Radiation-induced Reactions Research Articles

Radiation synthesis of size-controllable ruthenium-based electrocatalysts for hydrogen evolution reaction

Ruthenium decorated reduced graphene oxide (Ru/rGO) catalysts were synthesized through γ-ray radiation induced reduction in aqueous media without additive reducing agent. The investigation of dose rate and RuCl3 concentration on the size of Ru nanoparticles (NPs) showed that both higher dose rate and lower precursor concentration contributed to smaller size. Then the formation mechanism of Ru NPs with different size was discussed in detail based on the principle of radiation-induced reduction reaction and nanocrystals growth. Finally, the Ru/rGO catalysts were applied in hydrogen evolution reaction (HER) under alkaline media. It is found that the size and content of Ru NPs played a critical role in the activity of HER and the Ru/rGO catalysts prepared at the dose rate of 365 Gy/min and RuCl3 concentration of 2 mM with a Ru diameter of ca. 2.1 nm showed excellent HER performance than commercial Pt/C especially at higher current density. It is expected that the result gained from this study may provide a scientific base for the future synthesis of novel Ru-based electrocatalysts.

ONS Guidelines™ for Cancer Treatment-Related Radiodermatitis.

Radiodermatitis is a side effect of radiation therapy. Evidence-based interventions to minimize severity or delay progression are important for clinical care. This guideline intends to support individuals with cancer, clinicians, and others in decisions regarding radiodermatitis treatment. A panel of healthcare professionals with patient representation was convened to develop a national clinical practice guideline for the management of radiodermatitis. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology and the National Academies of Sciences, Engineering, and Medicine criteria for trustworthy guidelines were followed. The Cochrane Collaboration risk-of-bias tool was used, and certainty of the evidence was assessed using the GRADE approach. A quantitative and narrative synthesis of the evidence was completed. The panel agreed on eight recommendations and made a conditional recommendation for deodorant/antiperspirant. Aloe vera and oral curcumin had knowledge gaps and were recommended only in the context of a clinical trial. The panel suggested against emu oil, calendula, and nonsteroidal interventions. This guideline summarizes evidence-based interventions for the management of radiodermatitis to guide clinical care. //bit.ly/2GEwJtT.

Gamma - Radiation-induced reaction of Sulfuric Acid with Silica gel: A Novel method for the formation of sulfonic acid - functionalized silica (SiO2-SO3H)

Radiation-induced reaction of sulfuric acid with silica gel (SG) was carried out using ɤ-radiation from a 60Co source at room temperature and, its mechanism were suggested. The formation of sulfonated SG (SiO2-SO3H) was confirmed by IR, thermal analysis (TGA/ DSC). Elemental analysis and morphological structure of treated SG (SGtreated) was investigated by scanning electron microscopy (SEM). According to the comparison of the SEM images of SG and SGtreated , it seems that, irradiation of SG in the presence of sulfuric acid leads to partial segmentation of SG particles. The IR spectra of the treated silica (SGtreated) is different from that of the SG. Where, peaks related to the presence of sulfunic group are observed, as well as shifts of SG peaks due to treatment. Also, TGA/ DSC of SGtreated is different from that of SG. Elemental analysis reveals that particle size of SG affects the S/O % value, where SGtreated with >0.16mm - 0.2mm particle size has the maximum value. Also, S/O% value, of >0.16mm - 0.2mm SG particle size, increased, linearly, with absorbed dose up to 80 kGy and then decresedat higher doses.

Bladder preservation therapy for muscle invasive bladder cancer: the past, present and future.

Radical cystectomy is the gold standard treatment for muscle invasive bladder cancer, but some patients have medically inoperable disease or refuse cystectomy to preserve their bladder function. Bladder preservation therapy with transurethral resection of the bladder tumor and concurrent chemoradiotherapy, known as trimodal treatment, is regarded to be a curative-intent alternative to radical cystectomy for patients with muscle invasive bladder cancer during the past decade. After the development of immune checkpoint inhibitors, a world-changing breakthrough occurred in the field of metastatic urothelial carcinoma and many clinical trials have been conducted against non-muscle invasive bladder cancer. Interestingly, preclinical and clinical studies against other malignancies have shown that immune checkpoint inhibitors interact with the radiation-induced immune reaction. As half of the patients with muscle invasive bladder cancer are elderly, and some have renal dysfunction, not only as comorbidity but also because of hydronephrosis caused by their tumors, immune checkpoint inhibitors are expected to become part of a new therapeutic approach for combination treatment with radiotherapy. Accordingly, clinical trials testing immune checkpoint inhibitors have been initiated to preserve bladder for muscle invasive bladder cancer patients using radiation and immune checkpoint inhibitors with/without chemotherapy. The objective of this review is to summarize the evidence of trimodal therapy for muscle invasive bladder cancer during the past decade and to discuss the future directions of bladder preservation therapy in immuno-oncology era.

Potential Functional Variants in DNA Repair Genes Are Associated with Efficacy and Toxicity of Radiotherapy in Patients with Non-Small-Cell Lung Cancer.

Background Lung cancer is one of the leading causes of cancer-related deaths. Radiotherapy, either alone or with chemotherapy, is still the primary treatment for patients with non-small-cell lung cancer (NSCLC). There are variations in how patients with NSCLC respond to radiotherapy and how toxic the therapy is. DNA repair gene polymorphisms are related to cancer development; however, their association with radiotherapy outcomes remains unknown. We hypothesized that gDNA repair gene variation could affect the efficacy and toxicity of radiotherapy in patients with NSCLC. Methods A total of 486 histologically confirmed patients with NSCLC were recruited from the Shengjing Hospital of China Medical University from July 2015 to September 2019. Eleven potentially functional single nucleotide polymorphisms (SNPs) in four DNA repair genes (XRCC1, XRCC2, XPD, and MSH2) were genotyped in these patients. A multiple factor logistic regression analysis was used to assess the association between these SNPs and the efficacy and toxicity of radiotherapy. Results Three SNPs, rs25487 (XRCC1), rs3218556 (XRCC2), and rs13181 (XPD), were all significantly associated with the efficacy of radiotherapy. The allele frequencies of the rs25487 CC genotype (OR = 0.457, 95% CI = 0.259–0.804, p=0.006) and the rs3218556 AG or AA genotypes (AG genotype: OR = 0.664, 95% CI = 0.442–0.999, p=0.049; AA genotype: OR = 0.380, 95% CI = 0.181–0.795, p=0.008) were both significantly higher in the response group than in the nonresponse group. For rs13181, the radiotherapy efficacy was associated with the heterozygous genotype GT (OR = 1.663, 95% CI = 1.057–2.614,p=0.027). Statistically significant associations between radiation-induced toxic reactions and rs25487 (XRCC1), rs3218556 (XRCC2), and rs13181 (XPD) were also observed. The rs13181GT genotype was associated with lower toxic reactions than the TT genotype (OR = 1.680, 95% CI = 1.035–2.728,p=0.035). Conclusions The variants rs25487 (XRCC1), rs3218556 (XRCC2), and rs13181 (XPD) all contribute to the efficacy and toxicity of radiotherapy in patients with NSCLC. Our findings may clarify the predictive value of DNA repair genes for prognosis in patients with NSCLC after radiotherapy. Further investigation of more genes and samples should be performed to confirm our findings.

Mepitel Film is superior to Biafine cream in managing acute radiation-induced skin reactions in head and neck cancer patients: a randomised intra-patient controlled clinical trial.

IntroductionWe previously showed that Mepitel Film decreased the severity of acute radiation‐induced skin reactions in head and neck cancer patients. In the current study, we compared the effect of Mepitel Film and Biafine cream on skin reaction severity in a larger cohort of head and neck cancer patients.MethodsA total of 44 head and neck cancer patients were recruited with 39 patients contributing full data sets for analysis. Patients received a dose of 50 Gy in 25 fractions to the bilateral lymph nodes in the neck. Left and right lymph node areas were randomised to either Mepitel Film or Biafine cream, applied prophylactically. Skin reaction severity was measured using Radiation‐Induced Skin Reaction Assessment Scale (RISRAS) and expanded Radiation Oncology group (RTOG) grades. Skin dose was measured using gafchromic Film.ResultsSkin reaction severity (combined RISRAS score) underneath Mepitel Film was decreased by 30% (P < 0.001) and moist desquamation rates by 41% (P < 0.001). Skin dose underneath Mepitel Film and Biafine cream was similar (P = 0.925) and unlikely to have affected skin reaction severity. The vast majority (80%) of patients preferred Mepitel Film over Biafine cream. Negative aspects of Mepitel Film included poor adherence (11/39) and discomfort (16/39) during hot weather and showering and itchy skin underneath Mepitel Film (12/39).ConclusionsMepitel Film was superior to Biafine cream in reducing the severity of acute radiation‐induced skin reactions and moist desquamation incidence in our head and neck patient cohort.

Acute radiation-induced skin toxicity in hypofractionated vs. conventional whole-breast irradiation: An objective, randomized multicenter assessment using spectrophotometry

PurposeRadiation dermatitis represents one of the most frequent side effects in breast cancer patients undergoing adjuvant whole-breast irradiation (WBI). Whether hypofractionated WBI induces comparable or less acute radiation-induced skin reactions than conventional WBI is still not fully clarified, as randomized evidence and objective assessments are limited. The aim of this study was to objectively determine frequency and severity of acute radiation-induced skin reactions during hypofractionated vs. conventionally fractionated adjuvant WBI. MethodsIn this randomized multicenter study, a total of 140 breast cancer patients underwent either hypofractionated or conventional WBI following breast-preserving surgery. Maximum radiation dermatitis severity was assessed at completion and during follow-up by physician-assessed CTCAE v4.03 and the patient-reported RISRAS scale. Additionally, photospectrometric skin readings were performed to objectify skin color differences between both treatment arms. ResultsRadiation dermatitis severity was significantly lower in patients receiving hypofractionation compared with conventional fractionation (mean 1.05 vs. 1.43, p = .024). Grade 0 radiation dermatitis occurred in 21.43% vs. 4.28%, grade ≥2 in 27.14% vs. 42.91% and grade ≥3 in 0% vs. 4.34% of patients following hypofractionated and conventional WBI, respectively. Objective photospectrometric measurements (n = 4200) showed both decreased erythema severity (p = .008) and hyperpigmentation (p = .002) in the hypofractionation arm. Patients allocated to hypofractionated WBI also reported less pain (p = .006), less hyperpigmentation (p = <0.001) and less limitations of day-to-day activities (p = <0.001). ConclusionPhysician and patient-assessed toxicity scorings as well as objective photospectrometric skin measurements revealed that hypofractionated WBI yielded lower rates and severity of acute radiation-induced skin toxicity.

SKIN DOSE MAPPING IN INTERVENTIONAL CARDIOLOGY: A PRACTICAL SOLUTION.

Numerous cases of radiation-induced tissue reactions following interventional cardiology (IC) procedures have been reported, resulting in the need for an optimized and personalized dosimetry. At present, there are many fluoroscopy units without Digital Imaging and Communications in Medicine (DICOM) Radiation Dose Structured Report globally installed. Many of these have not been updated yet, and may never be, therefore, the main objectives of this paper are to develop an offline skin dose mapping application, which uses DICOM headers for the peak skin dose (PSD) assessment and to compare the PSD assessment results to XR-RV3 Gafchromic film for common IC procedures. The mean deviation between the measured and the calculated PSD was 8.7±26.3%. Simulated skin dose map showed good matching with XR-RV3 Gafchromic film. The skin dose mapping application presented in this paper is an elegant solution and a suitable alternative to XR-RV3 Gafchromic film.

An audit of radiation-induced skin reactions in the inframammary fold; does breast size impact on the severity of the reaction?

IntroductionSkin toxicity is a clinically significant side effect of external beam radiation; moist desquamation is particularly prevalent for breast patients, mainly in the axilla and inframammary fold (IMF). The aim of this audit was to assess if there is a correlation between patient breast size and the presence and extent of radiotherapy skin reaction in the IMF. MethodsBetween 22/12/2017 and 31/05/2018 forty patients undergoing standard whole breast radiotherapy using 3D planned medial and lateral tangential fields had their skin reaction recorded weekly, whilst on treatment, using the Radiotherapy Oncology Group (RTOG) scoring system. Skin reactions were also documented at three and eight weeks post radiotherapy. A measurement of the patients IMF length and bra size were also noted. Statistical analysis was carried out using IBMÒ SPSS Statistics 24. ResultsSix patients presented with grade ≥2 during week three of radiotherapy. The mean IMF length of six patients with adverse reactions 6.1 cm (±3.6 cm). As the length of the IMF increases, severity of skin reactions also increases; a positive correlation was identified between the two at both week three of radiotherapy and three weeks post radiotherapy (r = 0.401, n = 34, p = 0.05 and r = 0.671, n = 29, p = 0.00 respectively). Only one patient displayed grade 2 at eight weeks post radiotherapy (IMF length 7.5 cm). ConclusionThe findings from this study would suggest that larger breasted patients do present earlier, and with more severe radiation-induced skin reactions. Implications for practiceChanges to skin care practice could be considered for patients with larger breasts. This could be in the form of more frequent check-ups during treatment or proactive side effect management rather than reactive management.

Hydrofilm Polyurethane Films Reduce Radiation Dermatitis Severity in Hypofractionated Whole-Breast Irradiation: An Objective, Intra-Patient Randomized Dual-Center Assessment.

Radiation-induced skin injury represents the most frequent side effect in breast cancer patients undergoing whole-breast irradiation (WBI). Numerous clinical studies on systemic and topical treatments for radiation dermatitis have failed to provide sustainable treatment strategies. While protective skin products such as dressings are undoubtedly the standard of care in wound care management, their utilization as preventive treatment in radiotherapy has been somewhat neglected in recent years. In this prospective, intra-patient randomized observational study, Hydrofilm polyurethane films were prophylactically applied to either the medial or lateral breast-half of 74 patients with breast cancer undergoing hypofractionated whole-breast irradiation following breast-preserving surgery. Maximum radiation dermatitis severity was assessed using Common Terminology Criteria for Adverse Events (CTCAE) v4.03 toxicity scores, photospectrometric erythema and pigmentation measurements and patient-assessed modified Radiation-Induced Skin Reaction Assessment Scale (RISRAS) scale. Phantom studies revealed a clinically negligible dose build-up of less than 0.1% with Hydrofilm. Compared to the control compartments physician-assessed radiation dermatitis severity was reduced in the hydrofilm compartments (mean 0.54 vs. 1.34; p = < 0.001). Objective photospectrometric skin measurements showed decreased erythema (p = 0.0001) and hyperpigmentation (p = 0.002) underneath Hydrofilm. Hydrofilm also completely prevented moist desquamation, and significantly reduced patients’ treatment-related symptoms of itching, burning, pain, and limitations of day-to-day-activities. Significant beneficial effects were observed in terms of radiation dermatitis severity, erythema, hyperpigmentation as well as subjective treatment-related symptom experiences, while adverse reactions were rare and minor. Therefore, a prophylactic application of Hydrofilm polyurethane films can be suggested in hypofractionated WBI.

О выборе соотношения доз нейтронов и фотонов при нейтронно-фотонной терапии злокачественных новообразований

Purpose: To evaluate the methodological approaches to the prevention of radiation-induced complications after neutron-photon therapy considering the neutron-photon dose ratio in the tumor. &#x0D; Material and methods: The linear-quadratic model (LQM) and principles of neutron and photon dose distributions in a tissue-equivalent medium were used. Cases with the highest risk of radiation-induced complications (treatment by a single or two opposite fields) were discussed. The number of neutron-photon therapy sessions to ensure a combined total neutron and photon dose was determined where the RBE concept was used. When calculating the total effect (TE) and TDF factor characterizing the damage to the irradiated tissue, the effect of the radiation field size and subcutaneous fat layer on their values was taken into account. &#x0D; Results: Methods for selecting the ratio of the neutron and photon dose contribution to the total dose, providing the maximum permissible radiation dose, were developed. It was established that the dependences of TDF and TE factors and the differences in the values of the allowable number of photon therapy sessions on the depth of the tumor were less pronounced in cases with two opposite radiation fields compared to those with a single field. It can be explained by the fact that with increasing depth, an increase in the entrance dose is compensated by a decrease in the dose contribution formed during irradiation from the opposite field. &#x0D; Conclusion: For neutron-photon therapy using a linear-quadratic model, methodical approaches that might be used to provide an acceptable level of radiation-induced skin reactions for any ratio of neutron-photon doses in a tumor were proposed. The use of these techniques for planning neutron-photon therapy will minimize the risk of radiation-induced complications.

Meta-analysis of self-adhesive soft silicone film dressings on preventing and treating radioactive skin lesion

Objective To systematically assess the effects of self-adhesive soft silicone film dressings on preventing and treating radioactive skin lesion. Methods Randomized controlled trials (RCT) about self-adhesive soft silicone film dressings on preventing and treating radioactive skin lesion were retrieved from PubMed, Web of Science, Cochrane Library, Embase, CNKI, VIP and Wanfang databases, and RevMan 5.3 was used for Meta-analysis of the trials which met the inclusion criteria. Results Totally 10 RCTs were included, with a sample size of 1 231 cases. Meta-analysis revealed that self-adhesive soft silicone film dressings could reducethe incidence of GradeⅡ or above radiodermatitis (OR=0.14, 95%CI 0.08-0.25, P<0.01) , shorten the occurrence time of radiodermatitis within the field of radiotherapy (OR=0.07, 95%CI 0.02-0.32, P<0.01) , and reduce subjective and objective symptom scores of radiodermatitis (Radiation-induced Skin Reaction Assessment Scale, RISRAS) (MD=-3.33, 95%CI-5.96--0.70, P<0.05) . Conclusions Self-adhesive soft silicone film dressings applied on the cutaneous surface within the field of radiotherapy can reduce the severity of radiodermatitis, shorten the occurrence time of radioactive skin lesion within the field of radiotherapy, and effectively ameliorate cutaneous discomfort within the field of radiotherapy and the effects of radiotherapy-induced skin reaction on daily activities. Key words: Radiodermatitis; Self-adhesive soft silicone film dressings; Skin lesion; Malignant neoplasms; Meta-analysis

An evaluation of the skincare management of patients receiving radiotherapy for breast cancer

AbstractAim:Breast cancer patients experience skin reactions during radiotherapy. Radiation-induced skin reactions can result in treatment delivery being interrupted. The aim of this paper is to evaluate the skincare management of patients receiving radiotherapy for breast cancer in order to inform best practice.Method:A literature search was undertaken using USearch and HONNI in support of the first-hand evidence gained from the supervised on-treatment review of patients receiving radiotherapy for breast cancer.Results:There is evidence to suggest that the skincare advice given to patients varies widely between departments in the UK with many not following nationally recommended guidelines. Studies demonstrate that there are ways to reduce skin reactions and that there are a range of effective management strategies being adopted. Prophylactic skincare has been explored to improve the resilience of the skin prior to commencing radiotherapy.Findings:Further investigation is required in order to clearly establish the optimum national skincare management for breast cancer patients. More studies are required to test the effectiveness and viability of prophylactic measures. Skincare guidance needs to be robustly developed and effectively promoted by therapeutic radiographers for radiotherapy patients to benefit from reduced, radiation-induced, skin reactions.

Radiation-induced reactions of ketoacids in aqueous solutions and their possible role in chemical evolution

Chemical evolution is the process through which simple compounds generate organic compounds essential for the development of life. The stability of organic compounds is an essential factor in the evaluation of plausible scenarios for the formation of organic molecules in the primitive Earth. In this context, we studied the steady-state γ-radiolysis of alpha-ketoacids (αKA) of prebiotic importance in aqueous solutions at high irradiation doses. These compounds participate in a variety of pathways in the metabolism of living organisms. The acids under study have the general formula R-(C=O)CO2H (R=CH3 pyruvic acid; R=CH2CO2H oxalacetic acid; R=CH2CH2CO2H α-ketoglutaric acid). We carried out the irradiation in a 60Co gamma source, with doses up to 300 kGy. For the analysis, we used various spectroscopic and chromatographic analytical methods. The gamma irradiation of α-ketoacids formed appreciable amounts the saturated carboxylic acid with one C-atom less compared to the target compound and the dimeric products.

Sulforaphane Attenuates Radiation-Induced Skin Damage By Regulating the Effects of Anti-Inflammation and Anti-Oxidation

Radiotherapy (RT) is a major treatment for malignant tumors. Skin changes can be experienced by up to 95% of radiotherapy patients. Inflammation and oxidative stress (OS) have been shown to be generally associated to radiation-induced skin reactions (RISRs). The treatment of RISRs is particularly critical. This study is to observe the protective effect of sulforaphane (SFN) on RISRs. The mechanism of SFN in the prevention and treatment of RISRs will be discussed. We selected C57BL/6J male mice aged 8 weeks. After 1 week of adaptive feeding, we irradiated one thigh of mice at a time under intravenous anesthesia to establish a RISRs model. Mice were randomly allocated into four groups, including control group, SFN group, irradiation (IR) group and IR plus SFN group. SFN group and IR/SFN group were subcutaneously given SFN at 0.5 mg/kg daily in five days of each week for 4 weeks, while mice in the IR group received radiation plus equal amount of normal saline. After 8 weeks, all mice were euthanized for experiments. We used H&E staining to observe the morphological changes of mice skin tissue and TUNEL staining to observe the apoptosis of skin tissue cells. Then we used western-blot and immunohistochemical methods to detect the changes of apoptosis-related indicators including BAX, Bcl2 and caspase-3 in mice skin tissue, as well as the inflammatory response and oxidative stress indexes such as IL-6, TNF-α, 4HNE and 3NT. The results of H&E staining showed that in the mice skin of IR group, significant keratinization of epidermis, destruction of endothelial cells and infiltration of inflammatory cells could be observed. These pathological changes were not obvious in the control group and SFN group, but the skin structure in the IR/SFN group was significantly improved compared with the IR group. TUNEL staining results showed that TUNEL positive cells were significantly increased in the IR group (the TUNEL positive cells were quantitatively analyzed by full positive cells /1000 skin tissue cells). The number of skin apoptosis cells was significantly reduced in the SFN group and IR/SFN group (P<0.05). Western-blot results showed that the proteins expression of BAX, caspase3, TNF-α and IL-6 were significantly higher in the IR group, but not in the SFN group. After SFN treatment, the expression of BAX, caspase3, TNF-α and IL-6 was decreased compared with the IR group (P<0.05), while the expression of Bcl2 was decreased in the IR group and increased after SFN intervention (P<0.05). Immunohistochemical results showed that the expressions of 4HNE and 3NT in the IR group were significantly increased, while those in the SFN group and IR/SFN group were significantly decreased (P<0.05). SFN can inhibit the inflammatory response and oxidative stress to prevent or alleviate the RISRs.

Platelet-rich plasma activates AKT signaling to promote wound healing in a mouse model of radiation-induced skin injury

BackgroundThe skin is impacted by every form of external radiation therapy. However, effective therapeutic options for severe, acute radiation-induced skin reactions are limited. Although platelet-rich plasma (PRP) is known to improve cutaneous wound healing, its effects in the context of high-dose irradiation are still poorly understood.MethodsWe investigated the regenerative functions of PRP by subjecting the dorsal skin of mice to local irradiation (40 Gy) and exposing HaCaT cells to gamma rays (5 Gy). The cutaneous benefits of PRP were gauged by wound size, histologic features, immunostains, western blot, and transepithelial water loss (TEWL). To assess the molecular effects of PRP on keratinocytes of healing radiation-induced wounds, we evaluated AKT signaling.ResultsHeightened expression of keratin 14 (K14) was documented in irradiated HaCaT cells and skin tissue, although the healing capacity of injured HaCaT cells declined. By applying PRP, this capacity was restored via augmented AKT signaling. In our mouse model, PRP use achieved the following: (1) healing of desquamated skin, acutely injured by radiation; (2) activated AKT signaling, improving migration and proliferation of K14 cells; (3) greater expression of involucrin in keratin 10 cells and sebaceous glands; and (4) reduced TEWL, strengthening the cutaneous barrier function.ConclusionsOur findings indicate that PRP enhances the functions of K14 cells via AKT signaling, accelerating the regeneration of irradiated skin. These wound-healing benefits may have merit in a clinical setting.

Pulse radiolysis of carboxylic acids used as ligands of metal oxide nanocluster resists

The radiation-induced reactions of ligands play an important role in the sensitization of metal oxide nanocluster resists. However, the details in the radiation chemistry of ligands for metal oxide nanocluster resists are still unknown. In this study, the radiation-induced reactions of carboxylic acid ligands were investigated using a pulse radiolysis method. The rate constants for the reactions of molecular and ionic forms of tiglic, angelic, o-toluic, and p-toluic acids with hydrated electrons were determined. The rate constants for the reactions of tiglic, angelic, benzoic, o-toluic, and p-toluic acids with dodecane radical cations were also determined. The radical ions of tiglic and angelic acids were more unstable than those of benzoic, o-toluic, and p-toluic acids. The results obtained in this study indicate that the molecular structures of ligands affect their reactivity to cationic and anion species and the stability of their radical cations and anions.

Dose-rate-independent and diffusion-free nanoclay-based radio-fluorogenic gel dosimeter

The gel dosimeter is expected to function as a true three-dimensional dosimeter for radiotherapy in tissue equivalent material. To improve sensitivity, a gel dosimeter employing fluorometric dose imaging is proposed. We report a nanoclay-based radiofluorogenic gel (NC-RFG) dosimeter employing dihydrorhodamine 123 (DHR 123), which avoids the main drawbacks of conventional RFG, namely, diffusion of the radiation products, dose rate dependence, and oxygen effects in radiation-induced reactions. The dose responses of the NC-RFG employing DHR 123 under X-ray irradiation were evaluated using a fluorescence spectrometer and 2D fluorescence gel scanner. The results show high linearity within the range 0–5 Gy, and the sensitivity was maintained by increasing the post-irradiation time to 37 days and the dose rate from 3.0 to 10.4 Gy/min. We also discussed the preparation conditions for the clay and radiosensitizers, trichloroacetic acid (TCAA) and Triton X-100. By scanning with a commercially available 2D fluorescence scanner, the 2D dose distribution can be evaluated as it has a linear dose response, and its spatial dose information is maintained for up to 73 days.

Effect of gamma radiation on pyromellitic acid (PMA) and [formula omitted] solutions

Abstract. In order to develop gamma radiation-induced polymeric materials for selective extraction of uranyl ions, functional stability (decarboxylation) of pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid) (PMA) exposed to different radiation dose was evaluated. In addition, decarboxylation of the compound was evaluated when carboxyl groups of the PMA are coordinated to uranyl ions. PMA and UO 2 2 + − PMA aqueous solutions in equimolar concentrations were irradiated up to 100 kGy absorbed dose with a Gammabeam 651 PT (60Co) irradiator at 13 kGy/h dose rate. Decarboxylation percentage was evaluated through potentiometric titrations before and after irradiation, and product characterization through infrared spectroscopy (FTIR) and proton magnetic resonance (1H-NMR). Results showed that PMA maintains its structure until 20 kGy absorbed dose, when decarboxylation and ring opening reactions begin, and showed that uranyl coordinated carboxylic groups of the PMA have greater resistance to decarboxylation compared to non-coordinated PMA (80% less at 50 kGy). Therefore, due to its resistance to gamma radiation-induced decarboxylation reactions when carboxyl groups are coordinated with uranyl ions, pyromellitic acid could be a viable candidate as a base compound for the development of ionic-imprinted materials for the selective extraction of uranyl ions in aqueous matrices.

Fast radiation-induced reactions in organic phase of SANEX system containing CyMe4-BTPhen extracting agent

The mechanism of radiation-induced fast reactions occurring in the early stages in the 1-octanol system containing 2,9-Bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo (Herbst et al., 2011; Nash et al., 2015; Bourg et al., 2015)triazin-3-yl)- (Herbst et al., 2011; Panak and Geist, 2013)phenanthroline (CyMe4-BTPhen) extracting agent were studied. This is a simplified model of the r-SANEX organic phase for the selective actinide(III)/lanthanide(III) separation. Effects of various scavengers as well as water content were under consideration. Radiation chemical yield of e−s (G(e−s)) and their molar absorption coefficient (ε(e−s)) in 1-octanol were found to be 130(10) nmol J−1 and 18500(700) M−1 cm−1, respectively. Rate constants of e−s reactions with H+, O2, CyMe4-BTPhen and its protonated form were found to be 1.5(3) × 109, 1.0(1) × 1010, 1.85(9) × 109, 1.9(6) × 109 M−1 s−1, respectively. The C37 value for scavenging of dry electrons (e−dry) by CyMe4-BTPhen was equal to 30.4(8) mM. Rate constants of H• reactions with CyMe4-BTPhen and its protonated form were found to be < 7.2 × 109 and 4.3(9) × 109 M−1 s−1, respectively. A relatively good extraction performance of the system studied under exposition to high radiation doses was explained on the basis of hydroxyloctyl substitution in a phenanthroline aromatic ring.