<title>Development of a 3D CT scanner using cone beam</title>

Abstract

In order to acquire 3D data of high contrast objects such as bone, lung and vessels enhanced by contrast media for use of 3D image processing, we have developed a 3D CT-scanner using cone beam X-ray. A 3D CT-scanner consisted of a gantry and a patient couch. The gantry consisted of an X-ray tube designed for cone beam CT and a large area two-dimensional detector mounted on a single frame and rotated around an object in 12 seconds. The large area detector consisted of a fluorescent plate and a charge coupled device video camera. The size of detection area was 600mm x 450mm capable of covering total chest. While an X-ray tube was rotated around an object, pulsed X-ray was exposed 30 times a second and 360 projected images were collected in a 12 second scan. 256 x 256 x 256 matrix image (1.25 mm x 1.25 mm x 1.25mm voxel) was reconstructed by a high-speed reconstruction engine. Reconstruction time was approximately 6 minutes. Cylindrical water phantoms, anesthetized rabbits with or without contrast media, a Japanese macaque were scanned with the 3D CT-scanner. The results seemed promising because they showed high spatial resolution in three directions, though there existed several points to be improved. Possible improvements were discussed.

Prototype heel effect compensation filter for cone-beam CT

“…Commensurate with higher quality imaging and resulting substantial diagnostic benefits, patient doses in clinical applications of CT have increased steadily over recent decades (IEC 1994). Among new developments in the technology of CT, cone beam CT (CBCT) has attracted particular attention in both the diagnostic and therapeutic fields (Saint et al 1994, Endo et al 1998, Ning et al 2005, Sonke et al 2005. Patient dosing with CBCT is of considerable concern, however, because the maximum beam width is greater than that of conventional multi-detector row CTs (MDCT), the latest of which has 64 segments with a segment size of 0.5-0.625 mm at the centre of rotation.…”