Visiting Professor Manjit Dosanjh

Abstract:

Objective

Very high-energy electrons (VHEEs) offer deep penetration, low scattering, and the potential for ultra-high dose rate (UHDR) delivery, making them promising candidates for future radiotherapy. However, the collimation of VHEE beams to achieve sharp beam penumbra remains poorly characterized. This study experimentally and computationally investigates how collimator material, thickness, and beam characteristics affect penumbra and leakage dose for VHEEs and establishes an initial foundation for the design of clinically feasible VHEE collimators.

Approach

Tungsten, lead, and brass 5-mm diameter collimators were evaluated using film dosimetry with a 200 MeV electron beam delivered at the CERN Linear Electron Accelerator for Research (CLEAR) and validated through Monte Carlo simulations. Experimental measurements of penumbra and leakage were compared with simulations that systematically varied material (tungsten, lead, brass), thickness (2-8 cm), and beam energy (150-250 MeV). Additional sensitivity tests quantified the impact of beam instability on field shaping.

Main results

For measurements in air, penumbrae increased linearly with distance from the collimator and was smallest for tungsten. Leakage dose decreased with increasing thickness, falling below 0.5% for a 40-mm thick tungsten collimator. Brass exhibited the highest leakage (up to 4.8%) and broadest penumbra. Monte Carlo models reproduced experimental trends within 5% for penumbrae but underestimated leakage, particularly for brass. The simulations indicated that VHEE beam divergence, beam size and collimator misalignment strongly influence beam penumbra and leakage.

Significance

The presented work demonstrates that collimator material and geometry play a critical role in defining VHEE beam quality. Tungsten provided optimal attenuation and sharpness compared to brass and lead. These results establish quantitative benchmarks for VHEE collimator design and emphasize the importance of beam stability.

Abstract:

Dr. C. Norman Coleman, a distinguished cancer specialist and researcher, brought a passion for addressing health disparities to all of his roles from being on the faculty as a Radiation Oncologist at Stanford, as Chair of the Joint Center for Radiation Oncology at Harvard, as Associate Director of the Radiation Research Program at the U.S. National Cancer Institute, as Senior Medical Advisor to the US Government Office of the Assistant Secretary for Preparedness and Response, and as co-founder and Senior Scientific Officer for the International Cancer Expert Corps. With his passing earlier this year, this commentary by his colleagues at the International Cancer Expert Corps presents an overview of his many and significant contributions to addressing cancer disparities globally.

Abstract:

Abstract:

The cancer problem is expanding, particularly in low‐ and middle‐income countries (LMICs). Preventive measures can reduce the incidence by 40–50%, and cure rates have increased during the past decades in a number of cancers. However, optimizing prevention programmes and increasing cure rates of cancer remain significant research challenges. The main focus of the conference was on P4 Cancer Medicine (Predictive, Preventive, Personalized and Participatory), a comprehensive strategy encompassing Health‐Related Quality of Life (HRQoL) research, aiming to enhance the well‐being of patients and individuals at risk. Addressing the cancer problem requires two key elements: translational cancer research and the development of relevant infrastructures. A Comprehensive Cancer Centre (CCC) acts as an innovation hub by integrating high‐quality, multidisciplinary therapy and care, with healthcare‐dependent prevention, research, and education. The United States has been at the forefront, providing quality‐assured CCCs and the Cancer Moonshot for strategic cancer research. The EU has followed with the European Research Council for basic research, the European Innovation Council to boost disruptive innovation, and two EU initiatives on cancer, Europe's Beating Cancer Plan (EBCP) and the Mission on Cancer. The increasing complexity of cancer biology and technologies presents both a research challenge and a healthcare demand. For most patients, a CCC is not available. A critical discussion focused on quality assurance of healthcare outside the catchment area of a CCC and involving patients in clinical research. The strategic deployment of resources to support collective healthcare efforts and research aimed at reducing the cancer problem was discussed with representatives from the United States, EU, Africa, China, India and Taiwan. Analyses of translational cancer research have revealed important gaps in implementing innovations, assessment of clinical effectiveness, HRQoL, outcome and health economics research. The increased release of new anticancer agents over the last 25 years, accompanied by insufficient information on clinical benefits, presents both an economic and ethical problem. Direct healthcare costs have increased due to expenses for anticancer agents for the treatment of patients with incurable diseases. Evidence‐based treatment based on HRQoL research is an unmet need. Basic/preclinical research aimed at increasing the cure rate should identify new, broader targets for therapy and develop extended diagnostic technologies for stratifying patients, to inform innovative clinical trials. Present research strategies convert cancer to a chronic disease, a growing burden for the healthcare systems. The increasing complexity of cancer biology and technology, the growing need for translational cancer research, and the demand for supporting infrastructures underscore the importance of international collaborations between CCCs. However, funding for cancer research is not currently aligned to reduce the cancer problem. While public funding for cancer research doubled between 2005 and 2024, the pharmaceutical industry's spending on cancer research increased tenfold. Increasing funding by public and non‐profit funding organizations is mandatory. Education is another significant need, but it is currently fragmented and underfunded. The last session of the conference summarized the strategies in a Statement with a strong emphasis on global collaboration addressing the growing cancer burden and pronounced inequalities. Expanding partnerships and fostering innovative, multidisciplinary approaches to cancer prevention, therapeutics/care, as well as research, are not just urgent but essential steps towards reducing incidence, increasing cure rates and enhancing the well‐being of cancer patients. Data‐driven cancer medicine is currently under development, and modern communication technologies for diagnostics may facilitate interactions across geographical distances. A global cancer research agenda can become a model of solidarity, sustainability, and ethical responsibility.

Abstract:

Radiochromic films (RCFs) offer effective two-dimensional dosimetry with a simple, low-cost operating principle, making them suitable for very high-energy electron (VHEE) and ultra-high dose rate (UHDR) applications, where dosimetry standards are lacking. However, achieving high-accuracy measurements with RCFs presents significant challenges, especially in the absence of standardised protocols. To ensure reliable and comparable outcomes, adapted protocols based on a thorough understanding of RCF behaviour are essential. Despite over 6,000 publications addressing RCF protocols, comprehensive guides for high-throughput research machines with small, non-uniform beams are scarce. This paper aims to be a comprehensive guide for non-expert users of RCFs, particularly in VHEE and UHDR research. We identify common errors in RCF preparation, scanning, and processing, proposing strategies to enhance accuracy and efficiency. Using our optimised RCF protocol at the CLEAR facility, we demonstrate a 5% agreement compared to alanine dosimeters irradiated with Gaussian VHEE beams, establishing this protocol as a solid foundation for reliable dosimetry in advanced radiotherapy research.