A solid target system with remote handling of irradiated targets for PET cyclotrons

Spot-welding solid targets for high current cyclotron irradiation

“…End of bombardment (EOB) 89 Zr production yields of 48 ± 4 MBq/(μA·hr) were consistent regardless of irradiation current and in good agreement with those observed with our previously used methods described in section I. Additionally, this yield is in agreement with the 49 ± 4 MBq/(μA·hr) measured by Siikanen et al (2014) and significantly higher than that observed by Dabkowskia et al (2015) and Ciarmatori et al (2011) irradiating thinner Y foils at lower proton energies. Thus, the significantly improved proton beam current durability of the Ta-welded Y target increased 89 Zr production capacity by more than threefold.…”

“…The amount of discoloration to the Y target foil was similar to that of a 15 μA irradiation of Y foil using the previously used 89 Zr production methods described in section I. This irradiation current is also significantly higher than that of Dabkowskia et al (2015) and Ciarmatori et al (2011) used to irradiate thin Y foils and slightly higher than the 45 μA that Siikanen et al (2014) used to irradiate large direct H 2 O-cooled Y foils. Irradiation of Ta-welded Sc and Ta-welded Ho targets with 50 μA protons for 1 – 3 hours yielded visual inspection results identical to that of Ta-welded Y with only slight discoloration and no visible target foil damage observed.…”

“…As a result, the main factor limiting 89 Zr production is in the design of Y targets that can withstand the hundreds to thousands of watts of thermal power deposited by such a proton beam. In recent years, target designs capable of withstanding 30 – 45 μA of proton irradiation of water- and He-cooled Y foils have been demonstrated by Dabkowskia et al (2015), Ciarmatori et al (2011), and Siikanen et al (2014). However, the former two of these methods utilize thin (0.15 mm) 89 Y target foils limiting the overall 89 Zr production capacity.…”

“…However, the former two of these methods utilize thin (0.15 mm) 89 Y target foils limiting the overall 89 Zr production capacity. On the contrary, Siikanen et al (2014) utilize a high mass (~3g) 89 Y target, which would limit the specific activity and therefore radiopharmaceutical utility of the produced 89 Zr.…”

Production of novel diagnostic radionuclides in small medical cyclotrons

“…In the case of custom made targets, it has been reported that one can achieve higher yields than this, while maintaining high radionuclidic purity of the final product (Sadeghi et al, 2012 ; Tang et al, 2016 ; Alfuraih et al, 2013 ). Custom made yttrium target developments published in recent years (Siikanen et al, 2014 ; Ellison et al, 2016 ), which encompass welding yttrium foils, modifications in yttrium foil thicknesses and water cooling, report applicable designs capable of delivering yields of up to 49 MBq/μAh with maximum currents of 45 μA, and a 90% separation efficiency. This gives about 1.4–2.2 GBq of radionuclidic pure 89 Zr in 1–2 h beam time, thus effectively shortening the irradiation times on the cyclotron or increasing the production capacity.…”