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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Whenever a radionuclide (mother) decays to another radioactive nuclide (daughter) we call this a generator system. Most of the natural radioactivity is produced in generator systems starting with the uranium isotopes and 232Th and involves about 50 radioactive daughters.
Management of Monitoring Programs
Published in Kenneth L. Miller, Handbook of Management of Radiation Protection Programs, 2020
The definition of what to monitor is the most important objective and will be called the measurement objective. This measurement objective identifies the types of radiations that must be assessed, the levels to be detected, the quantities to be measured, e.g., dose equivalent or radioactivity, and the accuracies needed. This objective is obviously influenced by the type of monitoring to be performed; there can be several such objectives established for the monitoring program. For example, individual monitoring in a large well-equipped hospital may have several measurement objectives for external dosimetry. One may address whole body dosimetry and, another, extremity dosimetry. For the latter concern, an objective could center on the measurement of the shallow dose equivalents from X-rays and beta particles from sources found in nuclear medicine and diagnostic radiology facilities.
Images from Radioactivity: Radionuclide Scans, SPECT, and PET
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
We describe the energies carried off by radioactive decay products using the unit of the electron-volt (eV) introduced in Chapter 5. Particles emitted by a radioactive decay process have energies measured in MeV (mega-eV or 106 eV). By comparison, the energies of biologically important chemical bonds and the energies of photons of visible light are typically several eV. Thus, a single radioactive decay product in theory has enough energy to break millions of chemical bonds. The term ionizing radiation is used to describe both energetic photons (x-rays and gamma rays) and particles of matter such as energetic neutrons, protons, electrons, positrons, and alpha particles. A particular form of ionizing radiation has the same properties whether produced by radioactivity or by some other process.
Evaluation of cytotoxicity and biodistribution of mesoporous carbon nanotubes (pristine/-OH/-COOH) to HepG2 cells in vitro and healthy mice in vivo
Published in Nanotoxicology, 2022
Yujing Du, Zhipei Chen, M. Irfan Hussain, Ping Yan, Chunli Zhang, Yan Fan, Lei Kang, Rongfu Wang, Jianhua Zhang, Xiaona Ren, Changchun Ge
Total cell uptake was determined by cell radioactive uptake assay (Bouvet et al. 2016; Kamal, Chadha, and Dhawan 2018) ( HepG2 cells were allowed to attach for 12 h in a 24-well plate. For time and concentration dependence measurements, cells were incubated with 1.25, 2.5, 5, 10, 20 and 40 μg/mL 99mTc-mCNTs for 1, 12, 24 and 48 h individually (10% FBS in DMEM). Cell-free wells with the corresponding dose of 99mTc-mCNTs (1.25 ∼ 40 μg/mL) were set as a blank control to reduce the interference of mCNTs deposition. After incubation, the medium was removed and ice-cold PBS was added to wash three times, and all buffer was collected as a supernatant sample. Then, RIPA lysis buffer (Lablead, China) was used to collect cell samples as cell-bound fractions. For temperature-dependent uptake, cells were incubated with 10 and 100 μg/mL 99 mTc-mCNTs in DMEM containing 10% FBS at 4 °C or 37 °C for 1 h. Cell-free wells with 99mTc-mCNTs (10 and 100 μg/mL) were set as a blank control. After incubation, supernatant sample and cell-bound fraction were collected as aforementioned. Radioactivity was determined by a γ-counter. The total cell uptake rate = CPMcell-bound sample/ (CPMcell-bound sample + CPMsupernatant sample). Each experiment was performed in triplicate.
Efficacy of nimotuzumab (hR3) conjugated with 131I or 90Y in laryngeal carcinoma xenograft mouse model
Published in International Journal of Radiation Biology, 2021
Thi-Thu Nguyen, Anh-Son Ho, Thi-Khanh-Giang Nguyen, Thi-Ngoc Nguyen, Van-Cuong Bui, Thanh-Binh Nguyen, Ho-Hong-Quang Dang, Dang-Khoa Nguyen, Thanh-Nhan Nguyen, Linh-Toan Nguyen
Iodination of hR3 with 131I was performed using the chloramine T method as described previously (Mythili et al. 2015). Briefly, 50 µL 370 MBq 131I and 100 µL (50 µg) freshly prepared chloramine T solution was added to a reaction vial containing 400 µL (2 mg) of hR3 and 100 µL 0.5 M PBS, pH 7.4. The mixture was incubated for 5 minutes at room temperature. For stopping the reaction, volume 100 µL (100 µg) of sodimmetabisulfite solution was added into the labeling solution and incubated for 30 seconds at room temperature. Residual free iodide in the reaction mixture was removed by gel filtration with a PD10 column (Sephadex G25, Pharmacia, GE) and eluted (30 cm3/h) with 100 mM PBS, pH 7.2 containing 1% human serum albumin. The purified 131I-hR3 was filtered with a 0.2 µm sterile filter. Labeling efficacy and radiochemical purity were determined by Thin Layer Chromatography (TLC) (Silicagel 60 F254, Merck) using methanol:0.9% saline, 85:15 (v/v) as the mobile phase and scan with a Bioscan (B-MS-1000, USA). Radioactivity measurements were conducted using a dose calibrator (Capintec ISOMED 2000, USA). The specific activity was expressed as radioactivity per milligram antibody. The specific activity of 131I-hR3 was determined by measured radioactivity of 131I using a gamma counter and the mass of hR3 was determined by UV spectrophotometry at 280 nm. The number of 131I atoms bound to an antibody molecule was calculated by multiplying the molar ratio of iodine per molecule of antibody and labeling yield (Andreas et al. 2004).
Dosimetry study on Auger electron-emitting nuclear medicine radioisotopes in micrometer and nanometer scales using Geant4-DNA simulation
Published in International Journal of Radiation Biology, 2020
Seifi Moradi Mahdi, Shirani Bidabadi Babak
From a dosimetry point of view, most Auger electrons in body tissue have a range of about a few nanometers to micrometers. Therefore, the intracellular position of Auger electron-emitting radioisotopes is very important (Roeske et al. 2008). A number of widely used diagnostic radioisotopes emit Auger electrons, which most of these Auger electrons due to their short-range in the tissue around a few nanometers to micrometers, low energy and moderate LET can leave significant effects on nanometer scale on living cells. Auger emitting radionuclides, in the form of a radiolabelled drug, are efficient in cell killing if they can be delivered to tumor nucleus with high efficiency (Nikjoo et al. 2008). Due to these features, these radioisotopes can produce high levels of toxicity in cancer cells, therefore, they are suitable for using in molecularly targeted radiotherapy (MTRT) (Kassis and Adelstein 2005; Howell 2008). Due to the short range of these electrons and their energy transfer at the site of decay, the irradiation of healthy cells adjacent to cancer cells is negligible and thus the radioactivity toxicity of healthy cells decreases. A number of radioisotopes used in nuclear medicine have been proposed for molecular radiotherapy of some small metastases in cancer cells (Rebischung et al. 2008; Pool et al. 2010; Vallis et al. 2014).