Early Detection and Molecular Imaging of Lung Cancer Using X-Ray Fluorescence Imaging Techniques
Abstract
Metal nanoprobes such as gold nanoparticles have successfully been conjugated with various tumor targeting moieties and shown to accumulate within tumors with high specificity. As shown in recent studies within the context of preclinical imaging, x-ray fluorescence (XRF) photons (or characteristic x-rays) from metal nanoprobes attached to (or internalized into) tumor cells can be induced by irradiating the tumor using typical diagnostic x-ray beams. One can then determine the location as well as the molecular characteristics of the tumor by reconstructing tomographic images based on detected/extracted XRF signals, i.e., a technique known as XRF computed tomography (or XFCT). Unlike conventional x-ray imaging or CT, XRF imaging does not, in principle, rely on the attenuation properties (contrast differences) of tissues/tumors. Moreover, compared to popular nuclear imaging modalities such as positron emission tomography (PET), XRF imaging does not require any radiotracers, possibly reducing the cost of molecular imaging procedures and also alleviating radiation safety concerns. Furthermore, it could, in theory, provide better image resolution than PET, enabling the early detection of small tumors and microscopic diseases. While the foregoing concepts of XRF imaging or XFCT are attractive enough and the proof-of-principles of it have already been established for preclinical animal imaging, human application of XRF imaging is generally far more challenging due to several technical difficulties (e.g., short penetration depths of XRF photons, long scanning time, excessive x-ray dose), and the feasibility of it is yet to be demonstrated. Thus, this project aims to demonstrate such feasibility by a judicious selection of the disease sites (e.g., organs with significantly low tissue density such as lungs) and a careful optimization of XRF imaging algorithms and setup including the deployment of energy-resolving photon-counting detectors. Upon successful completion, the proposed XRF imaging approach could lead to the development of an economic and practical alternative to PET (or PET/CT) for early detection and molecular imaging of lung cancer, as the entire XRF imaging setup can be seamlessly integrated into a conventional CT unit. Additionally, since the proposed approach works fundamentally differently from other spectral x-ray imaging modalities based on conventional/transmission CT in terms of material identification/quantification, operating conditions, and image reconstruction, XFCT (alone or combined with conventional/transmission CT) will further improve the sensitivity and specificity of x-ray imaging studies for more accurate diagnosis and functional imaging of early-stage lung cancer. Ultimately, the availability of an x-ray imaging device that enables complementary and simultaneous XRF imaging (or XFCT) within the same platform without requiring any additional x-ray dose will offer a promising option to considerably improve the accuracy of conventional x-ray imaging modalities for future lung cancer screening trials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610118
Entities
People
- Sang Hyun Cho
Organizations
- United States Army
- University of Texas at Austin