Environmental Inhaled Agents and Their Relation to Lung Cancer
Jacob Loke in Pathophysiology and Treatment of Inhalation Injuries, 2020
Ionizing radiation is radiation that removes electrons from atoms, and includes energetic particles such as alpha-(a) and beta-(/3) particles and protons, and electromagnetic rays such as x- and gamma-rays (Boice and Land, 1982). Human beings have always been exposed to natural background radiation from cosmic rays and terrestrial radiations due to natural occurrence of radioisotopes (Klement et al., 1972; NCRP, 1975). Uranium and thorium are abundant in the earth s crust, and they give rise to a series of decay products that emit radioactive particles including a-particles and /3-particles (Parkes, 1982a). a-Particles are positively charged helium nuclei with great mass and ionizing power but only weak penetrating capacity. They are therefore radiations of high linear energy transfer that release energy in short tracks of dense ionization (Boice and Land, 1982). When applied to the airways, they cause ionization maximally when they have passed through the bronchial mucosa and reached the basal cells (Parkes, 1982a). The double-strand DNA molecule is thought to be the critical target for radiation-induced cellular damage (Boice and Land, 1982). 13-Particles are electrons with great penetrating capacity but less ionizing power. Since ionization is thought to be the cause of malignant transformation in living cells, inhaled a-particles are considered more important than /3-particles in the development of lung cancer.
Our Radiation Environment
T. D. Luckey in Radiation Hormesis, 2020
This chapter provides a background of the different types and sources of ionizing radiation which constitute our radiation environment. This information allows careful evaluation of the biologic effects of chronic and acute whole-body exposures to low doses of ionizing radiation greater than our background radiation. Our total whole-body exposure to ionizing radiation can be estimated from the components discussed (Table 1.12). The relatively high value for cosmic rays includes consideration for those persons who live or vacation in the interior of the U.S. Radiation from radionuclides which emit gamma rays is assumed to deposit all the energy within the body; this error increases as the energy exceeds 2 MeV. The average adult exposure without medical diagnosis or therapy is about 2 mGy/year, about 5 μGy/d. When medical exposures are deleted, endogenous, cosmic, and terrestrial radiation contribute about equal amounts. Endogenous radiation becomes the largest single source when an estimate for delta rays is included. It is listed separately because it has not been generally recognized.
Radiation Therapy and Radiation Safety in Medicine
Suzanne Amador Kane, Boris A. Gelman in Introduction to Physics in Modern Medicine, 2020
The National Cancer Institute estimates that half of all US cancer patients now are treated with ionizing radiation in radiation therapy (or radiotherapy), while enormous numbers of lifesaving medical exams (see Chapters 5 and 6) make routine use of small doses of radiation. In spite of this, a widespread perception exists that any amount of radiation represents a serious hazard. The truth is complicated: ionizing radiation can be used to diagnose and treat cancer and other illnesses, and yet itself can be a carcinogen (cancer-causing agent), or cause an illness called radiation sickness. In this chapter, we review the risks and benefits involved in using ionizing radiation in medicine. We will see that the radiation doses used in medical imaging have been lowered over time, until the benefits of proper medical care almost always outweigh the risk. In fact, the compromise between risk and benefit in modern medical imaging is more favorable than that presented by many common drugs, few of which are absolutely complication-free and some of which cause lethal reactions in an extremely small number of cases.
Individual response of the ocular lens to ionizing radiation
Published in International Journal of Radiation Biology, 2023
Stephen G. R. Barnard, Nobuyuki Hamada
Health effects of ionizing radiation exposure can vary among individuals. In addition to physical factors (e.g. dose, dose rate, radiation quality, irradiation volume), there are various potential factors that may modify individual responses, such as sex, age, lifestyle, comorbidity, coexposure, genetics, and epigenetics (Foray et al. 2016). However, such factors and mechanisms underlying such individual responses are complex and remain largely uncharacterized (Applegate et al. 2020). In 2018, the International Commission on Radiological Protection (ICRP) therefore established Task Group (TG) 111 ‘Factors governing the individual response of humans to ionising radiation’ to review the current science relevant to the individual response to radiation and develop a report for publication in the Annals of the ICRP. Here we give an overview of our review of scientific literature in relation to radiation cataracts conducted as part of the work of TG 111.
Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review
Published in International Journal of Radiation Biology, 2020
Michalina Gramatyka, Maria Sokół
Biological effects of ionizing radiation are related to the energy deposition in living matter. The units to measure a dose and its biological effects are required to assess the impact of ionizing radiation on human health and to set the guidelines in radioprotection (Hall and Giaccia 2018). The fundamental dosimetric quantities of ionizing radiation are absorbed and equivalent dose. Absorbed dose is indicated in Grays – 1 Gy equals 1 Joule of absorbed energy per kilogram of mass, e.g. tissue. Because equal doses of different types of ionizing radiation are not equally absorbed in biological matters radiation exposure can be expressed as tissue equivalent dose in Sieverts: 1 Sv is the absorbed dose multiplied by a radiation weighting factor accounting for differences in the biological response (Pfalzner 1983).
Pharmacological management of ionizing radiation injuries: current and prospective agents and targeted organ systems
Published in Expert Opinion on Pharmacotherapy, 2020
Common forms of ionizing radiation include electromagnetic radiation (γ-rays and X-rays) and particulate radiation (a stream of atomic or subatomic particles; electrons, neutrons, protons, β-, and α-particles). The extent of ionization deposited along a track of radiation defines the magnitude of linear energy transfer (LET). γ-Rays and X-rays are of low LET and characterized by sparse ionization while α-particles and neutrons are of high LET and track high ionization [5]. Now, it is well understood that the free radicals generated by radiolysis of cellular aqueous milieu and their interaction with one another and also with oxygen are primarily responsible for inflicting radiation injuries. Free radicals (primarily hydroxy radicals) are responsible for the indirect radiation action producing approximately 75% of low LET damage. This part may potentially be prevented by radical scavengers. By contrast, radical scavenger does not protect against damage by high-LET radiation which is produced predominantly by direct radiation action in DNA. Variation in an individual’s response to radiation may be as a result of an individual’s ability to detoxify radiation-induced free radicals. Such detoxification of free radicals is due to endogenous antioxidant enzymes, thiols, and various exogenous antioxidant nutrients; vitamin E, selenium, carotenoids, vitamin C, and flavonoids.
Related Knowledge Centers
- Alpha Particle
- Atom
- Beta Particle
- Gamma Ray
- Ionization
- Molecule
- Ultraviolet
- X-Ray
- Laser
- NON-Ionizing Radiation