Today technetium-99m (99mTc), a radioisotope (RI) of Tc, is widely used in the examination
and diagnosis of cancer. Recently rhenium-186 (186Re, half-life 90.6 h) and 188Re (16.9 h), RIs of Re which belongs to the same family as Tc
in the periodic table, have been watched with keen interest by
the medical field. We have been developing a method to produce
these RIs and to produce labeled compounds suitable for medical
applications. As shown in Table 3-2, 186Re is produced either by the irradiation of enriched 185Re in a nuclear reactor or by the irradiation of tungsten-186
(186W) with a proton beam from a cyclotron. 188Re can be obtained as the daughter nuclide of 188W (69.4 d) via neutron irradiation of enriched 186W in a nuclear reactor. A simple generator has been devised to
separate 188Re from 188W, which consists of an alumina column that retains 188W and of an anion exchange resin column connected to the alumina
column. This generator will facilitate the development of applications
of 188Re.
Synthetic methods for the production of compounds labeled with
Re shown in Table 3-2 have been developed. The HEDP compound (1-hydroxyethane-1,
1-diphosphonic acid) is expected to relieve pain due to metastatic
bone tumors. It accumulates in the bone, as shown in the whole
body scintigram of a mouse in Fig. 3-12, which was obtained by
intravenous injection of 186Re-HEDP. The 188Re-labeled MAb (monoclonal antibody) compound will be used as
a medicine, which will be applicable to diagnosis and therapy
simultaneously. The 188Re-DMSA (dimercaptosuccinic acid) is used widely for the diagnosis
of kidney diseases. Carrier-free 188Re obtained from a 188W/188Re generator is used for the labeling. |
