A Novel Bioluminescence Tomography System Compatible with CBCT-guided Small Animal Irradiators for High-Precision Preclinical Radiation Research.

Abstract

Widely used cone-beam computed tomography (CBCT)-guided irradiators struggle to localize soft-tissue targets due to low imaging contrast. While bioluminescence tomography (BLT) offers a promising functional imaging solution, its adoption in pre-clinical radiotherapy research has been limited. To address this, we developed MuriGlo, a novel BLT system compatible with CBCT-guided small animal irradiators to support high-precision radiation studies. We demonstrate MuriGlo's capabilities in supporting both in vitro and in vivo experiments. MuriGlo consists of a detachable mouse bed, thermostatic control, mirrors, filters, and a charge-coupled device (CCD) camera, enabling multi-projection and multi-spectral bioluminescence imaging (BLI). The detachable bed facilitates animal transfer between MuriGlo and an irradiator for BLT-guided radiation study. We evaluated the thermostatic control's ability and demonstrated that it can maintain a consistent animal body temperature at 37°C throughout imaging. We also quantified detection sensitivity via signal-to-noise ratio (SNR) in detecting minimal cell quantities using glioblastoma (GL261) cells with Luc2 and AkaLuc reporters. The optical system can detect as few as 1173 GL261-Luc2 and 61 GL261-AkaLuc cells in vitro at SNR = 5. For image-guided capabilities, we present BLT-guided 5-arc, BLT-guided 2-field box, and BLI-guided single-field plans. The high conformal 5-arc plan fully covers gross tumor volume (GTV) at prescribed dose with minimal normal tissue exposure from moderate to high dose range, while the simplified, high-throughput BLT-guided 2-field box achieves 100% GTV coverage but results in larger normal tissue exposure. The choice of the planning strategy should therefore depend on the specific requirements for radiation accuracy and experimental throughput. Moreover, we compared MuriGlo's tumor localization accuracy for widely used irradiators, SARRP and SmART+. The localization accuracy of MuriGlo for both SARRP and SmART+ irradiators is < 1 mm with GTV coverage > 97%. This universal, BLT-guided platform enables plug-and-play integration with commercial irradiators, supporting functional image guidance and enhancing high-precision preclinical radiation research.