In the present invention, a reconstructed image containing external information is obtained by reconstruction of a non-cut sinogram (SNT) using a POCS-based reconstruction algorithm, and the obtained reconstructed image is again forward projection (forward projection). To generate a virtual sinogram (SOUT) including external information, and use the virtual sinogram (SOUT), the uncut sinogram (SNT), and the cut sinogram (ST) The present invention relates to a POCS-based external information restoration method applicable to a field modulation CT acquisition system that can obtain a high-quality image including external information by obtaining a reconstructed image using a nogram. The POCS-based external information restoration method in the field-modulated CT acquisition system of the present invention obtains projection data by irradiating X-rays on the subject at an angle of 360 degrees centered on the subject, adjusting the field of view, and cutting projection. A projection data acquisition step of alternately acquiring projection data of an image and projection data of an uncut projection image； The sinogram is obtained from the projection data received from the projection data acquisition unit, and the uncut sinogram (SNT) and the cut sinogram (ST) are extracted from the obtained sinogram. Nogram acquisition step； Applying and forwarding the POCS algorithm, which acquires a reconstructed image by applying the POCS algorithm to the uncut sinogram (ST), and obtains a virtual sinogram (SOUT) including external information by forward projecting the obtained reconstructed image Projection data recovery step by projection； A CT image by performing filtered back projection (FBP) reconstruction on the projection data obtained by summing the uncut sinogram (SNT), the cut sinogram (ST) and the virtual sinogram (SOUT). It characterized in that it comprises a； obtaining, FBP reconstructed CT image acquisition step.본 발명은, POCS 기반의 재구성 알고리즘을 사용하여 비 절단 사이노그램(SNT)에 대한 재구성을 진행
