A device of tomography included: a CT scanner that have a scanning area and a scanning table, the scanning table can move back and forth in the scanning area in a direction a auxiliary table that installed a side of the CT scanner and opposite to the scanning table, the auxiliary table have a extending position and a lying position, and a end of the extending position is combined to the lying position, and the extending position displaying a raising ramp, another end of the extending position forming a connecting end which abut against the scanning table. The scanning table pushes the auxiliary table to move in the scanning area in a direction, thus finally pushing the auxiliary table to move away from the scanning area. Thus, the auxiliary table could effectively avoid the radiation exposure of chest and abdominal cavity from the CT scanner.
