Læknablaðið : fylgirit - 01.05.1978, Page 89

Ti/2 = 9.3d
Eg (max) = 340 keV
(mean) = 97 keV
di/2 (eff) = 0.1 mm
ERBIUM CITRATE
particle size ^ 10 nm
169 Er 9.3d
DOSKS OUTSIDE THE SYNOVIAL CAVITY
^°Y (rad/%) 1í^Er (rad/jí)
LYMPH HODKS 4SO (inquinal; 20g) 35 (axillary; 5g)
(TYriCALLY) (?OOrad) (200rad)
TOTAL 30DY 0.13 0.0025
(TYPICALLY) (2.5rad) (0.05rad)
and here we can see that yttrium is a pure
beta omitter (gamma component is minimal;; only
0.017% of all deeoys).
The second slide shows corresponding charac-
teristics of l69Er. We can see that the beta
radiation energy is considerably lower than that
of 90Y. The half value layer is therefore lower,
too only 0.1 mm. The decoy scheme shows that
beta radiation is dominant; a weak 8 keV gamma
component has no significance.
The retention of yttrium is more than 9C% when
after the treatment, the patient is immobilized
for three days. If there is no immobilization
the leakage is substantially higher. Less than
1% of the leaked radionuclide is accumulated in
the inquinal lymp nodes and the rest is probably
distributed evenly - in the whole body. The
lymph node accumulation causes a radiation dose
about 450 rad/% the typical valve being 300 rad.
Corresponding whole body dose is 2.5 rad.
In treating finger joints with erbium a
considerably proportion is also leaked. The
accumulation in axillay nodes varies between 3
and 14%. The radiation dose in lymph nodes
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