Zugl.: Magdeburg, University, Diss., 2007. / Produktion und Logistik. XXI, 119 S.

Stuttgart, Univ., Diss., 1999.

Universiẗat, Diss., 2001--München.

Zugl.: Karlsruhe, Univ., Diss., 2008 / Hergestellt on demand

Darmstadt, Techn. Univ., Diss., 2004. / Dateien im PDF-Format

Introduction The worldwide use of PET has proven beyond dispute the importance for both routine diagnosis and physiological, oncological and pharmacological research. In many ways the present success of PET relies on the mature technology of PET compact medical cyclotrons. As long time developers of new targets, isotopes and com-pounds, we have been inclined to look for new block-buster applications, high power targets and sustainable ways of embracing the GMP and regional distribution, but recent pioneering development [1] around very small cyclotrons and “embedded synthesis and qc” has pointed out an old, but important nuclear physics lesson now halfway forgotten: that many PET isotopes can be made in high yields with proton energies far below 10 MeV [2]. This has opened a new interest in small cyclotrons and their targets. We have been testing the first GE Healthcare Prototype for a 7.8 MeV negative ion, internal ion source cyclotron with 3 production targets mounted on a short beamline. Here we present the first experimental yields of some of the important PET radionuclides. Materials and methods The prototype cyclotron (FIG. 1) has been in-stalled and tested without self-shield in designated experimental area in order to establish the neutron field around accelerator and targets in order to qualify design calculations for a future integrated shield. The cyclotron energy is fixed by the radial position of the extraction foil, while the azimuth determines which of the 3 targets are being irradiated. The beam energy at front of target foil was determined on several occasions: 7.8 ± 0.1 MeV by a 2 copper-foil sandwich method (adopted from [3]). The available beam inside the cyclotron at extractor position is > 50 μA, and 35 μA are easily and long term reliably extracted (> 90 %) on to any of the 3 target positions. The prototype is capable of delivering more than 40 μA to target, but target current was limited to 35 μA under present unshielded conditions. Results 18F We have tested the prototype gridded (> 80 % transmission) niobium body target with 10μm Havar foil using 95 % 18O water and 35 μA on target + grid with yields given in TABLE 1. The observed yields corrected for stopping in foil, grid loss and water enrichment are 75 % of theoretical. One Fastlab FDG run using 2 h irradiation yielded 16 GBq FDG EOS, confirming the “usual” 18F activity. Results 11C Using gridded target and a 10μm foil with 99% N2 + 1 % O2 at 10 bar followed by trapping into ascarite gave EOB activity as shown in TABLE 2. Results 13N We know that the 16O(p,alpha)13N cross section is a very steep function of energy around 7.8 MeV. In the hope of using the simple water target route to 13N NH3 we have measured the 13N yields (corrected for 18F contribution). It is still unclear if these yields can be improved to make useful single doses of ammonia. Results for other isotopes We have used solid targets to make 45Ti, 64Cu, 68Ga and 89Zr. The development of these solid targets is still in progress, but especially the 68Ga yield looks promising (3 GBq EOB after 1 h on natural Zn will give > 15 GBq on enriched 68Zn).

Techn. Universiẗat, Diss., 2001--Berlin.

Universiẗat, Diss., 2002--Kiel.

Introduction The worldwide use of PET has proven beyond dispute the importance for both routine diagnosis and physiological, oncological and pharmacological research. In many ways the present success of PET relies on the mature technology of PET compact medical cyclotrons. As long time developers of new targets, isotopes and com-pounds, we have been inclined to look for new block-buster applications, high power targets and sustainable ways of embracing the GMP and regional distribution, but recent pioneering development [1] around very small cyclotrons and “embedded synthesis and qc” has pointed out an old, but important nuclear physics lesson now halfway forgotten: that many PET isotopes can be made in high yields with proton energies far below 10 MeV [2]. This has opened a new interest in small cyclotrons and their targets. We have been testing the first GE Healthcare Prototype for a 7.8 MeV negative ion, internal ion source cyclotron with 3 production targets mounted on a short beamline. Here we present the first experimental yields of some of the important PET radionuclides. Materials and methods The prototype cyclotron (FIG. 1) has been in-stalled and tested without self-shield in designated experimental area in order to establish the neutron field around accelerator and targets in order to qualify design calculations for a future integrated shield. The cyclotron energy is fixed by the radial position of the extraction foil, while the azimuth determines which of the 3 targets are being irradiated. The beam energy at front of target foil was determined on several occasions: 7.8 ± 0.1 MeV by a 2 copper-foil sandwich method (adopted from [3]). The available beam inside the cyclotron at extractor position is > 50 μA, and 35 μA are easily and long term reliably extracted (> 90 %) on to any of the 3 target positions. The prototype is capable of delivering more than 40 μA to target, but target current was limited to 35 μA under present unshielded conditions. Results 18F We have tested the prototype gridded (> 80 % transmission) niobium body target with 10μm Havar foil using 95 % 18O water and 35 μA on target + grid with yields given in TABLE 1. The observed yields corrected for stopping in foil, grid loss and water enrichment are 75 % of theoretical. One Fastlab FDG run using 2 h irradiation yielded 16 GBq FDG EOS, confirming the “usual” 18F activity. Results 11C Using gridded target and a 10μm foil with 99% N2 + 1 % O2 at 10 bar followed by trapping into ascarite gave EOB activity as shown in TABLE 2. Results 13N We know that the 16O(p,alpha)13N cross section is a very steep function of energy around 7.8 MeV. In the hope of using the simple water target route to 13N NH3 we have measured the 13N yields (corrected for 18F contribution). It is still unclear if these yields can be improved to make useful single doses of ammonia. Results for other isotopes We have used solid targets to make 45Ti, 64Cu, 68Ga and 89Zr. The development of these solid targets is still in progress, but especially the 68Ga yield looks promising (3 GBq EOB after 1 h on natural Zn will give > 15 GBq on enriched 68Zn).

Vor dem Hintergrund der aktuellen energiepolitischen Entwicklungen und des zunehmenden Kostendruckes steigen die Anforderungen an eine präzise und zugleich praxisnahe Bilanzierung, Bewertung und Optimierung des Biogasprozesses. Dies beinhaltet sowohl die detaillierte Charakterisierung und Qualitätsbewertung der individuell eingesetzten Substrate als auch die Effizienzbewertung ihrer verfahrensspezifischen Umsetzung im Fermenter. Grundsätzlich existieren in der Wissenschaft und Praxis vielfältige Untersuchungsverfahren und Berechnungsmethoden, um die Eigenschaften der eingesetzten Substrate oder den aktuellen Prozesszustand zu charakterisieren. Eine direkte Vergleichbarkeit der unterschiedlichen Verfahren auf Basis der Trockensubstanz (TS, oTS, FoTS), Futtermittel-, Elementar- oder Brennwertanalyse ist bis heute nicht gegeben. Unter Berücksichtigung der konkreten Prozessbedingungen liefern experimentelle Batchtests oder kontinuierliche Laborversuche realitätsnahe Aussagen zum Methanertrag einzelner Substrate. In der großtechnischen Anlagenpraxis haben sich dabei die allgemeinen Richtwerte für Gasausbeuten des Kuratoriums für Technik und Bauwesen in der Landwirtschaft e. V. (KTBL) etabliert, welche auf einer Vielzahl an Einzelmessungen von Batchversuchen unterschiedlicher Labore und zusätzlichen Erfahrungswerten (Expertenwissen) beruhen. Ziel des vorliegenden Leitfadens ist es, die unterschiedlichen Verfahren zur Bestimmung des Methanbildungspotentials einzelner Substrate hinsichtlich ihrer praxisnahen Anwendung und Aussagekraft zu beschreiben. Auf Basis vereinfachter Massen- oder Energiebilanzen können die charakteristischen Kenngrößen der eingesetzten Substrate oder der anfallenden Gärreste dann zur Effizienzbewertung einer Biogasanlage verwendetet werden.