Affiliations: Cyclotron and Radioisotope Center, Tohoku University,
Sendai, Japan | Department of Physics, University of Surrey,
Guildford, United Kingdom | Graduate School of Pharmaceutical Sciences, Tohoku
University, Sendai, Japan | Sendai Kousei Hospital, Sendai, Japan
Abstract: In computed tomography (CT) systems, it is desirable to know the
X-ray energy spectra for various applications, including medical CT imaging,
and diagnostic field and heavy ion therapy. However, because of the restricted
space, the only practical solution is to use Compton spectroscopy, where the
incident spectrum is inferred from the scattered spectrum. The geometry of the
scatterer and its position within the CT can affect the spectrum of the
secondary beam, making it difficult to determine the primary spectrum during
operation of the CT system. A modified Compton spectrometer is described that
allows measurement of the X-ray energy spectra during operation, and most
importantly, in rotation mode. The geometry of the scatterer was optimized to
reduce the energy broadening of the secondary beam. The performance of the
system was evaluated by comparing the reconstructed exposure to that measured
directly using an ion chamber.
