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Quality Control of High-Energy External Beams
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Edwin Aird, W. P. M. Mayles, Cephas Mubata
Strontium-90 checks are useful on a regular basis to check the maintenance of the constancy of the response of the ionisation chamber/electrometer combination. Six-monthly checks of this nature should show a consistency of better than 1%. However, it is important to recognise that the sensitivity of a chamber to 90Sr beta particles may remain constant even when the sensitivity to photons, particularly at low energy, has changed markedly. In all cases, it is fundamental to correct the reading according to the decay of the reference source used (either 90Sr or other long-lived radionuclide).
Radiotherapy Physics
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Andrea Wynn-Jones, Caroline Reddy, John Gittins, Philip Baker, Anna Mason, Greg Jolliffe
One use for sealed sources in radiotherapy is for performing constancy checks (QC) on radiation monitoring equipment (such as ionisation chambers). When performing QC on a linear accelerator, it is essential to know that the variation measured is a result of fluctuation in the output of the linear accelerator and not due to changes in the sensitivity of the chamber. As the activity of the Strontium-90 source decays at a predictable rate (with a half-life of 29.1 years), it can be used to ensure a consistent response from the measurement equipment over many years. Typical strontium sources used for radiation monitoring QC have activities in the range of 10–900 MBq, and so to use sources in this way the HSE must be notified as they are more radioactive than the notification quantity of 10 kBq.
Inhalation Toxicity of Metal Particles and Vapors
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
The concern over adverse effects of strontium intake is based on the radiation damage, since strontium-90, present in nuclear fallout, is a potent environmental health hazard. Chemically, toxicity from strontium is almost nil. No adverse effects from industrial use have been reported.
A review of the impact on the ecosystem after ionizing irradiation: wildlife population
Published in International Journal of Radiation Biology, 2022
Georgetta Cannon, Juliann G. Kiang
Twenty-one years later after the Chernobyl power plant explosion, various isotopes of plutonium, strontium-90, americium-241, and cesium-137 were still detected at high levels causing adverse biological effects across the nearby areas (Voitsekhovych et al. 2007). Wildlife continued to be exposed to substantial radiation doses after humans were evacuated from these areas. The half-life of cesium-137 is approximately 30 years and it decays by β emission to a metastable isomer of barium-137. The half-life of barium-137 isomer is 2 minutes. Subsequently, the metastable isomer emits γ radiation and becomes ground state barium (Baum et al. 2002). Food or water contaminated with cesium-137 that are ingested lead to internal β and γ radiation doses in addition to external radiation doses. The half-life of cesium-134 is about 2 years. Cesium-134 emits β particles. The half-life of strontium-90 is approximately 29 years. Strontium-90 emits pure β radiation. Most of the plutonium isotopes emit α particles, which are ionizing and harmful, but have a short penetration distance. The half-life of plutonium-241 is approximately 14 years. It emits β radiation to become americium-241. The half-life of americium-241 is 432 years, and it emits α particles to become neptunium-237, with a by-product of γ emissions (Baum et al. 2002). This is the composition of radiation released and retained in the soil, water and air across the Chernobyl landscape. In addition to external radiation exposure, ingestion of contaminated food and water by wildlife occurred from the beginning of the disaster and continues to the present.
Peptide receptor radionuclide therapy in neuroendocrine neoplasms and related tumors: from fundamentals to personalization and the newer experimental approaches
Published in Expert Review of Precision Medicine and Drug Development, 2023
There are also issues related to the availability of 90Y in its NCA form on a large scale for clinical use. It is obtained from the 90Sr/90Y radionuclide generator system. The separation of NCA 90Y suitable for clinical utilization from 90Sr is highly challenging due to the strict regulatory requirement of a very low permissible limit of 90Sr in separated 90Y. Strontium-90 in ionic form localizes in the skeleton and owing to its long half-life (28.8 y) is radiotoxic [6]. This causes restrictions on the commercial availability and widespread use of clinical-grade 90Y.
The influence of changing dose rate patterns from inhaled beta-gamma emitting radionuclide on lung cancer
Published in International Journal of Radiation Biology, 2018
Stephanie Puukila, Christopher Thome, Antone L. Brooks, Gayle Woloschak, Douglas R. Boreham
When determining radiation risk to those exposed to internally deposited radioactive materials a proper calculation of dose rate is crucial. When inhaled or ingested, radioactive material will impact cells, tissue, and organs differently depending on the deposition, dose-distribution, and dose rate. Determining a metric to represent the dose rate of internally deposited radionuclides is challenging. Dose rate is dependent on both the physical and biological half-life of the radionuclide, is unique for each radionuclide, and can change rapidly as a function of time. Initial dose rate has been used to describe the relationship between dose rate and biological effects (Brooks et al. 2009). However, because of the wide range of effective half-lives this is not a very useful metric to evaluate biological changes. It has also been suggested that the dose rate could be estimated as a lifetime average dose rate (DRLA) (Raabe 1987, 1992, 2010, 2015). This metric is simply dividing the latent period, the time between the insult and the development of the disease or cancer, by the total dose. Such an approach has nothing to do with the relationship between energy, time, dose, dose rate and the induced molecular, cellular tissue or organ responses. The very short half-life of yttrium-90 (90Y) results in a very high and rapidly changing dose rate with the dose delivered over a few days (Table 1). The latent period for cancer induction is dependent on both the total dose and dose rate so that one would predict that 90Y would have the shortest latent period and the lowest lifetime average dose rate as calculated by Raabe (2010, 2015). The long-lived strontium-90 (90Sr) on the other hand results in a changing dose pattern that is protracted over a very long period of time and is more similar to a chronic low dose rate exposure. Figure 1 illustrates the changing dose rate and cumulative dose of each radionuclide. In this study, we propose a dose rate metric at the time of the effective half-life of each radionuclide in the lung when half the dose is delivered at a higher and half at a lower dose rate. The small number of animals in the studies used in this manuscript for inhaled relatively insoluble particles varying ineffective retention half-life in the pulmonary region precludes the use of the data to evaluate the LNT model in the low dose region. However, the data from these experiments will provide valuable insight into biological responses to internal exposure at a low dose rate.