²¹¹At radiocolloid therapy: Further observations and comparison with radiocolloids of ³²P, ¹⁶⁵Dy, and ⁹⁰Y

We compared the therapeutic efficacy of α and β emitting radiocolloids for the treatment of experimental malignant ascites. 211At is an almost pure α- emitter. As 211At-tellurium colloid, the dose survival curve is linear and extrapolates through the origin in a manner similar to other high linear energy transfer radiations. Doses of 25 μCi were curative. Less than curative doses showed a graded prolongation of median survival. In cured mice, long term histological changes were seen in thyroid tissue. Acute changes were seen in the gastrointestinal tract as early as 2 hr after radiocolloid administration; these changes reached a plateau at 6 hr and were essentially gone 36 hr later. By comparison, radiocolloids of the beta emitters 32P, 165Dy and 90Y were not curative, but relatively large doses did substantially prolong median survival. The doses for maximal effect were 150 μCi 32P-chromic phosphate, 8000 μCi 165Dy-ferric hydroxide macroaggregates and 200 μCi 90Y-citrate. The most compelling reason for the increased therapeutic efficacy of 211At-tellurium colloid is the direct and densely ionizing character of the emitted alpha radiations. © 1984.

Duke Scholars

Author Michael Rod Zalutsky Radiology