Medical Cyclotron Solid Target Preparation by Ultrathick Film Magnetron Sputtering Deposition

Abstract

Magnetron sputtering is proposed here as an innovative method for the deposition of a material layer onto an appropriate backing plate for cyclotron solid targets aimed at medical radioisotopes production. In this study, a method to deposit thick, high-density, high-thickness-uniformity, and stress-free films of high adherence to the backing was developed by optimizing the fundamental deposition parameters: sputtering gas pressure, substrate temperature, and using a multilayer deposition mode, as well. This method was proposed to realize Mo-100 and Y-nat solid targets for biomedical cyclotron production of Tc-99m and Zr-89 radionuclides, respectively. The combination of all three optimized sputtering parameters (i.e., 1.63 × 10−2 mbar Ar pressure, 500 °C substrate temperature, and the multilayer mode) allowed us to achieve deposition thickness as high as 100 µm for Mo targets. The 50/70-µm-thick Y targets were instead realized by optimizing the sputtering pressure only (1.36 × 10−2 mbar Ar pressure), without making use of additional substrate heating. These optimized deposition parameters allowed for the production of targets by using different backing materials (e.g., Mo onto copper, sapphire, and synthetic diamond; and Y onto a niobium backing). All target types tested were able to sustain a power density as high as 1 kW/cm2 provided by the proton beam of medical cyclotrons (15.6 MeV for Mo targets and 12.7 MeV for Y targets at up to a 70-µA proton beam current). Both short- and long-time irradiation tests, closer to the real production, have been realized.

Investigation of a Possible Material-Saving Approach of Sputtering Techniques for Radiopharmaceutical Target Production

“…In a recent work carried out at Legnaro National Laboratories [13], the process of nat Mo// 100 Mo deposition on a backing material by the MS technique was deeply investigated for cyclotron-based production of 99m Tc radionuclide. The potential of the MS usage for production of different CSTs was thus proved again with the nat Y solid target by different research groups [14,16]. The deposited layer made by this method has been shown to provide a great adhesion with backing, which led to better heat dissipation, and a lesser oxidation level, which was crucial in the case of the highly reactive Y material [10].…”

“…Other different manufacturing means may be adopted, such as electroplating, plasma spray, electrophoretic, sedimentation, etc. [9][10][11][12][13][14]. On the other hand, other techniques may be applied to produce such CST, by using the material under powder form and exploiting the spark plasma sintering (SPS) technique [15].…”

A Universal Cassette-Based System for the Dissolution of Solid Targets

“…The target sizes fit the target station of ACSI TR-19 Cyclotron, whose details can be found in [ 37 ] and is installed at SCDCH where the studies were performed.…”

A Step-by-Step Guide for the Novel Radiometal Production for Medical Applications: Case Studies with 68Ga, 44Sc, 177Lu and 161Tb

“…Several different methods such as sintering, rolling, melting, sedimentation, mechanical pressing, electrodeposition, magnetron sputtering, etc. are used for the cyclotron solid target preparation [39,40]. The use of mechanical methods (rolling and pressing) is most common, which consists of a mechanical reshaping of solid or powder materials to produce self-supporting targets.…”