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Radioactive Stents. Production and History. Comparison of IVUS data Average data of 157 radioactive und 140 non radioactive stents. Stent. Stent. remodeling. neointima. Plaque [mm 2 ]. „Edge Effekt“. In early days. 1991 Fischell: US-Patent: Radioactive Stent
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Radioactive Stents Production and History Klaus Schloesser, Forschungszentrum Karlsruhe, Technik und Umwelt /HZY
Comparison of IVUS data Average data of 157 radioactive und 140 non radioactive stents Stent Stent remodeling neointima Plaque [mm2] Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
„Edge Effekt“ Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
In early days • 1991 Fischell: US-Patent: Radioactive Stent • 1992 Hehrlein, Heidelberg wanted radioactive Stents -> animal trials • 1994 Liermann, Frankfurt Treatment of peripheral arteries (legs) 192Ir – Afterloader • 1995 Connado, Venezuela192Ir – Afterloader (manuel) Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Radioactive Stent in Rabbits • 55Co... left • 32Pright Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Methods of Activation Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Radioisotope • 1 day < halflife < 3 Weeks • Suitable radiation for Brachytherapy with stents Range about 2-5 mm • g-radiation of low energy • b- radiation of high energy • no a-radiation(does not reach target volume, too much damage in the vicinity) • No deeply penetration g-radiation (health physics problems) Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Phosphorous -32 Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Heavy Ion Implantation Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Ion Source Acceleration Mass separation Target M=31 M=32 Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
ECRIS – magnetic bottle x z y Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
N S S N S N N S N S S N ECRIS-radial Confinement by Hexapole x z y Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Precursor of Plasma is Gas • Red Phosphorous sublimates at about 440°C (ugh !) • gaseous compound: PH3 (Phosphine) • Phosphine is very poisonous • MAK = 0,1 ml/m³ = 1/10 threshold for smelling (Garlik) • Radio toxicity • Inhalation von 1 m³ Air (32P/31P) = 1/1000 results in effective dose > 5 Sv which corresponds to LD50 (ugh , really!) • So, let’s make only that much Phosphine at a time, so that the ion source is just filled. (0,5l at 10-4mbar) • H• + P PH• or. H+ + P PH+ etc. up to PH3 Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
100 M ECRIS – with two stage extraction and plasma chamber made of glass 60 kV 30 kV Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Overview of ion implanter Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Mass Spectrum 16O2 31PH 28SID2 14N2D2 12C16OD2 32P Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Ion source acceleration separation target M=31 M=32 Irradiation chamber Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Irradiation Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Irradiation platform Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Discharge behaviour ca. 3 h Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Performance of the ion source for 32P Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Quality control: Measurement of activity distribution Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Special activity distributions Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
Quality control: encapsulation of activity • Test method: washing of stents in isotonic sodiumchlorid (0,9% NaCl) in an ultrasonic bath Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
How much activity (how many ions) fits on a stent? > 30° < 30° Klaus Schloesser, Forschungszentrum Karlsruhe / HZY
If „drug – eluting“ works, prevention of restenosis with radioactive stents is not the first choice • perspectives • e.g. oncology dose application within 2mm distancebut restricted to target volume Klaus Schloesser, Forschungszentrum Karlsruhe / HZY