Biomedical Engineering Reference
In-Depth Information
ranging from 5 to 400Gy (500
40 000 rad). The rabbits were sacrificed
over a period of 14 months, during which time there were no deaths due
to radiation-related complications.
Histological examination of both kidneys, as well as other organs,
revealed no damage of significance except to the kidney in which the
153
Smmicrospheres had been injected. The only change in nearby organs
was a slight scarring of the fat tissue adjacent to the target kidney. On
the other hand, the degree of histological damage to the target kidney
was significant and increased with increasing dose. At the time it was
surgically removed, the size of the irradiated (150Gy) kidney was only
25-35% of that of the control (non-injected) kidney.
It is encouraging that none of the rabbits showed any outward sign of
radiation effects, even at the highest dose, and the only organ showing
any detectable histological change was the kidney injected with the
radioactive
153
SmAS microspheres. The favorable histological evidence
from this study indicates that this
in situ
, highly localized radiation
treatment of inoperable tumors in the kidney offers the possibility for
sterilizing such tumors prior to their surgical removal.
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13.8 TREATMENT OF RHEUMATOID ARTHRITIS:
RADIATION SYNOVECTOMY
Rheumatoid arthritis is a chronic inflammatory disease that can cause
destruction of articular cartilage in joints and can also affect the lungs
and other tissues. Primarily an inflammatory response occurs in the
synovial membrane (synovial tissue) of joints, which is the soft tissue
encapsulating the synovial fluid and the joint.
The injection of radioactive substances into an arthritic joint for
the purpose of reducing the swelling and inflammation of the synovial
tissue, a procedure commonly referred to as radiation synovectomy,
is an established procedure in Europe. A schematic where biodegrad-
able radioactive glass microspheres or particles are used is shown in
Figure 13.10. In this treatment, particles containing radioisotopes such
as
90
Y,
198
Au,
186
Re, and
169
Er and ranging in size from a few nanome-
ters (colloids) to 5-15
m (one to three times the diameter of a red blood
cell) are injected into the affected joint [26].
In this application, it is considered desirable for the particles to
eventually degrade
in situ
or otherwise be eliminated from the joint
being treated. Encouraging results have been obtained from animal
experiments where the stifle (knee) joint of rabbits and rats have been
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