Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, 710071, Shaanxi, China.
Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.
Biomed Eng Online. 2018 Apr 24;17(1):45. doi: 10.1186/s12938-018-0480-x.
Radionuclide-excited luminescence imaging is an optical radionuclide imaging strategy to reveal the distributions of radioluminescent nanophosphors (RLNPs) inside small animals, which uses radioluminescence emitted from RLNPs when excited by high energy rays such as gamma rays generated during the decay of radiotracers used in clinical nuclear medicine imaging. Currently, there is no report of tomographic imaging based on radioluminescence.
In this paper, we proposed a gamma rays excited radioluminescence tomography (GRLT) to reveal three-dimensional distributions of RLNPs inside a small animal using radioluminescence through image reconstruction from surface measurements of radioluminescent photons using an inverse algorithm. The diffusion equation was employed to model propagations of radioluminescent photons in biological tissues with highly scattering and low absorption characteristics.
Phantom and artificial source-implanted mouse model experiments were employed to test the feasibility of GRLT, and the results demonstrated that the ability of GRLT to reveal the distribution of RLNPs such as GdOS:Tb using the radioluminescent signals when excited by gamma rays produced from Tc.
With the emerging of targeted RLNPs, GRLT can provide new possibilities for in vivo and noninvasive examination of biological processes at cellular levels. Especially, combining with Cerenkov luminescence imaging, GRLT can achieve dual molecular information of RLNPs and nuclides using single optical imaging technology.
放射性核素激发发光成像是一种光学放射性核素成像策略，用于揭示放射性发光纳米磷光体（RLNP）在小动物体内的分布，它利用放射性示踪剂衰变过程中产生的伽马射线等高能射线激发 RLNP 发出的放射发光。目前，还没有基于放射发光的断层成像的报道。
在本文中，我们提出了一种伽马射线激发的放射发光断层成像（GRLT）方法，通过使用逆算法从放射性发光光子的表面测量中重建图像，利用放射性发光来揭示小动物体内 RLNP 的三维分布。扩散方程用于模拟具有高散射和低吸收特性的生物组织中放射发光光子的传播。
采用体模和人工源植入小鼠模型实验来测试 GRLT 的可行性，结果表明，GRLT 能够利用 Tc 产生的伽马射线激发的放射发光信号来揭示 RLNP（如 GdOS：Tb）的分布。
随着靶向 RLNP 的出现，GRLT 可为在细胞水平上进行体内和非侵入性的生物过程检查提供新的可能性。特别是，结合切伦科夫发光成像，GRLT 可以使用单一的光学成像技术实现 RLNP 和核素的双重分子信息。
