Download Rhodium isotopes in medicine The beta particles of Rh are used in

Stable
isotope
103
Rh
Relative
atomic mass
102.905 50
Mole
fraction
1
Rhodium isotopes in medicine
The beta particles of 105Rh are used in target radiotherapy to kill cancer cells or cause cancer
cell sterilization [332]. The gamma rays from 105Rh enable in vivo tracking during radiotherapy
[332]. 105Rh is being studied for use in the treatment of bone pain (Figure 1) [331, 332].
Ocular brachytherapy currently is performed using 125I or ruthenium/106Rh seeds [336].
Brachytherapy can allow a good spatial dose distribution over the ocular tumor with lower
radiation on adjacent tissues. In the case of irradiation of the eyeball with ruthenium/106Rh,
80 percent of the dose has been absorbed within a depth of 5.2 mm and 90 percent has been
absorbed within 7.2 mm (Figure 2). This limits the application of 106Rh; however, when 106Rh
can be used, the radiation dose can be lower, which is preferred.
Fig. 1: Bone cancer cells that have been pap stained and magnified to 400 times. The beta
particles and gamma rays of 105 Rh are used, respectively, in radiotherapy to kill cancer cells
and for in vivo tracking during radiotherapy. (Photo Source: National Cancer Institute at the
National Institutes of Health) [337].
Fig. 2: Variation in absorbed dose of 106Rh as a function of tissue depth in ocular
brachytherapy (modified from [338]).
Glossary
atomic number (Z) – The number of protons in the nucleus of an atom.
brachytherapy – the treatment of cancer, especially prostate cancer, by the insertion of
radioactive implants directly into the tissue near the tumor. [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 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. [return]
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.
in vivo – in the living body (plant or animal). [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).
ocular - connected with the eyes or vision. [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).
radiography – an imaging technique that uses electromagnetic radiation other than visible light,
especially X-rays and gamma rays, to view the internal structure of non-uniform objects, such
as metal parts, welded pipes, and the human body.
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
331. T. S. I. Inc. Ruthenium Isotopes. Trace Sciences International Inc. 2014 Feb. 26.
http://www.tracesciences.com/ru.htm
332. A. R. Ketring, Ehrhardt, G.J., Embree, M.F., Tyler, T.T., Gawenis, J.A., Jurisson, S.S.,
Engelbrecht, H.P., Smith, C.J., and Cutler, C.S. Alasbimn Journal. 5 (19) (2003).
336. a. T. P. R. D. C. A. P. Mourão. Radiologia Brasileira. 42 (1), 43 (2009).
337. D. L. L. Laboratory. National Cancer Institute at the National Institutes of Health (1988).
703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book"). Blackwell Scientific Publications, Oxford (1997).