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Stable
isotope
159
Tb
Relative
atomic mass
158.925 35
Mole
fraction
1
Terbium isotopes in medicine
149
Tb is being studied for use in targeted radiotherapy using alpha particles and labeling
radioimmunoconjugates in cancer treatments [463, 464]. 161Tb attached to a bioconjugate (two
covalently linked molecules, one or more of which is a biomolecule) is being studied for use in
cancer therapy as a targeted radiation treatment of cancer cells [464, 465]. 161Tb is being studied
for imaging purposes as it allows for on-line monitoring of its distribution using gamma
cameras [464, 465]. 149Tb is produced by the reaction 142Nd(12C,5n)149Dy → 149Tb + β + and by
141
Pr(12 C,4n)149Tb, and beam geometry is important for satisfactory yield of 149Tb (Figure 1)
[466].
Fig. 1: Relative production of 149Tb from the reaction 142Nd(12C,5n)149 Dy → 149Tb + β + for two
different beam geometries. A ten-fold increase in production is achieved by optimal beam
geometry (January 1996) (modified from [466]).
Glossary
alpha particle – a positively charged nuclear particle identical with the nucleus of a helium atom
consisting of two protons and two neutrons. [return]
atomic number (Z) – The number of protons in the nucleus of an atom.
covalently - share electron pairs between atoms. [return]
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].
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. [return]
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.
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.
monoclonal antibodies (mAb or moAb) - identical immune cells that are all clones of a unique
parent cell, in contrast to polyclonal antibodies, which are made from several different immune
cells.
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).
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).
radioimmunoconjugate – radioactive substance that carries radiation directly to cancer cells
and is made by attaching a radioactive molecule to an immune substance, such as a monoclonal
antibody, that can bind to cancer cells; used to kill cancer cells without harming normal cells
[714]. [return]
radiotherapy (radiation therapy) – the treatment of disease by means of radiation from
radioactive substances or X-rays. [return]
stable isotope – an atom for which no radioactive decay has ever been experimentally measured.
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.
References
463. N. G. Zaitseva, Dmitriev, S. N., Maslov, O. D., Molokanova, L. G., Starodub, G. Ya.,
Shishkin, S. V., Shishkina, T. V., and Beyer, G. J. Czechoslovak Journal of Physics Supplement.
53 (1), A455 (2003).
464. G. J. Beyer, Miederer, M., Vranjes-Duric, S., Comor, J.J., Kunzi, G., Hartley, O.,
Senekowitsch-Schmidtke, R., Soloviev, D., and Buchegger, F. European Journal of Nuclear
Medicine and Molecular Imaging. 31, 547 (2004).
465. S. Lehenberger, Barkhausen, C., Cohrs, S., Fischer, E., Grünberg, J., Hohn, A., Köster,
U., Schibli, R., Türler, A., and Zhernosekov, K. Nuclear Medicine and Biology. 38 (6), 917
(2011). 10.1016/j.nucmedbio.2011.02.007
466. B. J. A. S. Sarkar, S. Imam, G. Goozee, J. Leigh, and H. Meriaty. In Second international
conference on isotopes (C. J. Hardy, ed.), pp. 206. Australian Nuclear Association Inc.,
Sutherland, NSW (Australia) (1997).
703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book"). Blackwell Scientific Publications, Oxford (1997).
714. N. N. C. Institute. NCI Dictionary of Cancer Terms-radioimmunoconjugate. NIH
National Cancer Institute. 2016 June 22. http://www.cancer.gov/publications/dictionaries/cancerterms?cdrid=649775