Brian W Pogue1,2, Rongxiao Zhang1,2, Xu Cao1, Jeremy Mengyu Jia3, Arthur Petusseau1, Petr Bruza1, Sergei A Vinogradov4,5. 1. Thayer School of Engineering at Dartmouth, Hanover, New Hampshire, United States. 2. Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States. 3. Stanford University School of Medicine, Department of Radiation Oncology, Palo Alto, California, United States. 4. University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics,, United States. 5. University of Pennsylvania, School of Arts of Sciences, Department of Chemistry, Philadelphia, Penns, United States.
Abstract
SIGNIFICANCE: Deep-tissue penetration by x-rays to induce optical responses of specific molecular reporters is a new way to sense and image features of tissue function in vivo. Advances in this field are emerging, as biocompatible probes are invented along with innovations in how to optimally utilize x-ray sources. AIM: A comprehensive review is provided of the many tools and techniques developed for x-ray-induced optical molecular sensing, covering topics ranging from foundations of x-ray fluorescence imaging and x-ray tomography to the adaptation of these methods for sensing and imaging in vivo. APPROACH: The ways in which x-rays can interact with molecules and lead to their optical luminescence are reviewed, including temporal methods based on gated acquisition and multipoint scanning for improved lateral or axial resolution. RESULTS: While some known probes can generate light upon x-ray scintillation, there has been an emergent recognition that excitation of molecular probes by x-ray-induced Cherenkov light is also possible. Emission of Cherenkov radiation requires a threshold energy of x-rays in the high kV or MV range, but has the advantage of being able to excite a broad range of optical molecular probes. In comparison, most scintillating agents are more readily activated by lower keV x-ray energies but are composed of crystalline inorganic constituents, although some organic biocompatible agents have been designed as well. Methods to create high-resolution structured x-ray-optical images are now available, based upon unique scanning approaches and/or a priori knowledge of the scanned x-ray beam geometry. Further improvements in spatial resolution can be achieved by careful system design and algorithm optimization. Current applications of these hybrid x-ray-optical approaches include imaging of tissue oxygenation and pH as well as of certain fluorescent proteins. CONCLUSIONS: Discovery of x-ray-excited reporters combined with optimized x-ray scan sequences can improve imaging resolution and sensitivity.
SIGNIFICANCE: Deep-tissue penetration by x-rays to induce optical responses of specific molecular reporters is a new way to sense and image features of tissue function in vivo. Advances in this field are emerging, as biocompatible probes are invented along with innovations in how to optimally utilize x-ray sources. AIM: A comprehensive review is provided of the many tools and techniques developed for x-ray-induced optical molecular sensing, covering topics ranging from foundations of x-ray fluorescence imaging and x-ray tomography to the adaptation of these methods for sensing and imaging in vivo. APPROACH: The ways in which x-rays can interact with molecules and lead to their optical luminescence are reviewed, including temporal methods based on gated acquisition and multipoint scanning for improved lateral or axial resolution. RESULTS: While some known probes can generate light upon x-ray scintillation, there has been an emergent recognition that excitation of molecular probes by x-ray-induced Cherenkov light is also possible. Emission of Cherenkov radiation requires a threshold energy of x-rays in the high kV or MV range, but has the advantage of being able to excite a broad range of optical molecular probes. In comparison, most scintillating agents are more readily activated by lower keV x-ray energies but are composed of crystalline inorganic constituents, although some organic biocompatible agents have been designed as well. Methods to create high-resolution structured x-ray-optical images are now available, based upon unique scanning approaches and/or a priori knowledge of the scanned x-ray beam geometry. Further improvements in spatial resolution can be achieved by careful system design and algorithm optimization. Current applications of these hybrid x-ray-optical approaches include imaging of tissue oxygenation and pH as well as of certain fluorescent proteins. CONCLUSIONS: Discovery of x-ray-excited reporters combined with optimized x-ray scan sequences can improve imaging resolution and sensitivity.
Authors: Ang Li; Greg Boverman; Yiheng Zhang; Dana Brooks; Eric L Miller; Misha E Kilmer; Quan Zhang; Elizabeth M C Hillman; David A Boas Journal: Appl Opt Date: 2005-04-01 Impact factor: 1.980
Authors: K K Dwivedi; M S Prasad; G N Rao; R K Dogra; R K Upreti; R Shanker; C R Murti; S S Kapoor; M Lal; K V Viswanathan Journal: Int J Environ Anal Chem Date: 1980 Impact factor: 2.826