Physics And Chemistry Basis Of Biotechnology - De Cuyper - tiera.ru

Radioactive microspheres for medical applications
Figure 8. Treatment of 9L-glioblastoma brain tumours in Sprague Dawley rats The
treatment and toxicity group received 50 µCi 186 Re and 188 Re in 0.5 mg glass
microspheres contained in 30 µl of fibrin glue.
Radioactive microspheres filled with magnetite and radiolabelled with the b -emitter 90 Y
can also be used for targeted cancer therapy. This has been shown with 30% magnetitecontaining
poly(lactic acid) microspheres sized 20 to 30 µm that were injected
intraperitoneally into C57BL6/N mice and targeted to a subcutaneously growing EL-4
murine lymphoma of about 0.5 g [141]. The injection of microspheres took place inside
the peritoneal cavity as far from the tumour as possible. After injection, a round, 2 mm
thick rare earth magnet with a diameter of 10 mm was taped directly above the tumour.
The magnetic field on top of the magnet was 0.12-0.16 Tesla. A dose dependent
decrease in tumour size was observed after the 7 day treatment period (Figure 9). Close
examination revealed that 3 out of 4 tumours in the 80 Gy group and 2 out of 4 tumours
in the 120 Gy group were completely eradicated, but that the remaining 1 or 2 tumours,
respectively, had grown. It was precisely these tumours that had initially been found to
be oblong or flattened out, thus causing the magnetic microspheres to be concentrated
farther than 5 mm away from the edges of the tumour. Considering that 90% of the
dose of 90
Y is deposited within 2.8 mm [30], it follows that the tumour cells farther
away were undertreated with the applied amount of radioactivity. The tumours which
were not eradicated were therefore local treatment failures.
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