A generator for the production of radiolabelled ultrafine carbonaceous particles for deposition and clearance studies in the respiratory tract

Abstract: A generator for the production of radiolabelled ultrafine carbonaceous particles for inhalation and clearance studies is described. A Technegas generator in combination with Tc labelling is a device used in clinical routine to investigate the ventilation of the human lung. However, under standard operating conditions the Technegas generator does not provide ultrafine particles with a stable radiolabel. The removal of saline from the Tc-eluate by an ion exchange column yielded low leaching rates of the radiolabel from the particles of below 4% within 24h (12% under standard conditions) and guaranteed non-hygroscopic aerosol properties. Short burning times (2s; standard 15s) and immediate dilution of the generated aerosol into a conductive bag yielded stable ultrafine particles in the size range between 40 and 100nm count median diameter (standard 200nm), with a geometric standard deviation of 1.6. We adapted the generator to a bolus inhalation system, allowing regional aerosol deposition into different lung regions and appropriate clearance studies. In addition the particles can be labelled by In instead of Tc, extending the investigation time of clearance studies from 1day to some weeks. [Copyright &y& Elsevier]