nuclear reactor, during the latter part 
of the week they are received. 
Radiogold seeds received from a 
distant point of preparation will always 
put the therapist to the same dis- 
advantages that now prevail for those 
physicians who receive radon seeds 
from commercial sources. The varia- 
tion of source strengths to provide the 
flexibility required for individualization 
of patterns to meet the multitudinous 
clinical variations encountered in prac- 
tice, is not possible with sources of 
initially fixed strengths. 
2. It was shown previously (3, 6) 
that the leakage of the undesirable beta 
particles through the thinned parts of 
the ends of Au! seeds prepared here 
is insignificant in comparison with the 
escape of highly energetic and pene- 
trating beta particles from a radon 
seed obtained from a commercial 
source. Measurements made by Sin- 
clair revealed a beta-particle emission 
from the platinum-sheathed Au! 
sources he prepared that differed only 
slightly from that of radon seeds. 
3. The cost of nonradioactive gold 
for sheathing material to absorb the 
same fraction of the beta particles 
emitted from the enclosed radiogold is 
only about one-fourth as great as that 
for the platinum sheaths used by 
Sinclair. Moreover, the expense in- 
curred ‘for the precision machining and 
welding that is required to encapsulate 
the gold within the platinum is avoided 
in the method devised here. 
Clinical Uses 
Radiogold seeds may be utilized to 
form permanent implantations by 
means of the same applicators that are 
now widely used for radon seeds. 
Alternatively, Au8 seeds may be 
loaded into Nylon tubing that is 
threaded through tumors and with- 
drawn at the end of the exposure time, 
which is usually 7 days. An advan- 
tage of implanting Au!’ seeds per- 
manently is that it is unnecessary to 
load the seeds into Nylon tubing. 
However, permanent implantations by 
free-hand techniques have not resulted 
in the regular patterns of sources that 
are usually obtained readily when the 
seeds are first enclosed in Nylon 
tubing. 
Another advantage of the Nylon- 
tube method is that errors in alignment 
of the pattern during implantation can 
be corrected by pulling the Nylon tubes 
into the proper position, as indicated 
by roentgenograms. Also, no foreign 
body remains in the tissue after the 
150 
Nylon tubes are withdrawn at the end 
of aweek. Experiences at this medical 
center have demonstrated that the 
Nylon-tube technique is generally to 
be preferred to the permanent im- 
plantation of the seeds. 
Improved implantation method. 
The Nylon-tube implantation method, 
previously developed here for use with 
Co® (8-10), has recently been im- 
proved in several respects. Since 
details of this new Nylon-tube tech- 
nique will be reported independently 
by Henschke, only the principal 
features of it will be outlined briefly 
here. First, in place of the thick- 
walled, relatively stiff Nylon tube 
formerly employed at The Ohio State 
University Medical Center, a thin- 
walled, narrow Nylon tube is now used. 
In this new Nylon tube, the radio- 
active sources are held firmly in place 
by the resiliency of the Nylon without 
the need for the metallic spacers used 
formerly. These new tubes are much 
more flexible and can be bent more 
readily than the previous tubes. 
Moreover, should the loaded suture 
break inadvertently, the radioactive 
sources cannot fall out as they could 
with the old method. 
A second major improvement in the 
Nylon-tube technique has been evolved 
and is now used in many cases. The 
Nylon tubes are not loaded with the 
radioactive sources prior to implanta- 
tion; instead, Nylon tubes loaded with 
dummy metal seeds, or thin stainless- 
steel wires are inserted in the tumor 
area at the time of operation. Roent- 
genograms are then made and an 
appropriate distribution for the radio- 
active sources is determined from the 
spatial relationships. Nylon tubes are 
loaded with the radioactive sources 
accordingly and are pulled into position 
after attachment to the dummy- 
loaded Nylon tubes or to the stainless- 
steel wires. This substitution of the 
Nylon tubes loaded with active sources 
for the ones containing the dummy 
sources, or the wires, causes little dis- 
comfort and is usually done satisfac- 
torily without anesthesia. 
It will be apparent that this tech- 
nique enables the surgeon to prepare a 
patient during operation for subse- 
quent implantation with the radio- 
active seeds. The radiation therapist 
can then design an appropriate pattern 
and insert it at a time and place con- 
venient for him. This technique has 
proved mutually satisfactory to the 
surgeon and the radiotherapist mem- 
bers of the team here. 
Clinical experience. Fifty-one ap- 
plications of Au! seeds clinically in 
46 patients thus far have included 31 
permanent implantations, 12 Nylon- 
tube implantations, 2 intrauterine 
applications, 2 intraesophageal appli- 
cations, 2 nasopharyngeal applications, 
1 intraoral mold, and 1 skin mold. 
No untoward or unusual reactions 
have been noted in any case in which 
the Au! seeds have been used. The 
clinical regressions of tumor tissue 
have been comparable to those ob- 
served with other methods of inter- 
stitial irradiation. And they have 
been consistent with the preliminary 
animal experiments in which it was 
demonstrated that it is possible to 
deliver a cancerocidal dose to tumor 
tissue with Au? seeds alone (1, 2). 
However, the preferred practice here 
usually is to use Au! seeds in com- 
bination with high-voltage external 
irradiation. In some cases two inser- 
tions of radiogold seeds spaced 1-8 
weeks apart have been used to deliver 
the total dose over a longer period. 
* * * 
This study was supported, in part, by a 
grant-in-aid from the Ohio Department of 
Health, the Ohio State University Develop- 
ment Fund, the Julius F. Stone Fund for 
Medical Research, and cancer research grant 
C-1899 from the National Cancer Institute 
approved by the National Advisory Cancer 
Council. 
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a W.G Myers, B. H. Colmery, Jr. Radio- 
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sind (Thesis, The Qhio State University, 
S. W. M. MclLellon. The use of radioactive 
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