Cancer treatment is a significant healthcare challenge, costing Europe up to €199 billion annually. The burden will grow substantially, with a projected 60% increase in cancer cases from 2018 to 2040. To address these challenges, the ScanNanoTreat consortium consisting of Claude Bernard Lyon 1 University, Maastricht University, Guerbet, Philips, and Inlecom Commercial Pathways is developing a revolutionary theranostic approach combining advanced photonics and nanotechnology. The innovative system integrates Spectral Photon Counting Computed Tomography (SPCCT) with X-ray-activated Photodynamic Therapy (X-PDT) using gadolinium-based nanoprobes. This approach enables simultaneous imaging and treatment of solid tumours, with an initial focus on breast and pancreatic cancers. By leveraging low-energy X-rays and optimized nanoprobes, ScanNanoTreat aims to reduce radiation doses by over 30% compared to conventional radiotherapy. This technology is expected to radically shorten the diagnosis-treatment cycle, leading to improved prognosis and better patient outcomes, and up to 40% reduction in cancer treatment costs. If successfully deployed, ScanNanoTreat could revolutionize the European theranostic market, aiming to capture 10-17% of the projected €493 million market by 2032, suggesting a potential market size of €35-€60 million by 2035. The project will advance the technology from TRL 3 to TRL 5, preparing for clinical trials by 2027 and potential market entry by 2035. Additionally, a business plan and exploitation strategy will be developed, targeting a spinoff creation to commercialize the technology. The support of the EIC Transition grant is crucial to conduct preclinical studies, optimize the SPCCT system, and develop a comprehensive regulatory strategy. By addressing critical healthcare needs and aligning with EU strategic autonomy in MedTech, ScanNanoTreat will radically improve cancer care and contribute to the sustainability of European healthcare systems.