A report on Radioactive tracer

Chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products.

- Radioactive tracer

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Violet iodine vapour in a flask.

Iodine

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Chemical element with the symbol I and atomic number 53.

Chemical element with the symbol I and atomic number 53.

Violet iodine vapour in a flask.
I2•PPh3 charge-transfer complexes in CH2Cl2. From left to right: (1) I2 dissolved in dichloromethane – no CT complex. (2) A few seconds after excess PPh3 was added – CT complex is forming. (3) One minute later after excess PPh3 was added, the CT complex [Ph3PI]+I− has been formed. (4) Immediately after excess I2 was added, which contains [Ph3PI]+[I3]−.
Structure of solid iodine
Iodine monochloride
Structure of iodine pentoxide
Structure of the oxidising agent 2-iodoxybenzoic acid
Testing a seed for starch with a solution of iodine
Diatrizoic acid, an iodine-containing radiocontrast agent
The thyroid system of the thyroid hormones T3 and T4
Comparison of the iodine content in urine in France (in microgramme/day), for some regions and departments (average levels of urine iodine, measured in micrograms per liter at the end of the twentieth century (1980 to 2000))

Iodine-131 is also used as a radioactive tracer.

Image of a typical positron emission tomography (PET) scanner

Positron emission tomography

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Image of a typical positron emission tomography (PET) scanner
PET/CT-System with 16-slice CT; the ceiling mounted device is an injection pump for CT contrast agent
Whole-body PET scan using 18F-FDG. The normal brain and kidneys are labeled, and radioactive urine from breakdown of the FDG is seen in the bladder. In addition, a large metastatic tumor mass from colon cancer is seen in the liver.
PET scan of the human brain
Schematic view of a detector block and ring of a PET scanner
Schema of a PET acquisition process
Complete body PET-CT fusion image
Brain PET-MRI fusion image

Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption.

A nuclear medicine PET scan

Nuclear medicine

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Medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease.

Medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease.

A nuclear medicine PET scan
Iodine-123 whole body scan for thyroid cancer evaluation. The study above was performed after the total thyroidectomy and TSH stimulation with thyroid hormone medication withdrawal. The study shows a small residual thyroid tissue in the neck and a mediastinum lesion, consistent with the thyroid cancer metastatic disease. The observable uptakes in the stomach and bladder are normal physiologic findings.
A nuclear medicine whole body bone scan. The nuclear medicine whole body bone scan is generally used in evaluations of various bone-related pathology, such as for bone pain, stress fracture, nonmalignant bone lesions, bone infections, or the spread of cancer to the bone.
Nuclear medicine myocardial perfusion scan with thallium-201 for the rest images (bottom rows) and Tc-Sestamibi for the stress images (top rows). The nuclear medicine myocardial perfusion scan plays a pivotal role in the noninvasive evaluation of coronary artery disease. The study not only identifies patients with coronary artery disease; it also provides overall prognostic information or overall risk of adverse cardiac events for the patient.
A nuclear medicine parathyroid scan demonstrates a parathyroid adenoma adjacent to the left inferior pole of the thyroid gland. The above study was performed with Technetium-Sestamibi (1st column) and iodine-123 (2nd column) simultaneous imaging and the subtraction technique (3rd column).
Normal hepatobiliary scan (HIDA scan). The nuclear medicine hepatobiliary scan is clinically useful in the detection of the gallbladder disease.
Normal pulmonary ventilation and perfusion (V/Q) scan. The nuclear medicine V/Q scan is useful in the evaluation of pulmonary embolism.
Thyroid scan with iodine-123 for evaluation of hyperthyroidism.
A nuclear medicine SPECT liver scan with technetium-99m labeled autologous red blood cells. A focus of high uptake (arrow) in the liver is consistent with a hemangioma.
Maximum intensity projection (MIP) of a whole-body positron emission tomography (PET) acquisition of a 79 kg female after intravenous injection of 371 MBq of 18F-FDG (one hour prior measurement).
Normal whole body PET/CT scan with FDG-18. The whole body PET/CT scan is commonly used in the detection, staging and follow-up of various cancers.
Abnormal whole body PET/CT scan with multiple metastases from a cancer. The whole body PET/CT scan has become an important tool in the evaluation of cancer.

The radionuclide introduced into the body is often chemically bound to a complex that acts characteristically within the body; this is commonly known as a tracer.

Artificial nuclide americium-241 emitting alpha particles inserted into a cloud chamber for visualisation

Radionuclide

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Nuclide that has excess nuclear energy, making it unstable.

Nuclide that has excess nuclear energy, making it unstable.

Artificial nuclide americium-241 emitting alpha particles inserted into a cloud chamber for visualisation
Americium-241 container in a smoke detector.
Americium-241 capsule as found in smoke detector. The circle of darker metal in the center is americium-241; the surrounding casing is aluminium.

An imaging tracer made with radionuclides is called a radioactive tracer.

The Space Shuttle Main Engine burnt hydrogen with oxygen, producing a nearly invisible flame at full thrust.

Hydrogen

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Chemical element with the symbol H and atomic number 1.

Chemical element with the symbol H and atomic number 1.

The Space Shuttle Main Engine burnt hydrogen with oxygen, producing a nearly invisible flame at full thrust.
Depiction of a hydrogen atom with size of central proton shown, and the atomic diameter shown as about twice the Bohr model radius (image not to scale)
Hydrogen gas is colorless and transparent, here contained in a glass ampoule.
Phase diagram of hydrogen. The temperature and pressure scales are logarithmic, so one unit corresponds to a 10x change. The left edge corresponds to 105 Pa, which is about atmospheric pressure.
A sample of sodium hydride
Hydrogen discharge (spectrum) tube
Deuterium discharge (spectrum) tube
Antoine-Laurent de Lavoisier
Hydrogen emission spectrum lines in the visible range. These are the four visible lines of the Balmer series
NGC 604, a giant region of ionized hydrogen in the Triangulum Galaxy
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is known as tritium and contains one proton and two neutrons in its nucleus. It is radioactive, decaying into helium-3 through beta decay with a half-life of 12.32 years. It is so radioactive that it can be used in luminous paint, making it useful in such things as watches. The glass prevents the small amount of radiation from getting out. Small amounts of tritium are produced naturally by the interaction of cosmic rays with atmospheric gases; tritium has also been released during nuclear weapons tests. It is used in nuclear fusion reactions, as a tracer in isotope geochemistry, and in specialized self-powered lighting devices. Tritium has also been used in chemical and biological labeling experiments as a radiolabel.

Technetium-99m

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Metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope in the world.

Metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope in the world.

A technetium injection contained in a shielded syringe
Technetium scintigraphy of a neck of a Graves' disease patient

Technetium-99m is used as a radioactive tracer and can be detected in the body by medical equipment (gamma cameras).

Tritium

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Rare and radioactive isotope of hydrogen.

Rare and radioactive isotope of hydrogen.

Radioluminescent 1.8 Ci 6 x tritium vials are thin, tritium-gas-filled glass vials whose inner surfaces are coated with a phosphor. The vial shown here is brand-new.
Swiss Military watch with tritium-illuminated face

It is used in a medical and scientific setting as a radioactive tracer.

White phosphorus exposed to air glows in the dark

Phosphorus

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Chemical element with the symbol P and atomic number 15.

Chemical element with the symbol P and atomic number 15.

White phosphorus exposed to air glows in the dark
The tetrahedral structure of P4O10 and P4S10.
A stable diphosphene, a derivative of phosphorus(I).
Robert Boyle
Guano mining in the Central Chincha Islands, ca. 1860.
Mining of phosphate rock in Nauru
Match striking surface made of a mixture of red phosphorus, glue and ground glass. The glass powder is used to increase the friction.
Phosphorus explosion

, a beta-emitter (1.71 MeV) with a half-life of 14.3 days, which is used routinely in life-science laboratories, primarily to produce radiolabeled DNA and RNA probes, e.g. for use in Northern blots or Southern blots.

Iodine-131 decay scheme (simplified)

Iodine-131

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Important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley.

Important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley.

Iodine-131 decay scheme (simplified)
Per capita thyroid doses in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site from 1951 to 1962. A Centers for Disease Control and Prevention/ National Cancer Institute study claims that nuclear fallout might have led to approximately 11,000 excess deaths, most caused by thyroid cancer linked to exposure to iodine-131.
A pheochromocytoma tumor is seen as a dark sphere in the center of the body (it is in the left adrenal gland). The image is by MIBG scintigraphy, showing the tumor by radiation from radioiodine in the MIBG. Two images are seen of the same patient from front and back. The image of the thyroid in the neck is due to unwanted uptake of radioiodine (as iodide) by the thyroid, after breakdown of the radioactive iodine-containing medication. Accumulation at the sides of the head is from salivary gland due to uptake of I-131 mIBG by the sympathetic neuronal elements in the salivary glands. Meta-[I-131]iodobenzylguanidine is a radio-labeled analog of the adrenergic blocking agent guanethidine. Radioactivity is also seen from uptake by the liver, and excretion by the kidneys with accumulation in the bladder.

Iodine-131 is also one of the most commonly used gamma-emitting radioactive industrial tracer.

The portion of the total radiation activity (in air) contributed by each isotope versus time after the Chernobyl disaster, at the site. Note the prominence of radiation from I-131 and Te-132/I-132 for the first week. (Image using data from the OECD report, and the second edition of 'The radiochemical manual'. )

Isotopes of iodine

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Stable.

Stable.

The portion of the total radiation activity (in air) contributed by each isotope versus time after the Chernobyl disaster, at the site. Note the prominence of radiation from I-131 and Te-132/I-132 for the first week. (Image using data from the OECD report, and the second edition of 'The radiochemical manual'. )
A Pheochromocytoma is seen as a dark sphere in the center of the body (it is in the left adrenal gland). Image is by MIBG scintigraphy, with radiation from radioiodine in the MIBG. Two images are seen of the same patient from front and back. Note the dark image of the thyroid due to unwanted uptake of radioiodine from the medication by the thyroid gland in the neck. Accumulation at the sides of the head is from salivary gland uptake of iodide. Radioactivity is also seen in the bladder.

125I is used as the radiolabel in investigating which ligands go to which plant pattern recognition receptors (PRRs).