JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

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Development of a Head Module for Multi-Head
Si/CdTe Compton Camera System
M. Yamaguchi a, c) , T. Kamiya a) , T. Satoh a) , N. Kawachi b) , N. Suzui b) , S. Fujimaki b) ,
H. Odaka c, d) , S. Ishikawa c, d) , M. Kokubun c) , S. Watanabe c, d) , T. Takahashi c, d) ,
H. Shimada c) , K. Arakawa a, e) , Y. Suzuki f) , K. Torikai e) , Y. Yoshida e) e, f)
and T. Nakano
a) Department of Advanced Radiation Technology, TARRI, JAEA, b) Radiation-Applied Biology
Division, QuBS, JAEA, c) Institute of Space and Astronautical Science, JAXA, d) Department of
Physics, University of Tokyo, e) Gunma University Heavy Ion Medical Center, Gunma University,
f) Graduate School of Medicine, Gunma University
For the mainstream imaging techniques in the field of life
science research like PET or SPECT, simultaneous imaging
of multiple nuclei is difficult because the energy of the
measurable gamma ray is specific or in a restricted energy
range. We are constructing a three-dimensional imaging
system for life science applications as a device that can
provide simultaneous imaging, having high spatial and
energy resolutions and wide energy range from several tens
of keV to a few MeV, applying the most advanced
space-observation technology, Si/CdTe semiconductor
1)
Compton camera, developed at ISAS/JAXA . The
Si/CdTe Compton camera was developed under the
assumption of use at moderate temperature and the analog
ASIC for signal processing. Moreover, because its solid
and thin scattering layer allows close placement of the
measured object, good angular resolution corresponds to
good spatial resolution directly. These aspects allow
construction of compact medical system.
In contrast to space-observation use, three-dimensional
imaging ability becomes important for life science research.
In order to achieve a good three-dimensional spatial
resolution, modularizing the Compton camera into a small
camera head, which parmits multi-angle imaging with
2)
multi-head structure, is required . In this work, a head
module has been developed as a prototype module of the
multi-head system. Figure 1 shows the inner circuit of the
prototype module. The upper part is layer of front end
cards including Si/CdTe detectors and analog ASIC’s. The
bottom part contains DC voltage transform circuits and
digital signal transform circuits. The plate in the middle
part is a heat sink. Sensor and circuit modules are closely
arranged and put in a compact vacuum-insulating cylindrical
housing having a height of 24 cm and a diameter of 22 cm.
Each of camera heads will be fixed on robot arms to adjust
the position and the direction. Performance evaluation test
was made for the prototype module with a sealed Ba-133
point-type source. The source was put at two positions in
the measurement. We confirmed that the resultant image
was almost consistent with the source positioning (see
Fig. 2). The angular resolution measure was estimated to
be 4.5 degrees.
JAEA-Review 2010-065
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Fig. 1 A picture of the internal circuit of the prototype
module.
Fig. 2 A diagram of source position and the resultant
image. Left diagram shows the source positions in the
experiment. Red filled circles represent the source
positions. During the experiment, the source was
moved in two places. Right diagram represents the
imaging result. The resulting image was almost
consistent with the source positioning.
References
1) T. Takahashi, Exp. Astron. 20 (2006) 317-331.
2) M. Yamaguchi, et al., IEEE Nucl. Sci. Symp. Med.
Imaging Conf. Record 2008, 4 (2009) 4000-4002.