Electron Beam Dose Research Articles

High-density and high-uniformity InAs quantum nanowires on Si(111) substrates

InAs nanowires (NWs) were grown on SiOx pinholes formed on Si(111) substrates by molecular beam epitaxy. Influences of electron-beam (EB) irradiation on the SiOx layer on the pinhole formation and the subsequent InAs NW growth were studied. As the EB irradiation dose increased, the pinhole density in the SiOx layer decreased. From atomic force microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy results, it was found that the pinhole etching of the SiOx layer by Ga droplets was suppressed by carbon adsorption due to the EB irradiation. By forming high-density pinholes on the SiOx layer without the EB irradiation, high-density InAs NWs with 1–2 × 1010 cm−2 were grown successfully, and the uniformity in the NW diameter improved. The standard deviation of the NW diameter was 1.8 nm (8.8%) for high-density NWs. In addition, the NW diameter decreased with decreasing EB dose, and the NW diameter was controlled by adjusting the diameter of Ga droplets forming the pinholes. As the NW diameter decreased, photoluminescence spectra of the NWs shifted to higher energies than the bandgap energy of the wurtzite InAs bulk. From these results, we successfully fabricated high-density and high-uniformity InAs NWs with quantum size effects on EB-unirradiated SiOx/Si(111).

Effect of electron irradiation on alternating current electrical properties of gelatin – cadmium sulfide nano‐composite films

AbstractGelatin was doped with 1 %, 3 %, 5 % and 10 % cadmium sulfide nanoparticles in weight concentrations forming the gelatin‐cadmium sulfide nanocomposites and irradiated by various electron beam doses equals 50 kGy, 75 kGy, 100 kGy, and 150 kGy using 3 MeV – 3 mA electron accelerator. The applied alternating current electrical field frequency ranging from 70 Hz to 5 MHz is what caused the fluctuation in dielectric properties and alternating current electrical conductivity of these nanocomposites. The results showed that the films of 1 %, 3 %, 5 %, and 10 % for blank (nanocomposite film without electron beam irradiation) nanocomposites had the highest dielectric parameters (έ, ϵ′′, tan δ) at 0.5 kHz with values of (0.696, 0.0233, 0.034), (0.533, 0.0114, 0.0215), (0.402, 0.001196, 0.003), and (0.459, 0.00418, 0.0091), respectively. However, the lowest dielectric parameters were (0.645, 0.00618, 0.0066), (0.523, 0.00165, 0.0215), (0.417, 0.00035, 0.0008), and (0.455, 0.00066, 0.0015) at 5 MHz, respectively. The highest conductivity values for blank nanocomposites of 1 %, 3 %, 5 %, and 10 % were 1.79×10−4 S/m, 1.45×10−4 S/m, 1.16×10−4 S/m, 1.27×10−4 S/m at 5 MHz, and the lowest values were 1.92×10−8 S/m, 1.49×10−8 S/m, 1.13×10−8 S/m, 1.26×10−8 S/m at 0.5 kHz, respectively. For irradiated nanocomposites at 5 MHz, the dielectric constant order for 1 % was 100 kGy, 150 kGy, 50 kGy, and 75 kGy with values 0.63, 0.537, 0.532, and 0.523, respectively. For 10 % weight concentration, the order was 50 kGy, 100 kGy, 150 kGy, and 75 kGy with values 0.515, 0.477, 0.47, and 0.437, respectively. Otherwise the dielectric constant order for 3 % and 5 % was 100 kGy, 75 kGy, 150 kGy, and 50 kGy. The highest dielectric properties and conductivity values for blank and irradiated nanocomposites were observed at 100 kGy for 1 %, 3 %, and 5 %.

The Development and Evaluation of an All-Purpose Bolus for Radiotherapy

The purpose of this study was to develop on a new bolus (HM bolus) which had tissue equivalence, transparency, reusability, and free shaping at approximately 40°C for excellent adhesion, and to evaluate its features could be satisfy ideal bolus conditions for clinical use. The newly developed HM bolus was controlled to prevent phase separation by adjusting the contents of ethylene propylene rubber, styrene, butadiene rubber, thermoplastic resin, temperature-sensitive adjuster, and silica. The element ratios (wt%) in the HM bolus are H: 10.2%, C: 63.5%, O: 17.1%, and Si: 9.2%. The density was adjusted to 0.96 g cm-3. We evaluated dose characteristics, a vinyl gel sheet bolus (Gel bolus) and HM bolus placed on a water-equivalent phantom were used to obtain the percent depth dose (PDD) of electron (6 MeV, 9 MeV) and photon (4 MV,6 MV) beams. The average dose difference of the HM bolus and Gel bolus was calculated. The Gel bolus, a soft rubber bolus (SR bolus), and HM bolus were placed in adherence to a pelvic phantom. CT images taken after shaping and 1, 2, and 3 weeks after shaping were used to evaluate the adhesion and reproducibility using air gap and dice similarity coefficient (DSC) metrics. The visibility of letters (maximum: 80 pt, minimum: 10 pt) through a plate-shaped bolus and the visibility of markers when each bolus was set up on the pelvic phantom under normal room lighting were evaluated. The average dose difference for electron beams was 0.16% ± 0.79% and photon beams was 0.06% ± 0.34%, both within 1% of the PDD results. The HM bolus showed the same build-up effect and dose characteristics as the Gel bolus. The mean air gap values for the Gel bolus, SR bolus, and HM bolus were 96.02 ± 43.77 cm3, 34.93 ± 21.44 cm3, and 4.40 ± 1.50 cm3 44, respectively. The mean DSC values for the Gel bolus, SR bolus, and HM bolus were 0.363 ± 0.035, 0.556 ± 0.042, and 0.837±0.018. The HM bolus showed the smallest air gap at all time points and the DSC closest to 1. Excellent adhesion was observed in the CT simulation and during the treatment period. The letter visibility through the HM bolus and Gel bolus was sufficient, and when the HM bolus was set up on the pelvic phantom, the markers that were completely invisible with the SR bolus were visible. We succeeded in developing an all-purpose bolus with unique characteristics for clinical use. The HM bolus had the same build-up effect and dose characteristics as a Gel bolus. Therefore, it can be used for CT simulation and dose calculation. The other advantages of the new bolus are tissue equivalence, transparency, reusability, and free shaping at approximately 40°C, providing excellent adhesion at each setup during the treatment period.

Comparison of the Direct Power Consumption for Different Linac Treatment Parameters in External Beam Radiation Therapy

The negative impact of climate change on the environment has led to increasing concern around the world. Relatively little is known about the contribution of radiation oncology systems to carbon emissions. This study measures the energy utilization of Linac-based EBRT for different treatment parameters and techniques, which was then converted to power use (kWh) and ultimately a carbon footprint of various photon treatment approaches. A Varian TrueBeam was evaluated. The direct power consumption was measured using a Fluke 1736 Power Logger, recorded in one-second intervals for one week. Different photon and electron beam energies, dose rates, treatment techniques (3D, IMRT, gated), and imaging types (kV, MV) were evaluated. Clinical treatment plans were reviewed, and average treatment times used to determine kWh. IRB approval was obtained. The Greenhouse Gas Equivalencies Calculator was used to determine kg of CO2. Power draw for 6 MV, 10 MV, and 18 MV at a rep rate of 600 MU/min was 31.6, 32.0, and 27.5 kW, respectively. The power draw for end of range dose rates for 6 MV (60, 600), 6 FFF (400, 1400), 10 FFF (400, 2400), and 6 MeV (100, 1000) were (22.2, 31.6 kW), (23.7, 31.6 kW), (19.6, 32.1 kW), and (22.6, 23.6 kW), respectively. 6 MV open 2D fields, modulated IMRT fields, and gated/beam hold fields had similar power draw at 31.6, 31.7, and 31.9 kW, respectively. Portal MV imaging with 2.5 MV beam was 32.5 kW, while CBCT and kV/kV imaging was ∼11 kW and not distinguishable from baseline power fluctuations. A total of 191 delivered treatment plans were reviewed. Electron plans (n = 8) treatment time was on average 29 sec (16 sec STDEV) per fraction and 635 sec (185 sec STDEV) per course, 2D/3D plans (n = 63) were 77 sec (32 sec STDEV) and 1004 sec (1002 sec STDEV), and IMRT plans (n = 120) were 182 sec (60 sec STDEV) and 5351 sec (2401 sec STDEV), respectively. The kWh per treatment for electron, 2D/3D, and IMRT plans were 0.19, 0.68, and 1.6 kWh, respectively. The CO2 equivalent for electrons, 2D/3D, and IMRT techniques are 0.08, 0.29, and 0.7 kg. There was some variability in the power draw for different energies and different dose rates but was relatively stable around 32 kW. Power consumption for clinical therapy is a result of kW power draw multiplied by duration of beam delivery, which for our patients varied significantly as a function of technique and number of fractions delivered. Reduction in radiation oncology carbon footprint will likely be driven more by number of fractions and type of treatment technique, and length of patient commute, rather than beam energy and dose rate selection.

Effect of nanographene oxide and ionizing radiation on mechanical, physical, and thermal properties of composites based on high‐density polyethylene and waste bagasse fibers

AbstractThe impact of graphene oxide (GO) nanoparticle content and exposure to electron beam (EB) on the tensile, dynamic mechanical, water uptake, and thermal properties of high‐density polyethylene/bagasse fibers composite was investigated. The GO was added at different loading levels: 0.25, 0.5, 0.75, and 1 parts per hundred parts of plastic (php), while 2 doses of EB were used (100 and 200 kGy). The influence of adding 10 php of carbon black (CB) to the HDPE/BF was also investigated. The addition of GO and irradiation up to 100 kGy, along with the inclusion of 10 php of CB, led to improvements in tensile strength, elastic modulus, storage modulus, and hardness. The composite containing 1 php of GO and exposed to 100 kGy, demonstrated the highest tensile strength value, with a 47.3% improvement compared with the unirradiated one. This composite also, exhibited the lowest values of water absorption percent (3.7%) and diffusion coefficient (0.007 mm2/h) compared with the unirradiated HDPE/BF composite. These results suggest that the resulting composite has potential for use in advanced industrial applications due to its improved physicomechanical properties.Highlights Composites based on high‐density polyethylene (HDPE) and bagasse fibers (BF) were fabricated The incorporation of graphene oxide (GO) improved the mechanical properties. GO and electron beam (EB) irradiation enhanced the water resistance of HDPE/BF composite. Both GO and EB increased the thermal stability of HDPE/BF composite.

Effect of electron beam irradiation on estrogens removal from treated wastewater

In order to remove micro pollutants such as estrogens efficiently from wastewater, it is often recommended that conventional wastewater treatment plants (WWTP) be retrofitted with an advanced oxidation process (AOP) for post-treatment purposes. This study examined the effects of electron beam (EB) absorbed dose on the removal of estrogens from biologically treated wastewater. Known concentrations of E1, E2, E3 and EE2 (0.2, 0.5, 5.0 and 10 µg/l) were spiked into samples obtained from a municipal wastewater plant, which were then irradiated with EB doses of 0.2, 2.0, 5.0 and 10.0 kGy. Levels of estrogen after irradiation were analyzed using the liquid-chromatography mass-spectrometry (LC-MS). According to the results obtained, the concentration of estrogens decreased steadily with an increasing absorbed dose up to 2 kGy. However, there was no significant increase in estrogen removal at EB doses above 2 kGy. It is estimated that the removals of the different types of estrogen are ranged from 86 % to 99 %. E2 was found to be the fastest estrogen to be degraded, followed by E3, EE2, and E1.

Nanoscale Lithium Distribution within a Secondary Cathode Particle for Li-Ion Battery Using Identical Location (S)TEM-EELS

Energy density of LIBs are primarily limited by cathodes and further development of cathode materials requires in-depth understanding of the structural and compositional changes spanning across various length scales involved during electrochemical delithiation/lithiaton. Cathode materials are usually synthesized as secondary particles (∼10 µm) that are sintered agglomerates of smaller primary particles (∼100s µm). Lithium distribution may not necessarily be uniform across the entirety of these particles in typical state-of-the-art layered cathodes during electrochemical cycling. A detailed knowledge of lithium distribution within secondary particles is crucially important for obtaining a comprehensive understanding of the energy storage system. To truly understand the structural changes taking place at the nano and atomic scales, high spatial resolution techniques are of paramount importance for understanding the lithium distribution and optimizing/developing future LIB cathodes. STEM-EELS is ideally suited for obtaining such information at the desired (atomic) spatial resolution. In the present work, nanoscale lithium-ion distribution was investigated among various primary particles within a secondary particle of state-of-the-art Ni-rich layered LIB cathode using identical location scanning transmission electron microscopy with electron energy loss spectroscopy (IL-STEM-EELS) by making use of a specially designed electrochemical cell employing TEM grids. Identical location allows for the imaging of the same location before and after electrochemical testing to evaluate localized changes. Nanoscale lithium-ion distribution along with the electron beam dose effects on the nanoscale/atomic structure of layered NMC532 cathodes at various charge stages will be presented.

Effects of Irradiation Dose of Sheet-Like Electron Beam and its Cathode Voltage on Impact Strength of Carbon Fiber Reinforced Thermoplastic Polyamide just before Shipping

Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (Vc) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, higher strength is desired. Therefore, EB setting applying electron beam (EB) irradiation with cathode potential (Vc) to 170, 210, 225 or 250 kV was applied to CFRTPA (carbon fiber reinforced thermoplastic polyamide) articles just before shipping. Specimens were 9 CF plies alternating between 10 PA (polyamide) sheets, designated [TPA]10[CF]9. When optimal EB dose of 43.2 kGy is applied to both finished specimen surfaces after fabrication, experimental results show higher Vc setting of 250 kV can increase impact strength of the [TPA]10[CF]9 over that at 170 kV. In summary, the 250 kV-EB (250 kV) strengthens [TPA]10[CF]9 significantly, about 25 to 27% larger than that of 170 kV and zero (untreated). Based on Christenhusz and Reimer equation to calculate penetration depth, Dth of EBI into polymers, increasing Vc to 250 kV increased Dth to more than 2 times that at 170 kV.

The Atomic Observation of the Structural Change Process in Pt Networks in Air Using Environmental Cell Scanning Transmission Electron Microscopy.

The structural change in Pt networks composed of multiple chain connections among grains was observed in air at 1 atm using atomic-resolution environmental cell scanning transmission electron microscopy. An aberration-corrected incident electron probe with a wide convergence angle made it possible to increase the depth resolution that contributes to enhancing the signal-to-noise ratio of Pt network samples in air in an environmental cell, resulting in the achievement of atomic-resolution imaging. The exposure of the Pt networks to gas molecules under Brownian motion, stimulated by electron beams in the air, increases the collision probability between gas molecules and Pt networks, and the Pt networks are more intensely stressed from all directions than in a situation without electron irradiation. By increasing the electron beam dose rate, the structural change of the Pt networks became significant. Dynamic observation on an atomic scale suggested that the structural change of the networks was not attributed to the surface atomic-diffusion-induced step motion but mainly caused by the movement and deformation of unstable grains and grain boundaries. The oxidized surface layers may be one of the factors hindering the surface atomic step motion, mitigating the change in the size of the grains and grain boundaries.

Fundamental evaluation of dose and dose distribution under applied topical agents and dressings used for skin care in radiotherapy

PurposeRadiation dermatitis is a common adverse event in radiotherapy and is treated using topical agents or dressings; however, it may be exacerbated by increasing the skin dose during irradiation. This study investigated the effects on the dose and dose distribution assuming irradiation without wiping the agent off. MethodsFive types of topical products and dressings available in clinical settings were used in this study. These products were applied to a tough water phantom, and the dose and dose distributions of photon and electron beam were measured using an ionization chamber and an EBT3 Gafchromic film, respectively. For dose measurements, topical products were applied to thicknesses of 0, 1, 2, 3, 4, 5, and 10 mm, and 100 monitor units (MU) were irradiated. The dressings were pasted onto the phantom. For dose distribution measurements, the Gafchromic film was placed parallel to the radiation flux. The thicknesses of the topical products were 0, 1, and 5 mm. ResultsThe doses of 6 and 10 MV X-rays increased 0.35–0.82% and 0.25–0.55% with topical product thicknesses of 4 or 5 mm, respectively. In contrast, the electron beam dose decreased by 10.67% at 6 MeV and 2.11% at 12 MeV with a topical product thickness of 5 mm. The applied topical products shifted the X-ray and electron beam dose distributions toward the surface. However, the dressings did not affect the dose and dose distributions. Specifically, dose changes were less than 0.3% for all employed dressings. ConclusionBased on the results of this study, we suggest that topical agents and dressings do not affect the dose and dose distribution except when topical agents are applied particularly thickly. However, the actual dose received by the skin needs to be investigated in the future.

Interlacing in Atomic Resolution Scanning Transmission Electron Microscopy.

Fast frame rates are desirable in scanning transmission electron microscopy for a number of reasons: controlling electron beam dose, capturing in situ events, or reducing the appearance of scan distortions. While several strategies exist for increasing frame rates, many impact image quality or require investment in advanced scan hardware. Here, we present an interlaced imaging approach to achieve minimal loss of image quality with faster frame rates that can be implemented on many existing scan controllers. We further demonstrate that our interlacing approach provides the best possible strain precision for a given electron dose compared with other contemporary approaches.

One-pot production of multiple stacked lithium-ion batteries with gel polymer electrolyte through high-energy electron beam irradiation

Gel polymer electrolytes (GPEs) have garnered considerable interest in lithium-ion battery (LIB) applications owing to their ability to combine the desirable attributes of liquid electrolytes (e.g., high conductivity) with the stability of solid electrolytes. They are fabricated by immobilizing the liquid electrolyte within a polymer matrix. Notably, the utilization of high-energy electron beam (EB) technology is a promising approach for the in situ preparation of GPEs, which establishes the need for an initiator or thermal treatment. The simultaneous generation of multiple GPEs via EB irradiation confers significant economic advantages. This study reports the simultaneous production of GPEs from multiple-stacked LIBs through a single-step irradiation of high-energy EB. In particular, we used trimethylolpropane propoxylate triacrylate with a trifunctional acrylate ester as the cross-linker for the GPE, and investigated the effect of the EB dose on the properties of the individual cell components and its electrochemical performance to determine the optimal EB dose of 15 kGy. Thereafter, we tested the penetration of EB irradiation on 0.5-Ah-level pouch cells. As observed, an EB of ∼ 15 kGy could penetrate seven pouch cells, which displayed stable cell performances when fabricated using simultaneous EB irradiation. Overall, the results demonstrated the economic feasibility of the proposed method owing to its high productivity on a commercial scale.

Understanding the mechanisms of anisotropic dissolution in metal oxides by applying radiolysis simulations to liquid-phase TEM

Iron-based redox-active minerals are ubiquitous in soils, sediments, and aquatic systems. Their dissolution is of great importance for microbial impacts on carbon cycling and the biogeochemistry of the lithosphere and hydrosphere. Despite its widespread significance and extensive prior study, the atomic-to-nanoscale mechanisms of dissolution remain poorly understood, particularly the interplay between acidic and reductive processes. Here, we use insitu liquid-phase-transmission electron microscopy (LP-TEM) and simulations of radiolysis to probe and control acidic versus reductive dissolution of akaganeite (β-FeOOH) nanorods. Informed by crystal structure and surface chemistry, the balance between acidic dissolution at rod tips and reductive dissolution at rod sides was systematically varied using pH buffers, background chloride anions, and electron beam dose. We find that buffers, such as bis-tris, effectively inhibited dissolution by consuming radiolytic acidic and reducing species such as superoxides and aqueous electrons. In contrast, chloride anions simultaneously suppressed dissolution at rod tips by stabilizing structural elements while promoting dissolution at rod sides through surface complexation. Dissolution behaviors were systematically varied by shifting the balance between acidic and reductive attacks. The findings show LP-TEM combined with simulations of radiolysis effects can provide a unique and versatile platform for quantitatively investigating dissolution mechanisms, with implications for understanding metal cycling in natural environments and the development of tailored nanomaterials.

The development and characterization of an all-purpose bolus for radiotherapy

Objective. The purpose of this study was to develop a new bolus (HM bolus), with tissue equivalence, transparency, reusability, and free shaping at approximately 40 °C for excellent adhesion, and to evaluate the feasibility of clinically using this bolus as an ideal bolus. Approach. We summarized the advantages and disadvantages of existing boluses. To evaluate dose characteristics, a vinyl gel sheet bolus (Gel bolus) and HM bolus placed on a water-equivalent phantom were used to obtain the percentage depth dose (PDD) of electron (6 MeV, 9 MeV) and photon (4 MV, 6 MV) beams. The average dose difference of the HM bolus and Gel bolus was calculated. The Gel bolus, a soft rubber bolus (SR bolus), and HM bolus were placed in adherence to a pelvic phantom. CT images taken after shaping and 1, 2, and 3 weeks after shaping were used to evaluate the adhesion and reproducibility using air gap and dice similarity coefficient (DSC). Main results. The average dose difference for electron beams was 0.16% ± 0.79% and photon beams was 0.06% ± 0.34%, both within 1% of the PDD results. The HM bolus showed the same build-up effect and dose characteristics as the Gel bolus. The mean air gap values for the Gel bolus, SR bolus, and HM bolus were 96.02 ± 43.77 cm3, 34.93 ± 21.44 cm3, and 4.40 ± 1.50 cm3, respectively. The mean DSC values compared to initial images for the Gel bolus, SR bolus, and HM bolus were 0.363 ± 0.035, 0.556 ± 0.042, and 0.837 ± 0.018, respectively. Excellent adhesion was observed in the CT simulation and during the treatment period. Significance. The HM bolus has unique features, such as tissue equivalence, transparency, reusability, and free shaping for excellent adhesion, and is thus an ideal bolus for use in clinical cases.

Intracellular microcystins degradation and acute toxicity decrease towards Daphnia similis by low electron-beam irradiation doses

Ionizing radiation has attracted attention due to its ability to inhibit pathogens and microorganisms, with low doses reported as being able to degrade cyanotoxins and inhibit toxic cyanobacteria growth. In this context, the aim of the present study was to investigate how electron beam irradiation (EBI) applied at doses between 1 and 10 kGy affect intracellular and extracellular microcystin variants. Effects on M. aeruginosa culture recovery, as well as changes in physico-chemical cyanobacterial suspension parameters and water quality alterations were assessed through ecotoxicity assays. The findings indicate that doses over 2 kGy may are lethal to M. aeruginosa even at 48 h post-irradiation. Concerning physico-chemical parameters, exposure to 2–5 kGy doses decrease pH values and later stabilizing. At least 50 % of intracellular MC led to significant degradation of all variants at 3 kGy. No acute toxicity effects were observed in Daphnia similis exposed to sample supernatants. Statistically significant differences were observed when cladocerans were exposed to M. aeruginosa cells treated with EBI doses ranging from 3 to 10 kGy compared to non-treated cyanobacterial suspensions. These findings suggest that low EBI radiation doses are suitable for the control of toxic cyanobacteria in water treatment processes, providing a less toxic environment compared to non-treated solutions.

Production and Patterning of Fluorescent Quantum Dots by Cryogenic Electron-Beam Writing.

Graphene quantum dots (GQDs) have emerged as a promising type of functional material with distinguished properties. Although tremendous effort was devoted to the preparation of GQDs, their applications are still limited due to a lack of methods for processing GQDs from synthesis to patterning smoothly. Here, we demonstrate that aromatic molecules, e.g., anisole, can be directly converted into GQD-containing nanostructures by cryogenic electron-beam writing. Such an electron-beam irradiation product exhibits evenly red fluorescence emission under laser excitation at 473 nm, and its photoluminescence intensity can be easily tuned with the electron-beam exposure dose. Experimental characterizations on the chemical composition of the product reveal that anisole undergoes a carbonization and further graphitization process during e-beam irradiation. With conformal coating of anisole, our approach can create arbitrary fluorescent patterns on both planar and curved surfaces for concealing information or anticounterfeiting applications. This study provides a one-step method for production and patterning of GQDs, facilitating their applications in highly integrated and compact optoelectronic devices.

Comparison of effectiveness and efficiency of electron beam over gamma rays to induce novel mutations in mungbean (Vigna radiata L. Wilczek)

Induced mutation is very useful in mungbean as it is having less natural genetic variation. The present study was conducted to induce variability through induced mutation, compare efficiency and effectiveness of gamma rays with electron beam on the basis of physiological changes in M1 generation; mutation frequency, spectrum of mutant phenotype and efficiency to produce novel mutations in M2 generation. Seeds of mungbean variety TM 96–2 were irradiated with doses of 200, 300, 400 and 500 Gy gamma rays and electron beam. On the basis of M1seedling growth, the effective mutagen dose (Growth Reduction Dose 50 i.e. GR50) was 440 Gy of gamma rays and 470 Gy of electron beam for TM-96–2. In M2 generation, electron beam treatments were found to induce greater frequency of chlorophyll mutations than gamma rays. The frequency of total mutants in electron beam (1.967) was found to be higher than gamma rays (1.343) along with mutation spectrum. The highest mutation spectrum was observed in 200 Gy dose of electron beam followed by 200 Gy gamma rays. Four novel mutants viz., four primary leaves in 400 Gy gamma rays, lanceolated leaves in 200, 300 and 500 Gy electron beam, yellow pod and yellow seed coat colour in 200 Gy treatment of electron beam were identified and isolated. Desirable mutants like early and synchronous maturity, large seed size and long root with drought tolerance were identified and isolated in different doses of both gamma rays and electron beam which were found true breeding in subsequent generations. Mutagenic efficiency of electron beam was higher in 200 and 400 Gy treatment as compared to same doses of gamma rays, while it was less than gamma rays in 300 and 500 Gy treatments. Mutagenic effectiveness was found to be highest in 200 Gy dose of electron beam which was more than twice that of the same dose of gamma rays.

Feasibility of a multigroup Boltzmann–Fokker–Planck solution for electron beam dose calculations

Legacy nuclear-reactor Boltzmann solvers start clinical deployment as an alternative to Monte Carlo (MC) codes and Fermi–Eyges semiemprical models in radiation oncology treatment planning. Today’s certified clinical solvers are limited to photon beams. In this paper, ELECTR, a state-of-the-art multigroup electron cross sections generation module in NJOY is presented and validated against Lockwood’s calorimetric measurements, EGS-nrc and GEANT-4 for 1–20 MeV unidirectional electron beams. The nuclear-reactor DRAGON-5 solver is upgraded to access the library and solve the Boltzmann–Fokker–Planck (BFP) equation. A variety of heterogeneous radiotherapy and radiosurgery phantom configurations were used for validation purpose. Case studies include a thorax benchmark, that of a typical breast Intra-Operative Radiotherapy and a high-heterogeneity patient-like benchmark. For all beams, 100% of the water voxels satisfied the American Association of Physicists in Medicine accuracy criterion for a BFP-MC dose error below 2%. At least, 97.0% of adipose, muscle, bone, lung, tumor and breast voxels satisfied the 2% criterion. The average BFP-MC relative error was about 0.56% for all voxels, beams and materials combined. By irradiating homogeneous slabs from Z=1 (hydrogen) to Z=99 (einsteinium), we reported performance and defects of the CEPXS mode [US. Sandia National Lab., SAND-89-1685] in ELECTR for the entire periodic table. For all Lockwood’s benchmarks, NJOY-DRAGON dose predictions are within the experimental data precision for 98% of voxels.

Characteristics Performance of Newly Developed Parallel Plate Chamber in Electron Beams.

To investigate the dosimetric performance of newly developed parallel plate chamber in electron beams. Rosalina Instruments India Private Limited (Mumbai, Maharashtra, India) has designed and fabricated PRATT2 parallel plate chamber. The various dosimetric characteristics, including pre- and post-irradiation leakage, stability, polarity effect, chamber response with bias voltage, dose linearity, dose rate effect, and chamber absorbed dose calibration, were performed for the developed chamber. The electron beam energies of 4, 6, 8, and 15MeV were used in this study. The pre- and post-irradiation leakage of the developed chamber was within the acceptable limit. The chamber shows good stability over the electron beams used in this study. The maximum error in polarity effect was 0.7% for the developed chamber. The chamber shows the good linear response with dose, and its response is independent of the dose rate for all electron beams. The beam quality correction factor (kQ, Q0) was determined for the all electron beam energies, which was used for determination absorbed dose in electron beams. The developed parallel plate chamber (PRATT2) is suitable for dosimetry of electron beams in radiotherapy. The chamber is cost effective and shows precise and reproducible response. The study carried out confirms that the newly designed and fabricated ion chamber can be used in the measurement of absorbed dose for therapeutic electron beams.

Commissioning and Performance Evaluation of Varian TrueBeam Linear Accelerator

Aim: The aim of this study is to present a report on the commissioning results of the Varian TrueBeam machine with available photon energies so that it can benefit medical physicists during the entire commissioning process. Subjects and Methods: All tests were performed as per the recommendation of the Atomic Energy Regulatory Board. The beam profiles and percentage depth dose of both photon and electron beams were measured with Sun nuclear Radiation Field Analyzer and 0.125 cc ionization chamber. Output accuracy and consistency of photon and electron beams were measured using 0.6 cc cylindrical ionization chamber and 0.350 cc parallel plate ionization chamber, respectively. To measure the congruency of radiation and optical field and isocenter check with respect to gantry, collimator, and couch, self-developed films were used. Results: Isocenter shift due to gantry, collimator, and couch, rotation was found to be within ± 2-mm diameter circle. Congruency of optical and radiation fields was measured for symmetric fields 5 cm × 5 cm, 10 cm × 10 cm, 20 cm × 20 cm, and 30 cm × 30 cm for all available energy and was within ± 2 mm. Dosimetric leaf gap value for the multi-leaf collimator was measured with 0.125 cc ionization chamber and values are −0.853 mm, −1.106 mm, −1.097 mm, −0.765 mm, and −1.005 mm for energies 6 MV, 10 MV, 15 MV, 6 flattening filter free (FFF), and 10 FFF, respectively. Conclusions: All electrical, mechanical, dosimetric, and safety measurement were found to be within permissible limits. Before clinical use, the beam data are crosschecked with point dosimetry, portal dosimetry, and MapCHECK two-dimensional detector array and results are within tolerance.