Summary and Development of a New Approach to Senescence
Nate F. Cardarelli in The Thymus in Health and Senescence, 2019
In 1974 Rothen reported that the thickness of an antibody layer absorbed on a nickel slide coated with serum bovine albumin depends upon the time of day in which the experiment is performed.234 In a further report, he noted that such slides remain active at night, but shortly after sunrise they begin to lose activity, reaching a minimum at noon.235 Full activity is regained at sunset. The inactivation experienced can be prevented using a 1- or 3.5-cm lead shield between the sample and solar radiant flux. (It is obvious, I believe, that the radiation involved has wavelengths of less than 0.5 Å and thus is either high-energy X-radiation, low-energy gamma rays, or both.) Terrestrial radiation was excluded by happenstance. On December 13, 1974, there was an eclipse of the sun, with a 65% occultation at Rothen’s laboratory site. The antibody activity increased by a substantial amount during the eclipse. Magnetic fields also altered activity but not to as great an extent. The author speculates that the radiation involved may be a soft component of cosmic radiation, and that the circadian activity noted in antibody-antigen interaction in vivo is due to radiation originating in space.
Radioactive Noble Gases for Medical Applications
Garimella V. S. Rayudu, Lelio G. Colombetti in Radiotracers for Medical Applications, 2019
Currently, 133Xe is the noble gas isotope most commonly used in nuclear medicine. 133Xe de-excites via an 81-keV gamma ray which can be detected externally by conventional nuclear-medicine imaging equipment. The energy of this gamma ray however, is less than ideal for imaging studies. The 133Xe gamma rays are highly attenuated in tissue and thus the contribution to the image of gamma rays originating from the peripheral regions of the body is accentuated relative to the contribution of those occurring in the center of the body. In addition, the spatial resolution of images obtainable with 133Xe is limited by the fact that its 81-keV gamma rays may be Compton-scattered over relatively large angles and still fall in the photopeak window.
Preclinical Molecular Imaging Systems
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
There are several challenges in designing a preclinical imaging system. The spatial resolution of the detector system has to be within the same order of magnitude or higher than the dimensions of the structure to be imaged. In PET imaging, this means that the size of the detector elements has to be reduced to the same dimension as the structure to be imaged. This requires a radical change in the design of the detector technology used compared to what is used in human systems. In SPECT imaging, a conventional parallel hole collimator cannot be used due to the poor resolution properties. Instead, pinhole collimators have to be used to achieve the necessary spatial resolution [5, 6]. The magnification of the pinhole collimator reduces the limitation of the spatial resolution of the detector used (e.g., scintillation camera) and the spatial resolution is primarily limited by the size and absorption properties of the pinhole. The material and the shape of the pinhole will also affect the spatial resolution due to the penetration of the gamma rays [10, 11]. However, the efficiency of a pinhole collimator is low and, in order to improve the sensitivity, multiple pinholes have to be used [6].
Decontamination of rat and human skin experimentally contaminated with 99mTc, 201Tl and 131I radionuclides using “Dermadecon” – a skin decontamination kit: an efficacy study
Published in Cutaneous and Ocular Toxicology, 2018
Dhruv Kumar Nishad, Supriya Bhalla, Kushagra Khanna, Braj Gaurav Sharma, Harish Singh Rawat, Gaurav Mittal, Aseem Bhatnagar
Radioactive material releases alpha, beta and gamma radiations. Alpha particles, consisting of protons (2) and neutrons (2), are an ionizing type of radiation with low capacity to penetrate living tissue (less than 0.1 mm)3. Beta particles are electrons or positrons that are less ionizing, but have more penetrating power (up to a few millimeters). Beta radiation travels only a short distance in tissue, depending on its energy and could be a substantial source of dose to skin. Gamma rays are sparsely ionizing electromagnetic radiation that penetrates the living tissue, typically generating fast electrons that deposit energy resulting in tissue damage. The health hazards resulting from radionuclides that emit these types of particles largely occur after internal deposition4 exposures to gamma radiation will affect skin as a result of external contamination and possible secondary internal (systemic) uptake of radionuclide. The acceptable levels of radionuclide particle contamination should be averaged over 10−2 m2 in the case of skin generally, or over 3 × 10−2 m−2 in the case of hands5. The stratum corneum functions as a reservoir for radionuclide and as a medium for percutaneous absorption. The rapidly growing germinativum layer of epidermal cells is predominantly susceptible to engrossed energy of beta and gamma emissions6.
Radiosensitivity of seedling traits to varying gamma doses, optimum dose determination and variation in determined doses due to different time of sowings after irradiation and methods of irradiation in faba bean genotypes
Published in International Journal of Radiation Biology, 2023
Rajdeep Guha Mallick, Subhradeep Pramanik, Manas Kumar Pandit, Akhilesh Kumar Gupta, Subhrajit Roy, Sanjay Jambhulkar, Ashutosh Sarker, Rajib Nath, Somnath Bhattacharyya
To initiate an induced mutagenesis programme the first step is to select a suitable mutagen. A long-held idea, which probably has been influencing the choice of mutagen (chemical vs. physical) is that the chemical mutagens more favorably induce point mutations, whereas physical mutagens encourage gross lesions, such as chromosomal aberration and rearrangement. The chemical mutagens are said to be highly toxic. On the other hand, the side effects on the health caused by physical mutagens are considerably less. The choice of mutagen completely depends on its availability, allied expenditures and existing infrastructures. Gamma rays are quite easy in application; it penetrates easily due to their non-particulate nature and causes higher mutation frequency. In this experiment, gamma rays have been used for seed irradiation.
Innate lymphoid cells regulate radiation-induced skin damage via CCR10 signaling
Published in International Journal of Radiation Biology, 2020
Yiwen Mao, Rui Tao, Xiaoping Cao, Qin Bao, Dong Wang, Ye Zhao
Radiation therapy is used to treat many cancers. It is a form of electromagnetic radiation using X-rays of the wavelength between 0.01 and 10 nm, which are shorter than ultraviolet rays and usually longer than gamma rays. It is generally believed that radiation therapy has biological effects within hours to weeks after exposure, causing extensive damage to nuclear and mitochondrial DNA and inhibiting cell division and replication capabilities. This damage causes structural destruction of tissues, production of reactive oxygen species (ROS), reduction of functional stem cells, inflammatory reactions in the epidermis and dermis and necrosis of skin cells, which is generally termed ‘radiation damage’. Radiation damage could lead to many complications in patients, such as acute radiation dermatitis (ARDs).
Related Knowledge Centers
- Alpha Particle
- Beta Particle
- Nuclear Fission
- Radioactive Decay
- Radionuclide
- Atomic Nucleus
- X-Ray
- Gamma Spectroscopy
- Very-High-Energy Gamma Ray
- Terrestrial Gamma-Ray Flash