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External Beam Radiotherapy and Brachytherapy
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Sophia C. Kamran, Jason A. Efstathiou
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).
Physics of Radiation Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
With the exception of , each nucleus with an atomic number greater than 82 is unstable. Many nuclei with atomic numbers less than 82 are unstable. By 1965, 259 stable and 1130 unstable nuclides had been identified. Unstable nuclei undergo transitions such as nuclear fission or, more frequently, radioactive decay. Energy is released during this transition. The types of radioactive decays are described below.
Autoradiography
Published in Howard J. Glenn, Lelio G. Colombetti, Biologic Applications of Radiotracers, 2019
Sven Ullberg, Bengt Larsson, Hans Tjälve
Radioactive decay produces emission of particles or high energetic electromagnetic gamma radiation. The former include beta-particles (nuclear electrons), positrons, and alpha particles (helium nuclei), while the gamma radiation is shortwaved with a high penetration, thus being of less importance in autoradiography. Common to all types of radioactive emission is the ability to ionize matter, which is the basis for their photographic registration.
Gastrin-releasing peptide receptor agonists and antagonists for molecular imaging of breast and prostate cancer: from pre-clinical studies to translational perspectives
Published in Expert Review of Molecular Diagnostics, 2022
Joana Gorica, Maria Silvia De Feo, Luca Filippi, Viviana Frantellizzi, Orazio Schillaci, Giuseppe De Vincentis
The main objective of nuclear medicine is to investigate and gauge metabolic and molecular changes during pathological processes in living subjects through the administration of radiolabeled molecules as imaging probes [19]. Once the radiolabeled probe (i.e. radiopharmaceutical) has been administered, photons produced in the process of radioactive decay and interaction with neighboring tissues are detected by employing appropriate technologies. In the case of gamma-emitting radiopharmaceuticals, such as 99mTc or 111In, imaging is performed by employing the gamma-camera, also through single-photon emission tomography (SPECT) or SPECT/CT hybrid devices [20,21]. When positron-emitting radiopharmaceuticals are utilized, such as 18F or 68Ga, positron emission computed tomography (PET/CT), characterized by superior sensitivity and spatial resolution than SPECT or SPECT/CT, is applied. The use of GRPR analogs for the molecular imaging of prostate cancer patients has provided promising preliminary results. Various bombesin analogs have been labeled with different radioisotopes (64Cu, 18F, 68Ga, 66Ga). GRPR antagonists replaced agonists because of their more favorable pharmacokinetics; they block the receptor instead of activating it (as agonists do), resulting in no gastrointestinal side effects and increased binding [22].
Prostate-specific membrane antigen-directed imaging and radioguided surgery with single-photon emission computed tomography: state of the art and future outlook
Published in Expert Review of Medical Devices, 2022
Luca Filippi, Barbara Palumbo, Viviana Frantellizzi, Susanna Nuvoli, Giuseppe De Vincentis, Angela Spanu, Orazio Schillaci
Nuclear medicine is based on the administration of radiopharmaceuticals aimed to investigate physio-pathological phenomena at a cellular and molecular level. After radiotracers’ injection and localization in the site of interest, imaging is obtained through the detection of the photons produced during the process of radioactive decay and the interaction with the neighboring tissues. When single-photon emitting tracers are employed, detection is carried out by gamma-camera through planar images and/or SPECT. The main advantage of planar images is their capability to register in real-time radiotracers’ biodistribution through dynamic acquisition, while the main limitation is the low sensitivity since only photons emitted parallel to the collimators (or within a certain angular region, if collimators different from parallel are employed) are allowed to reach the detectors [19]. SPECT is obtained by rotating detectors around the patient, so that it is possible to acquire the activity distribution under multiple angles, namely ‘projections,’ that are then reconstructed into a 3D volume through several software packages. Hybrid SPECT/CT, combining a variable-angle gamma-camera with an X-ray tube, allows an accurate co-registration of functional and anatomical images and also provides attenuation map of the patient [20].
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
Ra-226 has a radioactive half-life of 1600 years and is formed when naturally occurring uranium (U-238) undergoes radioactive decay (i.e. radioactive transformation). Ra-226 transitions by alpha decay to form radon-222. Ra-226 decay products (Rn-222, Pb-214, and Bi-214) emit alpha, beta, and gamma radiation in various combinations depending upon which decay product is being evaluated. Ra-226 and its decay products can pose both an external and internal radiological hazard and are responsible for a major fraction of natural radiation dose received by humans. It is naturally present at various concentrations in soils and water in the United States and throughout the world (ICRP 2008; Johnson et al. 2012). Devices that contained Ra-226 (i.e. ship deck markers), the presence of Ra-226 containing radioluminescent paint, and Ra-226 waste storage at HPNS were the primary reasons for its identification as an ROC at the site (USN 2004).