Three-dimensional fusion imaging of radioscintigraphy and CT for minimal invasive treatment of malignancies.

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In the first year, we engaged to investigate the visualization of body contours for the fusion of radio-scintigrams and CT images. We applied to the acquisition method using the double energy windows where the scattered photons with lower energy produced by Comp ton scattering are used to visualize the body contours. In SPECT imaging, additional external sources were used to enhance the scattered photons. When syringes with 1ml of Tc-99m (37MBq) were put at the edge of each detector of SPECT camera and images were acquired with 12 degree step of 30 seconds, the body contour clear enough to apply fusion of images could be obtained.These scintigrams were merged to CT images on workstation (GMS-5500A/PI, Toshiba, Tokyo) using ART (automatic registration tool) and merged images could show the clear identification of the anatomical location of SLN. The gaps between the LN image on the CT and hot spot on scintigrams were clinically acceptable.In the second year, we engaged in coded aperture imaging to improve the sensitivity of 3D scintigraphic imaging. Coded aperture can provide more excellent sensitivity than parallel-hole collimator keeping as good spatial resolution as pinhole collimator, resulting in the shorter acquisition time in the intra-operative imaging. We could obtain the combination of parameters that show the best sensitivity and the best spatial resolution.