CAREER: Utilization of Unique Atomic and Nuclear Properties of Gadolinium in Nuclear and Radiological Sciences

钆（Gd）是一种有趣的元素，具有各种有趣的特性。它的一种同位素Gd-157比所有其他已知的稳定核具有最大的捕获热中子的速率。在钆中子俘获疗法（GdNCT）中，由于中子俘获而发射的辐射可用于癌症治疗。与其他放射疗法相比，GdNCT的一个显著优势是含有钆的初始药物溶液是非放射性的。只有在中子相互作用后才能诱导出核和原子的激发态，由此产生的辐射可以用来摧毁附近的癌细胞。该项目的重点是使用各种钆纳米颗粒材料表征与GdNCT相关的辐射及其放射剂量。这些材料将被来自马萨诸塞州洛厄尔研究反应堆（UMLRR）的中子照射，产生的伽马射线和电子将使用马萨诸塞州洛厄尔最近设计的新探测器阵列进行测量。与此同时，将研究钆在新型薄膜中子和X射线探测器中的潜在用途。辐射探测技术是低能和高能核物理实验发现的前沿。安全应用、反恐、核医学成像和扫描都需要新技术。基于具有Gd层的薄膜的新型辐射探测技术的拟议工作将通过能够测量X射线和中子剂量的小柔性薄膜的设计来推进辐射探测领域。本科生和研究生的参与将是这些研究活动的重点。来自三个不同的认证研究生课程的学生：（1）放射科学和保护，（2）医学物理学和（3）物理学和应用物理学，将有助于本文提出的活动。该项目开发的能力将用于在麻省大学洛厄尔物理和应用物理系开设一门新课程，“高级放射性测量实验室”，中子俘获后钆的核去激发导致伽马射线和内部转换电子的发射，随后是俄歇电子的发射，以解决原子激发。这些电子可以有效地将局部剂量递送到用含有钆的药物溶液饱和的肿瘤。在该项目中，将使用高分辨率伽马射线光谱和高效量热法相结合的方法来测量纳米材料中钆的中子捕获反应产生的伽马射线和电子。相关发射的细节将使用快速纳秒符合方法进行探测。还将根据经验证的物理模型和新改进的相关原子和核数据库，对局部组织和邻近器官中的捕获级联和剂量分布进行全面的计算模拟。将研究纳米颗粒的大小和形态，以控制和优化发射电子的范围，从而可能调整肿瘤的局部剂量。同样，高保真蒙特-卡罗辐射输运模拟将指导薄膜中子和X射线探测器的设计和开发。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Gadolinium (Gd) is an intriguing element that has a variety of interesting properties. One of its isotopes, Gd-157, has the largest rate of capturing thermal neutrons than all other known stable nuclei. In Gadolinium Neutron Capture Therapy (GdNCT), the radiation emitted as a result of neutron capture can be used for cancer treatment. A striking advantage of GdNCT compared to other radiation therapy treatments is that the initial pharmaceutical solution with the gadolinium content is non-radioactive. Nuclear and atomic excited states are induced only after neutron interactions, and the resultant radiations can be used to destroy nearby cancer cells. The focus of this project will be the characterization of the radiations associated with GdNCT and their radiological dose using various gadolinium nanoparticle-based materials. The materials will be irradiated by neutrons from the UMass Lowell Research Reactor (UMLRR), and the resultant gamma rays and electrons will be measured using a new detector array recently designed at UMass Lowell. In parallel, the potential use of gadolinium in a novel thin-film neutron and x-ray detector will be studied. The radiation detection technologies are at the forefront of all experimental discoveries in low and high energy nuclear physics. New technologies are needed in security applications, counter terrorism, nuclear medicine imaging and scanning. Proposed work on a novel radiation detection technology based on thin films with Gd layer will advance the field of radiation detection with designs of small flexible films capable of measuring doses of x-rays and neutrons. The involvement of undergraduate and graduate students will be a strong emphasis of these research activities. Students from three different accredited graduate programs: (1) Radiological Sciences and Protection, (2) Medical Physics and (3) Physics and Applied Physics, will contribute to the activities proposed herein. The capabilities developed during this project will be used to launch a new course, “Advanced Radiological Measurements Laboratory”, in the UMass Lowell Physics and Applied Physics Department.The nuclear de-excitation of gadolinium after neutron capture results in the emission of gamma rays and internal conversion electrons, followed by the emission of Auger electrons to resolve atomic excitations. These electrons can efficiently deliver local dose to tumors saturated with a pharmaceutical solution containing gadolinium. In this project, the resultant gamma rays and electrons produced by neutron capture reactions on gadolinium in nanoparticle-based materials will be measured using the combination of high-resolution gamma-ray spectroscopy and high-efficiency calorimetry. Details of correlated emissions will be probed using fast nanosecond coincidence methods. Comprehensive computational simulations of the capture cascades and the dose distributions in local tissue and neighboring organs also will be performed based on validated physics models and new improved correlated atomic and nuclear data libraries. The size and morphology of the nanoparticles will be studied to control and optimize the range of emitted electrons to potentially tune the local dose to the tumor. Likewise, high-fidelity Monte-Carlo radiation transport simulations will guide design and development of the thin-film neutron and x-ray detector.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.