radiation beam
Recently Published Documents


TOTAL DOCUMENTS

359
(FIVE YEARS 71)

H-INDEX

21
(FIVE YEARS 3)

Author(s):  
Ai Yanagihara ◽  
Katsumi KISHINO

Abstract In this study, the monolithic integration of LEDs with different emission colors (wavelengths of 543, 573, and 597 nm) with the directional radiation profiles was demonstrated. InGaN/GaN nanocolumn arrays ordered in a triangular lattice were prepared side by side, changing the diameter of the n-GaN nanocolumn (Dn-GaN). The periodic arrangement of the nanocolumns led to the photonic crystal (PC) effect. The photonic band edge wavelength (λB) and the InGaN bandgap were controlled by the Dn-GaN. By controlling λB closely at the bandgap wavelength, the PC effect provided directional beam radiation from the LEDs with radiation angles of approximately ±30°


Author(s):  
Benjamin K. Hendricks ◽  
Joseph D. DiDomenico ◽  
Igor J. Barani ◽  
F. David Barranco

<b><i>Introduction:</i></b> The ZAP-X Gyroscopic Radiosurgery system (ZAP Surgical Systems, Inc., San Carlos, CA, USA) is a novel high-dose targeted stereotactic radiosurgery platform for outpatient use that includes self-shielding, X-ray image guidance, and the capacity to aim the radiation beam gyroscopically at an intracranial lesion using 5 independent degrees of freedom. The ZAP-X Gyroscopic Radiosurgery system accomplishes these actions while meeting widely accepted standards for dose gradient and accuracy. This retrospective study examined data of patients treated with gyroscopic radiosurgery (GRS) to document clinical outcomes. <b><i>Methods:</i></b> Medical records of all outpatients treated with GRS over a 20-month period from January 2019 to August 2020 were searched to extract relevant details, including follow-up data until August 2021 (32-month study interval). Patients with &#x3c;6 months of radiographical follow-up data were excluded unless death occurred. Data collection included pretreatment clinical history, pathological diagnosis, radiographical features, treatment parameters, and long-term clinical and radiographical follow-up. <b><i>Results:</i></b> Sixty-eight patients received outpatient treatment with GRS during the 20-month treatment interval, with 59 patients remaining after exclusion for the minimum follow-up threshold, with a mean (standard deviation [SD]) fractionation of 1.85 (1.63). Eighty-two lesions were treated across a very heterogeneous patient population, including meningiomas (42.4%), metastases (39.0%), gliomas (6.8%), schwannomas (1.7%), and pituitary tumor (1.7%). Mean (SD) radiographical follow-up data (14.7 [6.60] months) were available for 56 patients. During that interval, 13 treated lesions in 13 patients (15.9%) demonstrated progression, 9 of which were stable during the initial posttreatment imaging surveillance period. Mean lesion volume was stable from pretreatment (2.54 cm<sup>3</sup> [4.37 cm<sup>3</sup>]) to most recent follow-up (2.80 cm<sup>3</sup> [8.20 cm<sup>3</sup>]) (<i>t</i> [79] = −0.310; <i>p</i> = 0.76). Minor adverse clinical events were noted in 3 (5.1%) of the 59 patients during the posttreatment phase that may have been related to the treatment. Ten (16.9%) patients died within the 32-month study interval. <b><i>Discussion/Conclusion:</i></b> This preliminary assessment of the first series of patients treated with the Zap-X Gyroscopic Radiosurgery system documents its overall feasibility in clinical applications. Although the duration of follow-up was brief, GRS appeared to be both safe and effective. Additional analysis, with an ongoing prospective registry, is underway.


Metrologia ◽  
2021 ◽  
Vol 59 (1A) ◽  
pp. 06001
Author(s):  
C Kessler ◽  
D Burns ◽  
B Downton ◽  
M McEwen

Main text A new key comparison of the standards for absorbed dose to water of the National Research Council of Canada (NRC), Canada and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in October 2020. The comparison result, based on the calibration coefficients for three transfer standards and evaluated as a ratio of the NRC and the BIPM standards for absorbed dose to water, is 0.9995 with a combined standard uncertainty of 3.4 parts in 103. The result agrees within the uncertainties with the comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).


Metrologia ◽  
2021 ◽  
Vol 59 (1A) ◽  
pp. 06002
Author(s):  
C Kessler ◽  
D Burns ◽  
B Downton ◽  
M McEwen ◽  
E Mainegra-Hing

Main text A new key comparison of the standards for air kerma of the National Research Council of Canada (NRC), Canada and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in October 2020. The comparison result, based on the calibration coefficients for three transfer chambers and expressed as a ratio of the NRC and the BIPM standards for air kerma, is 1.0022 with a combined standard uncertainty of 2.2 parts in 103. The result agrees within the uncertainties with the indirect comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).


2021 ◽  
Author(s):  
Richard Victor Biswas ◽  
Farhadur Arifin

Abstract A graphene-based modified bowtie plasmonic nanoantenna resonating in the optical frequency spectrum with the periodic directors created by the slots on top of the radiating structure has been proposed in this paper. In the field of nanophotonics, a few optical nanoantennas have been reported to construct multipath wireless nanolinks. At the telecommunication wavelength of 1550 nm (193.5 THz), the maximum directivity of 9.67 dBi has been reached due to the maximum absorption power of graphene sheet by selecting the chemical potential of 0.5 eV. Since graphene supports surface plasmon polariton waves and acts either as an absorptive or transparent medium for distinct chemical potentials, the proposed graphene-based slotted bowtie optical nanoantenna has been optimized to obtain a dynamically controlled triple-directional radiation beam. With this distinctive nature, a multipath intra or inter on-chip wireless nanolink for secure optical data transfer can be realized by integrating a set of our proposed optical plasmonic nanoantennas.


2021 ◽  
Vol 2119 (1) ◽  
pp. 012148
Author(s):  
K.A. Finnikov ◽  
V.V. Vinokurov ◽  
A.D. Nikolenko ◽  
Y.V. Zubavichus ◽  
O.A. Kabov

Abstract Numerical simulation of heat transfer in a mirror for focusing a synchrotron radiation beam and its thermally stressed state has been carried out. The choice of the method for cooling the mirror through contact with the water-cooled plates, which provides the specified limitations on thermal deformation, has been substantiated. The modes of heat transfer, implemented under different conditions of heat transfer at the boundary of the mirror with water-cooled plates, are compared.


2021 ◽  
Author(s):  
Elmira Eslami ◽  
Ezatolah Kazeminejad ◽  
Azizeh Karimian

Abstract BackgroundsLasers and optics have extensively been used in dental procedures in recent years, so realizing the optical properties of the tooth represents a milestone in its successful applications. the aim of this study was to compare the absorption and transmission of applied wavelengths in 190-1100 nm range in various dentin thicknesses and the effect of changing the direction of beam emission in dentinal tubules.MethodsFifteen dentin specimens with a thickness of 300, 600, and 1000 µm and five specimens from each thickness were prepared by a transverse incision at the upper pulpal roof area of the human molars.Considering the Corono-apical and Apico-coronal direction, we measured the absorption and transmission of parallel light beams perpendicular to the dentin specimens in various thicknesses and two directions using a UV/ Visible spectrometer.ResultsThe ultraviolet wavelength's absorption rate was significantly higher than visible and infrared light irradiation from both directions in three thicknesses (p-value<0.001). Additionally, The radiation beam displacement had no significant differences in the absorption and transmission of ultraviolet, visible, and infrared light in any of the three thicknesses (p-value>0.05).ConclusionAccording to the results, the change in the beam direction during irradiation does not cause a significant difference in light absorption. Furthermore, the results are expected to develop a suitable method for evaluating the trans-dental performance of different optical parameters for diagnostic purposes in the dental tissues.


Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2439
Author(s):  
Youchung Chung ◽  
Teklebrhan H. Berhe

This paper presents a design of a radio frequency identification (RFID) tag antenna in the ultra-high-frequency (UHF) range, which is applicable to a vehicular license plate attached to a vehicle bumper. The main goals are to first improve the identification ratio by controlling the radiation beam pattern and, second, to control the beam direction. Since every vehicle has a license plate, the available plate structure is used to design the antenna. The shape of the tag is rectangular and has a dimension of 525 mm × 116 mm, which is smaller than the typical size of standard plates, 540 mm × 120 mm, used in Europe and Korea. The fabricated tag antenna, the license plate, and the vehicular bumper are fixed by volt and nut. For vehicle tracking and identification, RFID readers are deployed on the road side. For efficient identification, a long distance passive UHF RFID license plate with a patch antenna is proposed to provide not only line-of-sight identification but also left and right beams. Unlike the general UHF tag antennas, in this paper, the patch antenna is designed to attach to the metal part of the car, the license plate holder. The beam patterns of the RFID tag antenna can be controlled by the patch antenna parameter values. The simulation result demonstrates that the proposed UHF RFID tag antenna has a beam radiation pattern as required at 920 MHz. In addition, the estimated read range of the proposed plate meets the requirement of RFID systems.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dirk A. Bartkoski ◽  
Aharon Bar-David ◽  
Michael Kleckner ◽  
Dragan Mirkovic ◽  
Ramesh Tailor ◽  
...  

AbstractWe describe the development and analysis of a new teletherapy modality that, through a novel approach to targeted radiation delivery, has the potential to provide greater conformality than conventional photon-based treatments. The proposed system uses an X-ray lens to reflect photons from a conventional X-ray tube toward a focal spot. The resulting dose distributions have a highly localized peak dose, with lower doses in the converging radiation cone. Physical principles governing the design of this system are presented, along with a series of measurements analyzing various characteristics of the converging beam. The beam was designed to be nearly monoenergetic (~ 59 keV), with an energy bandwidth of approximately 10 keV allowing for treatment energies lower than conventional therapies. The focal spot was measured to be approximately 2.5 cm long and 4 mm wide. Mounting the proposed X-ray delivery system on a robotic arm would allow sub-millimeter accuracy in focal spot positioning, resulting in highly conformal dose distribution via the optimal placement of individual focal spots within the target volume. Aspects of this novel radiation beam are discussed considering their possible clinical application as a treatment approach that takes maximum advantage of the unique properties afforded by converging X-ray beam therapy.


2021 ◽  
Vol 66 (4) ◽  
pp. 62-69
Author(s):  
I. Galstyan ◽  
A. Bushmanov ◽  
Nelya Metlyaeva ◽  
V. Solov'ev ◽  
L. Mershin ◽  
...  

Purpose: To analyze the features of the clinical course of chronic radiation syndrome (CRS) due to external non-uniform chronic exposure to prolonged household contact with a lost source of ionizing radiation. Material and methods: Analysis of 2 clinical observations of patients who developed subacutecourse of CRS and chronic radiation dermatitis due to external non-uniform exposure of the lost sources of ionizing radiation are presented. Results: Boy A. K. from the age of 1 year for 7 years was external radiation exposed (for 1.5 years non-uniform exposure ) to the total dose according EPR tooth enamel about 6.3 Gy, according to the data of retrospective dose recovery on red bone marrow using voxel modeling – 26 (19–37) Gy. F. V. V., male, 38 years, was external non-uniform radiation exposed for 5 months, the total dose according cytogenetic studies of 7.9 Gy (dose rate about 0.035 Gy/h). During the examination in the hospital, the patients were diagnosed with CRS. Within the framework of the bone marrow syndrome, deep thrombocytopenia, moderate leuko- and neutropenia, and moderate anemic syndrome were observed. The latter is not typical for the typical course of CRS and is a criterion indicating a subacute course of the disease. In addition, signs of chronic radiation dermatitis were found in the projection of the action of the ionizing radiation beam. After stopping the radiation exposure, the patients did not recover their hematopoietic function, and in the period of immediate consequences, they developed myelodysplastic syndrome (MDS) with further transformation into acute leukemia. Conclusion: 1. Accidental prolonged household or criminal contact with a source of ionizing radiation can lead to the formation of CRS with an atypical subacute course and the formation of MDS with transformation to acute leukemia in the outcome of the disease or in the period of its consequences. 2. It can be assumed that with external non-uniform radiation exposure, leading to the development of CRS and chronic radiation damage to the skin, agranulocytosis in the subacute course of CRS may be absent. 3. Adverse prognostic signs for the development of MDS and leukemia in the outcome or in the period of the consequences of subacute CRS with non-uniform exposure are long-lasting deep thrombocytopenia and anemic syndrome after the end of radiation exposure.


Sign in / Sign up

Export Citation Format

Share Document