Page 37 - PR 2014 2016 03 Applications of Ionizing Radiations

Applications of Ionizing Radiations | Progress Report 79

a mixture of hydrocarbons. However, the
catalyst gradually loses its activity, either PHOTO: MARCOS POLITI
by changing its original molecular structure
or by its contamination from other petro-
leum molecules. The application of ionizing
radiation (electron beam and gamma rays)
over these spent catalysts was studied to
contribute with the extraction of metals or
rare-earths of high added-value. Tests carried
out with FCC catalysts used the techniques Figure 56. The skin of Tilapia fish
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of Co irradiation and electron beam (EB)
and had as a subject the extraction of lantha- Radiosterilization for tissue banks
num (La O ), regeneration and utilization of
2 3
these catalysts. However, the use of ionizing In Latin America, the industrial level ionizing
radiation has not contributed in these pro- radiation sterilization has been used for more
cesses. Meanwhile with HCC catalysts, the than three decades in food and medical, phar-
irradiation used was electron beam and had maceutical and cosmetics products. Later, this
as a subject the extraction of molybdenum activity was extended to the sterilization of
(MoO ). In temperature around 750°C, these human tissues for graft and reinforced in some
3
irradiated catalysts of the lower region have countries by the technical cooperation and
an extraction yield twice higher compared to International Atomic Energy Agency - IAEA
non-irradiated ones, in other words 57.65% financial support. In the last few years, pre-
and 26.24% respectively. served tissue allograft, such as bone, cartilage,
tendon, skin, amnion and other not viable tis-
Health applications of sues, have been used in reconstructive surgery
ionizing radiation and by many clinical specialties, like orthopedic

Radioactive Sources and plastic surgery. The transmission risk of
infectious diseases by allograft, however, is
a constant concern. To this end, many steps
Sterilization of Nile Tilapia (Oreochromis should be taken, including tissue sterilization.
Niloticus) skin by ionizing radiation This technique is used to minimize the immu-

nogenicity, to kill bacteria and to reduce the
The skin of Tilapia fish has been studied to be contagious diseases transferring risk. As an
used as another alternative in the treatment of example, the skin glycerol preservation has
burns and for this type of use it is essential to a bacteriostatic effect after certain time, on
be sterile. To this end, several doses and rates of the other hand, skin sterilization by ionizing
doses were studied in both the multipurpose radiation may reduce the quarantine period for
irradiator and the electron beam in order to ra- transplantation in patients, and their safety
diosterilize this material without significantly is considered excellent. The ionizing radia-
altering its physico-chemical structure. With tion is a very efficient sterilization technique;
the result of these studies, it was possible to nevertheless, its deployment is still contested
establish the dose of 30 kGy as the ideal dose since there are few data on its effects upon
to radiosterilize these fish skins, already packed, the tissue allograft. At the Radiation Technol-
in our gamma irradiator with Co source. ogy Center, procedures using two sources of
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