A general purpose Cellular Array Processor(CAP) with distributed frame buffers for fast parallel subimage generation has been developed. CAP consists of many processor elements called cells. A cell has video memory for subimage storage, a window controller to map each subimage to an area on the monitor screen, and communication devices, in addition to ordinary microcomputer components such as MPU, RAM, and ROM. Image data in a cell is directly displayed via the video bus. The mapping pattern and the position on the screen of subimages can be changed dynamically. Various hidden surface algorithms can be implemented in CAP using mapping patterns appropriate for the algorithm.Our goal is an efficient interactive visual solid modeler. We adopted a general CSG hidden surface algorithm that enables display of both Boundary representation and Constructive Solid Geometry. A technique for hidden surface removal of general CSG models, requiring less memory space for large models in many cases, has been proposed. This technique subdivides the model into submodels by dividing the CSG tree at union nodes. Imagse of each submodel are generated by a CSG or a z-buffer algorithm. If a submodel is just a primitive, it is processed by the z-buffer algorithm, otherwise by the CSG algorithm. Hidden surface removal between submodels is done by comparing the z values for each pixel which are saved in the z-buffer.

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Diagnosis by CTHA CT during hepatic arteriography and CTAP CT during arterio-portography is indispensable in the treatment of hepatocellular carcinoma HCC. An IVR-CT system makes it possible to perform accurate diagnosis and treatment of HCC in a short period of time. In recent years, attention has been drawn to cone-beam CT CBCT using a flat panel detector FPD angio-system, and the application of CBCT for CTAP and CTHA has been reported. However, it is well known that CBCT easily generates artifacts on the images, so it is necessary to use CBCT according to the intended purpose. The purpose of this study was to evaluate 3-D images reconstructed by MDCT or CBCT, image noise, and low-contrast resolution in a phantom with a tumor mimic model. From our results, CBCT images showed distortion and blurring, and it was difficult to visualize a tumor model of 7 mm or less. In addition CBCT can create only a small area of 3-D vascular mapping. In conclusion, it is considered that CBCT cannot be used in place of conventional CTHA or CTA for the treatment of HCC.

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