NANODOS - SYNTHESIS OF NANO-PHOSPHORS AND SPIN-TRAPPING NANO-CRYSTALS AS ENERGY-INDEPENDENT DOSIMETERS FOR RADIOTHERAPY BEAMS

Strålebehandling er, etter kirurgi, den mest brukte behandlingen av kreft. Omtrent 50% av alle kreftpasienter vil få strålebehandling som en del av kurativ behandling eller symptomlindring. Måling og estimering av stråledose - dosimetri - er veldig viktig i strålebehandling, siden stråledosen bestemmer både kontroll av kreftsykdommen og nivå av senskader. Hvis doseringen blir feil, kan dette føre til redusert sjanse for sykdomskontroll eller økt sannsynlighet for behandlingsrelatert toksisitet. I partikkelterapi benyttes akselererte protoner og tyngre partikler som karbonioner i strålebehandling, og det er et behov for bedre dosimetrimetoder for denne typen strålebehandling. Protonterapisentre er under etablering i Oslo og Bergen, og første pasientbehandling er planlagt sent i 2024 eller tidlig 2025. Dette prosjektet - NanoDos - kombinerer kompetanse og ressurser i Oslo og New Dehli for utvikling av nye dosimetermaterialer og for testing av disse materialene i protonstråler. Testing av termoluminescens-materialene bariumsulfat og kalsiumfluorid er ferdigstilt, og tre artikler om disse stoffene er nå publiserte i fagfellevurderte tidsskrift. Testene er foretatt ved Oslo syklotronlaboratorium, Universitetet i Oslo, og en bordtopp-akselerator ved Inter-University Accelerator Centre (IUAC), New Delhi. Stoffene viste en lineær strålingsrespons med lite signaltap, og har dermed gode egenskaper som proton-detektorer. Prøver har vært analysert ved laboratorier i Oslo og New Delhi for materialkarakterisering. Vi har også jobbet med videreutvikling av dosimetermaterialet alanin (en aminosyre der det stabiliseres store mengder radikaler ved bestråling) ved å dope krystaller av denne aminosyren med metaller slik som kobber. Preliminære eksperimenter og beregninger tydet på at dette forbedret detektorresponsen, spesielt for røntgenstråling. Men videre eksperimenter viste at metalldopingen førte til at radikalsignalet henfalt uventet raskt, hvilket gjør at dosimetermaterialet ikke kan anvendes i praktiske sammenhenger. Oppsummert har prosjektet bidratt til ny kunnskap om strålingsdosimetri, til utvikling av nye detektor med et lovende potensiale og til etablering av langsiktig samarbeid med indiske forskere.

The achieved impacts are: Development of Functional Nanophosphors: The studies have successfully developed functional nanophosphors. These nanophosphors exhibit specific luminescent properties, making them promising candidates for dosimetry applications. Optimized Dopant Concentrations: The optimization of dopant concentrations for the nanophosphors demonstrates a crucial step in enhancing the sensitivity and response of these materials to radiation. Linear Dose Response: Both nanophosphors exhibit a linear dose response for various radiation types and energies. This linear behavior is crucial for precise and reliable dosimetry, providing a consistent and predictable relationship between the absorbed dose and the detected signal. Characterization of Nanophosphors: Detailed characterization of the nanophosphors provides insights into their structural and luminescent properties. This is essential for understanding the materials' behavior under irradiation and optimizing their dosimetric performance. The potential impacts and effects are: Application in Radiation Therapy and Particle Therapy Dosimetry: The demonstrated linear dose response and sensitivity of these nanophosphors suggest their potential application as dosimeters in radiation therapy. This could enhance the precision of radiation treatments. With the establishment of proton therapy centers in Oslo and Bergen, there is a potential to apply these nanophosphors in relevant applications there. International Collaboration and Knowledge Exchange: The collaboration between Oslo and New Delhi in the NanoDos project has established a foundation for ongoing international cooperation. This collaboration not only contributes to the advancement of dosimetry but also fosters knowledge exchange and shared expertise between researchers in different regions. Development of Alternative Dosimeter Materials: The project's exploration of dosimeter materials opens for the development of alternative materials with improved dosimetric properties. This may lead to the discovery of novel dosimeters with enhanced performance in specific radiation therapy scenarios. Future Improvements in Dosimeter Materials: The preliminary experiments with metal-doped alanine, despite encountering challenges, suggest a potential avenue for future improvements in dosimeter materials. Continued research in this direction may unveil new materials with optimized detector responses, especially for X-rays.

This project proposal describes our Indian-Norwegian research collaboration plan with the aim to improve health and promote new medical technology. Radiotherapy is, second to surgery, the most widely used treatment of cancer. It is estimated that roughly 50 % of all cancer patients should receive radiotherapy as part of curative treatment or symptom relief. To avoid disease relapse and/or radiation-induced toxicity it is of utmost importance to maintain a high standard of care for these patients. Radiation dose assessment - dosimetry - is pivotal in this aspect, as the radiation dose delivered to a given cancer patient relies on accurate dosimetry. In radiotherapy the use of protons and heavier ions like carbon ions have the potential to reduce side effects from radiation injury in numerous cancer patients and is attracting considerable interest internationally. Proton therapy centers are under establishment in Norway and India. Nanodos will employ expertise and resources both in Oslo, Norway and New Dehli, India for synthesis of new dosimeter materials based on nano-phosphors and spin-trapping nano-crystals and for testing these materials in proton and carbon ion beams. We will develop a pipeline for systematic testing of potential new dosimeters, focusing both on their radiation dose response and their response to radiations of different types and energies. The proposed project aims at performing novel independent research of high quality at the international forefront, and our group of Norwegian and Indian researchers will combine competence and expertise within radiation physics, radiotherapy, dosimetry and material science. The project is expected to provide unique knowledge with impact on future methodologies of relevance for radiotherapy in general. Finally, the project will aid establishing a long-term collaboration platform between Indian and Norwegian researchers in radiotherapy and dosimetry.