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May 1975

Counting Statistics Required for 32P Detection of Choroidal Melanoma

Author Affiliations

Farmington, Conn

Arch Ophthalmol. 1975;93(5):390-391. doi:10.1001/archopht.1975.01010020402021

To the Editor.  —In reviewing recent claims for improvements in the 32P uptake test, it appears to us that critical parts of earlier evaluations have been overlooked.Reports by Hagler et al1 and Jarrett et al2 imply that modifications of instrumentation and method have brought a new accuracy to this procedure. This may well be so. However, the test is basically mathematical and very little numerical information (except as relative percents) has been offered to support it. We refer especially to the absence of counting rate values, total count, probable error, and tumor weight data.In the late 1950s we found that two choroidal melanomas (weight, 1.2 and 0.22 gm) contained 0.11 and 0.05, 24 hours after intravenous injection of 500 microcuries of 32P.3 We later found low counting rates over six posterior choroidal tumors, (0.06 to 0.73 gm; 245 to 1,225 counts per minute), 24 hours after the same

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