Dispersal rates of astatine-211 from aqueous solutions and chloroform

Abstract

The dispersal rates of 211 At, which is a promising nuclide for targeted alpha therapy, from aqueous solutions and chloroform were studied to provide experimental evidence for the reasonable evaluation of its airborne concentration in a radiation-controlled area. Using a collection unit for dispersed 211 At during ventilation, radioactivity of the trapped 211 At was quantified. The dispersal rates of 211 At in chloroform as well as acidic, neutral, and alkaline solutions, in addition to a neutral solution containing ascorbic acid, were determined. Thin-layer chromatography was also performed to identify the formed chemical species of 211 At. The dispersal rate of 211 At was very low in the neutral solution containing ascorbic acid and in chloroform. The chemical forms of 211 At in aqueous solutions are also briefly discussed.

Dispersion of Alpha-Nuclides during Animal Experiments

“…211 At was produced in the 209 Bi(a, 2n) 211 At reaction using the K140 AVF cyclotron at Research Center of Nuclear Physics, Osaka University. 211 At was separated from the 209 Bi target by dry distillation according to the literature procedures 11,12) . The aqueous solution containing 211 At was obtained by dissolution of 211 At in distilled water.…”

Simulation of the distribution of astatine-211 solution dispersion in a lab room

“…Evaluating the vaporization and the movement of 211 At in the air is challenging because of the low detection capability for α-particle-emitter especially in a large space as a lab room. Some literature referred to the radiation safety of 211 At in production, but we could not find any literature referring to this phenomenon as a radiation safety issue [ 4 , 5 ].…”

Response to the letter to the editor

“…In the production of [ 211 At]NaAt solutions for the current clinical trial, we add ascorbic acid and adjust the pH to increase the Atcomponent, which then stabilizes the behavior of 211 At [3]. As a result, the volatility of 211 At is dramatically decreased, and 211 At can be safely handled by healthcare professionals [4,5]. Nevertheless, as safe handling is the most important aspect of clinical application, we need to pay special attention to contamination.…”