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

Radiation therapy is, after surgery, the most commonly used treatment for cancer. Approximately 50% of all cancer patients will undergo radiation therapy as part of curative treatment or symptom relief. Measurement and estimation of radiation dose - dosimetry - are crucial in radiation therapy, as the radiation dose determines both the control of the cancer and the level of late effects. Incorrect dosage can lead to a reduced chance of disease control or an increased likelihood of treatment-related toxicity. Particle therapy uses accelerated protons and heavier particles such as carbon ions in radiation therapy, and there is a need for better dosimetry methods for this type of treatment. Proton therapy centers are being established in Oslo and Bergen, and the first patient treatment is planned for late 2024 or early 2025. This project - NanoDos - combines expertise and resources in Oslo and New Delhi for the development of new dosimeter materials and for testing these materials in proton beams. Testing of thermoluminescent materials such as barium sulfate and calcium fluoride has been completed, and three articles on these substances are now published in peer-reviewed journals. The tests were conducted at Oslo Cyclotron Laboratory, University of Oslo, and at a tabletop accelerator at the Inter-University Accelerator Centre (IUAC), New Delhi. The substances showed a linear radiation response with minimal signal loss, making them suitable as proton detectors. Samples have been analyzed at laboratories in Oslo and New Delhi for material characterization. The project also involved further development of the dosimeter material alanine (an amino acid that stabilizes large amounts of radicals upon irradiation) by doping crystals of this amino acid with metals such as copper. Preliminary experiments and calculations suggested that this improved detector response, especially for X-rays. However, further experiments revealed that metal doping unexpectedly led to rapid decay of the radical signal, rendering the dosimeter material impractical for practical use. In summary, the project has contributed to new knowledge about radiation dosimetry, development of new detectors with promising potential, and establishment of long-term collaboration with Indian researchers.

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.