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This paper proposes a new respiratory gated radiation treatment system that allows real-time tumor localization while avoiding invasive operation to a patient. The proposed system employs a three-dimensional (3D) ultrasound device, a 3D digital localizer, and a real-time image processing system. At the planning time, CT and 3D ultrasound reference data are simultaneously acquired under a breath-hold condition. At the treatment time, ultrasound data on three orthogonal planes are acquired and transferred to the image processing system on a real-time basis. Subsequently, normalized image correlation indices using the reference and the real-time ultrasound data are calculated for the three orthogonal planes after performing real-time coordinate transform using the 3D digital localizer attached to an ultrasound probe. Prior to the system execution, the coordinate transform matrices are partially calculated using an ultrasound calibration phantom and the 3D digital localizer. A trigger pulse to a linac can be generated when the normalized image correlation index exceeds a predetermined threshold level. Experiments have been carried out using a moving-target phantom that simulates a patient respiratory motion. We have observed that the variation of the calculated real-time correlation index synchronizes with the periodical motion of the moving-target, suggesting that real-time localization for a moving tumor is feasible with the proposed system.

We designed a new image scanner using the reflective optics of a compound eye system that can easily assemble plural imaging optical units (called imaging cells) and is compact with a large depth of field (DOF). Our image scanner is constructed from 32 reflective imaging cells, each of which takes an image of approximately a 10-mm field of view (FOV) that slightly overlap the adjacent imaging cells. The total image is rebuilt by combining the 32 images in post processing. We studied how to fold the optical path in the imaging cells and simplified the structure, resulting in the following three advances of our previous work: 1) greater compactness (50 × 31 mm2 in the cross section), 2) less variable optical characteristics among the imaging cells, and 3) easy assembly thanks to small number of optical components constructing the imaging cell.