Isotopes of iodine
Encyclopedia
There are 37 known isotope
s of iodine
(I) and only one, 127I, is stable. Iodine is thus a monoisotopic element
.
Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million years, which is far too short for it to exist as a primordial nuclide
. Cosmogenic
sources of 129I produce very tiny quantities of it that are too small to affect atomic weight measurements; iodine is thus also a mononuclidic element—one that is found in nature essentially as a single nuclide. Most 129I derived radioactivity on Earth is man-made: an unwanted long-lived byproduct of early nuclear tests and nuclear fission accidents.
All other iodine radioisotopes have half-lives less than 60 days, and four of these are used as tracers and therapeutic agents in medicine. These are 123I, 124I, 125I, and 131I. Essentially all industrial production of radioactive iodine isotopes involves these four useful radionuclides.
The isotope 135I has a half-life less than seven hours, which is too short to be used in biology. Unavoidable in situ production of this isotope is important in nuclear reactor control, as it decays to 135Xe, the most powerful known neutron absorber, and the nuclide
responsible for the so-called iodine pit
phenomenon.
In addition to commercial production, 131I (half life 8 days) is the most common radioactive fission-product of nuclear fission
, and is thus produced inadvertently in very large amounts inside nuclear reactor
s. Due to its volatility, short half life, and high abundance in fission products, 131I, (along with the short-lived iodine isotope 132I from the longer-lived 132Te with a half life of 3 days) is responsible for the largest part of radioactive contamination during the first week after accidental environmental contamination from the radioactive waste
from a nuclear power plant.
The standard atomic mass for iodine is 126.90447(3) u.
produced newly by the supernovas which created the dust and gas from which the solar system formed. This isotope has long decayed and is thus referred to as "extinct." Historically, 129I was the first extinct radionuclide
to be identified as present in the early solar system
. Its decay is the basis of the I-Xe iodine-xenon radiometric dating
scheme, which covers the first 85 million years of solar system
evolution.
(129I; half-life
15.7 million years) is a product of cosmic ray spallation
on various isotopes of xenon
in the atmosphere
, in cosmic ray
muon
interaction with tellurium-130, and also uranium
and plutonium
fission, both in subsurface rocks and nuclear reactors. Artificial nuclear processes, in particular nuclear fuel reprocessing and atmospheric nuclear weapons tests, have now swamped the natural signal for this isotope. Nevertheless, it now serves as a groundwater tracer as indicator of nuclear waste dispersion into the natural environment. In a similar fashion, 129I was used in rainwater studies to track fission products following the Chernobyl disaster
.
In some ways, 129I is similar to 36Cl
. It is a soluble halogen, fairly non-reactive, exists mainly as a non-sorbing anion, and is produced by cosmogenic, thermonuclear, and in-situ reactions. In hydrologic studies, 129I concentrations are usually reported as the ratio of 129I to total I (which is virtually all 127I). As is the case with 36Cl/Cl, 129I/I ratios in nature are quite small, 10−14 to 10−10 (peak thermonuclear 129I/I during the 1960s and 1970s reached about 10−7). 129I differs from 36Cl in that its half-life is longer (15.7 vs. 0.301 million years), it is highly biophilic, and occurs in multiple ion
ic forms (commonly, I− and IO3−
) which have different chemical behaviors. This makes it fairly easy for 129I to enter the biosphere as it becomes incorporated into vegetation, soil, milk, animal tissue, etc.
, where the isotope never has a chance to be released for chemical interaction with the body's tissues.
(I131) is a beta-emitting
isotope with a half-life of eight days, and comparatively energetic (190 KeV average and 606 KeV maximum energy) beta radiation, which penetrates 0.6 to 2.0 mm from the site of uptake. This beta radiation can be used in high dose for destruction of thyroid nodule
s and for elimination of remaining thyroid tissue after surgery for the treatment of Grave's disease. Especially in Grave's disease, often a thyroidectomy
is performed before the radiotherapy, in order to avoid side effects of epilation
and radiation toxicity. The purpose of this therapy, which was first explored by Dr. Saul Hertz
in 1941, is to destroy the remaining thyroid tissue that was impossible to be removed by surgery. In this procedure, I131 is administered either intravenously or orally following a diagnostic scan. This procedure may also be used to treat patients with thyroid cancer
or hyperfunctioning thyroid tissue.
After the intake, the beta particles emitted by the high dose of radioisotope destroys the associated thyroid tissue with little damage to surrounding tissues (more than 2.0 mm from the tissues absorbing the iodine). Due to similar destruction, iodine-131 is the iodine radioisotope used in other water-soluble iodine-labeled radiopharmaceuticals (such as MIBG) which are intended to be used therapeutically to destroy tissues.
The high energy beta radiation from I-131 causes it to be the most carcinogenic of the iodine isotopes, and it is thought to cause the majority of the excess in thyroid cancers seen after nuclear fission contamination (such as bomb fallout or severe nuclear reactor accidents like the Chernobyl disaster
).
(half-life 13 hours), and (less commonly) the longer-lived and less energetic iodine-125
(half-life 59 days) are used as nuclear imaging
tracers to evaluate the anatomic and physiologic function of the thyroid. Abnormal results may be caused by disorders such as Graves' disease
or Hashimoto's thyroiditis
. Both isotopes decay by electron capture
(EC) to the corresponding tellurium nuclides, but in neither case are these the metastable nuclides Te-123m and Te125m (which are of higher energy, and are not produced from radioiodine). Instead, the excited tellurium nuclides decay immediately (half-life too short to detect). Following EC, the excited Te-123 from I-123 emits a high-speed 127 keV internal conversion
electron (not a beta ray) about 13% of the time, but this does little cellular damage due to the nuclide's short half-life and the relatively small fraction of such events. In the remainder of cases, a 159 keV gamma ray is emitted, which is well-suited for gamma imaging.
Excited Te-125 from EC decay of I-125 also emits a much lower-energy internal conversion electron (35.5 keV) which does relatively little damage due to its low energy, even though its emission is more common. The relatively low-energy gamma from I-125/Te-125 decay is poorly suited for imaging, but can still be seen, and this longer-lived isotope is necessary in tests which require several days of imaging, for example fibrinogen scan imaging to detect blood clots.
Both I-123 and I-125 emit copious low energy Auger electron
s after their decay, but these do not cause serious damage (double-stranded DNA breaks) in cells, unless the nuclide is incorporated into a medication that accumulates in the nucleus, or into DNA (this is never the case is clinical medicine, but it has been seen in experimental animal models).
Iodine-125
is also commonly used by radiation oncologists in low dose rate brachytherapy
in the treatment of cancer at sites other than the thyroid, especially in prostate cancer
. When I-125 is used therapeutically, it is encapsulated in titanium seeds and implanted in the area of the tumor, where it remains. The low energy of the gamma spectrum in this case limits radiation damage to tissues far from the implanted capsule. Iodine-125, due to its suitable longer half-life and less penetrating gamma spectrum, is also often preferred for laboratory tests that rely on iodine as a tracer that is counted by a gamma counter
, such as in radioimmunoassay
ing.
Most medical imaging with iodine is done with a standard gamma camera
. However, the gamma rays from iodine-123
and iodine-131
can also be seen by single photon emission computed tomography
(SPECT) imaging.
. The most common starting material used is 124Te.
Iodine-124 as the iodide salt can be used to directly image the thyroid using positron emission tomography
(PET). Iodine-124 can also be used as a PET radiotracer with a usefully longer half-life compared with fluorine-18
. In this use, the nuclide is chemically bonded to a pharmaceutical to form a positron-emitting radiopharmaceutical, and injected into the body, where again it is imaged by PET scan.
. It is produced in relatively large amounts as a fission product
, and decays to xenon-135
, which is a nuclear poison
with a very large slow neutron cross section, which is a cause of multiple complications in the control of nuclear reactor
s. The process of buildup of xenon-135
from an accumulated iodine-135 can temporarily preclude a shut-down reactor from restarting. This is known as xenon-poisoning or "falling into an iodine pit
."
, or to xenon-128 by beta decay
. It has a specific radioactivity of 2.177 x 106 TBq/g.
scintigraphy
and therapy with some radioiodinated compounds that are not targeted to the thyroid, such as iobenguane
(MIBG), which used to image or treat neural tissue tumors, or iodinated fibrinognen, which is used in fibrinogen scans to investigate clotting. These compounds contain iodine, but not in the iodide form. However, since they may be ultimately metabolized or break down to radioactive iodide, it is common to administer non-radioactive potassium iodide to insure that iodide from these radiopharmaceuticals is not sequestered by the normal affinity of the thryoid for iodide.
Potassium iodide
has been distributed to populations exposed to nuclear fission
accidents such as the Chernobyl disaster
. The iodide solution SSKI, a saturated solution of potassium (K) iodide in water, has been used to block absorption of the radioiodine (it has no effect on other radioisotopes from fission). Tablets containing potassium iodide are now also manufactured and stocked in central disaster sites by some governments for this purpose. In theory, many harmful late-cancer effects of nuclear fallout might be prevented in this way, since an excess of thyroid cancers, presumably due to radioiodine uptake, is the only proven radioisotope contamination effect after a fission accident, or from contamination by fallout from an atomic bomb (prompt radiation from the bomb also cases other cancers, such as leukemias, directly). Taking large amounts of iodide saturates thyroid receptors and prevents uptake of most radioactive iodine-131
that may be present from fission product exposure (although it does not protect from other radioisotopes, nor from any other form of direct radiation). The protective effect of KI lasts approximately 24 hours, so must be dosed daily until a risk of significant exposure to radioiodines from fission products no longer exists. Iodine-131 (the most common radioiodine contaminant in fallout) also decays relatively rapidly with a half-life of eight days, so that 99.95% of the original radioiodine has vanished after three months.
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s of iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
(I) and only one, 127I, is stable. Iodine is thus a monoisotopic element
Monoisotopic element
A monoisotopic element is one of 26 chemical elements which have only a single stable isotope . A list is given in a following section....
.
Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million years, which is far too short for it to exist as a primordial nuclide
Primordial nuclide
In geochemistry and geonuclear physics, primordial nuclides or primordial isotopes are nuclides found on the earth that have existed in their current form since before Earth was formed. Only 288 such nuclides are known...
. Cosmogenic
Cosmogenic nuclide
See also Environmental radioactivity#NaturalCosmogenic nuclides are rare isotopes created when a high-energy cosmic ray interacts with the nucleus of an in situ solar system atom, causing cosmic ray spallation...
sources of 129I produce very tiny quantities of it that are too small to affect atomic weight measurements; iodine is thus also a mononuclidic element—one that is found in nature essentially as a single nuclide. Most 129I derived radioactivity on Earth is man-made: an unwanted long-lived byproduct of early nuclear tests and nuclear fission accidents.
All other iodine radioisotopes have half-lives less than 60 days, and four of these are used as tracers and therapeutic agents in medicine. These are 123I, 124I, 125I, and 131I. Essentially all industrial production of radioactive iodine isotopes involves these four useful radionuclides.
The isotope 135I has a half-life less than seven hours, which is too short to be used in biology. Unavoidable in situ production of this isotope is important in nuclear reactor control, as it decays to 135Xe, the most powerful known neutron absorber, and the nuclide
Nuclide
A nuclide is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons Z, its number of neutrons N, and its nuclear energy state....
responsible for the so-called iodine pit
Iodine pit
Iodine pit, also called iodine hole and xenon pit, is a temporary disabling of a nuclear reactor due to buildup of short-lived nuclear poisons in the core of a nuclear reactor. The main isotope responsible is xenon-135, mainly produced by natural decay of iodine-135. Iodine-135 is a weak neutron...
phenomenon.
In addition to commercial production, 131I (half life 8 days) is the most common radioactive fission-product of nuclear fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...
, and is thus produced inadvertently in very large amounts inside nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s. Due to its volatility, short half life, and high abundance in fission products, 131I, (along with the short-lived iodine isotope 132I from the longer-lived 132Te with a half life of 3 days) is responsible for the largest part of radioactive contamination during the first week after accidental environmental contamination from the radioactive waste
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
from a nuclear power plant.
The standard atomic mass for iodine is 126.90447(3) u.
Iodine-129 as an extinct radionuclide
Excesses of stable 129Xe in meteorites have been shown to result from decay of "primordial" iodine-129Iodine-129
Iodine-129 is long-lived radioisotope of iodine which occurs naturally, but also is of special interest in the monitoring and effects of man-made nuclear fission decay products, where it serves as both tracer and potential radiological contaminant....
produced newly by the supernovas which created the dust and gas from which the solar system formed. This isotope has long decayed and is thus referred to as "extinct." Historically, 129I was the first extinct radionuclide
Extinct radionuclide
An extinct radionuclide is one that scientists believe was formed by primordial processes, such as stellar nucleogenesis in the supernova that contributed radioisotopes to the early solar system, about 4.6 billion years ago...
to be identified as present in the early solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. Its decay is the basis of the I-Xe iodine-xenon radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
scheme, which covers the first 85 million years of solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
evolution.
Iodine-129 as a long-lived marker for nuclear fission contamination
Iodine-129Iodine-129
Iodine-129 is long-lived radioisotope of iodine which occurs naturally, but also is of special interest in the monitoring and effects of man-made nuclear fission decay products, where it serves as both tracer and potential radiological contaminant....
(129I; half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
15.7 million years) is a product of cosmic ray spallation
Cosmic ray spallation
Cosmic ray spallation is a form of naturally occurring nuclear fission and nucleosynthesis. It refers to the formation of elements from the impact of cosmic rays on an object. Cosmic rays are highly energetic charged particles from outside of Earth ranging from protons, alpha particles, and nuclei...
on various isotopes of xenon
Xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. The element name is pronounced or . A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts...
in the atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
, in cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
muon
Muon
The muon |mu]] used to represent it) is an elementary particle similar to the electron, with a unitary negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton...
interaction with tellurium-130, and also uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
fission, both in subsurface rocks and nuclear reactors. Artificial nuclear processes, in particular nuclear fuel reprocessing and atmospheric nuclear weapons tests, have now swamped the natural signal for this isotope. Nevertheless, it now serves as a groundwater tracer as indicator of nuclear waste dispersion into the natural environment. In a similar fashion, 129I was used in rainwater studies to track fission products following the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
.
In some ways, 129I is similar to 36Cl
Chlorine-36
Chlorine-36 is an isotope of chlorine. Chlorine has two stable isotopes and one radioactive environmental isotope: the cosmogenic isotope 36Cl. The ratio of 36Cl to stable 37Cl in the environment is ~700 × 10−15. Its half-life is 301,000 ± 4,000 years. The long half-life of 36Cl makes it...
. It is a soluble halogen, fairly non-reactive, exists mainly as a non-sorbing anion, and is produced by cosmogenic, thermonuclear, and in-situ reactions. In hydrologic studies, 129I concentrations are usually reported as the ratio of 129I to total I (which is virtually all 127I). As is the case with 36Cl/Cl, 129I/I ratios in nature are quite small, 10−14 to 10−10 (peak thermonuclear 129I/I during the 1960s and 1970s reached about 10−7). 129I differs from 36Cl in that its half-life is longer (15.7 vs. 0.301 million years), it is highly biophilic, and occurs in multiple ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
ic forms (commonly, I− and IO3−
Iodate
An iodate is a conjugate base of iodic acid. In the iodate anion, iodine is bonded to three oxygen atoms and the molecular formula is IO3−. The molecular geometry of iodate is trigonal pyramidal....
) which have different chemical behaviors. This makes it fairly easy for 129I to enter the biosphere as it becomes incorporated into vegetation, soil, milk, animal tissue, etc.
Radioiodines I-123, I-124, I-125, and I-131 in medicine and biology
Due to preferential uptake of iodine by the thyroid, radioiodine isotopes are extensively used in imaging and (in the case of I-131) destroying dysfunctional thyroid tissues, and other types of tissue that selectively take up certain iodine-131-containing tissue-targeting and killing radiopharmaceutical agents (such as MIBG). Iodine-125 is the only other iodine radioisotope used in radiation therapy, but only as an implanted capsule in brachytherapyBrachytherapy
Brachytherapy , also known as internal radiotherapy, sealed source radiotherapy, curietherapy or endocurietherapy, is a form of radiotherapy where a radiation source is placed inside or next to the area requiring treatment...
, where the isotope never has a chance to be released for chemical interaction with the body's tissues.
Iodine-131
Iodine-131Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
(I131) is a beta-emitting
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
isotope with a half-life of eight days, and comparatively energetic (190 KeV average and 606 KeV maximum energy) beta radiation, which penetrates 0.6 to 2.0 mm from the site of uptake. This beta radiation can be used in high dose for destruction of thyroid nodule
Thyroid nodule
Thyroid nodules are lumps which commonly arise within an otherwise normal thyroid gland. They indicate a thyroid neoplasm, but only a small percentage of these are thyroid cancers.-Presentation:...
s and for elimination of remaining thyroid tissue after surgery for the treatment of Grave's disease. Especially in Grave's disease, often a thyroidectomy
Thyroidectomy
A thyroidectomy is an operation that involves the surgical removal of all or part of the thyroid gland. Surgeons often perform a thyroidectomy when a patient has thyroid cancer or some other condition of the thyroid gland...
is performed before the radiotherapy, in order to avoid side effects of epilation
EPilation
EPilation is the first full-length release from Brisbane musician Tara Simmons. Although a full-length, EPilation contains no new material and is a compilation of Tara's first two EPs Pendulum and All The Amendments...
and radiation toxicity. The purpose of this therapy, which was first explored by Dr. Saul Hertz
Saul Hertz
Saul Hertz, M.D. was an American physician who discovered the use of radioactive iodine for the treatment of thyroid disease.-Early life and education:...
in 1941, is to destroy the remaining thyroid tissue that was impossible to be removed by surgery. In this procedure, I131 is administered either intravenously or orally following a diagnostic scan. This procedure may also be used to treat patients with thyroid cancer
Thyroid cancer
Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm , such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected...
or hyperfunctioning thyroid tissue.
After the intake, the beta particles emitted by the high dose of radioisotope destroys the associated thyroid tissue with little damage to surrounding tissues (more than 2.0 mm from the tissues absorbing the iodine). Due to similar destruction, iodine-131 is the iodine radioisotope used in other water-soluble iodine-labeled radiopharmaceuticals (such as MIBG) which are intended to be used therapeutically to destroy tissues.
The high energy beta radiation from I-131 causes it to be the most carcinogenic of the iodine isotopes, and it is thought to cause the majority of the excess in thyroid cancers seen after nuclear fission contamination (such as bomb fallout or severe nuclear reactor accidents like the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
).
Iodine-123 and iodine-125
The gamma-emitting isotopes iodine-123Iodine-123
Iodine-123 is a radioactive isotope of iodine used in nuclear medicine imaging, including single photon emission computed tomography . The isotope's half-life is 13.22 hours; the decay by electron capture to tellurium-123 emits gamma radiation with predominant energies of 159 keV and 127 keV...
(half-life 13 hours), and (less commonly) the longer-lived and less energetic iodine-125
Iodine-125
Iodine-125 is a radioisotope of iodine which has uses in biological assays, nuclear medicine imaging and in radiation therapy as brachytherapy to treat prostate cancer and brain tumors. It is the second longest-lived radioisotope of iodine, after iodine-129.Its half-life is around 59 days and it...
(half-life 59 days) are used as nuclear imaging
Nuclear medicine
In nuclear medicine procedures, elemental radionuclides are combined with other elements to form chemical compounds, or else combined with existing pharmaceutical compounds, to form radiopharmaceuticals. These radiopharmaceuticals, once administered to the patient, can localize to specific organs...
tracers to evaluate the anatomic and physiologic function of the thyroid. Abnormal results may be caused by disorders such as Graves' disease
Graves' disease
Graves' disease is an autoimmune disease where the thyroid is overactive, producing an excessive amount of thyroid hormones...
or Hashimoto's thyroiditis
Hashimoto's thyroiditis
Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease in which the thyroid gland is gradually destroyed by a variety of cell- and antibody-mediated immune processes. It was the first disease to be recognized as an autoimmune disease...
. Both isotopes decay by electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
(EC) to the corresponding tellurium nuclides, but in neither case are these the metastable nuclides Te-123m and Te125m (which are of higher energy, and are not produced from radioiodine). Instead, the excited tellurium nuclides decay immediately (half-life too short to detect). Following EC, the excited Te-123 from I-123 emits a high-speed 127 keV internal conversion
Internal conversion
Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower atomic orbitals, causing the electron to be emitted from the atom. Thus, in an internal conversion process, a high-energy electron is emitted from the radioactive atom, but...
electron (not a beta ray) about 13% of the time, but this does little cellular damage due to the nuclide's short half-life and the relatively small fraction of such events. In the remainder of cases, a 159 keV gamma ray is emitted, which is well-suited for gamma imaging.
Excited Te-125 from EC decay of I-125 also emits a much lower-energy internal conversion electron (35.5 keV) which does relatively little damage due to its low energy, even though its emission is more common. The relatively low-energy gamma from I-125/Te-125 decay is poorly suited for imaging, but can still be seen, and this longer-lived isotope is necessary in tests which require several days of imaging, for example fibrinogen scan imaging to detect blood clots.
Both I-123 and I-125 emit copious low energy Auger electron
Auger electron
The Auger effect is a physical phenomenon in which the transition of an electron in an atom filling in an inner-shell vacancy causes the emission of another electron. When a core electron is removed, leaving a vacancy, an electron from a higher energy level may fall into the vacancy, resulting in...
s after their decay, but these do not cause serious damage (double-stranded DNA breaks) in cells, unless the nuclide is incorporated into a medication that accumulates in the nucleus, or into DNA (this is never the case is clinical medicine, but it has been seen in experimental animal models).
Iodine-125
Iodine-125
Iodine-125 is a radioisotope of iodine which has uses in biological assays, nuclear medicine imaging and in radiation therapy as brachytherapy to treat prostate cancer and brain tumors. It is the second longest-lived radioisotope of iodine, after iodine-129.Its half-life is around 59 days and it...
is also commonly used by radiation oncologists in low dose rate brachytherapy
Brachytherapy
Brachytherapy , also known as internal radiotherapy, sealed source radiotherapy, curietherapy or endocurietherapy, is a form of radiotherapy where a radiation source is placed inside or next to the area requiring treatment...
in the treatment of cancer at sites other than the thyroid, especially in prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...
. When I-125 is used therapeutically, it is encapsulated in titanium seeds and implanted in the area of the tumor, where it remains. The low energy of the gamma spectrum in this case limits radiation damage to tissues far from the implanted capsule. Iodine-125, due to its suitable longer half-life and less penetrating gamma spectrum, is also often preferred for laboratory tests that rely on iodine as a tracer that is counted by a gamma counter
Gamma counter
A Gamma Counter is a machine to measure gamma radiation emitted by a radionuclide. Up to 300 samples are placed in sealed vials or test tubes, and move along a serpentine track on a horizontal plane. One at a time, they move down inside a shielded detector, set to measure specific energy windows...
, such as in radioimmunoassay
Radioimmunoassay
Radioimmunoassay is a very sensitive in vitro assay technique used to measure concentrations of antigens by use of antibodies...
ing.
Most medical imaging with iodine is done with a standard gamma camera
Gamma camera
A gamma camera, also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy...
. However, the gamma rays from iodine-123
Iodine-123
Iodine-123 is a radioactive isotope of iodine used in nuclear medicine imaging, including single photon emission computed tomography . The isotope's half-life is 13.22 hours; the decay by electron capture to tellurium-123 emits gamma radiation with predominant energies of 159 keV and 127 keV...
and iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
can also be seen by single photon emission computed tomography
Single photon emission computed tomography
Single-photon emission computed tomography is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera. However, it is able to provide true 3D information...
(SPECT) imaging.
Iodine-124
Iodine-124 is a proton-rich isotope of iodine with a half-life of 4.18 days. Its modes of decay are: 74.4% electron capture, 25.6% positron emission. 124I decays to 124Te. Iodine-124 can be made by numereous nuclear reactions via a cyclotronCyclotron
In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...
. The most common starting material used is 124Te.
Iodine-124 as the iodide salt can be used to directly image the thyroid using positron emission tomography
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
(PET). Iodine-124 can also be used as a PET radiotracer with a usefully longer half-life compared with fluorine-18
Fluorine-18
Fluorine-18 is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380 u and its half-life is 109.771 minutes....
. In this use, the nuclide is chemically bonded to a pharmaceutical to form a positron-emitting radiopharmaceutical, and injected into the body, where again it is imaged by PET scan.
Iodine-135 and nuclear reactor control
Iodine-135 is an isotope of iodine with a half-life of 6.6 hours. It is an important isotope from the viewpoint of nuclear reactor physicsNuclear reactor physics
Nuclear reactor physics is the branch of science that deals with the study and application of chain reaction to induce controlled rate of fission for energy in reactors....
. It is produced in relatively large amounts as a fission product
Fission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The...
, and decays to xenon-135
Xenon-135
Xenon-135 is an unstable isotope of xenon with a half-life of about 9.2 hours. 135Xe is a fission product of uranium and Xe-135 is the most powerful known neutron-absorbing nuclear poison , with a significant effect on nuclear reactor operation...
, which is a nuclear poison
Nuclear poison
A neutron poison is a substance with a large neutron absorption cross-section in applications, such as nuclear reactors. In such applications, absorbing neutrons is normally an undesirable effect...
with a very large slow neutron cross section, which is a cause of multiple complications in the control of nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s. The process of buildup of xenon-135
Xenon-135
Xenon-135 is an unstable isotope of xenon with a half-life of about 9.2 hours. 135Xe is a fission product of uranium and Xe-135 is the most powerful known neutron-absorbing nuclear poison , with a significant effect on nuclear reactor operation...
from an accumulated iodine-135 can temporarily preclude a shut-down reactor from restarting. This is known as xenon-poisoning or "falling into an iodine pit
Iodine pit
Iodine pit, also called iodine hole and xenon pit, is a temporary disabling of a nuclear reactor due to buildup of short-lived nuclear poisons in the core of a nuclear reactor. The main isotope responsible is xenon-135, mainly produced by natural decay of iodine-135. Iodine-135 is a weak neutron...
."
Iodine-128 and other isotopes
Iodine fission-produced isotopes not discussed above (iodine-128, iodine-130, iodine-132, and iodine-133) have a life lives of a couple of hours or minutes, rendering them almost useless in other applicable areas. Those mentioned are neutron-rich and so go through beta decay to their xenon counterparts. Iodine-128 (25 min half-life) can decay to either tellurium-128 by electron captureElectron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
, or to xenon-128 by beta decay
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
. It has a specific radioactivity of 2.177 x 106 TBq/g.
Non-radioactive iodide as protection from unwanted radioiodine uptake by the thyroid
Thyroid iodine uptake blockade with potassium iodide is used in nuclear medicineNuclear medicine
In nuclear medicine procedures, elemental radionuclides are combined with other elements to form chemical compounds, or else combined with existing pharmaceutical compounds, to form radiopharmaceuticals. These radiopharmaceuticals, once administered to the patient, can localize to specific organs...
scintigraphy
Scintigraphy
Scintigraphy is a form of diagnostic test used in nuclear medicine, wherein radioisotopes are taken internally, and the emitted radiation is captured by external detectors to form two-dimensional images...
and therapy with some radioiodinated compounds that are not targeted to the thyroid, such as iobenguane
Iobenguane
Iobenguane, also known as metaiodobenzylguanidine or mIBG, or MIBG is a radiopharmaceutical, used in a scintigraphy method called MIBG scan...
(MIBG), which used to image or treat neural tissue tumors, or iodinated fibrinognen, which is used in fibrinogen scans to investigate clotting. These compounds contain iodine, but not in the iodide form. However, since they may be ultimately metabolized or break down to radioactive iodide, it is common to administer non-radioactive potassium iodide to insure that iodide from these radiopharmaceuticals is not sequestered by the normal affinity of the thryoid for iodide.
Potassium iodide
Potassium iodide
Potassium iodide is an inorganic compound with the chemical formula KI. This white salt is the most commercially significant iodide compound, with approximately 37,000 tons produced in 1985. It is less hygroscopic than sodium iodide, making it easier to work with...
has been distributed to populations exposed to nuclear fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...
accidents such as the Chernobyl disaster
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...
. The iodide solution SSKI, a saturated solution of potassium (K) iodide in water, has been used to block absorption of the radioiodine (it has no effect on other radioisotopes from fission). Tablets containing potassium iodide are now also manufactured and stocked in central disaster sites by some governments for this purpose. In theory, many harmful late-cancer effects of nuclear fallout might be prevented in this way, since an excess of thyroid cancers, presumably due to radioiodine uptake, is the only proven radioisotope contamination effect after a fission accident, or from contamination by fallout from an atomic bomb (prompt radiation from the bomb also cases other cancers, such as leukemias, directly). Taking large amounts of iodide saturates thyroid receptors and prevents uptake of most radioactive iodine-131
Iodine-131
Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...
that may be present from fission product exposure (although it does not protect from other radioisotopes, nor from any other form of direct radiation). The protective effect of KI lasts approximately 24 hours, so must be dosed daily until a risk of significant exposure to radioiodines from fission products no longer exists. Iodine-131 (the most common radioiodine contaminant in fallout) also decays relatively rapidly with a half-life of eight days, so that 99.95% of the original radioiodine has vanished after three months.
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe Age of the universe The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model... ) |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 108I | 53 | 55 | 107.94348(39)# | 36(6) ms | α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (90%) |
104Sb | (1)# | ||
| β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (9%) |
108Te | ||||||||
| p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... (1%) |
107Te | ||||||||
| 109I | 53 | 56 | 108.93815(11) | 103(5) µs | p (99.5%) | 108Te | (5/2+) | ||
| α (.5%) | 105Sb | ||||||||
| 110I | 53 | 57 | 109.93524(33)# | 650(20) ms | β+ (83%) | 110Te | 1+# | ||
| α (17%) | 106Sb | ||||||||
| β+, p (11%) | 109Sb | ||||||||
| β+, α (1.09%) | 106Sn | ||||||||
| 111I | 53 | 58 | 110.93028(32)# | 2.5(2) s | β+ (99.91%) | 111Te | (5/2+)# | ||
| α (.088%) | 107Sb | ||||||||
| 112I | 53 | 59 | 111.92797(23)# | 3.42(11) s | β+ (99.01%) | 112Te | |||
| β+, p (.88%) | 111Sb | ||||||||
| β+, α (.104%) | 108Sn | ||||||||
| α (.0012%) | 108Sb | ||||||||
| 113I | 53 | 60 | 112.92364(6) | 6.6(2) s | β+ (100%) | 113Te | 5/2+# | ||
| α (3.3×10−7%) | 109Sb | ||||||||
| β+, α | 109Sn | ||||||||
| 114I | 53 | 61 | 113.92185(32)# | 2.1(2) s | β+ | 114Te | 1+ | ||
| β+, p (rare) | 113Sb | ||||||||
| 114mI | 265.9(5) keV | 6.2(5) s | β+ (91%) | 114Te | (7) | ||||
| IT (9%) | 114I | ||||||||
| 115I | 53 | 62 | 114.91805(3) | 1.3(2) min | β+ | 115Te | (5/2+)# | ||
| 116I | 53 | 63 | 115.91681(10) | 2.91(15) s | β+ | 116Te | 1+ | ||
| 116mI | 400(50)# keV | 3.27(16) µs | (7-) | ||||||
| 117I | 53 | 64 | 116.91365(3) | 2.22(4) min | β+ | 117Te | (5/2)+ | ||
| 118I | 53 | 65 | 117.913074(21) | 13.7(5) min | β+ | 118Te | 2- | ||
| 118mI | 190.1(10) keV | 8.5(5) min | β+ | 118Te | (7-) | ||||
| IT (rare) | 118I | ||||||||
| 119I | 53 | 66 | 118.91007(3) | 19.1(4) min | β+ | 119Te | 5/2+ | ||
| 120I | 53 | 67 | 119.910048(19) | 81.6(2) min | β+ | 120Te | 2- | ||
| 120m1I | 72.61(9) keV | 228(15) ns | (1+,2+,3+) | ||||||
| 120m2I | 320(15) keV | 53(4) min | β+ | 120Te | (7-) | ||||
| 121I | 53 | 68 | 120.907367(11) | 2.12(1) h | β+ | 121Te | 5/2+ | ||
| 121mI | 2376.9(4) keV | 9.0(15) µs | |||||||
| 122I | 53 | 69 | 121.907589(6) | 3.63(6) min | β+ | 122Te | 1+ | ||
| 123I Iodine-123 Iodine-123 is a radioactive isotope of iodine used in nuclear medicine imaging, including single photon emission computed tomography . The isotope's half-life is 13.22 hours; the decay by electron capture to tellurium-123 emits gamma radiation with predominant energies of 159 keV and 127 keV... Has medical uses Nuclear medicine In nuclear medicine procedures, elemental radionuclides are combined with other elements to form chemical compounds, or else combined with existing pharmaceutical compounds, to form radiopharmaceuticals. These radiopharmaceuticals, once administered to the patient, can localize to specific organs... |
53 | 70 | 122.905589(4) | 13.2235(19) h | β+ | 123Te | 5/2+ | ||
| 124I | 53 | 71 | 123.9062099(25) | 4.1760(3) d | β+ | 124Te | 2- | ||
| 125I Iodine-125 Iodine-125 is a radioisotope of iodine which has uses in biological assays, nuclear medicine imaging and in radiation therapy as brachytherapy to treat prostate cancer and brain tumors. It is the second longest-lived radioisotope of iodine, after iodine-129.Its half-life is around 59 days and it... |
53 | 72 | 124.9046302(16) | 59.400(10) d | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
125Te | 5/2+ | ||
| 126I | 53 | 73 | 125.905624(4) | 12.93(5) d | β+ (56.3%) | 126Te | 2- | ||
| β- (44.7%) | 126Xe | ||||||||
| 127IFission product Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The... |
53 | 74 | 126.904473(4) | Observationally StableTheoretically capable of spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
5/2+ | 1.0000 | |||
| 128I | 53 | 75 | 127.905809(4) | 24.99(2) min | β- (93.1%) | 128Xe | 1+ | ||
| β+ (6.9%) | 128Te | ||||||||
| 128m1I | 137.850(4) keV | 845(20) ns | 4- | ||||||
| 128m2I | 167.367(5) keV | 175(15) ns | (6)- | ||||||
| 129I Iodine-129 Iodine-129 is long-lived radioisotope of iodine which occurs naturally, but also is of special interest in the monitoring and effects of man-made nuclear fission decay products, where it serves as both tracer and potential radiological contaminant.... Can be used to date certain early events in Solar System history and some use for dating groundwater |
53 | 76 | 128.904988(3) | 1.57(4)×107 a | β- | 129Xe | 7/2+ | TraceCosmogenic nuclide Cosmogenic nuclide See also Environmental radioactivity#NaturalCosmogenic nuclides are rare isotopes created when a high-energy cosmic ray interacts with the nucleus of an in situ solar system atom, causing cosmic ray spallation... , also found as nuclear contamination |
|
| 130I | 53 | 77 | 129.906674(3) | 12.36(1) h | β- | 130Xe | 5+ | ||
| 130m1I | 39.9525(13) keV | 8.84(6) min | IT (84%) | 130I | 2+ | ||||
| β- (16%) | 130Xe | ||||||||
| 130m2I | 69.5865(7) keV | 133(7) ns | (6)- | ||||||
| 130m3I | 82.3960(19) keV | 315(15) ns | - | ||||||
| 130m4I | 85.1099(10) keV | 254(4) ns | (6)- | ||||||
| 131I Iodine-131 Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical... |
53 | 78 | 130.9061246(12) | 8.02070(11) d | β- | 131Xe | 7/2+ | ||
| 132I | 53 | 79 | 131.907997(6) | 2.295(13) h | β- | 132Xe | 4+ | ||
| 132mI | 104(12) keV | 1.387(15) h | IT (86%) | 132I | (8-) | ||||
| β- (14%) | 132Xe | ||||||||
| 133I | 53 | 80 | 132.907797(5) | 20.8(1) h | β- | 133Xe | 7/2+ | ||
| 133m1I | 1634.174(17) keV | 9(2) s | IT | 133I | (19/2-) | ||||
| 133m2I | 1729.160(17) keV | ~170 ns | (15/2-) | ||||||
| 134I | 53 | 81 | 133.909744(9) | 52.5(2) min | β- | 134Xe | (4)+ | ||
| 134mI | 316.49(22) keV | 3.52(4) min | IT (97.7%) | 134I | (8)- | ||||
| β- (2.3%) | 134Xe | ||||||||
| 135IProduced as a decay product of 135Te in nuclear reactors, in turn decays to 135Xe, which, if allowed to build up, can shut down reactors due to the iodine pit Iodine pit Iodine pit, also called iodine hole and xenon pit, is a temporary disabling of a nuclear reactor due to buildup of short-lived nuclear poisons in the core of a nuclear reactor. The main isotope responsible is xenon-135, mainly produced by natural decay of iodine-135. Iodine-135 is a weak neutron... phenomenon |
53 | 82 | 134.910048(8) | 6.57(2) h | β- | 135Xe Xenon-135 Xenon-135 is an unstable isotope of xenon with a half-life of about 9.2 hours. 135Xe is a fission product of uranium and Xe-135 is the most powerful known neutron-absorbing nuclear poison , with a significant effect on nuclear reactor operation... |
7/2+ | ||
| 136I | 53 | 83 | 135.91465(5) | 83.4(10) s | β- | 136Xe | (1-) | ||
| 136mI | 650(120) keV | 46.9(10) s | β- | 136Xe | (6-) | ||||
| 137I | 53 | 84 | 136.917871(30) | 24.13(12) s | β- (92.86%) | 137Xe | (7/2+) | ||
| β-, n Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (7.14%) |
136Xe | ||||||||
| 138I | 53 | 85 | 137.92235(9) | 6.23(3) s | β- (94.54%) | 138Xe | (2-) | ||
| β-, n (5.46%) | 137Xe | ||||||||
| 139I | 53 | 86 | 138.92610(3) | 2.282(10) s | β- (90%) | 139Xe | 7/2+# | ||
| β-, n (10%) | 138Xe | ||||||||
| 140I | 53 | 87 | 139.93100(21)# | 860(40) ms | β- (90.7%) | 140Xe | (3)(-#) | ||
| β- (9.3%) | 139Xe | ||||||||
| 141I | 53 | 88 | 140.93503(21)# | 430(20) ms | β- (78%) | 141Xe | 7/2+# | ||
| β-, n (22%) | 140Xe | ||||||||
| 142I | 53 | 89 | 141.94018(43)# | ~200 ms | β- (75%) | 142Xe | 2-# | ||
| β-, n (25%) | 141Xe | ||||||||
| 143I | 53 | 90 | 142.94456(43)# | 100# ms [>300 ns] | β- | 143Xe | 7/2+# | ||
| 144I | 53 | 91 | 143.94999(54)# | 50# ms [>300 ns] | β- | 144Xe | 1-# | ||