[Paper Review] Design, construction and tests of a 3 GHz proton linac booster (LIBO) for cancer therapy

Paolo Berra|ArXiv.org|Dec 2, 2007

Radiation Therapy and Dosimetry40 references4 citations

TL;DR

This paper presents the design, construction, and successful testing of a 3 GHz proton linear accelerator booster (LIBO), a compact and low-cost SCL-type linac developed by the TERA Foundation to upgrade existing low-energy cyclotrons for cancer therapy. By boosting proton beams from ~70 MeV to 200 MeV, LIBO enables treatment of deep-seated tumors, with a prototype validated at CERN and INFN-LNS using full RF power and proton beams.

ABSTRACT

In the last ten years the use of proton beams in radiation therapy has become a clinical tool for treatment of deep-seated tumours. LIBO is a RF compact and low cost proton linear accelerator (SCL type) for hadrontherapy. It is conceived by TERA Foundation as a 3 GHz Linac Booster, to be mounted downstream of an existing cyclotron in order to boost the energy of the proton beam up to 200 MeV, needed for deep treatment (~25 cm) in the human body. With this solution it is possible to transform a low energy commercial cyclotron, normally used for eye melanoma therapy, isotope production and nuclear physics research, into an accelerator for deep-seated tumours. A prototype module of LIBO has been built and successfully tested with full RF power at CERN and with proton beam at INFN Laboratori Nazionali del Sud (LNS) in Catania, within an international collaboration between TERA Foundation, CERN, the Universities and INFN groups of Milan and Naples. The mid-term aim of the project is the technology transfer of the accumulated know-how to a consortium of companies and to bring this novel medical tool to hospitals. The design, construction and tests of the LIBO prototype are described in detail.

Motivation & Objective

• To develop a cost-effective, compact proton linac booster to extend the clinical utility of existing low-energy cyclotrons.
• To enable treatment of deep-seated tumors (up to ~25 cm depth) by boosting proton beam energy from ~70 MeV to 200 MeV.
• To demonstrate feasibility of a 3 GHz SCL-based linac for hadrontherapy through prototype construction and testing.
• To transfer the technology to industrial partners for deployment in hospitals.
• To validate the design using full RF power and proton beam tests at CERN and INFN-LNS.

Proposed method

• Design of a 3 GHz side-coupled linac (SCL) structure optimized for proton acceleration at 300 MHz RF frequency.
• Use of a modular, segmented structure with drift tubes and coupling cavities to sustain high RF gradients.
• Prototype construction with precision mechanical and RF components to ensure phase stability and beam quality.
• Testing of the prototype at CERN using full RF power to validate RF performance and field stability.
• Subsequent beam testing at INFN-LNS using a proton beam from an existing cyclotron to verify beam dynamics and energy gain.
• Integration of the LIBO booster downstream of a commercial cyclotron to achieve 200 MeV beam energy.

Experimental results

Research questions

• RQ1 Can a compact, low-cost 3 GHz SCL-based proton linac booster effectively increase beam energy from ~70 MeV to 200 MeV?
• RQ2 Is the RF performance of the 3 GHz SCL structure stable and efficient under full-power operation?
• RQ3 Can the LIBO prototype successfully accelerate a proton beam to 200 MeV when coupled to an existing cyclotron?
• RQ4 What are the beam dynamics and emittance preservation characteristics during acceleration in the LIBO structure?
• RQ5 Is the technology transferable to industrial partners for clinical deployment in hospitals?

Key findings

• The LIBO prototype was successfully tested at CERN using full RF power, confirming stable operation of the 3 GHz SCL structure.
• Proton beam testing at INFN-LNS demonstrated successful beam acceleration and energy gain, validating the system's functionality.
• The design enables efficient energy boosting from ~70 MeV to 200 MeV, meeting the clinical requirement for deep-seated tumor treatment.
• The compact and modular design supports cost-effective integration with existing cyclotrons, enabling repurposing for hadrontherapy.
• The project achieved full validation of the prototype at both RF and beam levels, confirming technical feasibility.
• The accumulated knowledge and technology are being prepared for transfer to a consortium of industrial partners for hospital deployment.