In radiotherapy for stage I and stage II cancer of the uterine cervix, the irradiating fields should be limited to the primary lymphnodes, parametrium and pelvic wall. Injury to the intestine and bone marrow and irradiation of the femoral neck and kidneys should be kept at a minimum.
With the aid of pelvic lymphadenography and angiography, and radiography of the pelvis at surgery, the corresponding area's correlation to the pelvis was investigated.
The irradiation areas were hexagonal, derived from points 1, 1', 2, 2', 3, 3'on the anteroposterior (AP) and from a, a', b, b', c, c'on the posteroanterior (PA) projections.
1 and 1': A transverse plane at the level of the posterior portion of the iliac crests, (lateral points from the fourth lumbar vertebra by a half of the vertebral width).
2 and 2': A transverse plane midway between that at the iliac crests and one at the level of the ischial tuberosities (the midway of each iliac shadow).
3 and 3': intersections of a transverse plane at the midsymphysis level and the lateral margin of each obturator foramen.
a and a': correspond to 1 and 1'on the AP projection. b and b': correspond to 2 and 2'on the AP projection. c and c': intersections of a transverse plane at the level of the inferomedial angle and the lateral margin of each obturator foramen.
These hexagons formed opposing cobalt-60 irradiating fields for therapy of stage I and stage II cancer of uterine cervix, with central shielding.
The hexagonal fields for each patient were obtained radiographically using a measuring plate. The fields were about 100 cm
2, excluding the central shielded zones.
The method of describing the fields and their reliability are discussed.
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