Photon Radiation Research Articles

Green synthesis of bismuth vanadate nanostructures for efficient photocatalytic and biological studies

In the current investigation, BiVO4 nanoparticles were prepared via a simple combustion approach followed by annealing at 400°C using rain tree pod extract. The physicochemical and morphological features were examined through spectroscopic techniques. Optical studies were carried out using a UV–visible spectrophotometer, revealing a bandgap of 2.4 eV. Photocatalytic efficiency was assessed through degradation studies using methylene blue (MB) dye under visible photon irradiation, demonstrating an impressive 94 % degradation rate. Consequently, this synthesized bismuth vanadate serves as an outstanding photocatalyst under visible irradiation. Furthermore, these nanoparticles exhibited favorable responses in antifungal, antibacterial, and molecular docking studies. Bismuth vanadate nanoparticles had substantial antifungal efficacy, with the Bi2 version successfully suppressing Aspergillus Niger at a 50 % concentration. At 100 mg/ml, Bi2 showed a 6 mm zone of inhibition against Gram-positive Staphylococcus aureus and a 5 mm zone against Gram-negative Escherichia coli for antibacterial evaluation. The protein 7BLY and Bismuth vanadate had four hydrogen bond interactions and a strong binding affinity, as shown by molecular docking, of −5.0 Kcal/mol. Therefore, bismuth vanadate nanoparticles synthesized through green methods show promise in combating fungal and bacterial infections, as well as potential applications in various fields.

Secondary neutrons in proton and light ion beam therapy: a review of current status, needs and potential solutions

The advantages of proton and light ion beam therapy compared to conventional photon radiation therapy are well-known, mainly thanks to the characteristic depth dose distribution of ions and their radio-biological effectiveness. Nevertheless, the use of ions implies different nuclear reactions that generate secondary particles, with neutrons among them. These secondary neutrons can travel far away from the treatment volume, their measurement is a challenging complex task, and their biological effects are particularly high for neutrons with energies in the MeV range. In this review, a comprehensive description of secondary neutron dosimetry in proton and light ion beam therapy is given. Many studies have been conducted on the quantification of the secondary neutron dose, most of them have been performed for proton beams, whereas for other ions like carbon, the available information is scarce. The main measurement campaigns are summarised, focusing on the type of detectors used. In line with the detectors’ advantages and limitations, measurements performed inside and outside anthropomorphic phantoms are considered. The role of Monte Carlo radiation transport simulations is discussed since many experimental detection techniques need additional simulations to provide dose estimates. A focus on the current challenges for the measurements of neutrons with energies above 20 MeV is given, as this is one of the main components of secondary neutrons produced by therapeutic ion beams. Finally, the potential clinical relevance of the available and needed secondary neutron dose data is discussed, in terms of its impact on the treatment of patients. For this, the relative biological effectiveness of neutrons and the potential risk of cancer induction re-incidence or secondary cancer due to secondary neutron doses play a key role.

LMIC-13. ENCOURAGING EXPERIENCE OF CONCURRENT CARBOPLATIN DURING CRANIOSPINAL IRRADIATION USING IMAGE GUIDED INTENSITY MODULATED PROTON BEAM (IMPT) IN HIGH-RISK EMBRYONAL TUMORS: FIRST REPORT FROM A LOW MIDDLE-INCOME COUNTRY

Abstract BACKGROUND Concurrent carboplatin during craniospinal irradiation (CSI) using photon radiotherapy in High risk (HR) embryonal tumors has been shown to improve the event free survival in select subgroup of patients. Experience of using concurrent carboplatin during CSI using proton therapy is limited. METHOD A retrospective audit was done in Children <18 years from January 2018 to December 2023 diagnosed with HR embryonal tumors who received image guided pencil beam intensity modulated proton beam therapy-based CSI (35Gy/21#) along with concurrent carboplatin 35mg/m2 at least for 15 fractions. The patient demographics, pathological diagnosis, treatment related toxicities and date of follow-up were recorded in predesigned proforma using electronic medical record. RESULTS Twenty children with HR embryonal tumors with median age at diagnosis 5 years (Range: 1-15 years) with M: F ratio of 3:1 were included in the study. Fifteen (75%) of the patients had HR medulloblastoma defined by spinal metastases or HR molecular subtype of which 5 patients had group 3 medulloblastoma (3- leptomeningeal disease at baseline, 2- MYC amplification) while rest had embryonal tumors (3-NOS, 1-Pinealoblastoma and 1-ETMR). Carboplatin was well tolerated, however 12 (60%) patients developed neutropenia requiring daily G-CSF for an average of 5 days. Average time to complete radiotherapy was 45 days with median interruption of 4 days (Range 1-7). Radiotherapy induced toxicities included Grade 3 skin toxicity in 6 (30%) and grade 2 weight loss in 3 (15%). At a median follow up of 14 months (Range: 4-58), the PFS was 80% in the whole cohort while in the Group 3 Medulloblastoma the PFS was only 20% which was statistically significant(p=0.004). CONCLUSIONS Carboplatin along with proton CSI is well tolerated in children with HR embryonal tumors without significant adversities. Experience is encouraging especially in non-group 3 medulloblastoma patients in our cohort of children with HR embryonal tumors.

HGG-44. BRAINSTEM HIGH-GRADE ASTROCYTOMA WITH PILOID FEATURES (HGAP) WITH AN NTRK FUSION: A HISTOLOGICAL MIMICKER AND RARE PEDIATRIC BRAIN TUMOR

Abstract BACKGROUND HGAP is a recently defined rare glial neoplasm, whose classification requires pathognomonic epigenetic signatures. HGAP can arise anywhere within the central nervous system but most have been reported in the cerebellum (74%). Rarely seen in children, the diagnosis of HGAP can be challenging due to morphologic overlap with other glial neoplasms, especially pilocytic astrocytoma (PA). CASE We present an 11-year male with history of poor weight gain and bilateral sensorineural hearing loss detected on routine screening. Examination showed ataxia, with nystagmus on lateral gaze. MRI brain showed a solid/cystic, dorsally exophytic, cervicomedullary tumor with extension into the 4th ventricle, and hydrocephalus. The tumor showed heterogeneous enhancement with no restricted diffusion, nor intracranial or spinal metastases. Histologic sections from the biopsy suggested classic biphasic PA, with abundant Rosenthal fibers, vascular sclerosis, and no obvious mitoses. Ki67 index was low (<5%; hotspots up to 5-10%+). ATRX mostly retained, even within the most atypical nuclei. The histological impression was classic PA. Comprehensive molecular analysis with DNA methylation showed a high confidence match (0.9883) for HGAP. Paired exome sequencing revealed CDKN2A/2B biallelic loss, missense variant and copy number loss involving NF1, loss of function splice variant in ATRX with no germline alterations detected. Interestingly, fusion panel revealed a BCR::NTRK2 fusion. He received focal photon radiation (54Gy) and adjuvant therapy with Larotrectinib. He remains well with stable disease (EFS 7months). CONCLUSION A comprehensive 2023 review of literature revealed only 14 pediatric cases (range 4-18yo) out of 144 reported cases. Including our patient, 9 were male; 8 posterior fossa, 4 supratentorial, 1 spinal cord, and 2 of unknown location. Molecular analysis of the previously reported 14 pediatric cases showed only one case with a different NTRK fusion. We herein present a unique pediatric HGAP, with entirely classic biphasic and benign PA-like features, brainstem location, and targetable NTRK2 fusion.

QOL-30. NEUROPSYCHOLOGICAL FUNCTIONING AFTER WHOLE VENTRICULAR OR CRANIOSPINAL PROTON RADIATION FOR PEDIATRIC INTRACRANIAL GERM CELL TUMORS

Abstract BACKGROUND In Western countries, intracranial germ cell tumors (ICGT) represent 3-5% of central nervous system tumors, with peak incidence in the second decade of life. Compared to those receiving photon radiation therapy, pediatric patients receiving proton radiation therapy demonstrate stronger neurocognitive outcomes, particularly in verbal and visual reasoning. Ongoing treatment advances aim to reduce morbidity, such as neurocognitive late effects. This study characterizes memory functioning for patients with intracranial germinoma treated with either whole ventricular (WV) or craniospinal (CSI) proton radiation therapy. METHODS 29 patients received proton radiation therapy (17 WV, 12 CSI) for an ICGT (20 germinoma, 8 NGGCT, 1 mixed GCT; 3 disseminated at diagnosis). Age at diagnosis was 5-21 years (M=14.14; SD=3.91) with age at neuropsychological evaluation 8-25 years (M=17.66, SD=4.11). Evaluations occurred 0.71-7.85 years after diagnosis (M=3.52; SD=2.02). Patients (82.8% male, 65.5% white, 44.8% Very High Childhood Opportunity Index [COI]) had multiple additional interventions (surgeries, chemotherapy) prior to neuropsychological evaluation. RESULTS Patients in the WV group did not differ from patients in the CSI group on sex, COI, race, or ethnicity. Mean performance was stronger in the WV group than the CSI group for Full Scale IQ (FSIQ; t(27)=2.50, p=.019, Cohen’s d =0.94), Verbal Reasoning (VCI; t(24)=2.52, p=.019, d=1.0), Visual Memory (WRAML-2 Picture Memory Recognition; t(14)=2.51, p=.025, d=1.26), and Verbal Memory [(WRAML-2 Story Memory Delay, t(15.32)=2.82, p=.013, d=1.25); (WRAML-2 Story Memory Recognition, t(20)=2.34, p=.03, d=1.0)], all with large effect sizes. CONCLUSIONS Within this small ICGT sample with various medical treatments and comorbidities, demographic factors did not differ between groups, and WV proton radiation therapy appears to have less negative impact on aspects of reasoning and memory abilities compared to CSI proton radiation therapy.

RADT-05. MATURE OUTCOMES OF A PHASE II PROSPECTIVE STUDY OF PROTON RADIOTHERAPY FOR LOCALIZED BRAIN TUMORS

Abstract BACKGROUND Proton radiotherapy (PRT) is a highly targeted form of radiation that spares more normal brain tissue compared to modern photon radiotherapy. Therefore, we expect the late effect profile in children treated with PRT with curable brain tumors should be improved. METHODS Between 2010-2022, 100 patients were enrolled, treated with PRT, and then followed for disease control, hearing, neurocognitive and endocrine outcomes. Late effects of the tumor and treatment delivered were graded using CTCAE v4.0. RESULTS Median age at PRT was 8.0 years (1.1-20.8) and median follow up was 8.7 years (0.3-12.7). Tumor types included 40 (40%) ependymomas, 19 (19%) low grade gliomas (LGG), 21 (21%) craniopharyngiomas, and 20 (20%) other histologies. 26% of patients were treated with chemotherapy in addition to PRT. The location of PRT was 38 (38%) infratentorial, 56 (56%) supratentorial, and 6 (6%) both. The median radiation dose was 52.2 GyRBE (48.6-59.4). 8-year event-free survival (EFS) and overall survival (OS) was 71.7% and 86.2% for all patients. 8-year EFS and OS was 59.9% and 82.4% for ependymomas, 78.2% and 94.7% for LGG, 80.0% and 87.7% for craniopharyngiomas and 79.1% and 84.7% for all other tumor types. 19% of patients had new grade 3+ toxicities that were at least possibly related to radiotherapy. Baseline full-scale intelligence quotient (FSIQ) was 98.0 and follow-up FSIQ was 101.8 (p=0.14). 43% of patients had new endocrine deficiencies after radiation. 8 patients suffered new high-grade hearing loss after PRT. Dosimetry on critical brain structures was collected and correlated with late effects. More details will be presented at the conference. CONCLUSION PRT remains an effective treatment for children with curable brain tumors. While late effects of the tumor and treatment are still present, the overall burden of late effects is lower than other reports.

Twisted-photons distribution emitted by relativistic electrons at axial channeling

Within the framework of quantum electrodynamics we have developed a theory for radiation of twisted photons by axially channeled electrons that allowed us for the first time to draw the angular distribution of twisted photons emitted by channeled electrons.

Оценка функционирования дозиметрического оборудования при проведении измерений в полях импульсного микросекундного фотонного излучения с известными характеристиками

This paper continues the series of articles [1,2,3] devoted to the determination of the main dosimetric characteristics of the fields of high-energy pulsed microsecond photon radiation generated by medical linear electron accelerator (LINAC for short) and assessment of the possibility of using LINAC as a source of reference radiation field for calibration of dosimetric equipment. This publication presents the results of evaluation of the portable dosimeter DKSAT1123 and detection unit BDKG-206 when measuring in such fields under different modes of LINAC operation. The possibility of this dosimetric equipment operation in the fields was assessed by comparing dosimeter readings with reference values of dosimetric characteristics of these fields, namely: average ambient dose equivalent rate H*(10), measured with the help of high-precision reference dosimeter DKS-AT5350. It was found that the deviation of H*(10) measurements conducted with the help of the DKS‑AT1123 and BDKG-206 from the reference values strongly depends on the radiation properties, namely the H*(10) value in the pulse. It is shown that at the H*(10) value in the pulse less than 0,2 mSv/s the deviation does not exceed 10%, at the H*(10) value in the pulse 0,2–0,4 mSv/s the deviation does not exceed 33%, and at the H*(10) value in the pulse more than 0,5 mSv/s the deviation can reach 72%.

Investigation of ionization chamber-specific beam quality correction factor (kQ,Q0) used for absorbed dose determination in megavoltage photon beams

In the recent past (Andreo et al., 2020), new ionization chamber-specific beam quality correction factors (kQ,Q0) were published in the literature for the determination of the absorbed dose to water in high energy radiotherapy photon beams. In a previous experimental investigation, made at our laboratory, five various Farmer-type cylindrical ionization chambers, i.e. Exradin A12, IBA FC65-G, NE-2571, PTW 30011 and PTW 30012, were studied to examine their responses with reference to the determination of the absorbed dose to water in an inter-chamber comparison. In the present work, measurements were made to experimentally study the relation or ratio of the kQ,Q0 correction factors using the five various types of the ionization chambers employed in our previous investigation. In total, nine ionization chambers, two of each type, were included in the present study, with the exception of a single PTW 30011 ionization chamber. The photon beams employed were the 6 MV and the 15 MV beam. The outcomes of this work displayed excellent agreement between the ratio of the ionization chamber-specific kQ,Q0 correction factors, for the ionization chambers utilized, and the corresponding ratio calculated using the published kQ,Q0 correction factors. The discrepancy obtained in these comparisons was within 0.1%, for both the photon beams examined, which is much smaller than the uncertainty associated with the determination of this relationship.

Optimizing the composition of barium-borate glasses for enhancing thermal neutron shielding efficiency: Monte Carlo simulation

A transparent window with thermal neutron shielding properties was an important part of the stations of the nuclear reactors and the particle accelerators. The borate glass with a high neutron cross section was a candidate as a glass network for the neutron shielding window. In order to slow down thermal neutrons, they were trapped by boron and subsequently emitted secondary radiation, such as alpha particles and gamma-ray radiation. This work was to optimize the content between a ratio of borate with a high cross-section neutron interaction and barium for shielding alpha and gamma ray. The barium-borate glasses were successfully synthesized using the melting technique in the atmosphere. Measurements of mechanical and optical glass properties were presented. The measured results showed that an increase in barium oxide content in the glass ratio enhanced the glass density and the transmittance at a visible wavelength. In the calculation of radiation shielding properties, FLUKA code based on Monte Carlo Simulation was demonstrated. The calculated results revealed that an increase in the barium oxide content in the glass composition reduced the thermal neutron shielding properties of the glass samples. In contrast, the glass with barium contents enhanced the photon-shielding efficiency, as indicated by the mass attenuation coefficient and half-value layer. Not only the ratio of the barium and borate contents affected the shielding properties, but the increased glass thickness also enhanced the shielding properties. Thus, the utilization of cooperative borate glasses and barium with appropriate thickness could potentially serve as a viable option for simultaneously protecting against thermal neutrons and photons. The barium-borate glasses with our composition might be used as a window in a thermal neutron station as well as for photon radiation.

Multiple alanine pellet dosimeter: Design and first test results

Existing nuclear accident dosimeters are based on the activity measurements of the neutron activation products. Those dose measurements require the use of expensive counting equipment. The other significant problem of existing accident dosimeters is that they need to be analyzed in a very short period, due to the short half-life of the activated products. The crystalline L-α-alanine is a well-known material for Electron Paramagnetic Resonance (EPR) dosimetry. It is widely used in radiation laboratories for both reference and transfer dosimetry. Alanine pellets are made from L-α-alanine powder mixed with 10–20% of a binder. The L-α-alanine pellets have ideal dosimetric properties. Alanine is sensitive to alpha, photon, and neutron irradiation. Until recently there was no way to distinguish separate dose contributions from multiple types of radiation. To overcome this shortfall, the multiple alanine pellet holder has been proposed, designed, and tested. It contains cadmium, lead, and 6LiF filters. The proposed approach allows for the separation of photon and neutron dose contributions. Use of the developed holder can also reduce negative effects of humidity and direct sun light on the alanine dosimetric properties. The developed holder design can be produced by a 3D printer at a low cost. Here we present and discuss the design and test results of the multiple alanine pellet dosimeter.

A scientometric review of knowledge domains on nuclear radiation

Nuclear energy is an important energy component to achieve the goal of “carbon peak and carbon neutrality”. Nuclear radiation is one of the hot spots in the development and utilization of nuclear energy. This study used bibliometric methods to gain a preliminary understanding of the knowledge system in the field of nuclear radiation and explored the network relationships of cooperation in the field of nuclear radiation. The literature data for the study were obtained from the Web of Science core collection database. All literature from 2008 to 2023 was downloaded, totalling 1602 articles. VOSviewer and CiteSpace were used to analyze several aspects such as article volume, keyword clustering and collaborative network relationships. The research showed that the years 2011–2014 and 2017–2020 were periods of vigorous literature development, with a sharp increase in the number of literature. In the collaborative network, the author collaborative network was divided into five different clusters, mainly dominated by Tsubokura, Masaharu and Yasumura, Seijiz. Research and development in various countries were uneven, and cooperation between underdeveloped national institutions in this field was even more limited. In the keyword clustering, five cluster models have been established, including the investigation and related treatment of nuclear radiation hazards, the Fukushima nuclear accident in Japan, research on nuclear radiation products, optical properties of nuclear radiation, and research on shielding materials. Recently, radiation shielding materials, photons and neutrons have become research hotspots. Through this study, we can gain a deeper understanding of the development status, cooperation networks, and cutting-edge research information in the nuclear field, which can serve as a reference for researchers.

Transient synergistic damage mechanism and characterization of silicon bipolar junction transistor

The silicon bipolar junction transistor (Si BJT) is widely used as a discrete device, but it is susceptible to damage from both ionization and displacement in nuclear radiation environments. Current research primarily focuses on steady-state irradiation to study the synergistic damage mechanism caused by ionization and displacement, with a lack of research on transient synergistic damage. This paper studies the energy deposition and distribution with different incident angles and energies when neutrons and photons are simultaneously incident, and found similarities in the energy deposition between low-energy photons and 1 MeV neutrons as well as high-energy photons and 1 MeV neutrons in synergistic damage. Additionally, transient current under simultaneous neutron and photon irradiation was calculated using COMSOL software. Simulation results indicate that by adjusting the number of photons, it is feasible to simulate the transient electrical characteristics of high-energy photons utilizing low-energy photons for synergistic damage. Hence, a novel characterization method, combining laser simulation and neutron sources, is developed to test the transient electrical characteristics of Si BJT with synergistic damage.

Interim 18F-FDG-PET based response-adaptive dose escalation of proton therapy for head and neck cancer: a treatment planning feasibility study

BackgroundImage-driven dose escalation to tumor subvolumes has been proposed to improve treatment outcome in head and neck cancer (HNC). We used 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) acquired at baseline and into treatment (interim) to identify biologic target volumes (BTVs). We assessed the feasibility of interim dose escalation to the BTV with proton therapy by simulating the effects to organs at risk (OARs). MethodsWe used the semiautomated just-enough-interaction (JEI) method to identify BTVs in 18F-FDG-PET images from nine HNC patients. Between baseline and interim FDG-PET, patients received photon radiotherapy. BTV was identified assuming that high standardized uptake value (SUV) at interim reflected tumor radioresistance. Using Eclipse (Varian Medical Systems), we simulated a 10% (6.8 Gy(RBE1.1)) and 20% (13.6 Gy(RBE1.1)) dose escalation to the BTV with protons and compared results with proton plans without dose escalation. ResultsAt interim 18F-FDG-PET, radiotherapy resulted in reduced SUV compared to baseline. However, spatial overlap between high-SUV regions at baseline and interim allowed for BTV identification. Proton therapy planning demonstrated that dose escalation to the BTV was feasible, and except for some 20% dose escalation plans, OAR doses did not significantly increase. ConclusionOur in silico analysis demonstrated the potential for interim 18F-FDG-PET response-adaptive dose escalation to the BTV with proton therapy. This approach may give more efficient treatment to HNC with radioresistant tumor subvolumes without increasing normal tissue toxicity. Studies in larger cohorts are required to determine the full potential for interim 18F-FDG-PET-guided dose escalation of proton therapy in HNC.

DNA-PKcs Inhibition Sensitizes Human Chondrosarcoma Cells to Carbon Ion Irradiation via Cell Cycle Arrest and Telomere Capping Disruption.

In order to overcome the resistance to radiotherapy in human chondrosarcoma cells, the prevention from efficient DNA repair with a combined treatment with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) inhibitor AZD7648 was explored for carbon ion (C-ion) as well as reference photon (X-ray) irradiation (IR) using gene expression analysis, flow cytometry, protein phosphorylation, and telomere length shortening. Proliferation markers and cell cycle distribution changed significantly after combined treatment, revealing a prominent G2/M arrest. The expression of the G2/M checkpoint genes cyclin B, CDK1, and WEE1 was significantly reduced by IR alone and the combined treatment. While IR alone showed no effects, additional AZD7648 treatment resulted in a dose-dependent reduction in AKT phosphorylation and an increase in Chk2 phosphorylation. Twenty-four hours after IR, the key genes of DNA repair mechanisms were reduced by the combined treatment, which led to impaired DNA repair and increased radiosensitivity. A time-dependent shortening of telomere length was observed in both cell lines after combined treatment with AZD7648 and 8 Gy X-ray/C-ion IR. Our data suggest that the inhibition of DNA-PKcs may increase sensitivity to X-rays and C-ion IR by impairing its functional role in DNA repair mechanisms and telomere end protection.

A comprehensive research on γ-ray and particle radiation interaction parameters of Cerium doped heavy oxide inorganic scintillators

In this study, the interaction cross sections of heavy oxide scintillators, which have a very important place in high energy physics research, with photon and particle radiation were comparatively investigated. In this context, the interaction parameters of six different Ce-doped heavy oxide scintillators were obtained using updated software. The interactions of photons with energies between 1 keV and 100 GeV with scintillators were evaluated in the light of the results produced by the Phy-X/PSD software. In addition to the continuous energy range, calculations were also made on the photon energies emitted with the highest probability of emission from sources 241Am (59.54 keV), 133Ba (356 keV), 22Na (511 and 1280 keV), 137Cs (662 keV) and 152Eu (1460 keV). Additionally, evaluations of energy absorption build-up factors valid under broad beam conditions are also included in this study. Fast neutron absorption cross sections and changes in the range (R) values for heavy particle radiation in the range of 1 keV–20 MeV were also determined with SRIM and ESTAR software. All data obtained depending on energy are explained according to the mass percentages of Lu, Gd, Hf, Y, Al and O elements in the scintillators. The highest interaction cross section for photons was obtained in the Lu2Gd2SiO5 (Ce 0.3%) scintillator (HOS2). The interaction cross section of this scintillator was obtained as 3.115 and 0.042 cm2/g at 0.1 MeV and 10 MeV photon energies, respectively. On the other hand, the highest cross-sections of the fast neutrons were observed in the scintillator (HOS5) containing GdAlO3 (Ce 1.0%) as 0.148 cm−1. This difference in neutron radiation has been explained by calculating the individual attenuation abilities of the elements in the structures. It is hoped that the data obtained will guide researchers working on the detection of different types of radiation.

The orbital angular momentum of radiation from relativistic electrons in the laser wave field with linear polarization

The paper reports the results of calculations of the generation of twisted photons by relativistic electrons in the laser wave field with linear polarization. It is shown that in this case the probability of radiation of twisted photons obeys the selection rule that n + m is an even number. The radiation of the probability of detecting a twisted photon is numerically investigated depending on various parameters: photon energy, helicity and the cone opening of the twisted photon. In general, the radiation of twisted photons by electrons in the laser wave field with linear polarization is a mixture of twisted photons at the total angular momentum of the photons; however, we have found conditions when generation of twisted photons will be an almost pure source of twisted photons.

Recycled cathode ray tube waste glasses for radiation shielding applications: Role of Na2CO3

The aim of the study is to evaluate the ability of cathode-ray tube funnel waste glasses (CRT-F) to shield photons (gamma and X-ray) and other forms of radiation with rest masses (i.e., neutrons and charged particles) after their Pb content was reclaimed. The lead (Pb) content of cathode-ray tube funnel waste glasses (CRT-F) was reduced using Na2CO3 as the reducing agent CRT-F(Na2CO3). CRT-F and CRT-F(Na2CO3) were produced using the melt and quench processes using the powder of pristine funnel glass from discarded cathode ray tube glass and the reduced glass powder, respectively, as the starting materials. The X-ray fluorescence technique was adopted for determining the chemical composition of CRT-F and CRT-F(Na2CO3) glasses. The parameters relating to the gamma photon, fissile neutron, moderated neutron, slow neutron, and charged radiation (β, H+, He2+, and C6+) attenuation abilities of pristine CRT-F and CRT-F(Na2CO3) were evaluated. The FLUKA simulation code and XCOM were used to estimate the mass attenuation coefficient of the glasses. The stopping power (Sp) and range (R) of β, H+, and He2+ were evaluated by using the NIST data-based calculators (ESTAR for β, PSTAR for H+, and ASTAR for He2+) while Sp and R data for C6+ was determined using SRIM. The cross section for fast, thermal (25 meV), and slow neutrons (0.1–10 meV) was also estimated. The Pb reclamation from the CRT-F drastically increased the half value layer of photons by at least a factor of 4 at 0.1 MeV and by more than 90 % at 10 MeV. The CRT-F interacts more with fissile and thermal neutrons compared to CRT-F(Na2CO3). Although, CRT-F showed a better ability to attenuate all the radiation types considered, both glasses are better absorbers of radiation (especially photons) than some common shields. The reduction of Pb weight in CRT-F resulted in a drastic reduction in the ability of the glass to attenuate radiation; the resulting glass (CRT-F(Na2CO3)) is however, an environmentally safer glass shield.

Radiation dose escalation and local control for intermediate-risk rhabdomyosarcoma on ARST1431: A report from the Children’s Oncology Group

10007 Background: The objective of this study was to evaluate local failure (LF) rates for patients with intermediate-risk rhabdomyosarcoma (IR-RMS) treated on the Children’s Oncology Group (COG) ARST1431 clinical trial. To improve local control, the radiation therapy (RT) dose was increased to 59.4 Gy for patients with tumors > 5cm at diagnosis and residual gross disease at the time of RT. Methods: The297 patients randomized on ARST1431 were included. LF was defined as progression or relapse at the primary tumor site. Gray’s test was used to compare the cumulative incidence of LF across variables. Results: There was a trend for lower 3-year LF in group III patients with fusion-positive disease (11.1%, 95% confidence interval (CI) 4.5%-21.1%) compared to patients with fusion-negative disease (21.8%, 95% CI 15.8%-28.4%), p = 0.09.There was no difference in the 3-year LF rate for patients who underwent proton RT (16.3%, 95% CI 9.6%-24.7%) compared to photon RT (16.2%, 95% CI 10.2%-23.6%;), p = 0.8. The 3-year LF rate for all patients with tumors > 5cm at diagnosis (24.9%, 95% CI 18.6%-31.7%) was significantly higher than that of patients with tumors ≤5cm at diagnosis (9.9%, 95% CI 5.2%-16.4%), p < 0.01. Of 81 patients with tumors > 5cm and residual gross disease after induction chemotherapy who went on to receive RT, 62 (76.5%) received the protocol-specified boost to 59.4 Gy. Patients who received the boost had a 3-year LF rate of 32.1% (95% CI 20.1%-44%), while patients who did not undergo an RT boost had a 3-year LF rate of 16.1% (95% CI 3.8%-36.2%), p = 0.3. For patients with group III, non-parameningeal disease, those who underwent delayed primary excision (DPE) had a significantly lower LF rate compared to those who did not undergo DPE (3-year rate of 5.6% (95% CI 1.4%-14.0%) vs. 22.0% (95% CI 14.5-30.7%), p < 0.01). Conclusions: On ARST1431, larger tumors ( > 5cm at diagnosis) were associated with increased risk of LF. Dose escalation to 59.4 Gy did not improve local control for patients with tumors > 5cm at diagnosis with residual gross disease at the time of RT. For a select group of non-parameningeal, group III patients who underwent DPE followed by RT, local control was improved. Clinical trial information: NCT02567435 .

Multicolor tunable persistent luminescence mechanism in well-designed inorganic composites.

Herein, by ball milling CsPb(Br/I)3 quantum dot glass powder with Sr2MgSi2O7:Eu2+, Dy3+ phosphor, multicolor tunable long persistent luminescence (LPL) in inorganic composites with more than 700 min attenuation time can be obtained via a radiation photon reabsorption process. Attractively, the wide color gamut of LPL spectra overlaps the National Television System Committee space 74%. Notably, the luminescence intensity remains stable when the inorganic composites are composed with UV light for 100 h. Finally, practical anticounterfeiting application is successfully realized based on the prepared LPL inorganic composites. This work provides a new, to the best of our knowledge, perspective to achieve polychromatic adjustment of LPL.