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Basic dosimetry and beam-quality characterization
Published in Gavin Poludniowski, Artur Omar, Pedro Andreo, Calculating X-ray Tube Spectra, 2022
Gavin Poludniowski, Artur Omar, Pedro Andreo
A radiation field is a group of particles, that is, photons, electrons, positrons, protons, neutrons, etc., each having radiant energy and moving in a certain direction. Radiant energies exclude the particle rest energy. For particles with a mass, the radiant energy is the kinetic energy of the particle and the symbol E is used throughout this book for electrons; the energy of photons is represented by the symbol k.
Organization and Management of a Nonionizing Radiation Safety Program
Published in Kenneth L. Miller, Handbook of Management of Radiation Protection Programs, 2020
The three basic concepts of ionizing radiation protection are equally important for nonionizing radiation protection: Minimize exposure time (this often means less dose to the exposed individual)Maximize the distance from the source of radiation, since the intensity of most (but not all) radiant energy decreases with the square of the distance from the source)Make maximum use of shielding where possible. The user should realize: that different materials used for shielding have varying degrees of effectiveness; that the shielding effectiveness often is a function of the wavelength/frequency of the radiation; and that (especially in the lower frequency RF portion of the spectrum), the shielding effectiveness is often very different for the electric field component compared to the magnetic field component of the radiation.
The Physical Environment
Published in Vilma R. Hunt, Kathleen Lucas-Wallace, Jeanne M. Manson, Work and the Health of Women, 2020
Vilma R. Hunt, Kathleen Lucas-Wallace, Jeanne M. Manson
The expanding use of nonionizing radiant energy, which includes ultraviolet, infrared, visible light, microwaves, radio-frequency waves, and coherent light sources (lasers) occurred during a time when the research emphasis was being placed on ionizing radiation. Biological effects of microwave radiation are belatedly under closer scrutiny in part because of the reevaluation of the occupational exposure standard of 10 mW/cm2 for an 8-hr work day. A power density in excess of 10 mW/cm2 should not occur for a period any longer than 6 min. The performance standard for microwave ovens specifies a maximum level of 1 mW/cm2 at 5 cm from the external surface of the oven at manufacture and a maximum of 5 mW/cm2 at 5 cm from the external surface of the oven throughout the life of the product. Microwave ovens are extensively used in restaurants, during drying procedures for a wide variety of manufacturing procedures, and more recently in the home kitchen.
UV-Photokeratitis Associated with Germicidal Lamps Purchased during the COVID-19 Pandemic
Published in Ocular Immunology and Inflammation, 2021
Jesse D. Sengillo, Anne L. Kunkler, Charles Medert, Benjamin Fowler, Marissa Shoji, Nathan Pirakitikulr, Nimesh Patel, Nicolas A. Yannuzzi, Angela J. Verkade, Darlene Miller, David H Sliney, Jean-Marie Parel, Guillermo Amescua
The recent global outbreak of coronavirus disease 2019 (COVID-19), caused by the emergence of the novel human coronavirus SARS-CoV-2, has resulted in significant morbidity and mortality worldwide.1 In order to prevent the spread of disease, individuals and local businesses are seeking novel sanitation strategies against the virus. One such method of sterilization includes the use of consumer-grade UV lamps.2 Germicidal light is radiant energy used to inactivate microbes such as bacteria, mold, fungi, and viruses. Wavelengths on the shorter end of the ultraviolet spectrum are known to be effective for disinfection, specifically UV-C (100–280 nm), while larger wavelengths require more energy and duration of exposure.3,4
The influence of luminous intensity on the eyelid aperture and measurement of the margin reflex distance
Published in Orbit, 2022
Martha Pereira Lima Lang, Diane Ruschel Marinho, Fernando Procianoy
Light, or visible light as it is physically characterized, is a form of radiant energy emitted as photons by a light source. It is the physical agent that acts on the retina to produce visual sensations. The light we perceive has a frequency in the range of 4 × 1014 Hz (red) to 8 × 1014 Hz (violet).6 Illuminance is the amount of incident light per unit area, measured in lux (lux = l m/m2). It is an international unit of measurement for lighting under different conditions.
Modelling the effect of light through commercially available blue-blocking lenses on the human circadian system
Published in Clinical and Experimental Optometry, 2022
Hind Saeed Alzahrani, Sieu K Khuu, Maitreyee Roy
Figure 1 shows the modelled circadian efficiency (CLA,BBL) of radiant energy when viewing light through different BBLs. These results indicate a degree of variability in the circadian sensitivity responses between lenses that is consistent with their transmittance properties, particularly the degree to which they block blue light. The most significant change in the circadian system’s spectral sensitivity was observed for Blu-OLP lenses which attenuated light the most at short wavelengths.