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At least 109 records · Page 6

Radiobiology, Omics and Microdosimetry of Systemic and Targeted Radiotherapeutics Workshop

The Radiobiology, Omics and Microdosimetry of Systemic and Targeted Radiotherapeutics Workshop fostered engagement across disciplines on critical topics that impact the development of targeted radionuclide therapies, bringing together scientific and medical professionals actively involved in radiotherapeutic design, optimization testing, patient treatment, and clinical trials along with basic science researchers, whose novel techniques have the potential to further our understanding of targeted radionuclide therapy. Discussion of the applications of radiotherapeutics to pediatric and adult, brain, prostate and blood cancers, and metastatic disease allowed scientific research to be presented in the context of real-world medical applications and provided an important backdrop to the basic research performed in computers, laboratories, and animal facilities. The workshop format, presentations, and panel discussions were designed to consider a holistic approach to the development of systemic and targeted radiotherapies, integrating radiobiology and microdosimetry, biological assessments on the microscale, and physiologically relevant models of tumor and tissue microenvironments. Important needs highlighted in the workshop include better models to assess the biological effects of radionuclide therapy, novel strategies to target radiotherapeutics to disease sites with high specificity, and new dosimetry techniques that address the importance of tumor microenvironments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Artificial Intelligence for Accelerating Nuclear Applications, Science, and Technology

Artificial intelligence (AI) and machine learning (ML) methods have had significant impacts in science and technology in recent years. These methods for generating models from datasets or logic-based algorithms that emulate aspects of human performance can similarly accelerate the fields of nuclear applications, science, and technology toward the IAEA goals of contributing to peace, health, and prosperity. In order to accomplish advances with AI in general and ML in particular across these fields, IAEA can play a significant role by establishing, hosting and curating centralised resources, including databases, adhering to FAIR (findable, accessible, interoperable and reusable) principles and Open Science best practices, providing stewardship of data sharing, supporting training efforts and development of relevant workforces, as well as enabling connections among the scientific, technology, mathematics, AI and ethics communities. Many areas can benefit from the use of AI in the realm of nuclear applications. In human health, these areas include clinical research, epidemiology, nutrition, medical imaging, radiotherapy and education of health professionals. AI-based tools are also being used to facilitate different clinical tasks in imaging, computer-assisted diagnosis in mammography and lung cancer screening programmes, and dose prediction in nuclear medicine procedures. ML methods in particular may also increase the efficiency and accuracy of the analysis of computerised tomography and dual-energy absorptiometry scans for body composition and bone analysis. The application of AI methods to nuclear and related technologies in food and agriculture can lead to significant advances and improved efficiency in the optimisation of agricultural production, food product development, management of supply chains, food safety and food authenticity control. In the water and environmental sector, AI can help inform policies to mitigate the world’s water problems. The application of AI techniques to hydrology and environmental sciences is expected to improve patterns identification and enable model predictions under a changing climate.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Production of Radioisotopes of Scandium for Imaging and Therapy (Final Report)

The theranostic approach is a powerful technique that enables scientists and physicians to diagnose and treat diseases using the same targeting moiety labeled with radionuclides for imaging and therapy. A challenge behind synthesizing and evaluating these theranostic radiopharmaceuticals lies in the production of suitable radionuclides. This study aimed to investigate the production of high radionuclidic purity 43 Sc from enriched [ 46 Ti]TiO 2 for Positron Emission Tomography (PET) and 47 Sc from enriched [ 50 Ti]TiO 2 for targeted radiotherapy, as well as establish a target recycling technique for continued production of these radionuclides. Methods: Targets were prepared with 100 mg of either enriched [ 46 Ti]TiO 2 or [ 50 Ti]TiO 2 , pressed into pellets, and placed into Ta target holders with a 0.127 mm natTi cover foil. The 46 Ti targets were bombarded with 18 MeV protons at 20 µA for 1.5 h, while 50Ti targets were bombarded with 24 MeV protons at 20 µA for 4 or 8 h. The radioscandium nuclides were purified using branched N, N, N’, N’ -tetra-2-ethylhexyldiglycolamide (DGA) resin. The titanium targets were recycled by precipitating the dissolved Ti collected from the column effluent and wash streams, pH adjustment, vacuum filtration, and then drying the solid at 250 °C prior to reforming the target for the subsequent bombardment. The apparent molar activity of the isolated radioscandiums was analyzed by titration with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). The relative imaging performance of 18 F, 43 Sc, and 68 Ga were analyzed with PET images acquired with 30-min static scans. Results: The average radioscandium recovery for 43Sc was 91.7 ± 7.4 %, with a radionuclidic purity of 98.8 %. The average recovery of 47Sc was 89.9 ± 3.9 %, with a radionuclidic purity of 90.8%. The average recovery of enriched TiO2 was 96 ± 4.0 %. The highest apparent molar activity for [43Sc]Sc-DOTA was 23.2 GBq/µmol and 3.39 GBq/µmol for [ 47 Sc]Sc-DOTA. The order of PET resolution from highest to lowest was 18 F > 43 Sc > 68 Ga. Conclusions: This work demonstrates the feasibility of using enriched recycled [ 46 Ti]TiO 2 and [ 50 Ti]TiO 2 targets for the production of the 43 Sc and 47 Sc theranostic isotope pair in high purity.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Spread Out Carbon Bragg Peak at NSRL

Charged particles lose energy continuously while traversing non-vacuum medium but have a sharp peak of dE/dx near the end of the path length. This can be very beneficial for cancer radiotherapy where healthy tissues surrounding a tumor are left with little dose compared to traditional therapy methods. However, since the region of high dose is localized to such a small area, it can present challenges when attempting to treat tumors of larger volume. By utilizing a variable thickness degrader system, the treatment area can be expanded during clinical treatment applications. To accommodate these types of radiobiology experiments, NSRL has produced a spread-out Bragg peak degrader wheel which aims to widen the Bragg peak of a 108 MeV/n Carbon beam to deliver a constant linear energy transfer, in water, of 97.7 keV/µm over a range of 36.7 mm.

43 PARTICLE ACCELERATORS↗

“Production of High Specific Activity 155 Tb, 161 Tb and 203 Pb for Research and Clinical Applications: Effective Target Design, Target Material Recycling and Radioisotope Separation”

Radioisotopes are essential for the development and application of radiopharmaceuticals that target specific diseases, such as cancer, offering unique potential for precision medicine. The growing demand for theranostic radioisotopes underscores their critical role in personalized medicine, where they enhance diagnostic imaging, minimize patient radiation exposure, and improve targeted tissue uptake, particularly in receptor- and antigen-directed therapies. The theranostic pair terbium-155 (diagnostic) and terbium-161 (therapeutic) holds significant promise for advancing individualized, targeted, and dosimetry-driven radiotherapies. However, the United States currently lacks routine and reliable production of these isotopes. This project made significant progress toward addressing this supply issue by developing production and separation methods for terbium-155 and terbium-161 while also training the next generation of the nuclear and radiochemistry workforce. This grant also strengthened collaboration between scientists at the University of Washington, the University of Missouri and Brookhaven National Laboratory. The research effort focused on evaluating target preparation methods, optimizing irradiation parameters, and refining isolation processes. In addition, the project provided extensive hands-on training to graduate students and postdoctoral fellows, equipping them with expertise in radioisotope production technologies and fostering the growth of the nuclear science workforce.

07 ISOTOPE AND RADIATION SOURCES↗

A fast Monte Carlo cell-by-cell simulation for radiobiological effects in targeted radionuclide therapy using pre-calculated single-particle track standard DNA damage data

Introduction: We developed a new method that drastically speeds up radiobiological Monte Carlo radiation-track-structure (MC-RTS) calculations on a cell-by-cell basis. Methods: The technique is based on random sampling and superposition of single-particle track (SPT) standard DNA damage (SDD) files from a “pre-calculated” data library, constructed using the RTS code TOPAS-nBio, with “time stamps” manually added to incorporate dose-rate effects. This time-stamped SDD file can then be input into MEDRAS, a mechanistic kinetic model that calculates various radiation-induced biological endpoints, such as DNA double-strand breaks (DSBs), misrepairs and chromosomal aberrations, and cell death. As a benchmark validation of the approach, we calculated the predicted energy-dependent DSB yield and the ratio of direct-to-total DNA damage, both of which agreed with published in vitro experimental data. We subsequently applied the method to perform a superfast cell-by-cell simulation of an experimental in vitro system consisting of neuroendocrine tumor cells uniformly incubated with 177 Lu. Results and discussion: The results for residual DSBs, both at 24 and 48 h post-irradiation, are in line with the published literature values. Our work serves as a proof-of-concept demonstration of the feasibility of a cost-effective “in silico clonogenic cell survival assay” for the computational design and development of radiopharmaceuticals and novel radiotherapy treatments more generally.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Role of Magnetic Anisotropy on the Hyperthermia Efficiency in Spherical Fe3−xCoxO4 (x = 0–1) Nanoparticles

The use of magnetic nanoparticles in the treatment of cancer using alternating current hyperthermia therapy has shown the potential to replace or supplement conventional cancer treatments, radiotherapy and chemotherapy, which have severe side effects. Though the nearly spherical sub-10 nm iron oxide nanoparticles have their approval from the US Food and Drug Administration, their low heating efficiency and removal from the body after hyperthermia treatment raises serious concerns. The majority of magnetic hyperthermia research is working to create nanomaterials with improved heating efficiency and long blood circulation time. Here, we have demonstrated a simple strategy to enhance the heating efficiency of sub-10 nm Fe3O4 nanoparticles through the replacement of Fe+2 ions with Co+2 ions. Magnetic and hyperthermia experiments on the 7 nm Fe3−xCoxO4 (x = 0–1) nanoparticles showed that the blocking temperature, the coercivity at 10 K, and the specific absorption rate followed a similar trend with a maximum at x = 0.75, which is in corroboration with the theoretical prediction. Our study revealed that the heating efficiency of the Fe3−xCoxO4 (x = 0–1) nanoparticles varies not just with the size and saturation magnetization but also with the magnetocrystalline anisotropy of the particles.

36 MATERIALS SCIENCE↗

Oxidation of p-[125I]Iodobenzoic Acid and p-[211At]Astatobenzoic Acid Derivatives and Evaluation In Vivo

The alpha particle-emitting radionuclide astatine-211 (211At) is of interest for targeted radiotherapy; however, low in vivo stability of many 211At-labeled cancer-targeting molecules has limited its potential. As an alternative labeling method, we evaluated whether a specific type of astatinated aryl compound that has the At atom in a higher oxidation state might be stable to in vivo deastatination. In the research effort, para-iodobenzoic acid methyl ester and dPEG4-amino acid methyl ester derivatives were prepared as HPLC standards. The corresponding para-stannylbenzoic acid derivatives were also prepared and labeled with 125I and 211At. Oxidization of the [125I]iodo- and [211At]astato-benzamidyl-dPEG4-acid methyl ester derivatives provided materials for in vivo evaluation. A biodistribution was conducted in mice with coinjected oxidized 125I- and 211At-labeled compounds. The oxidized radioiodinated derivative was stable to in vivo deiodination, but unfortunately the oxidized [211At]astatinated benzamide derivative was found to be unstable under the conditions of isolation by radio-HPLC (post animal injection). Another biodistribution study in mice evaluated the tissue concentrations of coinjected [211At]NaAtO3 and [125I]NaIO3. Comparison of the tissue concentrations of the isolated material from the oxidized [211At]benzamide derivative with those of [211At]astatate indicated the species obtained after isolation was likely [211At]astatate.

59 BASIC BIOLOGICAL SCIENCES↗

T Cells Contribute to Pathological Responses in the Non-Targeted Rat Heart following Irradiation of the Kidneys

Heart disease is a significant adverse event caused by radiotherapy for some cancers. Identifying the origins of radiogenic heart disease will allow therapies to be developed. Previous studies showed non-targeted effects manifest as fibrosis in the non-irradiated heart after 120 days following targeted X-irradiation of the kidneys with 10 Gy in WAG/RijCmcr rats. To demonstrate the involvement of T cells in driving pathophysiological responses in the out-of-field heart, and to characterize the timing of immune cell engagement, we created and validated a T cell knock downrat on the WAG genetic backgrou nd. Irradiation of the kidneys with 10 Gy of X-rays in wild-type rats resulted in infiltration of T cells, natural killer cells, and macrophages after 120 days, and none of these after 40 days, suggesting immune cell engagement is a late response. The radiation nephropathy and cardiac fibrosis that resulted in these animals after 120 days was significantly decreased in irradiated T cell depleted rats. We conclude that T cells function as an effector cell in communicating signals from the irradiated kidneys which cause pathologic remodeling of non-targeted heart.

60 APPLIED LIFE SCIENCES↗

Novel theranostic agent for PET imaging and targeted radiopharmaceutical therapy of tumour-infiltrating immune cells in glioma

Background: Malignant gliomas are deadly tumours with few therapeutic options. Although immunotherapy may be a promising therapeutic strategy for treating gliomas, a significant barrier is the CD11b + tumour-associated myeloid cells (TAMCs), a heterogeneous glioma infiltrate comprising up to 40% of a glioma's cellular mass that inhibits anti-tumour T-cell function and promotes tumour progression. A theranostic approach uses a single molecule for targeted radiopharmaceutical therapy (TRT) and diagnostic imaging; however, there are few reports of theranostics targeting the tumour microenvironment. Methods: Utilizing a newly developed bifunctional chelator, Lumi804, an anti-CD11b antibody (αCD11b) was readily labelled with either Zr-89 or Lu-177, yielding functional radiolabelled conjugates for PET, SPECT, and TRT. Findings: 89 Zr/ 177 Lu-labeled Lumi804-αCD11b enabled non-invasive imaging of TAMCs in murine gliomas. Additionally, 177 Lu-Lumi804-αCD11b treatment reduced TAMC populations in the spleen and tumour and improved the efficacy of checkpoint immunotherapy. Interpretation: 89 Zr- and 177 Lu-labeled Lumi804-αCD11b may be a promising theranostic pair for monitoring and reducing TAMCs in gliomas to improve immunotherapy responses.

60 APPLIED LIFE SCIENCES↗

Organs at Risk Considerations for Thoracic Stereotactic Body Radiation Therapy: What Is Safe for Lung Parenchyma?

Stereotactic body radiation therapy (SBRT) has become the standard of care for inoperable early-stage non-small cell lung cancer and is often used for recurrent lung cancer and pulmonary metastases. Radiation-induced lung toxicity (RILT), including radiation pneumonitis and pulmonary fibrosis, is a major concern for which it is important to understand dosimetric and clinical predictors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗