Applications of Accelerators and Detectors to Cancer Treatment

Abstract:

The battle against cancer remains a top priority for society, with an urgent need to develop therapies capable of targeting challenging tumours while preserving patient's quality of life. Hadron Therapy (HT), which employs accelerated beams of protons, carbon ions, and other charged particles, represents a significant frontier in cancer treatment. This modality offers superior precision and efficacy compared to conventional methods, delivering therapeutic the dose directly to tumours while sparing healthy tissue. Even though 350,000 patients have already been treated worldwide with protons and 50,000 with carbon ions, HT is still a relatively young field and more research as well as novel, cost-effective and compact accelerator technologies are needed to make this treatment more readily available globally. Interestingly the very first patient was irradiated with protons in September 1954, the same month and year CERN was founded. Both of these endeavours are embedded in cutting edge technologies and multidisciplinary collaboration. HT is finally gaining ground and, even after 70 years, the particle therapy field continues innovating and improving for the benefits of patients globally. Developing technologies that are both affordable and easy to use is key and would allow access to more patients. Advances in accelerator-driven Boron Neutron Capture Therapy (BNCT), image-guided hadron beams delivery, clinical trials and immunotherapy, together with the recent interest and advances in FLASH therapy, which is currently an experimental treatment modality that involves ultrahigh-dose rate delivery, are just a few examples of innovation that may eventually help to provide access to a larger number of patients.

Abstract:

The European Council for Nuclear Research (CERN) was founded by 12 European countries in 1954 as one of Europe's first joint ventures. CERN's primary mission is to perform world-class research in fundamental particle physics research and its laboratory on the Franco-Swiss border near Geneva has both constructed and operated numerous ground-breaking particle accelerators and associated experiments throughout its 70-year history. Education and training, international collaboration, and technology development are also important complementing and facilitating parts of the organization's mission, and CERN is committed to identifying and making available opportunities for the dissemination and societal use of its results. In particular, the application of CERN's expertise and unique competencies in particle accelerators, detectors, and computing to the medical domain represents one of the most important opportunities in terms of potential impact on society. In this chapter, we describe CERN's experience and strategy within international engagement in the fields of particle and medical physics and summarize CERN's involvement in enhancing international collaborations for medical physicists.

Abstract:

As part of our search for radiation-hard techniques for beam profile monitoring, we tested a novel method based on hollow-core optical fibres. These fibres, filled with scintillating gases, combine exceptional radiation tolerance with the inherent radiation hardness of the gases. We tested this new technique at the CLEAR accelerator at CERN, demonstrating its potential for beam diagnostics. The standard deviation of the CLEAR electron beam transverse profile was successfully measured to be 1.15 mm ± 0.02 mm, close to the width of 1.30 mm ± 0.07 mm obtained from a YAG screen. No loss of signal was observed after the fibre received a dose of 0.915 MGy. The technique shows particular promise for FLASH therapy, where it could offer significant improvements in reliability and functionality compared to current instrumentation.

Abstract:

Objective. To evaluate spatially fractionated radiation therapy (SFRT) for very-high-energy electrons (VHEEs) delivered with pencil beam scanning. Approach. Radiochromic film was irradiated at the CERN linear electron accelerator for research using 194 MeV electrons with a step-and-shoot technique, moving films within a water tank. Peak-to-valley dose ratios (PVDRs), depths of convergence (PVDR ⩽ 1.1), peak doses, and valley doses assessed SFRT dose distribution quality. A Monte Carlo (MC) model of the pencil beams was developed using TOPAS and applied to a five-beam VHEE SFRT treatment for a canine glioma patient, compared to a clinical 6 MV VMAT plan. The plans were evaluated based on dose-volume histograms, mean dose, and maximum dose to the planning target volume (PTV) and organs at risks (OARs). Main results. Experimental PVDR values were maximized at 15.5 ± 0.1 at 12 mm depth for 5 mm spot spacing. A DOC of 76.5, 70.7, and 56.6 mm was found for 5, 4, and 3 mm beamlet spacings, respectively. MC simulations and experiments showed good agreement, with maximum relative dose differences of 2% in percentage depth dose curves and less than 3% in beam profiles. Simulated PVDR values reached 180 ± 4, potentially achievable with reduced leakage dose. VHEE SFRT plans for the canine glioma patient showed a decrease in mean dose (>16%) to OARs while increasing the PTV mean dose by up to 15%. Lowering beam energy enhanced PTV dose homogeneity and reduced OAR maximum doses. Significance. The presented work demonstrates that pencil beam scanning SFRT with VHEEs could treat deep-seated tumors such as head and neck cancer or lung lesions, though small beam size and leakage dose may limit the achievable PVDR.