188Re-SSS Lipiodol

Rhenium-188 (188Re) is of widespread interest for treating various diseases because of its attractive physical and chemical properties. The routine preparation of therapeutic doses of 188Re-labelled tracers can result in significant radiation exposure to the operator. We studied the impact of automating the preparation of 188Re-Lipiodol on the radiochemist's exposure, as well as the importance of the model of syringe shielding. To monitor radiation exposure continuously readable electronic personal dosimeters were used. Thermoluminescence dosimeters were fixed to the probable most exposed fingers of the radiochemist during preparation of the radiotracer and during the syringing. Dose rates were measured using a Babyline. Automation of the synthesis reduced personal dose equivalents from 2.60±4.35 to 1.61±1.20 µSv/GBq [Hp(10)] and from 38.37±55.28 to 21.84±16.14 µSv/GBq [Hp(0.07)]. Dose to the extremities was also reduced (-80% for the right hand; -58% for the left one). The Lemer-Pax PSWG syringe shield led to a slightly lower dose to the hands compared with the Medisystem (1.1±0.27 vs. 1.34±0.6 mSv/GBq for the right finger). Automation of the synthesis leads to a significant decrease in radiation exposure to the operator. The Lemer-Pax PSWG syringe shield provides better hand protection than the smaller Medisystem Mediclic.

Rhenium-188 (188Re) is a high energy beta-emitter with a physical half life of 17 hours. Various 188Re based radiopharmaceuticals were developed to treat liver malignancies. The vast majority of studies focus on patients suffering from hepatocellular carcinoma (HCC). Most radiopharmaceuticals are based on Lipiodol as a vehicle for the rhenium-188. The radiopharmaceutical that was tested clinically in detail is the 188Re-HDD/Lipiodol, developed by the Seoul University. Clinical data derived from several phase I and II studies using 188Re-HDD/Lipiodol suggest an excellent tolerance in patients with Child-Pugh A cirrhosis. A shortcoming in some trials was the occasional low labelling efficiency of 188Re-HDD/Lipiodol. Some newer 188Re based radiopharmaceuticals claim to have consistent high labelling efficiencies, however clinical data for these compounds are scarce or lacking at this moment. Hopefully, phase I clinical data will become available for promising radiopharmaceuticals such as 188Re-SSS-Lipiodol, developed by the group of Rennes, in the upcoming years. In Dresden a very different approach is used. They labelled human serum albumin microspheres with high activities of 188Re. In a small group of patients with liver metastasis and a few HCC patients, treatment proved safe. In the present clinical field, 188Re-based radiopharmaceuticals will have to proof firmly their strength and reliability in large patient groups if they want to compete with the commercially available yttrium-90 microspheres.