patient, and [veteran] at a meter distance would in this hypothetical
situation receive a maximum exposure of 0.1% of this or 0.35 mr. Thus,
in the unlikely situation that she assisted at twenty such examinations a
day, five days a week, her weekly exposure would be as high as 35 mr.
The maximum permissible dose even at today’s low levels is 100 mr per
week. | might add that this is only an exposure dose and does not
represent an absorbed dose, which is the important factor. The absorbed
dose would be even fess at the level of the ovaries, due to the
attentuation by the overlying tissues, plus the fact that the primary
beam is slightly softened by scatter. Thus, it is estimated that a 100 KV
primary beam would be reduced or be equivalent to 84 KV after 90
degree scatter. That is, a beam which is softer and less penetrating,
though not significantly so. If she stood behind the radiologist, her
exposure would probably be even less because of the increased shielding.
While these figures serve to iliustrate the situation possible under one
set of conditions, they, of course, are not valid for a case such asthis in
which none of the factors are known. However, they serve to point up
how little her exposure might have been even under these maximum
conditions, and also serve to bring up a discussion of the effects of
radiation.
,
the basis of admittedly indefinite dosimetric calculations, (where the
error should be on the side of calculation of doses in excess of what she
probably received), she could not possibly have received sufficient
radiation to produce or aggravate her anemia. Secondly, | know of no
known study relating carcinoma of the ovary to anemia as an etiologic
agent. Finally, while there is no unanimity of opinion as to the
relationship between radiation and carcinoma of the ovary under the
conditions of this case, the preponderance of opinion is that
predisposing conditions rather than radiation per se is the etiologic
factor in gynecologic neoplasms. Certainly, in view of the report
mentioned above, the probability is way, way below fifty per cent.
Findings of the BVA and Basis for Decision: In denying the appeal the Board
found that 1) carcinoma of the ovary was not present during service; 2)
carcinoma of the ovary was not present within one year after separation from
World War I! service; 3) carcinoma of the ovary is not etiologically related to
the service-connected anemia; and 4) carcinoma of the ovary was not caused by
exposure to X-ray during service.
To...direct this discourse toward the possibility of ovarian
carcinoma I feel | might point out that the reports of radiation induced
neoplasms of the ovary ...are rare. The early work of Furth, et al, in
1936 pointed out the striking sensitivity of ovarian tissues to whole
body irradiation. X-rays in single or fractional doses or chronic gamma
radiation has been carcinogenic in manystrains of mice with doses as low
as 50 to 110 r. Law at the National Cancer Institute stated that the total
accumulated dose of radiation is the deciding factor in the induction of
ovarian neoplasms though there is insufficient data to indicate the
influence of dose rate or fractionation and protraction.
it has been reported that a minimum dose of 600 1 is necessary to.
produce cessation of ovarian function...
Thus while no consistent conclusion is available in the literature, the
opinion of most authors is that the predisposing condition rather than
irradiation per se is the etiologic factor in gynecologic neoplasms. Thus
as noted by Furth and most radiation therapists, it is exceedingly rare
that a carcinoma or sarcoma develops at the site of irradiation following
therapeutic doses of X-rays. Doses which are much greater than
{veteran} could possibly have been exposed to.
In conclusion then, | would like to reiterate what I point out at the
beginning of this letter: | do not believe that the patient’s anemia was
the result of, nor aggravated by her exposure to radiation. | believe that
this patient was anemic prior to her admission in the Navy, and that on
72
73