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Radiometry
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The long-lived phosphorescence states, discussed above, is an important asset when measuring the accumulated dose to the detector. In contrast to prompt luminescent crystal materials, integrating luminescent detectors are designed to have long-lived energy states that can be deliberately de-excited by an external energy source. If the de-excitation is induced by thermal energy (heating the material), the process is called thermoluminescence (TL); if the excitation is induced by illumination with optical radiation, it is called optically stimulated luminescence (OSL). These detectors are often used as personal dosimeters to monitor occupational exposure, but also for environmental surveys or retrospective dose assessments. Figure 5.2 shows the energy levels and transitions in an integrating luminescent material.
Radiation Safety
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Debbie Peet, Elizabeth Davies, Richard Raynor, Alimul Chowdhury
There are several hazards associated with the use of lasers. Lasers and phototherapy equipment fall under the Control of Artificial Optical Radiation at Work Regulations (2010). There are many other sets of regulations and other requirements that also apply to the use of lasers which are described in the MHRA document “Lasers, intense light source systems and LEDs – guidance for safe use in medical surgical, dental and aesthetic practices” (MHRA 2015).
Organization and Management of a Nonionizing Radiation Safety Program
Published in Kenneth L. Miller, Handbook of Management of Radiation Protection Programs, 2020
The term “nonionizing radiation” refers to the group of electromagnetic radiations with energies less than about 10 eV, corresponding to wavelengths in the near ultraviolet (UV), visible (VIS), infrared (IR), and radiofrequency (RF)/microwave portions of the spectrum (Figure 1). This includes some of the energy often referred to as “optical” radiation, and that which is termed “light”, millimeter waves, radio and TV broadcast, power transmission, low-frequency electric and magnetic fields, and most coherent laser/maser energy. In addition, ultrasound (which is due to pressure variations/mechanical vibration) is also included under the heading of nonionizing radiation. The reader is reminded that ultrasonic energy is nonelectromagnetic energy. Other than ultrasound, this chapter does not deal with acoustic sound/audio energy or “noise”, despite its similarity to ultrasound.
Emerging drugs for the treatment of diabetic retinopathy
Published in Expert Opinion on Emerging Drugs, 2020
Elio Striglia, Andrea Caccioppo, Niccolò Castellino, Michele Reibaldi, Massimo Porta
Several ophthalmic lasers are employed in the treatment of DR. They induce thermal damage after absorption of energy by tissue pigments. They vary according to wavelength and the source of optical radiation. Green light argon laser (514 nm) is the standard of care, while krypton (647 nm) or diode laser (810 nm) are preferred in particular conditions such as cataract or intravitreal bleeding, for their higher penetration properties. Since 2006, lasers have been introduced which, unlike traditional ones, deliver multiple spots simultaneously, with consequent reduction in treatment time, pain, and side effects while maintaining unchanged effectiveness [14]. Pulsed sub-threshold laser reduces thermic damage to the neuroretina and choroid and the risk of reduced contrast and blind spots, as well as permeability of the blood retinal barrier (BRB).
Evaluating the blue-light hazard from solid state lighting
Published in International Journal of Occupational Safety and Ergonomics, 2019
John D. Bullough, Andrew Bierman, Mark S. Rea
Optical radiation, including visible, infrared and UV energy, can damage the retina in three possible ways [49]: (a) mechanical damage from intense pulsed lasers; (b) thermal damage from radiation absorption that increases the temperature of retinal tissues; (c) photochemical damage activated by absorbed photons of sufficient energy incident on the retina. The first two mechanisms require extremely high intensities not experienced with use cases for any type of light source used in architectural lighting. In the 1970s it was discovered that photochemical damage in the primate retina from the blue-light hazard can occur under specific exposure conditions [35], which might be experienced by humans from commercial light sources.
A feasibility study of a novel low-level light therapy for digital ulcers in systemic sclerosis
Published in Journal of Dermatological Treatment, 2019
M. Hughes, T. Moore, J. Manning, J. Wilkinson, S. Watson, P. Samraj, G. Dinsdale, C. Roberts, L. E. Rhodes, A. L. Herrick, A. Murray
Possible optical radiation hazards were assessed to verify that neither patient nor operator would be exposed to intensities exceeding those set in the UK Control of Artificial Optical Radiation at Work Regulations 2010. Nonetheless, both patient and operator wore goggles at all times the light device was in operation, as the light was slightly uncomfortable to directly observe. There was no contact between the DUs and the LEDs (Figure 1). Before and after each patient contact, the light device treatment area was cleaned with an alcohol-based wipe.