Fig. 57.--Loading radioactive beads
TABLE 31.
Sample
:
Location
Statistics oF Cs®? MicROSPHERES
|
No. of
INO. O
beads
|
-
n
|
& min
Top
100
58
10
Top
20
10
13
100
10
Top
Middle
Bottom
10
100
9
11
°
|
i
raeee
,
i
2
The usefulness of a phantomis solely dependent
:
S.D.
11,930 + 180
x?
|
|
11,850 + 179
6
12,070 + 218
10
12,690 + 140
10
ANALYSIS
12,450 + 240 |
1634
346
201
155
523
n = No. of samples counted.
i = mean counting time per sample.
About 25 radioelements are available from the 3M
Companyin microsphere form. For short-lived isotopes,
it would seem entirely feasible to load the nylon beads
with any desired stable element and produce the desired activity in situ by neutron irradiation. We have
not investigated this possibility in detail as yet.
its imitating the relevant dimensions and shape
body and of the radioactive organ, and on co)
locating one within the other. Obviously, the de
(customarily a single or multiple Nal erystal
possibly collimated) must be placed identically
respect to the body and the phantom. If we ar
cerned with calculating the burdenof a single indi
with precision, the uncertainties arising from n
variations in size and location must all be recog
dependent as these are upon the patient’s age
race, and habitus. But these considerations are con
to any calibration procedure.
As a preliminary to studyingthe statistical pro}
of many sources, an analysis was attempted «
minimum number and optimum spatial positi
discrete beads that are required to simulate a unif
active organ to any stated degree of accuracy