Download Gallium isotopes in medicine Ga is a radioactive isotope that emits

Stable
isotope
69
Ga
71
Ga
Relative
atomic mass
68.925 574
70.924 703
Mole
fraction
0.601 08
0.398 92
Gallium isotopes in medicine
68
Ga is a radioactive isotope that emits positrons, which are used to produce high-resolution
imaging with positron emission tomography (PET). Unlike 18F, which is most commonly used,
68
Ga is more easily produced using a cost-effective generator with the parent radionuclide 68Ge
(Figure 1). Once produced, 68Ga easily couples to biomolecules (most commonly peptides) that
target G-protein coupled receptors, which are over-expressed on human tumor cells. The
labeled protein acts as a radiotracer for cancer diagnostics. PET images are often coupled with
CT images to get a more complete picture of the body [252-258]. Radiopharmaceutical 67Ga is
a gamma-emitting isotope used in scintigraphy for medical imaging [259-261].
Fig. 1: Gallium-68 generator used to provide those in engaged in medical therapy with the
positron-emitting radionuclide 68Ga. The parent isotope, 68Ge, has a half-life of 271 days and
can be used as the source of 68Ga, which has a half-life of only 68 minutes. Image kindly
provided by Dr. Anatolii Razbash, Cyclotron Co. Ltd., Obninsk, Russia.
Glossary
atomic number (Z) – The number of protons in the nucleus of an atom.
CT scan (X-ray computed tomography or X-ray CT, computerized axial tomography scan
or CAT scan) – a computerized tomography (CT) scan combines a series of X-ray images taken
from different angles and uses computer processing to create cross-sectional images, or slices, of
the bones, blood vessels and soft tissues inside your body [702].
electron – elementary particle of matter with a negative electric charge and a rest mass of about
9.109 × 10–31 kg.
element (chemical element) – a species of atoms; all atoms with the same number of protons in
the atomic nucleus. A pure chemical substance composed of atoms with the same number of
protons in the atomic nucleus [703].
G-protein coupled receptors – the largest and most diverse group of membrane receptors in
eukaryotes (living organisms other than bacteria and archaeabacteria). These cell surface
receptors act like an inbox for messages in the form of light energy, peptides, lipids, sugars, and
proteins [704]. [return]
gamma camera (scintillation camera or Anger camera) – instrument used to track the
distribution in body tissue of radioactive isotopes (tracers) that emit gamma radiation (high
energy photons), a technique known as scintigraphy.
gamma rays (gamma radiation) – a stream of high-energy electromagnetic radiation given off
by an atomic nucleus undergoing radioactive decay. The energies of gamma rays are higher
than those of X-rays; thus, gamma rays have greater penetrating power.
half-life (radioactive) – the time interval that it takes for the total number of atoms of any
radioactive isotope to decay and leave only one-half of the original number of atoms. [return]
isotope – one of two or more species of atoms of a given element (having the same number of
protons in the nucleus) with different atomic masses (different number of neutrons in the
nucleus). The atom can either be a stable isotope or a radioactive isotope.
neutron – an elementary particle with no net charge and a rest mass of about 1.675 × 10–27 kg,
slightly more than that of the proton. All atoms contain neutrons in their nucleus except for
protium (1H).
over-expressed – to make too many copies of a protein or other substance, which may play a
role in cancer development. [return]
parent radionuclide – a radioactive isotope, commonly in a radionuclide generator, that decays
to produce a radioactive daughter. For example, the parent radionuclide 99Mo decays to 99mTc,
which is used in radionuclide angiography. [return]
peptides –a molecule consisting of 2 or more organic compounds containing a carboxyl (COOH) and an amino (-NH2) group [703].[return]
positron – the antimatter counterpart of the electron, with a mass identical to that of the electron
and an equal but opposite (positive) charge. [return]
positron emission tomography (PET) scan – an imaging technique that is used to observe
metabolic activity within the body. The system detects pairs of gamma rays emitted indirectly
by a radioactive isotope used as a tracer, which emits positrons and which is introduced into the
body on a biologically-active molecule. Three-dimensional images of the concentration of the
radioactive isotope within the body are then constructed by computer analysis. The imaging
often is performed with an X-ray CT scan in the same instrument. [return]
proton – an elementary particle having a rest mass of about 1.673 × 10–27 kg, slightly less than
that of a neutron, and a positive electric charge equal and opposite to that of the electron. The
number of protons in the nucleus of an atom is the atomic number.
radioactive decay – the process by which unstable (or radioactive) isotopes lose energy by
emitting alpha particles (helium nuclei), beta particles (positive or negative electrons), gamma
radiation, neutrons or protons to reach a final stable energy state.
radioactive isotope (radioisotope) – an atom for which radioactive decay has been
experimentally measured (also see half-life). [return]
radiolabeled – a mixture of an isotopically unmodified compound with one or more analogous
radioactive isotopically substituted compound(s).
radionuclide – a nuclide that is radioactive [703]. [return]
radionuclide angiography (also called gated equilibrium blood pool imaging) – a test using
the radioactive isotope 99mTc to evaluate the function of the right and left ventricles of the heart
by measuring radioactivity over the anterior chest as the radioactive blood flows through the
large vessels and the heart chambers.
radiopharmaceutical – radiolabeled compound used for diagnostic or therapeutic purposes.
[return]
scintigraphy – see gamma camera. [return]
stable isotope – an atom for which no radioactive decay has ever been experimentally measured.
tracer - substance used for tracking purposes.
X-rays – electromagnetic radiation with a wavelength ranging from 0.01 to 10 nanometers—
shorter than those of UV rays and typically longer than those of gamma rays.
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http://www.mayoclinic.org/tests-procedures/ct-scan/basics/definition/prc-20014610
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Book"). Blackwell Scientific Publications, Oxford (1997).
704. S. b. N. Education. GPCR. Nature Education. 2016 June 22.
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