Determination of human absorbed dose of 201Tl(III)-DTPA-HIgG based on biodistribution data in rats

Abstract

To estimate the absorbed dose in normal organs and inflamed tissue following i.v. administration of [201Tl](III)-DTPA-HIgG by using biodistribution data in inflamation bearing rats was attempted. The percentages of injected dose per gram of each organ were calculated. The medical internal radiation dose formulation was applied to calculate the absorbed dose for various organs. The inflamed tissue to blood activity concentration ratios were about 19 and 23.3 at 24 and 28 h post-injection, respectively. A 185-MBq injection of 201Tl-DTPA-HIgG into the human body, might result in an estimated absorbed dose of 14.4 mGy for the total body and the highest absorbed dose was in the kidney with 1195 (mGy) and second to the Spleen were the liver, the lungs and the adrenals, which received 250.5 (mGy), 58.64 (mGy) and 56.44 (mGy), respectively. Biodistribution of [201Tl](III)-DTPA-HIgG demonstrated significant inflamed tissue uptake and low muscle and blood uptake, allowing for imaging of inflamed tissues.

Preparation, Biological Evaluation and Dosimetry Studies of 175Yb-Bis-Phosphonates for Palliative Treatment of Bone Pain

“…In this study, the accumulated source activity was calculated by plotting the non-decay corrected time activity curves for each organ and computing the area under the curves. For this purpose, the data points which represent the percentage-injected dose were created and fitted to a mono-exponential, bi-exponential or uptake and clearance curve ( 17 ). In addition, the curves were extrapolated to infinity (5 times higher than physical half-life of 175Yb) by fitting the tail of each curve to a mono-exponential curve.…”