Program Information
Sensitivity Limitations of X-Ray Induced Luminescence Imaging
B Quigley*, J Souris , CT Chen , C Pelizzari , S Kron , LW Lo , R D Wiersma , P La Riviere , The University of Chicago, Chicago, IL
Presentations
SU-K-702-13 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: 702
Purpose: X-ray induced luminescence imaging (XIL) utilizes lanthanide-doped nanoparticles that phosphoresce when irradiated. The hybrid X-ray/optical imaging modality has the potential to yield clinically relevant information during radiation therapy, including in vivo nanodosimetry or confirming localization of radiosensitizers within prescribed treatment volumes. This research seeks to evaluate the dose-dependent sensitivity versus depth of XIL in various optical environments in order to determine the limitations of this technique in clinical applications.
Methods: Europium-doped yttrium oxide nanoparticles were inserted in a capillary tube creating an XIL point source. An optical gel phantom composed of Intralipid, black ink, and agar provided a diffuse optical environment for XIL imaging using a cooled CCD camera within a small animal irradiator. A model based on an analytical solution for diffuse optical transport was developed for the experimental setup and calibrated using the phantom’s surface radiance measurements. The model was used to simulate XIL images for various radiation doses using the experimental setup and one with more sensitive equipment. Signal-to-noise ratios were calculated for the simulated XIL images and the Rose criterion determined the minimum dose for signal detection.
Results: Initial results in the optically homogenous experimental phantom comparing measured FHWMs to the simulation demonstrated that the model accurately predicted the spreading of the optical signal from a point source at the depths of 1.6, 2.2, and 2.6 cm. Nanophosphor concentrations of 1 mg/mL exposed to 1 cGy of radiation in the simulated environment were detectable using the more sensitive setup at 2 to 3 cm depth depending on the optical phantom properties.
Conclusion: This initial work demonstrates the sensitivity of XIL is limited to depths less than 4 cm in optically homogenous environments using therapeutic radiation doses and mg/mL concentration levels. Future work seeks to expand these sensitivity simulations to optically heterogeneous environments found in tissue.
Funding Support, Disclosures, and Conflict of Interest: NIH Grants: R01 EB 017293, T32 EB 002103, R01 CA 164492
Contact Email: