The Scintillation Camera
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
A number of inorganic crystalline materials have been proposed for use in photon detection. However, the most commonly used in gamma cameras is thallium activated sodium iodide, NaI(Tl). The crystal is usually 9.5 mm thick, which is ideal for absorbing the 140 keV photons emitted from 99mTc. Thicker crystal detectors are also available (15.4 mm), which are more suited to higher energy emitters such as 131I. In the 1990s, 25.4 mm crystals were available for system capable of detecting 511 keV annihilation photons of positron emitters. However, since the clinical introduction of PET imaging these have become obsolete.
Mock examination
Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen in Get Through, 2020
False – resolution is generally poorer, about 1 Ip mm−1, compared with 5–10 Ip mm−1 in film radiography.True – it is at least 10 times better because there are no overlying structures in the image, and windowing allows small contrast levels to be made visible.False – a moving object will cause a streak artefact. Its movement will cause it to appear in different scan lines as the scan progresses. A star artefact is caused by a stationary high attenuation (usually metallic) object, which has a Hounsfield number so great that the image reconstruction algorithm is unable to allocate it to a single pixel.False – it is 50% of the surface dose.False – detectors used include solid-state detectors and xenon-filled ionisation chambers. Sodium iodide is used in gamma cameras.
Contrast enhancement agents and radiopharmaceuticals
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
Over several years experimentations took place with materials such as lead, barium salt and bismuth to create a form of chemical contrast, which resulted in the first experimental angiogram of an amputated hand in Vienna by Haschek and Lindenthal in 1896. The use of contrast media in clinical imaging was established in the 1920s thanks to the search for a treatment for syphilis using iodine. In 1923 it was discovered that patients treated with sodium iodide produced radio-opaque urine and, after a short period of research, it was used as a contrast agent in a femoral arteriogram. Sodium iodide, however, was extremely toxic and poorly tolerated by patients. The pioneer of variations to sodium iodide was a USA physician named Moses Swick, who researched agents that would have better tolerance and lead to the formation of today’s modern contrast agents.
Preclinical optimization of Ly6E-targeted ADCs for increased durability and efficacy of anti-tumor response
Published in mAbs, 2021
Josefa Dela Cruz Chuh, MaryAnn Go, Yvonne Chen, Jun Guo, Hanine Rafidi, Danielle Mandikian, Yonglian Sun, Zhonghua Lin, Kellen Schneider, Pamela Zhang, Rajesh Vij, Danielle Sharpnack, Pamela Chan, Cecile de la Cruz, Jack Sadowsky, Dhaya Seshasayee, James T. Koerber, Thomas H. Pillow, Gail D. Phillips, Rebecca K Rowntree, C. Andrew Boswell, Katherine R. Kozak, Andrew G. Polson, Paul Polakis, Shang-Fan Yu, Peter S. Dragovich, Nicholas J. Agard
Iodine-125 (125I) was obtained as sodium iodide in 0.1 N sodium hydroxide from Perkin Elmer. Indirect iodinations were done as previously described using 1 mCi of 125I (3 µL) to randomly iodinate tyrosine residues at a specific activity of ~5-8 mCi/mg with 125I using iodogen tubes (Pierce). Indium-111 (111In) was obtained as indium chloride in 0.05 N hydrogen chloride from BWX Technologies, Inc. Radiosynthesis of 111In-labeled antibodies (5–9 mCi/mg) was achieved through incubation of 111InCl3 and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated (site directed through cysteines) monoclonal antibody in 0.1 mol/L HEPES pH 5.5 at 37°C. Purification of all radioimmunoconjugates was achieved using NAP5 columns equilibrated in PBS and confirmed by radio-size-exclusion chromatography.
Site-specific conjugation allows modulation of click reaction stoichiometry for pretargeted SPECT imaging
Published in mAbs, 2018
Danielle Mandikian, Hanine Rafidi, Pragya Adhikari, Priya Venkatraman, Lidia Nazarova, Gabriel Fung, Isabel Figueroa, Gregory Z. Ferl, Sheila Ulufatu, Jason Ho, Cynthia McCaughey, Jeffrey Lau, Shang-Fan Yu, Saileta Prabhu, Jack Sadowsky, C. Andrew Boswell
Free thiols in 7C2 or TCO-7C2 THIOMAB™ antibody conjugates were capped with 2.5 molar equivalents of N-ethyl maleimide and purified by NAP-5 desalting columns (GE Healthcare) prior to iodination to limit potential interference with radioiodination. 7C2, 7C2-TCO2, 7C2-TCO4, and 7C2-TCO6 antibodies were radioiodinated through tyrosine residues by a modified indirect Chizzonite method as previously described.57 Briefly, 125I was obtained as sodium iodide in 0.1 N sodium hydroxide from Perkin Elmer (Boston, MA). 37 MBq of 125I (~3 µL) was used to label randomly through tyrosine residues at a specific activity of ~370 kBq/µg, with 125I activation achieved using Iodogen tubes (Pierce Chemical Co., Rockford, IL).
Different chemical proteomic approaches to identify the targets of lapatinib
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Tatjana Kovačević, Krunoslav Nujić, Mario Cindrić, Snježana Dragojević, Adrijana Vinter, Amela Hozić, Milan Mesić
Thallium (III) trifluoroacetate (2.93 g, 0.0054 mmol) was dissolved in 5.5 ml of Trifluoroacetic acid. After addition of trifluoromethanesulfonic acid (1.43 ml, 0.0162 mmol), the white precipitate was dissolved by dropwise addition of water (0.22 ml) (Scheme 6). 5a (410 mg, 0.0018 mmol) was added to this solution and the mixture was kept at 80 °C for 2 h. The reaction mixture was allowed to cool to room temperature and a solution of sodium iodide (4.05 g, 0.027 mmol) in 19 ml of water was added. After being stirred for 45 min in the dark, the elemental iodine that formed was reduced with sodium hydrogen sulphite. The solution was made alkaline with potassium hydroxide platelets. One volume of THF was added, and the yellow thallium(I)iodide precipitate was removed by filtration through Celite. The filtrate was extracted twice with Et2O, and the pooled organic phases were washed with water and dried over MgSO4. The solvent was evaporated under reduced pressure. The sample was purified by flush chromatography using a BIOTAGE SP1 purification device and a 25 g normal phase silica SNAP column (solvent system EtOAC-cyclohexane using gradient 0–20% of EtOAc in 15 CV). After evaporation of the solvent, 393.1 mg of product [2-Iodo-4–(3-trifluoromethyl-3H-diazirin-3-yl)-phenyl]-methanol (5b) was isolated as a white solid (yield = 64%).
Related Knowledge Centers
- Chemical Reaction
- Iodine
- Organic Chemistry
- Sodium
- Chemical Formula
- Ion
- Iodide
- Salt
- Sodium Hydroxide
- Chaotropic Agent