High Dose-rate Irradiation Research Articles

An investigation of γ radiation detection with a CMOS imaging sensor.

In this study, a feasibility of γ radiation detection using complementary metal-oxide semiconductor (CMOS) image sensors with a neural network algorithm to extract the γ rays interacted pixels has been investigated. The responses characteristics of the CMOS imaging sensor to γ-ray is studied by placed in a γ fields produced by standard60Co or137Cs isotope sources. The supported preview frame rate of the CMOS image sensor is 25 fps, establishing the functional relationship between the gray level histograms and the dose rate through the neural network, the high energy γ-ray from60Co and137Cs source radiation dose rate in µSv/h level can be detected using the CMOS imaging sensor. The results show that the proposed method can effectively identify the number of photon particles which detected by the radiation monitoring system based on CMOS image sensor, and infer that the CMOS imaging sensor with a radiation signal extraction algorithm can be used as a dose warner for radiation protection purpose.

Comparative Analysis of Cystamine and Cysteamine as Radioprotectors and Antioxidants: Insights from Monte Carlo Chemical Modeling under High Linear Energy Transfer Radiation and High Dose Rates.

This study conducts a comparative analysis of cystamine (RSSR), a disulfide, and cysteamine (RSH), its thiol monomer, to evaluate their efficacy as radioprotectors and antioxidants under high linear energy transfer (LET) and high-dose-rate irradiation conditions. It examines their interactions with reactive primary species produced during the radiolysis of the aqueous ferrous sulfate (Fricke) dosimeter, offering insights into the mechanisms of radioprotection and highlighting their potential to enhance the therapeutic index of radiation therapy, particularly in advanced techniques like FLASH radiotherapy. Using Monte Carlo multi-track chemical modeling to simulate the radiolytic oxidation of ferrous to ferric ions in Fricke-cystamine and Fricke-cysteamine solutions, this study assesses the radioprotective and antioxidant properties of these compounds across a variety of irradiation conditions. Concentrations were varied in both aerated (oxygen-rich) and deaerated (hypoxic) environments, simulating conditions akin to healthy tissue and tumors. Both cystamine and cysteamine demonstrate radioprotective and strong antioxidant properties. However, their effectiveness varies significantly depending on the concentration employed, the conditions of irradiation, and whether or not environmental oxygen is present. Specifically, excluding potential in vivo toxicity, cysteamine substantially reduces the adverse effects of ionizing radiation under aerated, low-LET conditions at concentrations above ~1 mM. However, its efficacy is minimal in hypoxic environments, irrespective of the concentration used. Conversely, cystamine consistently offers robust protective effects in both oxygen-rich and oxygen-poor conditions. The distinct protective capacities of cysteamine and cystamine underscore cysteamine's enhanced potential in radiotherapeutic settings aimed at safeguarding healthy tissues from radiation-induced damage while effectively targeting tumor tissues. This differential effectiveness emphasizes the need for personalized radioprotective strategies, tailored to the specific environmental conditions of the tissue involved. Implementing such approaches is crucial for optimizing therapeutic outcomes and minimizing collateral damage in cancer treatment.

Protective effect of melatonin against radiobiological damage in the brain of rats exposed to low and high dose rate radiotherapy

This study aimed to investigate the radioprotective effect of melatonin (MLT) on brain damage in rats exposed to low and high dose rate radiotherapy. The dose rates of 10 MV photon beams used in the study were 600 MU/min and 2400 MU/min for low dose rate radiotherapy (LDR_RT) and high dose rate radiotherapy (HDR_RT), respectively. A total of 46 female Wistar albino rats aged between 8 and 12 weeks were divided in 6 groups. These groups were control, MLT, LDR_RT, HDR_RT, LDR_RT plus MLT and HDR_RT plus MLT, respectively. Rats in the radiation group received 16 Gy single dose whole body radiotherapy. Rats in the LDR_RT plus MLT and HDR_RT plus MLT groups received 10 mg/kg melatonin by intraperitoneal injection 15 min before radiotherapy. The rats were sacrificed 48 h after radiotherapy. Biochemical and histopathological methods analyzed radiation damage in rats. There was a statistically significant difference between the LDR_RT and HDR_RT radiation groups and the control group in terms of biochemical and histopathological parameters (p < 0.05). In the groups that received only LDR_RT and HDR_RT, the moderate neuro-degeneration scores were 1 and 4, respectively, while the moderate neuro-degeneration scores were 0 and 2 when MLT was applied to these groups. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) enzymes were decreased due to radiotherapy, whereas these enzymes were improved in MLT-treated groups. In conclusion, melatonin was found to be effective as a radioprotective agent in the prevention of brain damage caused by exposure to 10 MV photon radiation at dose rates of 600 MU/min and 2400 MU/min.

Exploring predictive molecules of acute adverse events in response to volumetric‑modulated arc therapy for prostate cancer using urinary metabolites.

Volumetric-modulated arc therapy (VMAT) is a radiotherapy technique used to treat patients with localized prostate cancer, which is frequently associated with acute adverse events (AEs) that can affect subsequent treatment. Notably, the radiation dose of VMAT can be tailored to each patient. In the present study, a retrospective analysis was performed to predict acute AEs in response to a therapeutic high radiation dose rate based on urinary metabolomic molecules, which are easily collected as noninvasive biosamples. Urine samples from 11 patients with prostate cancer who were treated with VMAT (76 Gy/38 fractions) were collected. The study found that seven patients (~64%) exhibited genitourinary toxicity (Grade 1) and four patients had no AEs. A total of 630 urinary metabolites were then analyzed using a mass spectrometer (QTRAP6500+; AB SCIEX), and 234 relevant molecules for biological and clinical applications were extracted from the absolute quantified metabolite values using the MetaboINDICATOR tool. In the Grade 1 acute AE group, there was a significant negative correlation (rs=-0.297, P<0.05) between the number of VMAT fractions and total phospholipase A2 activity in the urine. Additionally, patients with Grade 1 AEs exhibited a decrease in PC aa C40:1, a phospholipid. These findings suggested that specific lipids found in urinary metabolites may serve as predictive biomarkers for acute AEs in response to external radiotherapy.

Effect of proton irradiation dose rate and implanted hydrogen ions on spinodal decomposition in thermally aged EQ308L stainless steel weld metal

Abstract Stainless steel welds with a ferritic phase are extensively utilized in nuclear power plants. Spinodal decomposition stands as the primary factor contributing to the degradation of their service performance. Ion irradiation has been widely employed to investigate the damage behavior of materials. However, varying irradiation parameters, such as dose rate and implanted ions, are believed to result in significant differences in the extent of spinodal decomposition. In this paper, proton irradiation experiments were conducted at different dose rates on thermally aged EQ308L stainless steel welds. Spinodal decomposition within the ferrite at various radiation depths was compared and analyzed by using atom probe tomography to unveil the effects of dose rate and implanted hydrogen ions. The results reveal that, under conditions of high dose rate irradiation, spinodal decomposition can be partially alleviated when compared to the initial thermally aged state. Conversely, under low dose rate irradiation conditions, spinodal decomposition exhibits an enhancement trend. This difference may be attributed to the interplay between irradiation-enhanced diffusion and atomic mixing. Therefore, the dose rate significantly influences the progression of spinodal decomposition. Furthermore, implanted hydrogen ions may also inhibit spinodal decomposition within the ferrite, potentially by promoting the recombination of irradiation defects.

Revisiting an Inverse Dose-Fractionation Effect of Ionizing Radiation Exposure for Ischemic Heart Disease: Insights from Recent Studies.

Over the last two decades, there has been emerging evidence suggesting that ionizing radiation exposures could be associated with elevated risks of cardiovascular disease (CVD), particularly ischemic heart disease (IHD). Excess CVD risks have been observed in a number of exposed groups, with generally similar risk estimates both at low and high radiation doses and dose rates. In 2014, we reported for the first time significantly higher risks of IHD mortality when radiation doses were delivered over a protracted period of time (an inverse dose-fractionation effect) in the Canadian Fluoroscopy Cohort Study. Here we review the current evidence on the dose-fractionation effect of radiation exposure, discuss potential implication for radiation protection policies and suggest further directions for research in this area.

Interaction of CsOH with structural steel 316L and simulated products of the steel-cladding reaction under assumed conditions relevant for the accident at the Fukushima Dai-Ichi Unit 2 and 3

A high radiation dose rate under the shield plugs of the Units 2 and 3 reactors at the Fukushima Dai-Ichi Nuclear Power Station (1F), raised an important question on volatile radioactive Cs migration, adsorption and retention on various structural materials during the accident. The high dose rate interferes with decommissioning work. The purpose of this study is to present basic knowledge on contamination mechanisms of a BWR reactor structural materials and post-accident debris by Cs compounds to help decommissioning companies consider the ways of decontamination and debris handling during 1F debris retrieval. Having this goal, a series of tests on CsOH contamination mechanism under assumed accident conditions for Units 2 and 3 was performed. The results may improve the accuracy of estimating the situation inside the reactor from the perspectives of accident analysis and materials’ properties. The test temperature and compounds were chosen based on the probable accident scenario. In particular, Cs adsorption was checked using preoxidized 316L stainless steel, a product of control blade degradation (steel-B4C eutectic) and a product of steel-channel box and cladding interaction (Zr-Fe based multiphase material). Penetration ability of Cs into the oxidized and metallic layers of materials was evaluated. CsOH most probable adsorption temperature range and new Cs containing phases’ formation temperature range were followed.

Melatonin administration in testicular damage caused by low and high-dose rate radiotherapy: An experimental study

ObjectiveThis study aimed to explore the radioprotective effect of melatonin against acute testicular injury caused by low- and high-dose-rate radiotherapy in rats. Materials and methodsA total of 40 12-week-old adult male rats were divided into 5 groups (n = 8). Group 1 comprised control rats who were not subjected to any procedures. A single dose of 8 Gy (Gy) radiotherapy was administered to the abdominopelvic regions of Group 2 (low-dose rate radiotherapy (LDRR) group) and Group 4 (high-dose rate radiotherapy (HDRR) group) rats at dose rates of 400 MU/min and 1400 MU/min, respectively. A single dose of 8 Gy radiotherapy was administered to Group 3 (low-dose rate radiotherapy + melatonin (LDRR + MEL) group) and Group 5 (high-dose rate radiotherapy + melatonin (HDRR + MEL) group) rats at dose rates of 400 MU/min and 1400 MU/min, respectively. Following this, 50 mg/kg/intraperitoneal melatonin was given to the rats 15 min before radiotherapy. The subjects were sacrificed 48 h after radiotherapy. Histological, immunohistochemical, immunofluorescence, and biochemical analyses of testicular tissue samples were performed. ResultsAs a result of comparing the FF and FFF radiotherapy groups with the control group, a statistically significant difference was observed in histopathological, biochemical, immunohistochemical and immunofluorescent parameters (p < 0.001). An improvement in these parameters was observed in the groups where melatonin was applied along with radiotherapy (p < 0.001). Additionally, no statistically significant difference was found between FF and FFF dose rates (p > 0.05). ConclusionNo significant difference was observed between these low- and high-dose rates of radiotherapy in terms of testicular damage and the effect of melatonin. Further, melatonin may be useful in preventing testicular damage caused by low- and high-dose rate radiotherapy.

Characterizing the Early Acidic Response in Advanced Small Modular Reactors Cooled with High-Temperature, High-Pressure Water

Utilizing Monte Carlo multi-track chemistry simulations along with a cylindrical instantaneous pulse (Dirac) irradiation model, we assessed the initial acidic response in both subcritical and supercritical water under high radiation dose rates. This investigation spans a temperature range of 300 to 500 °C at a nominal pressure of 25 MPa, aligning with the operational conditions anticipated in proposed supercritical water (SCW)-cooled small modular reactors (SCW-SMRs). A pivotal finding from our study is the observation of a significant ‘acid spike’ effect, which shows a notable intensification in response to increasing radiation dose rates. Our results bring to light the potential risks posed by this acidity, which could potentially foster a corrosive environment and thereby increase the risk of accelerated material degradation in reactor components.

Development of contamination detection system combined with various remote devices

The detection of alpha and beta contamination locations is important for decontaminating nuclear facilities. In the high radiation dose rate environment at the decommissioning sites, the contamination measurement by the workers is not effective. Thus, we developed a remote automatic contamination measurement system using a new scintillator-based detector. A 50 mmφ × 100-μm-thick YAlO3(Ce)(YAP:Ce) scintillator was coupled with a flat panel-type multianode photomultiplier tube. The detector was installed downwards at the bottom of a robot. It has an energy measurement capability, and the energy measurement could discriminate the alpha particles from the beta and 222Rn alpha particles. With the energy information, alpha and beta particles could be identified and mapped simultaneously. In addition, a slow-moving robot could be used to obtain statistically sufficient counts in a single run measurement, allowing the evaluation of surface contamination density using only alpha particles. The remote automatic contamination measurement system will be useful in visualizing the contamination distribution in environments that are inaccessible to workers.

A Novel Platform for Evaluating Dose Rate Effects on Oxidative Damage to Peptides: Toward a High-Throughput Method to Characterize the Mechanisms Underlying the FLASH Effect.

High dose rate radiation has gained considerable interest recently as a possible avenue for increasing the therapeutic window in cancer radiation treatment. The sparing of healthy tissue at high dose rates relative to conventional dose rates, while maintaining tumor control, has been termed the FLASH effect. Although the effect has been validated in animal models using multiple radiation sources, it is not yet well understood. Here, we demonstrate a new experimental platform for quantifying oxidative damage to protein sidechains in solution as a function of radiation dose rate and oxygen availability using liquid chromatography mass spectrometry. Using this reductionist approach, we show that for both X-ray and electron sources, isolated peptides in solution are oxidatively modified to different extents as a function of both dose rate and oxygen availability. Our method provides an experimental platform for exploring the parameter space of the dose rate effect on oxidative changes to proteins in solution.

Clinical use of high dose-rate brachytherapy in treatment of patients with localized prostate cancer and infravesical obstruction

Background. High dose-rate brachytherapy is a new method of interstitial radiation therapy for treatment of localized prostate cancer. The difference from low dose therapy is temporary implantation of radiation sources with targeted high dose-rate irradiation of the affected organ.Aim. To evaluate 3-year effectiveness and safety of high dose-rate brachytherapy in patients with infravesical obstruction. Materials and methods. Between January of 2017 and December of 2019 at the Central Clinical Hospital “RZD-medicine”, 49 patients (mean age 67.8 ± 7.5 years) with verified prostate cancer diagnosis underwent high dose-rate brachytherapy in the regimen of 2 sessions of 15 Gy with 192Ir source. The inclusion criteria were disease stage ≤сТ2с, Gleason score ≤7. Patients were divided into 2 groups: 1st – patients with incidental prostate cancer (n = 21) who previously (more than 6 months ago, mean time 9.4 ± 2.4 months) underwent transurethral prostatectomy; 2nd – patients with verified prostate cancer (mean prostate volume 56 cm3) and obstructive symptoms without previous transurethral prostatectomy (n = 28).Results. In both groups, no intraoperative complications were observed. In 6 (28 %) patients of the 1st group and 2 patients of the 2nd group, grade II genitourinary toxicity in the form of moderate dysuria and nocturia was observed. Acute gastrointestinal toxicity was observed in 3 (14 %) patients of the 1st group, in the 2nd group such complications were absent. In the 2nd group during the postoperative period after the 2nd session, 4 patients (14 %) experienced acute urinary retention requiring cystostomy.Conclusion. High dose-rate brachytherapy is a safe and effective radical treatment method for patients with localized prostate cancer with obstructive symptoms who have contraindications for surgical treatment.

Proof-of-Principle of Absolute Dosimetry Using an Absorbed Dose Portable Calorimeter with Laser-Driven Proton Beams

Charged particle beams driven to ultra-high dose rates (UHDRs) have been shown to offer potential benefits for future clinical applications, particularly in the reduction of normal-tissue toxicity. Studies of the so-called FLASH effect have shown promise, generating huge interest in high dose rate radiation studies. With laser-driven proton beams, where the duration of the proton burst delivered to a sample can be as short as hundreds of picoseconds, the instantaneous dose rates are several orders of magnitude higher than those used for conventional radiotherapy. The dosimetry of these beam modalities is not trivial, with conventional active detectors, such as ionisation chambers, experiencing saturation effects making them unusable at the extremely high dose rates. Calorimeters, measuring the radiation-induced temperature rise in an absorber, offer an ideal candidate for the dosimetry of UHDR beams. However, their application in the measurement of laser-driven UHDR beams has so far not been trialled, and their effective suitability to work with the quasi-instantaneous and inhomogeneous dose deposition patterns and the harsh environment of a laser-plasma experiment has not been tested. The measurement of the absorbed dose of laser-driven proton beams was conducted in a first-of-its-kind investigation, employing the VULCAN-PW laser system of the Central Laser Facility (CLF) at the Rutherford Appleton Laboratory (RAL), using a small-body portable graphite calorimeter (SPGC) developed at the National Physical Laboratory (NPL) and radiochromic films. A small number of shots were recorded, with the corresponding absorbed dose measurements resulting from the induced temperature rise. The effect of the electromagnetic pulse (EMP) generated during laser–target interaction was assessed on the system, showing no significant effects on the derived signal-to-noise ratio. These proof-of-principle tests highlight the ability of calorimetry techniques to measure the absorbed dose for laser-driven proton beams.

Further development and application of a method for assessing radionuclide surface activity distribution and source location based on measurements of ambient dose equivalent rate

A method has been developed for solving the Fredholm equation in the barrier geometry for reconstructing the surface activity density (SAD) from the results of measuring the ambient dose equivalent rate (ADER). Inclusion of the barrier geometry means that the method takes into account the shielding effect of buildings and structures on the contaminated site. The method was based on the representation of the industrial site, buildings and radiation fields in the form of a raster and the use of the visibility matrix (VM) of raster cells to describe the barrier geometry. The developed method was applied to a hypothetical industrial site with a size of 200 × 200 conventional units for four types of SAD distribution over the surface of the industrial site: ‘fragmentation’, ‘diffuse’, ‘uniform’ and ‘random’. The method of Lorentz curves was applied to estimate the compactness of the distributions of SAD and the ADER for the considered radiation sources. It was shown that the difference between the Lorentz curve for SAD and ADER means that the determination of the spatial distribution of SAD over the industrial site by solving the integral equation is essentially useful for determining the location of radiation source locations on the industrial site. The accuracy of SAD reconstruction depends on the following parameters: resolution (fragmentation) of the raster, the height of the radiation detector above the scanned surface, and the angular aperture of the radiation detector. The measurement of ADER is simpler and quicker than the direct measurement of SAD and its distribution. This represents a significant advantage if SAD distribution needs to be determined in areas with high radiation dose-rate during limited time. The developed method is useful for supporting radiation monitoring and optimizing the remediation of nuclear legacies, as well as during the recovery phase after a major accident.

Interleaved x-ray imaging: A method for simultaneous acquisition of quantitative and diagnostic digital subtraction angiography.

Flow altering angiographic procedures suffer from ill-defined, qualitative endpoints. Quantitative digital subtraction angiography (qDSA) is an emerging technology that aims to address this issue by providing intra-procedural blood velocity measurements from time-resolved, 2D angiograms. To date, qDSA has used 30 frame/s DSA imaging, which is associated with high radiation dose rate compared to clinical diagnostic DSA (up to 4 frame/s). The purpose of this study is to demonstrate an interleaved x-ray imaging method which decreases the radiation dose rate associated with high frame rate qDSA while simultaneously providing low frame rate diagnostic DSA images, enabling the acquisition of both datasets in a single image sequence with a single injection of contrast agent. Interleaved x-ray imaging combines low radiation dose image frames acquired at a high rate with high radiation dose image frames acquired at a low rate. The feasibility of this approach was evaluated on an x-ray system equipped with research prototype software for x-ray tube control. qDSA blood velocity quantification was evaluated in a flow phantom study for two lower dose interleaving protocols (LD1: and LD2: ) and one conventional (full dose) protocol ( . Dose was measured at the interventional reference point. Fluid velocities ranging from 24 to 45cm/s were investigated. Gold standard velocities were measured using an ultrasound flow probe. Linear regression and Bland-Altman analysis were used to compare ultrasound and qDSA. The LD1 and LD2 interleaved protocols resulted in dose rate reductions of -67.7% and -85.5%, compared to the full dose qDSA scan. For the full dose protocol, the Bland-Altman limits of agreement (LOA) between qDSA and ultrasound velocities were [0.7, 6.7] cm/s with a mean difference of 3.7cm/s. The LD1 interleaved protocol results were similar (LOA: [0.3, 6.9] cm/s, bias: 3.6cm/s). The LD2 interleaved protocol resulted in slightly larger LOA: [-2.5, 5.5] cm/s with a decrease in the bias: 1.5cm/s. Linear regression analysis showed a strong correlation between ultrasound and qDSA derived velocities using the LD1 protocol, with a of , a slope of and an offset of cm/s. Similar values were also found for the LD2 protocol, with a of , a slope of and an offset of cm/s. The interleaved method enables simultaneous acquisition of low-dose high-rate images for intra-procedural blood velocity quantification (qDSA) and high-dose low-rate images for vessel morphology evaluation (diagnostic DSA).

Ionizing Radiation Synthesis of Hydrogel Nanoparticles of Gelatin and Polyethylene Glycol at High Temperature.

Nanohydrogel particles of polyethylene glycol (PEG), gelatin (GEL), and PEG-GEL mixtures (MIXs) were synthesized with a high electron beam and 60Co gamma-ray radiation. The relatively novel technique of Asymmetrical Flow Field Flow Fractionation (AF4 or AFFFF) coupled to a Multi-Angle Laser Light Scattering (MALLS) detector was mainly used to determine the hydrodynamic diameter (Dh) of the radiation-synthesized PEG, GEL, and PEG-GEL nanohydrogel particles. Our approach to achieving nanohydrogel particles is to enhance the intracrosslinking reactions and decrease the intercrosslinking reactions of the C-centered radicals of the PEG and GEL. The intracrosslinking reactions of these free radicals were enhanced via irradiation at temperatures of 77-80 °C and using a high dose rate and pulsed irradiation. The shorter average distance between the C-centered free radicals on the backbone of the thermally collapsed PEG and GEL chain, due to the destruction of hydrogen bonds, enhances the intracrosslinking reactions. It was observed that increasing the dose and dose rate decreased the Dh. DLS results lined up with AF4 measurements. This study provides researchers with a clean method to produce GEL-PEG hydrogels without the use of toxic reagents. Particle size can be tuned with dose, dose rate, and temperature as demonstrated in this work. This is ideal for medical applications as the use of ionizing radiation eliminates toxicity concerns and provides simultaneous sterilization of the material.

Radioactive remote signatures derived from Sentinel-2 images and field verification in West Sulawesi, Indonesia.

Mamuju, West Sulawesi, is an area in Indonesia with high radiation levels. A high radiation dose rate was detected in Adang volcanic rock. Activities related to radioactive minerals contained in rocks and soil may release hazardous radiation into the environment. The study area generally exhibits a highly irregular morphology that provides limited access because of the high slope gradient of the volcanic terrain. Therefore, it is challenging to identify and map minerals carrying radioactive elements via Sentinel-2 remote sensing. Since optical satellite images are superior in land cover detection, we proposed a mapping technique for radioactive carrier minerals based on vegetation indices verified by chlorophyll field measurements. We applied band rationing to identify the distribution of hydrothermal alteration minerals and vegetation stress, while field chlorophyll measurements of Dryopteris marginalis and Nephrolepis exaltata were conducted. The Sentinel-2 color composite of images with 4/2, 8A/11, and 11/12 RGB band ratios revealed the distribution of iron oxide, ferromagnesian silicates, and clay minerals. High levels of uranium (U) were scattered in leucite basalt rocks, with a broad distribution of iron oxide minerals and small amounts of ferromagnesian minerals. In contrast, the presence of thorium was not affected by the presence of these minerals. In addition, band rationing of chlorophyll spectra captured by the red edge vegetation index (REVI) was used as the basis for vegetation stress mapping related to radiation exposure based on the chlorophyll content in ferns in the study area. The REVI image showed an anomalous vegetation stress concordant with the high radioactivity. To obtain more accurate results, ground measurements were also performed to identify the vegetation stress due to the presence of minerals carrying radioactive elements. The areas with radioactive mineralization and vegetation stress were located upstream of the Mamuju River and the Botteng and Ahu areas in Tapalang.

Implications of "flash" radiotherapy for biodosimetry.

Extremely high dose rate radiation delivery (FLASH) for cancer treatment has been shown to produce less damage to normal tissues while having the same radiotoxic effect on tumor tissue (referred to as the FLASH effect). Research on the FLASH effect has two very pertinent implications for the field of biodosimetry: (1) FLASH is a good model to simulate delivery of prompt radiation from the initial moments after detonating a nuclear weapon and (2) the FLASH effect elucidates how dose rate impacts the biological mechanisms that underlie most types of biological biodosimetry. The impact of dose rate will likely differ for different types of biodosimetry, depending on the specific underlying mechanisms. The greatest impact of FLASH effects is likely to occur for assays based on biological responses to radiation damage, but the consequences of differential effects of dose rates on the accuracy of dose estimates has not been taken into account.

Characterisation of the UK high energy proton research beamline for high and ultra-high dose rate (FLASH) irradiation

Objective. This work sets out the capabilities of the high energy proton research beamline developed in the Christie proton therapy centre for Ultra-High Dose Rate (UHDR) irradiation and FLASH experiments. It also characterises the lower limits of UHDR operation for this Pencil Beam Scanning (PBS) proton hardware. Approach. Energy dependent nozzle transmission was measured using a Faraday Cup beam collector. Spot size was measured at the reference plane using a 2D scintillation detector. Integrated depth doses (IDDs) were measured. EBT3 Gafchromic film was used to compare UHDR and conventional dose rate spots. Our beam monitor calibration methodolgy for UHDR is described. A microDiamond detector was used to determine dose rates at zref. Instantaneous depth dose rates were calculated for 70–245 MeV. PBS dose rate distributions were calculated using Folkerts and Van der Water definitions. Main results. Transmission of 7.05 ± 0.1% is achieveable corresponding to a peak instantaneous dose rate of 112.7 Gy s−1. Beam parameters are comparable in conventional and UHDR mode with a spot size of σ x = 4.6 mm, σ y = 6.6 mm. Dead time in the beam monitoring electonics warrants a beam current dependent MU correction in the present configuration. Fast beam scanning of 26.4 m s−1 (X) and 12.1 m s−1 (Y) allows PBS dose rates of the order tens of Grays per second. Significance. UHDR delivery is possible for small field sizes and high energies enabling research into the FLASH effect with PBS protons at our facility. To our knowledge this is also the first thorough characterisation of UHDR irradiation using the hardware of this clinical accelerator at energies less than 250 MeV. The data set out in this publication can be used for designing experiments at this UK research facility and inform the possible future clinical translation of UHDR PBS proton therapy.

Assessment of the Interatomic Potentials of Beryllium for Mechanical Properties

Beryllium finds widespread applications in nuclear energy, where it is required to service under extreme conditions, including high-dose and high-dose rate radiation with constant bombardments of energetic particles leading to various kinds of defects. Though it is generally known that defects give rise to mechanical degradation, the quantitative relationship between the microstructure and the corresponding mechanical properties remains elusive. Here we have investigated the mechanical properties of imperfect hexagonal close-packed (HCP) beryllium via means of molecular dynamics simulations. We have examined the beryllium crystals with void, a common defect under in-service conditions. We have assessed three types of potentials, including MEAM, Finnis–Sinclair, and Tersoff. The volumetric change with pressure based on MEAM and Tersoff and the volumetric change with temperature based on MEAM are consistent with the experiment. Through cross-comparison on the results from performing hydrostatic compression, heating, and uniaxial tension, the MEAM type potential is found to deliver the most reasonable predictions on the targeted properties. Our atomistic insights might be helpful in atomistic modeling and materials design of beryllium for nuclear energy.