College of Optical Sciences, The University of Arizona, Tucson, AZ.
Semin Nucl Med. 2018 Jul;48(4):367-376. doi: 10.1053/j.semnuclmed.2018.02.008. Epub 2018 Mar 22.
Promising therapies are being developed or are in early-stage clinical trials that employ the use of alpha- and beta-emitting radionuclides to cure hematologic malignancies. However, these targeted radionuclide therapies have not yet met their expected potential for cancer treatment. A primary reason is lack of biodistribution, dosimetry, and dose-response information at cellular levels, which are directly related to optimal targeting, achieving a requisite therapeutic dose, and assessing the safety profile in normal organs and tissues. The current set of imaging tools, such as film autoradiography, scintigraphy, and SPECT/CT, available to researchers and clinicians do not allow the effective assessment of radiation absorbed dose distributions at cellular levels because resolutions are poor, measurement and analytical times are long, and the spatial resolutions are low-generally resulting in poor signal-to-noise ratios. Recently, new radiation digital autoradiography imaging tools have been developed that promise to address these challenges. They include scintillation-, gaseous-, and semiconductor-based radiation-detection technologies that localize the emission location of charged particles on an event-by-event basis at resolutions up to 20 µm FWHM for alpha and beta emitters. These imaging systems allow radionuclide activity concentrations to be quantified to unprecedented levels (mBq/µg) and provide real-time imaging and simultaneous imaging capabilities of both high- and low-activity samples without dynamic range limitations that plague traditional autoradiography. Additionally, large-area imagers are available (>20 × 20 cm) to accommodate high-throughput imaging studies. This article reviews the various detector classes and their associated performance trade-offs to provide researchers with an overview of the current technologies available for selecting an optimal detector configuration to meet imaging requirement needs.
有前景的疗法正在被开发或处于早期临床试验阶段，这些疗法利用α和β发射放射性核素来治愈血液系统恶性肿瘤。然而，这些靶向放射性核素疗法尚未达到癌症治疗的预期效果。一个主要原因是缺乏细胞水平的生物分布、剂量测定和剂量反应信息，而这些信息与最佳靶向、达到所需治疗剂量以及评估正常器官和组织的安全状况直接相关。当前研究人员和临床医生可用的成像工具集，如胶片放射自显影、闪烁扫描和 SPECT/CT，无法有效评估细胞水平的辐射吸收剂量分布，因为分辨率差、测量和分析时间长，以及空间分辨率低，通常导致信噪比差。最近，已经开发出了新的辐射数字放射自显影成像工具，有望解决这些挑战。它们包括基于闪烁体、气体和半导体的辐射探测技术，这些技术能够以高达 20 μm FWHM 的分辨率对带电粒子的发射位置进行逐个事件的定位，适用于α和β发射器。这些成像系统能够以前所未有的水平（mBq/µg）定量放射性核素活度浓度，并提供实时成像和高、低活度样品的同时成像能力，而不会受到困扰传统放射自显影的动态范围限制。此外，还提供了大尺寸成像仪（>20×20 cm），以适应高通量成像研究。本文综述了各种探测器类别及其相关的性能权衡，为研究人员提供了当前可用技术的概述，以便选择最佳探测器配置来满足成像要求。
