts.Treating pts with CIEDs undergoing IMPT seems to be safe as long as pts are carefully monitored. Infrequent CIED resets may occur. Frequent CIED monitoring may be associated with reduced projected CIED battery longevity. Long term outcomes will be reviewed and reported at the meeting.

THE STUDY OF THE INFLUENCE OF X-RAY IRRADIATION ON DISLOCATION CHARACTERISTICS IN LiF CRYSTALS

The dependences of the absorption α and the ultrasound velocity in LiF single crystals with residual deformation ε = 0.65% at 300 K in the range of radiation doses 0...1057 R were studied using the acoustic pulse echo method at a frequency of 7.5 MHz. Based on the results of measurements of the acoustic characteristics, the absolute values of the parameters of the dislocation structure – the average effective length of the dislocation loop L and the dislocation density Λ and their dependences on the irradiation time are determined. The calculated characteristics are compared with the previously obtained results for the high-frequency branch of the damped dislocation resonance and using the selective etching method. The revealed noticeable discrepancy in the values of these parameters is explained by the impossibility of describing a single attenuation mechanism for acoustic measurements carried out in a wide frequency range.

Применение политетрафторэтилена для дозиметрического контроля по данным ЯМР 19F

The 13C, 19F NMR spectra of the initial and irradiated polytetrafluoroethylene samples were studied in the range of gamma radiation doses up to 50 kGy. In this range, the 19F NMR spectrum width increases linearly with an increase in the absorbed dose. It is concluded that it is possible to control technological doses by the NMR method using polytetrafluoroethylene as a detector.

A time-resolved experimental-mathematical model for predicting the response of glioma cells to single-dose radiation therapy.

To develop and validate a mechanism-based, mathematical model that characterizes 9L and C6 glioma cells' temporal response to single-dose radiation therapy in vitro by explicitly incorporating time-dependent biological interactions with radiation. We employed time-resolved microscopy to track the confluence of 9L and C6 glioma cells receiving radiation doses of 0, 2, 4, 6, 8, 10, 12, 14 or 16 Gy. DNA repair kinetics are measured by γH2AX expression via flow cytometry. The microscopy data (814 replicates for 9L, 540 replicates for C6 at various seeding densities receiving doses above) were divided into training (75%) and validation (25%) sets. A mechanistic model was developed, and model parameters were calibrated to the training data. The model was then used to predict the temporal dynamics of the validation set given the known initial confluences and doses. The predictions were compared to the corresponding dynamic microscopy data. For 9L, we obtained an average (± standard deviation, SD) Pearson correlation coefficient between the predicted and measured confluence of 0.87 ± 0.16, and an average (±SD) concordance correlation coefficient of 0.72 ± 0.28. For C6, we obtained an average (±SD) Pearson correlation coefficient of 0.90 ± 0.17, and an average (±SD) concordance correlation coefficient of 0.71 ± 0.24. The proposed model can effectively predict the temporal development of 9L and C6 glioma cells in response to a range of single-fraction radiation doses. By developing a mechanism-based, mathematical model that can be populated with time-resolved data, we provide an experimental-mathematical framework that allows for quantitative investigation of cells' temporal response to radiation. Our approach provides two key advances: (i) a time-resolved, dynamic death rate with a clear biological interpretation, and (ii) accurate predictions over a wide range of cell seeding densities and radiation doses.

Effect of Gamma Irradiation on Some Rice Varieties Properties

This study aimed to evaluate the effect of gamma irradiation at dose levels of 0, 1, 3 and 5kGy on the chemical composition, starch digestibility, pasting properties and cooking properties of two varieties of polished rice (Sakha104 and basmati). The results showed that the highest dose of gamma irradiation decreased the apparent amylose content, peak viscosity water absorption and minimum cooking time; while the fat absorption and solid loss were slightly increased. Irradiation showed increases in rabidly digestible starch (RDS) and slowly digestible starch (SDS), with consequent reductions in resistant starch (RS) for Sakha104variety. Furthermore, basmati rice displays a linear behavior over the range of radiation doses for RDS and SDS with a reduction in RS.

Dark Current Random Telegraph Signals in Short-Wavelength Infrared Image Sensors Based on InGaAs

Dark current and associated random telegraph signals are studied in short-wave infrared image sensors. The effects of space radiation on these parameters are analyzed and modeled to understand the degradation in this indium–gallium–arsenide (InGaA)-based technology. Multiple proton tests were performed to cover the space mission range of radiation dose. Comparison with existing data and damage factors is provided and highlights the behavior of such technology against radiation doses.

Evaluation of dose received by organs at risk in radiotherapy of brain tumors

Background: Radiation therapy (RT) is one of the common and successful treatments for brain malignancies and benign disorders. In spite of its irrefutable merits, it is associated with a number of complications caused by radiation damage to the important Organs at Risks (OARs), which is strongly correlated with the radiation dose during RT. This study aimed to determine the range of radiation dose to Hippocampus and certain OARs in the brain. Materials and Methods: Thirty-two patients with primary brain cancer, undergoing RT, were selected retrospectively. The selected OARs were contoured using the RT Treatment Planning Software through assessing the images from the computed tomography and magnetic resonance imaging (MRI). Dose parameters, namely maximum dose (Dmax) and median dose (Dmedian), to OARs (optic nerves, chiasm, retinas, lenses, orbits, lachrymal glands, brainstem, hippocampi, etc.) were assessed. Results: The mean age of the patients was 37.8±14.3 years (from 5 to 60 years), and 19 patients (59%) were male. Glioblastoma multiforme and astrocytoma were the most common tumors. The maximum dose received by the brainstem, lenses, and eye ranged between 32-62 Gy, 0.75-40 Gy, 1.5-65 Gy, respectively. The maximum dose received by the hippocampi was 62.7 Gy. Conclusion: Important OARs can tolerate the received doses which were lower than the threshold level of serious complications. However, the maximum dose received by the hippocampi was higher than the recommended tolerated radiation dose; therefore, it is recommended to conduct more studies in this regard.

Determining the Sterilization Doses under Hypoxia for the Novel Black Pupae Genetic Sexing Strain of Anastrepha fraterculus (Diptera, Tephritidae).

Simple SummaryThe sterile insect technique is an environmentally-friendly method that can be used to manage populations of the South American fruit fly Anastrepha fraterculus, but its sterilizing doses have been determined only under normoxia. To maintain sterile male fly quality without jeopardizing sterility, a strategy of applying the radiation dose under an oxygen-reduced atmosphere is commonly used. Therefore, this study tested a range of gamma radiation doses under hypoxia on pupae from a bisexual strain and a novel genetic sexing strain (GSS) of A. fraterculus. Four types of crosses between irradiated flies under hypoxia and nonirradiated flies of the bisexual strain were set to assess sterility for each strain and radiation dose. For males from both strains, the effect of radiation dose on the percentage of egg hatch, egg-to-pupa recovery, and recovery of adults were determined. A dose of 74 Gy reduced egg hatch by 99% regardless of the male strain and was considered the sterilizing dose. The fertility of irradiated females and development of their offspring were severely affected, even at low doses under hypoxia, and no eggs were laid with doses above 50 Gy.A common strategy used to maintain sterile fly quality without sacrificing sterility is to irradiate the insects under an oxygen-reduced atmosphere. So far, sterilizing doses for the South American fruit fly Anastrepha fraterculus have only been determined under normoxia. Our study reports for the first time the dose-sterility response under hypoxia for two different A. fraterculus strains. The pupae were derived from a bisexual strain (a Brazilian-1 population) and a recently developed genetic sexing strain (GSS-89). Two hours prior to irradiation, pupae were transferred to sealed glass bottles and irradiated when oxygen concentration was below 3%. Four types of crosses with nonirradiated flies of the bisexual strain were set to assess sterility for each radiation dose. For males from both strains, Weibull dose–response curves between radiation doses and the proportion of egg hatch, egg-to-pupa recovery, and recovery of adults were determined. The GSS males revealed high sterility/mortality levels compared to males from the bisexual strain at doses < 40 Gy, but a dose of 74 Gy reduced egg hatch by 99% regardless of the male strain and was considered the sterilizing dose. The fertility of irradiated females was severely affected even at low doses under hypoxia.

Two‐stage deep learning model for fully automated pancreas segmentation on computed tomography: Comparison with intra‐reader and inter‐reader reliability at full and reduced radiation dose on an external dataset

To develop a two-stage three-dimensional (3D) convolutional neural networks (CNNs) for fully automated volumetric segmentation of pancreas on computed tomography (CT) and to further evaluate its performance in the context of intra-reader and inter-reader reliability at full dose and reduced radiation dose CTs on a public dataset. A dataset of 1994 abdomen CT scans (portal venous phase, slice thickness≤3.75-mm, multiple CT vendors) was curated by two radiologists (R1 and R2) to exclude cases with pancreatic pathology, suboptimal image quality, and image artifacts (n=77). Remaining 1917 CTs were equally allocated between R1 and R2 for volumetric pancreas segmentation [ground truth (GT)]. This internal dataset was randomly divided into training (n=1380), validation (n=248), and test (n=289) sets for the development of a two-stage 3D CNN model based on a modified U-net architecture for automated volumetric pancreas segmentation. Model's performance for pancreas segmentation and the differences in model-predicted pancreatic volumes vs GT volumes were compared on the test set. Subsequently, an external dataset from The Cancer Imaging Archive (TCIA) that had CT scans acquired at standard radiation dose and same scans reconstructed at a simulated 25% radiation dose was curated (n=41). Volumetric pancreas segmentation was done on this TCIA dataset by R1 and R2 independently on the full dose and then at the reduced radiation dose CT images. Intra-reader and inter-reader reliability, model's segmentation performance, and reliability between model-predicted pancreatic volumes at full vs reduced dose were measured. Finally, model's performance was tested on the benchmarking National Institute of Health (NIH)-Pancreas CT (PCT) dataset. Three-dimensional CNN had mean (SD) Dice similarity coefficient (DSC): 0.91 (0.03) and average Hausdorff distance of 0.15 (0.09)mm on the test set. Model's performance was equivalent between males and females (P=0.08) and across different CT slice thicknesses (P>0.05) based on noninferiority statistical testing. There was no difference in model-predicted and GT pancreatic volumes [mean predicted volume 99cc (31cc); GT volume 101cc (33cc), P=0.33]. Mean pancreatic volume difference was -2.7cc (percent difference: -2.4% of GT volume) with excellent correlation between model-predicted and GT volumes [concordance correlation coefficient (CCC)=0.97]. In the external TCIA dataset, the model had higher reliability than R1 and R2 on full vs reduced dose CT scans [model mean (SD) DSC: 0.96 (0.02), CCC=0.995 vs R1 DSC: 0.83 (0.07), CCC=0.89, and R2 DSC:0.87 (0.04), CCC=0.97]. The DSC and volume concordance correlations for R1 vs R2 (inter-reader reliability) were 0.85 (0.07), CCC=0.90 at full dose and 0.83 (0.07), CCC=0.96 at reduced dose datasets. There was good reliability between model and R1 at both full and reduced dose CT [full dose: DSC: 0.81 (0.07), CCC=0.83 and reduced dose DSC:0.81 (0.08), CCC=0.87]. Likewise, there was good reliability between model and R2 at both full and reduced dose CT [full dose: DSC: 0.84 (0.05), CCC=0.89 and reduced dose DSC:0.83(0.06), CCC=0.89]. There was no difference in model-predicted and GT pancreatic volume in TCIA dataset (mean predicted volume 96cc (33); GT pancreatic volume 89cc (30), p=0.31). Model had mean (SD) DSC: 0.89 (0.04) (minimum-maximum DSC: 0.79 -0.96) on the NIH-PCT dataset. A 3D CNN developed on the largest dataset of CTs is accurate for fully automated volumetric pancreas segmentation and is generalizable across a wide range of CT slice thicknesses, radiation dose, and patient gender. This 3D CNN offers a scalable tool to leverage biomarkers from pancreas morphometrics and radiomics for pancreatic diseases including for early pancreatic cancer detection.

Impacts of ionization radiation on the cuticular hydrocarbon profile and mating success of male house crickets (Acheta domesticus)

Purpose Ionizing radiation is well known to have drastic impacts on major life history features including survivorship, growth, fertility, and longevity. What is much less appreciated is how radiation stress can cause changes to more subtle traits, such as those associated with sexual signaling, an underappreciated but vital aspect of insect reproduction. In the House Cricket (Acheta domesticus) cuticular hydrocarbons are vital for sex and species recognition, as well as a possible indicator of stress, making them crucial for successful mating and reproduction. Materials and methods Here, we analyze the impacts of ionizing radiation on the cuticular hydrocarbons of male crickets and its subsequent impacts on mating success. We exposed juvenile (14-day, 4th instar) male crickets to a broad range of radiation doses (2 Gy − 2 Gy). Results We detected significant changes in individual cuticular hydrocarbons across a broad range of doses in mature male crickets using gas-liquid chromatography. Specifically, dose was identified as a significant contributing factor to hydrocarbon increases p < .0001. Mating success was significantly reduced in 12 Gy (p < .0001), 10 Gy (0.0001), and 7 Gy (0.0060) groups compared to non-irradiated controls. Conclusion Insect chemical communication can be species specific, and functionally specialized. Here, we show that radiation can alter the chemical signals used to attract mates in a large bodied insect and this may be a contributing factor to the described reduction in male mating success. Further research should be conducted to further analyze the various modes of communication employed by male crickets to attract mates i.e. acoustic signaling, and how this may also contribute to the reduction in mating success seen in irradiated males.

Influence of electron beam irradiation on nitrogen-saturated biodiesel

The objective was to study changes in nitrogen-saturated biodiesel irradiated by electron beam and to analyse them considering the influence of absorbed dose. Based on the obtained results, it can be concluded that irradiation in presented condition did not affect ester groups in fatty acid methyl esters (FAME) molecules, but slightly influenced on double bonds. After irradiation was observed relatively small change in concentration of methyl esters. Slightly influence can be explained by absorption of radiation by nitrogen present in samples. Therefore, the use of ionizing radiation to improve Rapeseed Methyl Esters (RME) properties can be used only in specific radiation dose range (total ester concentration must not be lower than 96.5 wt%). The reduction in the total concentration of methyl esters was lower than after irradiation of FAME samples saturated with water and air, which was presented in previous works.

Efficacy and complications of ruthenium-106 brachytherapy for uveal melanoma: a systematic review and meta-analysis.

PurposeThe aim of this study was to evaluate the efficacy and vision-threatening complications of brachytherapy with ruthenium-106 (106Ru) plaque to treat uveal melanoma.Material and methodsA literature review was performed based on results from searching PubMed, Embase, Web of Science, Scopus, and Cochrane databases, using the following key words: “choroidal melanoma”, “uveal melanoma”, “brachytherapy”, and “ruthenium-106”. We included studies performed on more than 30 patients since 1986, reporting on local control rate, complications rate, mean radiation dose, and mean tumor thickness. The cumulative analysis was performed using Metaprop command of Stata v.16, and meta-regression was conducted based on mean tumor thickness and mean radiation dose to tumor’s apex.ResultsTwenty-one retrospective studies were selected, involving 3,913 patients treated primarily with 106Ru plaque brachytherapy. The range of radiation dose to tumor apex was from 70 Gy to 250 Gy. The local control rate following brachytherapy ranged from 59% to 98%, and the overall weighted mean of local control was 84%. However, the heterogeneity between studies’ reports was remarkable (I2 = 95.40%). Meta-regression based on tumor thickness and mean dose of radiation to the apex showed that the studies’ heterogeneity was minimally related to the difference in mean tumor size (I2 = 92%). The correlation between larger tumor size and lower local control rate was statistically significant (p-value = 0.024). There was no significant correlation between the mean radiation dose and local control rate (p-value = 0.679). The most commonly reported complications were cataract and radiation-related retinopathy.ConclusionsAlthough the studies’ heterogeneity was high, in a prescription dose ranging from 70 Gy to 250 Gy to the tumor apex, 106Ru brachytherapy seems to be successful in local control of uveal melanoma. The efficacy of 106Ru in controlling uveal melanomas decreased with the increase in tumor thickness. However, these outcomes should be verified in randomized comparative studies.

Plaque brachytherapy in iris and iridociliary melanoma: a systematic review of efficacy and complications.

PurposeTo evaluate the efficacy and vision-threatening complication rate of plaque brachytherapy with iodine-125 (125I), palladium-103 (103Pd), and ruthenium-106 (106Ru) for treatment of iris and iridociliary melanoma.Material and methodsA literature review was done based on results yielded from searching PubMed, Embase, and Cochrane database, using following key words: iris melanoma, iridociliary melanoma, brachytherapy, iodine-125 brachytherapy, palladium-103 brachytherapy, and ruthenium-106 brachytherapy. Initially, relationships between mean radiation dose to apex and local recurrence and complication rate were analyzed, and then, a comparison was performed between 125I, 103Pd, and 106Ru studies.ResultsTwelve retrospective and prospective studies were selected, with 491 patients treated primarily with plaque brachytherapy. The range of radiation dose to tumor apex were from 84 to 151.5 Gy. Ranges of mean and median of follow-up time were from 27 to 96 months. Local recurrence rate following brachytherapy ranged from 0 to 8%. A decrease in the average study dose was not associated with an increased local recurrence or metastasis rate (p = 0.373 and 0.195, respectively); however, an increase in radiation dose was associated with higher radiation-related cataract and glaucoma (p < 0.05). The rate of post-treatment glaucoma was higher in studies with 125I plaque brachytherapy (p = 0.004).ConclusionsFor brachytherapy of iris and iridociliary melanoma, in a range of 84 to 150 Gy, an increase in radiation dose may increase the risk of complications, while the tumor control rate does not change.

Effect of gamma irradiation on the growth and lipid productivity of green microalgae

In the present research, the impact of exposing cultures of Chlamydomonas sp., Scenedesmus ecornis, and S. communis microalgae to doses of gamma-rays (γ-ray) on their growth and the productivity of lipids was investigated. Biomass concentration (g L-1) of each microalga was periodically determined after exposure to a range of gamma irradiation doses of 0, 25, 50, 75, 100, 200, and 300 Gray (Gy) through 20 days of cultivation period. Then, the lipid content (%) and lipid productivity (mg L-1 day-1) of each species were also evaluated. Obtained results indicated that the S. ecornis growth was positively affected by gamma irradiation, that the maximum concentration of biomass was obtained after 15 days at 1.32 g L-1 by the irradiated S. ecornis exposed to a dose of 300 Gy while the non-irradiated culture achieved up to 1.10 g L-1. On the other hand, the growths of Chlamydomonas sp. and S. communis were significantly reduced by gamma irradiation treatment also significant variations have also been observed in the levels of lipid content and lipid productivity of each microalga. Irradiated S. ecornis at a dose of 300 Gy exhibited the maximum of lipid content percentage and lipid productivity to reach 28.4% and 24.9 mg L-1 day-1, respectively. Conversely, the best yields of lipid content and lipid productivity were achieved by a non-irradiated culture of S. communis (24.4% and 16.6 mg L-1 day-1, respectively), compared to irradiated culture, regardless of irradiation dose. The highest lipid content and lipid productivity gained by Chlamydomonas sp. were obtained by the cultures exposed to 25 Gy, being 27.3% and 21.3 mg L-1 day-1, respectively. In conclusion, results indicated that exposing cells of S. ecornis and Chlamydomonas sp. to specific doses of γ-rays has significantly stimulated lipid accumulation in cells, unlike S. communis which was negatively affected by gamma irradiation.

Phase-field modeling of irradiated void microstructure evolution of Fe-Cr alloy

As cladding materials, Fe-Cr alloys are used in the extreme environments of high temperature, high pressure, and energetic particle radiation, thus generating irradiation defects such as vacancies and interstitials. The clustering of irradiation defects leads the voids or dislocation loops to form, resulting in irradiation swelling and lattice distortion, and further radiation hardening or softening, finally, material failure. It is beneficial to tailor desired microstructures and obtain stable service performances by understanding defects cluster and voids formation process. In this paper, the phase-field method is employed to study the evolution of voids of Fe-Cr alloy. In the model the temperature effects on point defects and generation/recombination of vacancies and interstitials are taken into consideration. The 400–800 K temperature range and 0–16 dpa radiation dose range are selected, in which the voids’ formation process including generation and recombination, as well as vacancy clustering caused by vacancy diffusion, is studied for Fe-Cr alloy. The nucleation rate of the void cluster shows a trend of first increasing and then decreasing with temperature increasing from 400 to 800 K. This phenomenon is related to complex interactions among defects concentration, atomic diffusion, recombination, nucleation, and growth conditions. At a given temperature, the average radius and the volume fraction of the voids grow bigger as the radiation dose increases. With the increase of irradiation dose, the cascade collision reaction is strengthened, and the number of Frenkel defect pairs is also increases. A large number of vacancies and interstitial atoms are generated, and the rapid diffusion and accumulation of vacancies in the Fe-Cr alloy at high temperature form a larger number and larger size of voids. The incubation period of vacancy clusters and voids are quite different due to the influence of irradiation temperature and dose. The higher the irradiation dose, the shorter the incubation period is. The relationship between the incubation period and temperature is more complicated. When the temperature is relatively low, the incubation period is shortened as the temperature increases, and as the temperature continues to increase to a higher temperature, the incubation period is extended. This relates to the increase in the concentration of vacancies, the recombination of vacancies and interstitials, and the increase of the critical nucleus radius for the growth of voids when the temperature increases.

Transcriptomic and Mutational Analyses Identify Biological Processes Correlated with Bladder Cancer Cell Line (BlaCCL) Radiation Response

We aimed to identify biological pathways that correlate with in vitro radiation response of an expanded panel of BlaCCL based upon analysis of whole-transcriptomic RNA-seq and targeted mutational profiling. Twenty established BlaCCL were verified by genomic fingerprinting and profiled with RNA-seq and targeted mutational analysis. Raw RNA-seq counts were normalized via log(FPKM+1) and mutations were profiled via custom panel enriched for 176 genes involved in DNA-damage response, chromatin remodeling, cell cycle control, inflammatory signaling and others (Nextera). We performed colony forming assays on all cell lines in triplicate with cumulative survival quantified via area-under-the-cell-survival curve (AUC) through a range of radiation doses (0-8Gy). Unsupervised learning of complex biological processes based on RNA-seq data was conducted via the CoGAPS package v.3.6 in R v.3.6.2. CoGAPS was run for k = 13 at 10,000 iterations and resulting patterns were correlated with AUC via Spearman’s rho. Differences in number of mutations between radio-sensitive and -resistant lines (based on AUC relative to median) were compared via Student’s t-test. Gene ontology (GO) enrichment was conducted via String-DB with significant terms identified with an FDR cut-off <0.05. RNA-seq analysis identified 18,634 genes for the panel of BlaCCL and mutational calling identified mutations in 63/176 unique genes in 18 cell lines ranging from 2-15 mutations per cell line. Satisfactory colony forming results were obtained for 17/20 cell lines with AUC ranging from 3.40-5.94 with a median of 4.58. CoGAPS factorization of the RNA-seq dataset revealed 2/13 gene sets that had a significant correlation with AUC (Pattern 2, 605 genes, rho = -0.75, p = 0.0007; Pattern 9, 176 genes, rho = 0.56, p = 0.0190). Pattern 2 was significantly enriched for cytokine-mediated signaling and Pattern 9 was significantly enriched for 43 processes including epithelial cell differentiation and activation of immune response. Notably, radioresistant cell lines had significantly more mutations (median 10 vs 4, p = 0.039; 52 vs 25 unique genes mutated in total between groups). GO enrichment based on mutated genes was similar between the two groups including radiation response, hypoxia, and regulation of immune system processes although the top-10 GO-terms in the radioresistant group were notable for chromosome organization, cellular stress response and DNA repair as opposed to cell cycle processes in the sensitive group. Based on biological process enrichment analysis of RNA-seq and targeted mutational profiling, several processes, particularly inflammation, are correlated with in vitro radiation response in BlaCCL. Further mechanistic studies are necessary to determine true modulators of radiosensitivity and to establish potential genetic biomarkers for prospective clinical validation.

Constitutive modeling of γ-irradiated silicone rubber foams under compression and shear loading

Under the service conditions of nuclear engineering applications, silicone rubber foams should endure radiation of γ rays accompanied by compression and shear loading. In this paper, the Hyperfoam model is extended to characterize the mechanical behaviors of silicone rubber foams under γ-irradiation. After exposing silicone rubber foams to a wide radiation dose range from 0 to 500 kGy at room temperature, uniaxial compression and simple shear tests were carried out to establish the relationships between the model parameters of Hyperfoam model and radiation dose, and indentation tests were performed to verify the extended Hyperfoam model. The linear radiation dose-related hardening properties of the material are derived using the testing results, including the linear increases of the initial shear modulus, and the compression stress and the shear stress for a given strain condition, which result in the linear radiation dose-dependent relationships for the initial shear modulus-related model parameters and the radiation dose-independent hardening exponent-related model parameters of Hyperfoam model. The performances of the extended Hyperfoam model are demonstrated by comparing the fitted material responses with uniaxial compression and simple shear data. And the prediction ability is verified by comparing the simulated results of indentation using the finite element method with the test data. The extended model is capable of characterizing the coupling stress state of compression and shear in the investigated irradiation dose range, which is expected to aid in evaluating the safety of nuclear engineering structures.

Influence of γ-irradiation on mechanical behaviors of poly methyl-vinyl silicone rubber foams at different temperatures

In this study, the radiation dose effect of γ rays on the temperature-dependent mechanical behaviors of poly methyl-vinyl silicone rubber foams is investigated by uniaxial compression tests. After exposure to a wide radiation dose range from 0 to 500 kGy at room temperature, silicone rubber foams were tested at 10, 40, 70, and 100 °C. The test results show that temperature increase causes linear hardening for both unirradiated and irradiated samples due to the predominating entropy-related deformation of silicone rubber matrix. Moreover, increase of irradiation dose leads to linear hardening as a result of dominating cross-linking reactions of rubber networks. A stress hardening factor is introduced to characterize the effect of irradiation dose on temperature-related hardening behavior, which is defined as the ratio between the compressive stresses of irradiated and unirradiated samples for a given compression strain. The approximated constant stress hardening factor for each radiation dose condition implies that the irradiation dose does not affect the temperature-related hardening behavior. Based on the test findings, the Ogden Hyperfoam model was extended by correlating the initial shear modulus-related model parameters with radiation dose and temperature. The hardening exponent-related model parameters have been shown to be independent of radiation dose and temperature, and the Poisson's ratio-related model parameters are approximated to zero for the high porosity of the material. The prediction performance of the extended model is demonstrated by comparing the fitted model responses with test data over the studied irradiation doses and temperature range. The results are expected to be helpful for the safety evaluation of nuclear engineering structures.

Gamma- and x-ray accelerated tin whisker development

We observed accelerated whisker development in thin tin films under non-destructive gamma-ray and x-ray irradiation sources. The effect is mediated by charges induced in glass substrates supporting films, and becomes significant reaching the characteristic range of radiation doses of 20-30 kGy. We were able to change the radiation induced whisker growth rate by electrically disconnecting some parts of our experimental setup, thus demonstrating the electrostatic nature of the whisker development. Subject to additional qualification trials, the observed acceleration factors suggest that ionizing radiation can be used for accelerated whisker propensity testing.

The sub-millisievert era in CTCA: the technical basis of the new radiation dose approach.

Computed tomography coronary angiography (CTCA) has become a cornerstone in the diagnostic process of the heart disease. Although the cardiac imaging with interventional procedures is responsible for approximately 40% of the cumulative effective dose in medical imaging, a relevant radiation dose reduction over the last decade was obtained, with the beginning of the sub-mSv era in CTCA. The main technical basis to obtain a radiation dose reduction in CTCA is the use of a low tube voltage, the adoption of a prospective electrocardiogram-triggering spiral protocol and the application of the tube current modulation with the iterative reconstruction technique. Nevertheless, CTCA examinations are characterized by a wide range of radiation doses between different radiology departments. Moreover, the dose exposure in CTCA is extremely important because the benefit-risk calculus in comparison with other modalities also depends on it. Finally, because anatomical evaluation not adequately predicts the hemodynamic relevance of coronary stenosis, a low radiation dose in routine CTCA would allow the greatest use of the myocardial CT perfusion, fractional flow reserve-CT, dual-energy CT and artificial intelligence, to shift focus from morphological assessment to a comprehensive morphological and functional evaluation of the stenosis. Therefore, the aim of this work is to summarize the correct use of the technical basis in order that CTCA becomes an established examination for assessment of the coronary artery disease with low radiation dose.