signals for in vivo molecular imaging has yet to be developed. It was shown that
polychromatic X-rays from clinical sources are still able to detect low concentrations
of XF signals when all of the described XFCT data acquisition strategies are
exploited to their full potential. In fact, most of these strategies are also compatible
with monochromatic excitation which usually leads to sensitivity improvements by
one order of magnitude better with monochromatic excitation. In this context,
developments in the field of inverse Compton scattering are intriguing as they
allow the establishment of laboratory scaled monochromatic X-ray sources feasible
for clinical environments.
This chapter discussed studies which lay the foundation for the future development of human XFCT. While the concepts and initial results of XFCT are intriguing,
its widespread acceptance for molecular imaging depends critically on the achievable sensitivity, and further technology is required to increase the sensitivity. For
example, advanced imaging techniques like Compton imaging [50, 52] or time-offlight information will help to reach clinical sensitivities comparable to sensitivities
shown here.
Contrast agents like Gd- or Pt-based drugs have already been approved by the
FDA, and no regulatory hurdles need to be addressed for immediate clinical use.
When fully implemented in the clinic, XFCT will provide crucial information
about molecular processes taking place within the patient. Considering the large
number of CT exams done annually in the USA (~69 million/year, with an observed
annual growth rate of about 8% [53]), the potential impact of XFCT will be
enormous.
Acknowledgments The authors would like to thank the NIH for the support of several XFCT and
XLCT research projects and to the many researches who were involved in the related work at our
institute.
Compliance with Ethical Standards
Conflict of Interest Author Don Vernekohl declares that he has no conflict of interest. Author Lei
Xing declares that he has no conflict of interest.
Ethical Approval This article does not contain any studies with human participants or animals
performed by any of the authors.
References
1. Xiang L, Han B, Carpenter C, Pratx G, Kuang Y, Xing L (2013) X-ray acoustic computed
tomography with pulsed x-ray beam from a medical linear accelerator. Med Phys 40:010701
2. Rizk SL, Rizk SL, Sky-Peck HH (1984) Comparison between concentrations of trace elements
in normal and neoplastia human breast tissue. Cancer Res 44:5390–5394
3. Somervaille LJ, Chettle DR, Scott MC (1985) In vivo measurement of lead in bone using X-ray
fluorescence. Phys Med Biol 30:929
X-Ray Excited Fluorescent Materials for Medical Application
145
polychromatic X-rays from clinical sources are still able to detect low concentrations
of XF signals when all of the described XFCT data acquisition strategies are
exploited to their full potential. In fact, most of these strategies are also compatible
with monochromatic excitation which usually leads to sensitivity improvements by
one order of magnitude better with monochromatic excitation. In this context,
developments in the field of inverse Compton scattering are intriguing as they
allow the establishment of laboratory scaled monochromatic X-ray sources feasible
for clinical environments.
This chapter discussed studies which lay the foundation for the future development of human XFCT. While the concepts and initial results of XFCT are intriguing,
its widespread acceptance for molecular imaging depends critically on the achievable sensitivity, and further technology is required to increase the sensitivity. For
example, advanced imaging techniques like Compton imaging [50, 52] or time-offlight information will help to reach clinical sensitivities comparable to sensitivities
shown here.
Contrast agents like Gd- or Pt-based drugs have already been approved by the
FDA, and no regulatory hurdles need to be addressed for immediate clinical use.
When fully implemented in the clinic, XFCT will provide crucial information
about molecular processes taking place within the patient. Considering the large
number of CT exams done annually in the USA (~69 million/year, with an observed
annual growth rate of about 8% [53]), the potential impact of XFCT will be
enormous.
Acknowledgments The authors would like to thank the NIH for the support of several XFCT and
XLCT research projects and to the many researches who were involved in the related work at our
institute.
Compliance with Ethical Standards
Conflict of Interest Author Don Vernekohl declares that he has no conflict of interest. Author Lei
Xing declares that he has no conflict of interest.
Ethical Approval This article does not contain any studies with human participants or animals
performed by any of the authors.
References
1. Xiang L, Han B, Carpenter C, Pratx G, Kuang Y, Xing L (2013) X-ray acoustic computed
tomography with pulsed x-ray beam from a medical linear accelerator. Med Phys 40:010701
2. Rizk SL, Rizk SL, Sky-Peck HH (1984) Comparison between concentrations of trace elements
in normal and neoplastia human breast tissue. Cancer Res 44:5390–5394
3. Somervaille LJ, Chettle DR, Scott MC (1985) In vivo measurement of lead in bone using X-ray
fluorescence. Phys Med Biol 30:929
X-Ray Excited Fluorescent Materials for Medical Application
145