Irradiation System Research Articles

High LET-Like Radiation Tracks at the Distal Side of Accelerated Proton Bragg Peak.

Proton therapy is a type of hadron radiotherapy used for treating solid tumors. Unlike heavy charged elements, proton radiation is considered to be low LET (Linear Energy Transfer) radiation, like X-rays. However, the clinical SOBP (Spread Out Bragg Peak) proton radiation is considered to be higher in relative biological effectiveness (RBE) than both X-ray and their own entrance region. The RBE is estimated to be 1.1–1.2, which can be attributed to the higher LET at the SOBP region than at the entrance region. In order to clarify the nature of higher LET near the Bragg peak of proton radiation and its potential cytotoxic effects, we utilized a horizontal irradiation system with CHO cells. Additionally, we examined DNA repair mutants, analyzed cytotoxicity with colony formation, and assessed DNA damage and its repair with γ-H2AX foci assay in a high-resolution microscopic scale analysis along with the Bragg peak. Besides confirming that the most cytotoxic effects occurred at the Bragg peak, extended cytotoxicity was observed a few millimeters after the Bragg peak. γ-H2AX foci numbers reached a maximum at the Bragg peak and reduced dramatically after the Bragg peak. However, in the post-Bragg peak region, particle track-like structures were sporadically observed. This region contains foci that are more difficult to repair. The peak and post-Bragg peak regions contain rare high LET-like radiation tracks and can cause cellular lethality. This may have caused unwanted side effects and complexities of outputs for the proton therapy treatment.

Micromachining of polymers using atmospheric pressure inductively coupled helium plasma localized by a scanning nanopipette probe microscope

We developed a local irradiation system for atmospheric pressure inductively coupled plasma (ICP) using a quartz capillary nozzle (nanopipette) with a sub-micrometer diameter tip aperture for fine processing of material surface. Using this system, a polymethyl methacrylate (PMMA) film coated on a glass substrate was etched at the micrometer scale. Fine etching was achieved by the ICP localized by the nanopipette precisely placed near the surface, using the positioning capability of a homemade scanning probe microscope. The locally etched surface of the PMMA film was confirmed by imaging immediately after the etching process by scanning the nanopipette. For quantitative evaluation, the topographical image of the same location of the surface was then acquired using an atomic force microscope. The etching rate of the ICP was 20 times higher than that of the low-frequency atmospheric pressure plasma jet. The depth of the etched holes increased with increasing applied power and irradiation time and decreasing irradiation distance. In addition, line groove patterning with sub-micrometer width was successfully achieved. The proposed system is expected to be used in various applications such as processing and repairing of microdevices.

Induced Mutations Using Gamma Ray and Multiplication of Plantlet through Micro Cross Section Culture of Banana (Musa acuminata cv. Berangan)

The conventional breeding approach in banana was slow predominantly because of the limited genetic diversity, infertility and polyploid condition of the species. Induced mutation is one of the promising tools to create new varieties for the improvement of banana. While vitro propagation technique ensures a rapid and in an organized manner for production of banana. Thus, induced mutation using gamma ray in combination with in vitro culture micro cross section culture was conducted to evaluate the effects of gamma radiation on growth and development of plantlet of Musa acuminata cv. Berangan. Tissue cultured banana plantlet was used as the source of explant. The plantlet was cut into halved and radiated using gamma ray with the dose of 0 (control), 20, 25, 30, 35, 40, 45, 50, 55, 60 and 80 Gy. The highest survival rate (23.33%) was recorded in treatment 10 Gy while the lowest survival (0.33%) was in treatment 80 Gy. The lethal dose (LD50) which had caused 50% mortality to the irradiated material was found to be 37 Gy. The morphological study on the growth of in vitro irradiated plantlets showed that 25 Gy induced a stimulation effect on the number of shoot produced (5.56), root number per explant (8.5) and root length (37.36 cm) compared to untreated banana explants (0 Gy). Hence, this study introduces the in vitro multiplication of gamma irradiated culture system for future breeding of a new varieties of banana.

Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical Irradiation Box: Design, Characterization and Validation.

We report on the design, characterization and validation of a spherical irradiation system for inactivating SARS-CoV-2, based on UV-C 275 nm LEDs. The system is designed to maximize irradiation intensity and uniformity and can be used for irradiating a volume of 18 L. To this aim: (i) several commercially available LEDs have been acquired and analyzed; (ii) a complete optical study has been carried out in order to optimize the efficacy of the system; (iii) the resulting prototype has been characterized optically and tested for the inactivation of SARS-CoV-2 for different exposure times, doses and surface types; (iv) the result achieved and the efficacy of the prototype have been compared with similar devices based on different technologies. Results indicate that a 99.9% inactivation can be reached after 1 min of treatment with a dose of 83.1 J/m2.

Modification of polymer electrolyte blend PEO/PVDF–HFP by low-energy O+ ion irradiation to improve electrolyte behavior

PEO/PVDF–HFP [poly(ethylene oxide)/poly(vinylidene fluoride-co-hexafluoropropylene)] solid polymer electrolyte blend incorporating varying weights of LiTFSI [lithium bis (trifluoromethane) sulfonimide] salt was prepared. The blend with 20 wt.% of salt that exhibits maximum ionic conductivity was subjected to microstructural modification by exposing to low-energy ions of oxygen at different fluences. The ionic conductivity of the system increases by one order in magnitude when subjected to oxygen ion irradiation. The dielectric loss tangent curves are used to extract ions relaxation time. The relaxation time τ of the system is reduced from 1.42 to 0.71 μs upon irradiation which indicates enhanced segmental motion due to a rise in amorphous region in polymer matrix. The ion activation energy in the system decreases to 0.041 eV from 0.063 eV. Dielectric studies suggest an increase in dipoles in the irradiated systems possibly due to polymer chain scission in the matrix. The increase in disordered phase by ion irradiation is supported by change in crystallinity from 24% for the unirradiated systems to about 14% for the irradiated systems by X-ray diffraction and differential scanning calorimetry analysis. The shift in prominent peaks observed in Fourier transform infrared spectroscopy suggests possible scission of the polymer chains.

Dosimetric Assessment of a High Precision System for Mouse Proton Irradiation to Assess Spinal Cord Toxicity.

The uncertainty associated with the relative biological effectiveness (RBE) in proton therapy, particularly near the Bragg peak (BP), has led to the shift towards biological-based treatment planning. Proton RBE uncertainty has recently been reported as a possible cause for brainstem necrosis in pediatric patients treated with proton therapy. Despite this, in vivo studies have been limited due to the complexity of accurate delivery and absolute dosimetry. The purpose of this investigation was to create a precise and efficient method of treating the mouse spinal cord with various portions of the proton Bragg curve and to quantify associated uncertainties for the characterization of proton RBE. Mice were restrained in 3D printed acrylic boxes, shaped to their external contour, with a silicone insert extending down to mold around the mouse. Brass collimators were designed for parallel opposed beams to treat the spinal cord while shielding the brain and upper extremities of the animal. Up to six animals may be accommodated for simultaneous treatment within the restraint system. Two plans were generated targeting the cervical spinal cord, with either the entrance (ENT) or the BP portion of the beam. Dosimetric uncertainty was measured using EBT3 radiochromic film with a dose-averaged linear energy transfer (LETd) correction. Positional uncertainty was assessed by collecting a library of live mouse scans (n = 6 mice, two independent scans per mouse) and comparing the following dosimetric statistics from the mouse cervical spinal cord: Volume receiving 90% of the prescription dose (V90); mean dose to the spinal cord; and LETd. Film analysis results showed the dosimetric uncertainty to be ±1.2% and ±5.4% for the ENT and BP plans, respectively. Preliminary results from the mouse library showed the V90 to be 96.3 ± 4.8% for the BP plan. Positional uncertainty of the ENT plan was not measured due to the inherent robustness of that treatment plan. The proposed high-throughput mouse proton irradiation setup resulted in accurate dose delivery to mouse spinal cords positioned along the ENT and BP. Future directions include adapting the setup to account for weight fluctuations in mice undergoing fractionated irradiation.

WITHDRAWN: Zinc oxide assisted photcatalytic decolonization methyl violet dye: As a model for water treatment

This work attributed to photocatalytic removal of an aqueous solution of methyl violet dye (MV) in a suspension ZnO as a photocatalyst, was carried out by using irradiation system in a photoreaction cell of 100 ml at room temperature 298 K. Various parameters have been studied, such as effect of mass dosage, initial dye concentration, etc. the reduce of concentration was detected by disappear of color was monitored by using UV–VIS spectrophotometer.

Satellite communication station for Ka and Q-bands

The article reveals the features of the organization of satellite communication systems in the remote and northern territories of Russia. The importance of providing broadband access to multimedia resources and the Internet is shown. The problems of development of an earth station of satellite communication Ka and Q-bands, providing broadband communication, are considered. Its architecture and operating principles are presented. To ensure the possibility of operation of the station in two frequency ranges, replaceable irradiation systems with a microwave path are used. The features of their manufacture are disclosed in detail. The results of experimental studies of irradiating systems with a microwave path are presented. The gain of the irradiating system with a microwave path of the Q-band in the composition with a parabolic mirror with a diameter of 1.2 m was 51.8 dB at the transmission frequencies, and 45 dB at the receiving frequencies. The gain of the irradiating system with the Ka-band microwave path was 47.8 dB at the transmission frequencies and 43.8 dB at the receiving frequencies. Thus, the use of the proposed earth station of satellite communication Ka and Q-bands will allow organizing satellite broadband communication in remote and northern territories of Russia.

An Active Irradiation System with Automatic Beam Positioning and Focusing for a Medical Cyclotron

A novel active focusing system was developed for enhancing the irradiation performance of the 18 MeV medical cyclotron in operation at the Bern University Hospital in view of the production of non-conventional medical radioisotopes using solid targets. In several cases, such as the production of 43Sc and 44Sc, the beam has to be kept stable within a very small target of about 5 mm diameter. For this purpose, we conceived and realized an apparatus based on a compact focusing and steering magnet system followed by a two-dimensional beam monitoring detector and a specific feedback software that drives the magnet to optimize the beam for a given irradiation set-up. We report on the design, realization and validation beam tests performed using the research beam transfer line of the Bern cyclotron. We demonstrated that the beam spot can be kept on target thanks to the fact that the system automatically reacts to perturbations. Compactness is one of the key features of this system, allowing its use in accelerator facilities with limited space, such as medical cyclotrons for radioisotope production.

An irradiation system for evaluating individual electronic dosimeters in pulsed x-ray beams

Electronic dosimeters are widely used for individual monitoring, especially for direct dose equivalent assessment associated with a specific task. Most of x-ray beams used in diagnostic radiology have been considered as pulsed one due to their high intensity during a very short time. This work showed that a Rhos Vari X x-ray machine was feasible to be used to evaluate electronic dosimeters in high pulsed air kerma rates to detect deficiencies in their response. In comparison to continuous x-ray beams, it was observed that personal dose equivalent values were severely underestimated by some electronic dosimeters in pulsed radiation fields.

Ultraviolet Irradiation Units Installed In the Homes of Children With Asthma Reduces Asthma Severity

Multifaceted environmental control interventions recommended as part of asthma management can be costly and difficult to maintain. The objective of this study was to determine if the novel CREON2000A ultraviolet (UV) air irradiation system technology (General Innovation & Goods. Inc.) used as a single environmental intervention would reduce asthma severity in children with mild-moderate persistent asthma.

Development of a dose distribution shifter to fit inside the collimator of a Boron Neutron Capture Therapy irradiation system to treat superficial tumours.

The Kansai BNCT Medical Center has a cyclotron based epithermal neutron source for clinical Boron Neutron Capture Therapy. The system accelerates a proton to an energy of 30MeV which strikes a beryllium target producing fast neutrons which are moderated down to epithermal neutrons for BNCT use. While clinical studies in the past have shown BNCT to be highly effective for malignant melanoma of the skin, to apply BNCT for superficial lesions using this system it is necessary to shift the thermal neutron distribution so that the maximum dose occurs near the surface. A dose distribution shifter was designed to fit inside the collimator to further moderate the neutrons to increase the surface dose and reduce the dose to the underlying normal tissue. Pure polyethylene was selected, and a Monte Carlo simulation was performed to determine the optimum thickness of the polyethylene slab. Compared with the original neutron beam, the shifter increased the thermal neutron flux at the skin by approximately 4 times. The measured and simulated central axis depth distribution and off axis distribution of the thermal neutron flux were found to be in good agreement. Compared with a 2cm thick water equivalent bolus, a 26% increase in the thermal neutron flux at the surface was obtained, which would reduce the treatment time by approximately 29%. The DDS is a safe, simple and an effective tool for the treatment of superficial tumours for BNCT if an initially fast neutron beam requires moderation to maximise the thermal neutron flux at the tissue surface.

The Impact of Short-Wave UV Radiation on Peroxidase Activity in Soft Wheat Seeds

The effect of UV radiation on plants provokes oxidative stress, accompanied by the production of reactive oxygen species that can have a direct destructive effect on cellular structures and initiate free radical oxidation of proteins, lipids, and nucleic acids. There is an antioxidant defense system in plant cells that includes a complex of low and high molecular weight compounds. Antioxidants with high molecular weight are enzymes, the key of which is peroxidase [PO]. The paper studies changes in PO activity in soft spring wheat seedlings due to grain treatment with small and medium doses of short-wave UV radiation. A UV-dosed irradiation system (Bio-Link Vilber) with the exposure time 0–60 minutes in increments of 10 minutes was used for seed treatment. Pre-soaked wheat seeds were germinated in Petri dishes. PO activity was determined colorimetrically in three-day-old wheat seedlings, according to A. L. Boyarkin [3]. When the source was irradiated for up to 30 minutes, a clear dependence of the PO activity on the exposure time was not established. The maximum increase in peroxidase activity (by 25.9% relative to the control) was detected with 30-minute UV irradiation. A further increase in exposure time led to a significant decrease in enzyme activity. Moreover, vital feedback was revealed between the activity and exposure time in the range of 30–60 minutes.

Alternative to High Pressure Mercury Vapor Lamp for Photo Induced Fluorescence Analytical Methods; Application to the Determination of Pesticides in Water.

The photo-induced fluorescence method is often applied to determine non-native fluorescent compounds. It typically uses UV irradiation from a high pressure mercury vapor discharge lamp to create photo-induced fluorescent compounds, which are then quantified by fluorescence spectroscopy. However, these mercury lamps require a high-voltage power supply and may accidentally induce electric shocks and the release of mercury vapors. As an alternative, we have evaluated in this technical note new UV-C germicidal lamps. These lamps exhibit a higher power at 254 nm and allowed us to obtain a far greater amount of photo-induced compounds in a shorter time. For the first time, this new irradiation system has been applied for the determination of pesticides in water and has shown a significant increase in the method sensitivity. These good results allowed us to conclude that the new UV-C lamps are a relevant alternative to high pressure mercury vapor discharge lamps for use with photo induced fluorescent methods.

Measurement of absorbed dose rate in water phantom maintained at body temperature by 60Co irradiator – comparison of experimental results and Monte Carlo simulation

To analyze the biological effects of radiation, it is important that the conditions of in vitro experiments match closely with those of in vivo experiments. In this study, we constructed an irradiation system to conduct irradiation experiments under conditions similar to those of in vivo experiments. The Dongnam Institute of Radiological and Medial Sciences has a gamma irradiator including 60Co radioisotope for research purposes and accreditation for standard calibration of the ion chamber. The temperature of the water phantom was maintained the same as that of the normal human body, and the physical dosimetry was carried out accurately using the ion chamber with traceability. We report the measurement of lateral profiles, depth profiles, and absorbed dose rate in water, Dw, at the irradiation location of the blood samples using a farmer-type ion chamber. We simulated the source, collimator, irradiator, phantom, and extra structure of the gamma irradiation system using the Monte Carlo code and compared the simulated and the experimental results. The experimentally and theoretically evaluated dose rates were 0.2975 ? 0.0055 Gymin?1 (at coverage factor k = 2) and 0.2978 ? 0.0052 Gymin?1 (at coverage factor k = 2) at source-to-surface distance of 100 cm and 5 gcm?2 depth in the water phantom, respectively. Blood irradiation will be conducted in vitro, under conditions similar to in vivo conditions, to provide the dose-response curve based on dosimetry with traceability.

A Case of Buccal Mucosal Cancer with Function Preserved by Mold Irradiation

Surgical resection or brachytherapy has been used for curative treatment of oral cancer. Although only limited facilities perform brachytherapy, treatment results are as good as those of surgical resection and allow functional preservation. We report here the use of high-dose-rate brachytherapy with a remote after-loading system for mold irradiation for buccal mucosal cancer, in which function is expected to be impaired by surgical treatment. The patient was a woman in her 80s who visited a dental clinic complaining of pain in the left buccal mucosa. She was referred to our department, where a tumor with a rough surface of 39 mm×22 mm was found on the left buccal mucosa. Computed tomography showed a contrast-enhanced soft-tissue mass on the left cheek, with a thickness of 20 mm. Subsequent biopsy of the lesion revealed squamous cell carcinoma, and the tumor was classified as cT2N0M0 （stage Ⅱ）. Surgical resection would be expected to cause dysfunction through the skin on the cheek, therefore simultaneous chemoradiotherapy was planned. The thickness of the oral mucosa should be less than 15 mm, but was 20 mm in this case, making brachytherapy unsuitable. We therefore created a mold device using the occlusion plate to extend the buccal mucosa and maintain contact with the source of radiation, allowing irradiation of the tumor. Mold irradiation was performed using 192-Ir at a total dose of 60 Gy. The patient remains recurrence-free as of 2 years 6 months after mold irradiation.

Rapid green synthesis of non-cytotoxic silver nanoparticles using aqueous extracts of 'Golden Delicious' apple pulp and cumin seeds with antibacterial and antioxidant activity

A simple, facile and rapid microwave irradiated system was applied to synthesize silver nanoparticles using 'Golden Delicious' apple pulp (Malus domestica) and cumin (Cuminum cyminum) seed extracts. The phytosynthesized AgNPs were characterized by Ultraviolet–Visible Spectroscopy (UV–vis), Fourier transform infrared (FTIR), X-ray Diffraction (XRD) Transmission Electron Microscopy (TEM) and Zeta sizer analysis. In the study, the presence of face-centered cubic crystalline structured metallic silver in AgNPs from apple and cumin extracts and the monodisperse nature of AgNPs with the size distribution range of 5.46–20 nm and 1.84–20.57 nm were confirmed, respectively. This study established an efficient green synthesis approach that created so far, the smallest silver nanoparticles by using these two extracts. According to the results obtained, AgNPs synthesized using both extracts were non-toxic against L929 mouse fibroblast cells, while they were effective against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria with a greater effect on S. aureus. Moreover, AgNPs synthesized through cumin extract exhibited a higher ABTS scavenging ability (96.43 ± 0.78% at 160 μg/mL) in comparison to apple pulp extract mediated AgNPs, while both AgNPs showed lower activity for DPPH (27.84 ± 0.56% and 13.12 ± 0.32% from cumin seed and apple pulp extracts, respectively). In summary, our results suggest the green non-cytotoxic AgNPs synthesized in this study could be a promising template for further biological and clinical applications.Graphical abstract

深紫外激光辐照加速材料老化系统的光学设计

深紫外激光辐照加速材料老化系统的光学设计

Development of the multiplex prism for laser irradiation system attachable to an endoscope

Development of the multiplex prism for laser irradiation system attachable to an endoscope

Study of thermal modes of operation of SMD-LEDs in phyto-lamps

LED phyto-irradiators are promising for use in irradiation systems for growing plants in greenhouses using photoculture technology. Cases, when the thermal calculation of phyto-irradiators is performed incorrectly, have an overheating in the active area of the crystal. It results in faster degradation of the semiconductor, reduces the output luminous flux and the service life of the device. To evaluate and analyze scientific works studying thermal models of LED operating modes, examples of the application of modern methods for determining thermal resistances, to study local heating zones on phyto-irradiator boards when using different types of LEDs and modern thermal imagers to detect soldering defects. The authors classified and analyzed the collected materials according to application criteria and implementation prospects. In the course of the research the authors applied methods of systematic approach. To assess the effectiveness of dissipation of thermal energy released by a LED crystal, they calculate the following parameters: thermal resistance between p-n transition and housing, thermal resistance between housing and PCB, thermal resistance between PCB and the environment. The thermal resistance between the p-n junction and the housing is due to the design of the LED, other parameters are set by the thermal models of the developed lighting devices. The applied methods of cooling do not essentially influence the complexity of thermal models, liquid cooling allows to refuse radiator for the linear thermal model, that slightly raises the accuracy of measurements and simplifies the process of calculation of thermal resistance of transition-housing. The primary role in thermal management of luminaires with SMD elements lies in the following elements: power supply circuits, SMD LED soldering quality and materials used, LED locations, PCB dimensions and location in space, ambient temperature, adequate calculation of thermal resistance between the LED and the environment and selection of radiators.