External Beam Radiotherapy and Brachytherapy
Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple in Basic Urological Sciences, 2021
The radioactive decay of an atomic nucleus results in:Alpha radiation: emission of alpha particles (two protons, two neutrons).Beta radiation: emission of beta particles.beta− = electronsbeta+ = protonsGamma radiation: emission of electromagnetic energy (photon).
Fundamental properties of matter, radiation and radioactive decay
Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen in Get Through, 2020
False – although beta decay tends to occur if there is an excess of neutrons, there are other forms of decay. In electron capture or positron emission a nucleus with an excess of protons will covert a proton into a neutron to achieve stability.True – the half-life of a radioactive nuclide is the time taken for its radioactivity to reduce to half its original value. Decay is an exponential process.False – they are inversely proportional. Half-life = loge2/decay constant.True – radioactive decay is not dependent on physical conditions.True – the mean lifetime is the time taken to decay to I/e (1/2.7182) of the initial activity. The mean lifetime is I/(decay constant), so it is (half-life)/(loge2), or about 1.44 times the half-life.
Radiation safety in the cardiac catheterisation laboratory
John Edward Boland, David W. M. Muller in Interventional Cardiology and Cardiac Catheterisation, 2019
Humans are exposed to radiation from a variety of natural and artificial sources. Radioactive materials are in the environment due to the prevalence of naturally occurring radioactive minerals present since the early stages of formation of the universe. The main sources of natural radioactivity are isotopes of uranium, thorium and potassium, which have long half-lives, distributed throughout the earth’s crust. Natural radioactivity results in exposure to terrestrial gamma radiation from soil and building materials, release of radon and radon progeny to the atmosphere, and by uptake of radioactive materials in the food and drink that we consume. Natural radioactivity in food results in a natural level of radioactive potassium, uranium, and thorium in our bodies. Radiation exposure also results from cosmic radiation and from man-made radioactivity in the environment in the form of fallout from atmospheric nuclear weapons testing and nuclear accidents.
177Lu-doxycycline as potential radiopharmaceutical: electrochemical characterization, radiolabeling, and biodistribution in tumor-bearing mice
Published in International Journal of Radiation Biology, 2021
Zorana Milanović, Drina Janković, Sanja Vranješ-Đurić, Magdalena Radović, Željko Prijović, Gordana Zavišić, Marko Perić, Dalibor Stanković, Marija Mirković
To confirm the efficacy of radiolabeling and to determine the retention time of 177Lu and 177Lu-labeled doxycycline, high-performance liquid chromatography (HPLC) was performed. 177LuCl3 solution (20 µl) was injected (thrice) into the column, and the radioactivity profile was monitored. 177Lu -doxycycline (20 µl) was injected into the column in triplicate. The elution was monitored by observing the radioactivity profile. HPLC analysis was performed on a Hewlett Packard 1050 chromatography system coupled to a Raytest gamma flow detector. A reversed-phase C-18 column (4.6 × 250 mm, 5 µm particle size) was used for separation. The isocratic elution method was applied, using the mixture of acetonitrile and water (60:40, v/v). The temperature of the column was at room temperature (25 ± 1 °C), and the constant flow rate was set at 0.8 ml/min.
The influence of multiple oral administration on the pharmacokinetics and distribution profile of dalcetrapib in rats
Published in Xenobiotica, 2021
Hiroaki Takubo, Tomohiro Ishikawa, Toshio Taniguchi, Kazunori Iwanaga, Yukihiro Nomura
The absorption, distribution and elimination of dalcetrapib were investigated to characterize the accumulation of dalcetrapib in the body during multiple oral administration. Plasma and tissue concentrations of radioactivity in rats after the first dose of 100 mg/kg 14C-dalcetrapib are consistent with those in the single oral dose study previously reported by Takubo et al. (2014). The elimination half-life at the last dose and the cumulative excretion of radioactivity coincide with those in the previous single-dose study. The trough concentration was also comparable on days 3 and 7, indicating that the radioactivity in the plasma reached the steady state by day 4. Derks et al. (2011) had previously demonstrated that the concentration of the active form of dalcetrapib reached the steady state approximately on day 4 of multiple administration of dalcetrapib in a clinical study. They concluded that the results indicate minimal or no accumulation of dalcetrapib in the plasma. Since the active form of dalcetrapib forms covalent bonds with thiols in the body, there had been concern that it might accumulate in the plasma. However, our multiple administration of dalcetrapib study in rats provided no such evidence.
Neutrons are forever! Historical perspectives
Published in International Journal of Radiation Biology, 2019
Early investigations of the biological effects of neutrons were driven largely by scientific curiosity to catalog the effects and to gain understanding of the fundamental mechanisms of radiation action in biological systems, as well as to use this new radiation as an additional probe of normal biological processes (Zirkle et al. 1937; Zimmer and Timoféeff-Ressovsky 1939; Gray et al. 1940; Thoday and Lea 1942). Neutrons provided a new type of densely-ionizing radiation; neutron experiments could extend what was already known of densely-ionizing effects from natural alpha-particles from radioactive decay. Additionally, neutrons had the advantage of high penetration through biological samples, in contrast to the extremely short ranges of alpha-particles from radionuclide sources. By 1959, a wide range of biological effects had been studied in many different biological organisms. Illustrative selections are listed in Tables 1 and 2; these tables are not intended to provide comprehensive summaries of the extensive literature. Methods for cloning from single mammalian cells had not been developed until the mid-1950s (Puck and Marcus 1955) and were then beginning to be applied in radiobiology to obtain cell survival curves after irradiation with X rays (Puck and Marcus 1956; Puck et al. 1957).
Related Knowledge Centers
- Alpha Decay
- Beta Decay
- Gamma Ray
- Radionuclide
- Thorium
- Atomic Nucleus
- Half-Life
- Internal Conversion
- Nuclear Transmutation
- Potassium-40