Fluorinated radiopharmaceuticals sorption onto plasticized polyvinyl chloride automated injector tubings: implications for patient dosing.

BACKGROUND: The use of automated injectors for the administration of radiopharmaceuticals limits staff exposure and optimises the dose administered to patients, but many of these devices are only validated for a limited number of radiopharmaceuticals. The objectives of this study were to investigate the physicochemical phenomena occurring during the manipulation of fluorinated radiopharmaceuticals when in contact with injector tubings and to quantify and qualify the interactions between the radiopharmaceuticals and the tubing materials. RESULTS: For six of the radiopharmaceuticals tested, the measured doses reached 97.64 ± 0.24% of the programmed dose. These results indicate an absence of sorption phenomena and validate their use on the injector. In contrast, the three most lipophilic molecules caused the injector to malfunction, resulting in significant residual activity in the tubing of up to 67%. These results were confirmed by activimeter measurements and positron emission tomography images. RESULTS: from electronic microscopy results showed an alteration of the inner surface of the tubings that came into contact with lipophilic radiopharmaceuticals; however, this modification did not drastically alter the surface Zeta potential. Infrared spectroscopy confirmed the composition of the tubings as being plasticized polyvinyl chloride (PVCp), and plasticizer identification and quantification showed the presence of di-(2-ethylhexyl) adipate (reaching 37.5%) and di-(2-ethylhexyl) phthalate (more than 20%). A clear improvement was observed when co-extruded polyethylene / PVPp tubings were used. CONCLUSIONS: Unlike lipophilic radiopharmaceuticals, which exhibit sorption behaviour dependent on the presence of plasticizers, the tested hydrophilic radiopharmaceuticals demonstrated minimal interaction with PVCp tubing and can be reliably administered using the automated injector.