Development of technetium-99m (^99mTc) labeled carbon from palm kernel shell as lung scintigraphy agent

Specific and accurate diagnostic tools are important to determine diagnosis for various lung diseases with complex characteristics. In this study, high-energy milling (HEM) was utilized to prepare micro-sized carbon from palm kernel shell charcoal as a potential aerosol agent for lung ventilation scintigraphy. The HEM parameters investigated in this experiment were milling time and ball-to-powder ratio (BPR), while the characterization of the obtained powder involves particle size distribution, porosity, specific surface area, and XRD pattern. The optimization of technetium-99m (^99mTc) labeling of the obtained carbon powder was carried out concerning SnCl₂ amount, carbon dosage, incubation time, and pH. The optimal milling time and BPR were 180 min and 5:1, respectively, resulting in Dx(50) of 1.71 µm. Generally, the ^99mTc labeling yield increased with the increase of SnCl₂ amount, carbon dosage, and incubation time, while it decreased as the pH increased. The optimal ^99mTc labeling condition, SnCl₂ amount of 300 µg, carbon dosage of 50 mg, incubation time of 30 min, and pH 5, resulted in an adsorption capacity of 178.89 TBq of ^99mTc/g carbon. These results demonstrate that aerosol scintigraphy agents can potentially be prepared from palm kernel shell charcoal with optimization of radiolabeling method, milling process, and further in vitro aerosol performance prior to pre-clinical and clinical stages.