| 摘要 |
<p>TOMOGRAPHIC APPARATUS The invention relates to the apparatus and method for constructing a representation of the variation of attenuation of penetrating radiation in a planar slice of a patient positioned in a scan circle. The patient is irradiated with a fan shaped swath of radiation which is rotated about the patient for 180.degree. plus approximately the angle of the fan. Radiation passing through the scan circle is converted to sets of data, each set representing a radiation attenuation across a fan. The sets of data are filtered with a window function to remove data from some of the sets which represent radiation passing through a point in the scan circle by more than 180.degree. relative to radiation paths through the same point. The sets of data are serially convolved and back-projected into an image memory for display on a video monitor. The back projector addresses each set of data by generating subsequent addresses from the previous address and the incremental displacement between adjacent pixels of the image memory using pixel driven algorithms.</p> |
