Roentgen Therapy of Medulloblastoma Cerebelli

Abstract

IN 1924, Bailey and Cushing (2) presented a series of twenty-nine. centrally placed cerebellar tumors, arising from above the roof of the fourth ventricle and occurring mainly in children. For these tumors, they proposed the term “medulloblastoma,” and submitted evidence that they were composed mainly of indifferent cells, analogous to those described by Schaper in the developing cerebrum, and that most of these cells are potential neuroglia. At that time, they concluded that the best method of treatment consisted of a suboccipital decompression followed by persistent roentgenray therapy. The technic of this proposed therapy was not outlined in their first paper, which was not actually published until 1925. Bailey, in the same year, individually wrote another paper on the results of roentgen therapy on brain tumors. Olivecrona and Lysholm (8), in 1926, published excellent notes on the roentgen therapy of gliomas of the brain. One of the tumors reported by them seemed to have all the characteristics of a medulloblastoma and it reacted favorably to radiation. In 1928, Bailey, Sosman, and Van Dessel (4) outlined a technic of irradiation which they had employed during an eight-year period, in 456 patients with brain tumors. Of these, 222 had been classified as “gliomas” but they limited their considerations to 62 cases, and of these 12 were medulloblastomas. All treatments in their department had been given with an interrupterless 12-inch transformer, mechanically rectified, using 130 to 140 K.V. peak. According to the authors, the filter most often employed was 0.25 mm. of rolled copper, with one thickness of sole leather on the side next to the patient and occasionally 5.0 mm. of aluminum was used in place of the copper. A distance of 12 inches (30 cm.) from the center of the target to the skin surface, occasionally 10 inches when a shorter duration was expedient, or 16 inches when a more uniform depth dose was required, was used. The portals of entry were delimited by lead rubber on the patient's head and by various lead diaphragms ¼ inch thick placed beneath the tube, which was of the broad focus Universal Coolidge type. The authors stated that the portals varied between 8 and 15 cm. in diameter, the milliamperage was 6, and the usual time for a full dose was 25 minutes, which would produce epilation in practically all cases, but only a faint erythema occasionally, appearing in from ten to fourteen days. Such a dose could be repeated at intervals of three weeks, usually with a return of hair several months after the treatments were stopped, and with never more than slight tanning at any time They included physical data concerning their dose, which we take the liberty to repeat here. The average effective wave length with a Duane ionization chamber was 0.21 Ångström unit as determined by the half absorption method in copper, and an average intensity at 12 inches of from 0.54 to 0.66 electrostatic unit.