In a previous publication1 the two methods employed at the New England Deaconess Hospital for the determination of radioiodine (I131) uptake in the thyroid were compared and found by statistical analysis to give the same results. These two methods are (1) a single scintillation counter technique and (2) a setup with four Geiger-Mueller (bismuth cathode) tubes.2 After a modification of the scintillation counter by the manufacturer, it was found that by comparison with the four-tube setup the uptake measurements were high by approximately 20 to 25%. These high scintillation counter readings seem to indicate that scattering from the patients (Compton effect) is an important factor that requires evaluation.3
One approach to this problem would be to reduce the scatter by attaching various thicknesses of lead (0.43, 0.86, and 1.1 mm.) to the face of the scintillation counter.4 The percentage of uptake was determined for each
DeAmicis E, Cowing RF. VARIANCE OF MEASUREMENT OF THYROID UPTAKE OF RADIOIODINE DUE TO COMPTON EFFECT. JAMA. 1958;167(3):314–315. doi:10.1001/jama.1958.72990200005007b
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