Research at Varian on applied superconductivity for proton therapy

Abstract

Proton therapy is a rapidly increasing modality to treat cancerous tumors, but large-scale implementation, and therefore widespread availability for patients, is hindered by the size and upfront investment for treatment facilities. Superconducting technology can enable more compact, and therefore more affordable treatment systems, by increasing the magnetic field in the magnets for the proton accelerator (typically a cyclotron) and in the beam guidance up, over, and into the patient (the gantry). In this article, we discuss research at Varian Medical Systems Particle Therapy GmbH on various superconducting technologies for potential application in future, more compact cyclotrons and gantries. We discuss which technologies are feasible, and to what extent. We demonstrate why certain conductor choices are made, and show the development of novel new conductor and magnet technologies that will be required to enable the next generation of cryogen-free, conduction-cooled compact treatment systems. We conclude that superconductivity is certainly required for the next generation of proton treatment systems, but also that the amount of compactness that can eventually be achieved is not solely determined by the magnetic field strength that is generated in the magnets.

Thermoeconomic cost optimization of superconducting magnets for proton therapy gantries

“…In summary, both conductors show economic promise and have high field properties relevant for a carbon version of the fixed-field gantry, however the results here corroborate the recommendation in Ref. [6] to explore Bi-2223 in superconducting gantries.…”

“…The results of Ref. [6] motivate a quantitative cost analysis of the superconducting magnet system for the fixed-field gantry in Brouwer et al (2019) [5]. To balance competing objectives of conductor and cryogenics costs, a thermoeconomic model is required to convert capital and operating costs into a Net Present Value (NPV [$]) or cost rate ([$/hr]).…”

“…Realizing the opportunity of a fixed-field superconducting gantry with racetrack dipoles, a Varian-led study explored trade-offs in operating temperature, field strength, conductor performance and conductor cost for proton therapy and reported Bi-2223 tapes as a promising conductor for the application [6]. The results of reference [6] motivate a quantitative cost analysis of the superconducting magnet system for the fixedfield gantry in Brouwer et al (2019) [5].…”

“…Realizing the opportunity of a fixed-field superconducting gantry with racetrack dipoles, a Varian-led study explored trade-offs in operating temperature, field strength, conductor performance and conductor cost for proton therapy and reported Bi-2223 tapes as a promising conductor for the application [6]. The results of reference [6] motivate a quantitative cost analysis of the superconducting magnet system for the fixedfield gantry in Brouwer et al (2019) [5]. To balance competing objectives of conductor and cryogenics costs, a thermoeconomic model is required to convert capital and operating costs into a Net Present Value (NPV ($)) or cost rate ($/hr).…”

Mechanical and Thermal Analysis of an HTS Superconducting Magnet for an Achromatic Gantry for Proton Therapy

“…The innovative concept of using a combination of two identical superconducting bend magnets working at a fixed field in a proton therapy gantry, allows for a light and compact design, while being able to deliver protons over a range of 70 to 220 MeV, and is a further simplification of the design presented in [2]. The proposed concept uses the hightemperature superconductor (HTS) Bi-2223, as it has been shown to be competitive in terms of reduced manufacturing cost and improved thermal stability [3], [4]. The new design, as an HTS technology demonstrator, further simplifies the coil design, reducing the field and increasing the weight as a tradeoff.…”