The authors have reported on 108 patients with pituitary macroadenomas (measuring 2 cm in at least one diameter) who underwent 117 transsphenoidal operations and five craniotomies, and were followed for periods ranging from 6 months to 14 years. Vision improved in 90% of the patients. Gross total tumor removal with no evidence of residual tumor tissue demonstrable on the postoperative computerized tomography scan was accomplished in 41% of cases. However, gross total tumor removal is not synonymous with complete tumor removal. Endocrine cure was possible in 25% of prolactin-secreting and 20% of growth hormone-secreting adenomas. The incidence of recurrence was 12%, with the majority occurring from 4 to 8 years postoperatively. Both the tumors with suprasellar extension of more than 2 cm and the hard fibrotic tumors had a higher recurrence rate. Postoperative administration of radiation therapy has been associated with a significantly lower recurrence rate than when this therapy was withheld. Transsphenoidal surgery of pituitary macroadenomas confined to the extra-arachnoid space is associated with a relatively small number of complications. The operative technique used in this series is described.
A study of three 10-MV x-ray clinical accelerators with emphasis on the reduction of electron contamination was conducted. This study, which was performed with different types of trays and filters, suggests that, at 100-cm source-surface distance (SSD), Pb can be used as an effective filter material up to 30 X 30 cm2; however, due to its transparency, a Clear-Pb tray is useful for field sizes up to a 20 X 20 cm2. Percent depth doses for a few selected depths and field sizes at this nominal SSD were examined. No significant differences, with the exception of the location of Dmax, amongst the three accelerators were noticed.
The relative percent intensity reduction by lead (Pb) of 5 MeV electrons produced by Siemens Mevatron 77/74 for 5 cm diameter, 10 X 10, 15 X 15, and 20 X 20 cm2 cones both with and without buildup is measured. The thickness of lead (Pb) required to attenuate the intensity of the primary electron beam to 95% and 98% depends upon the cone size and upon the depth in phantom at which transmission measurements are made.
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