CT system, - wherein the CT system comprises a base structure, an additional structure, an X-ray source, an X-ray detector and a collimator plate, - wherein the additional structure is mounted on the base structure such that it can be rotated, so that the additional structure can be rotated relative to the base structure about an axis of rotation, - wherein the additional structure has an annular rotating frame, which extends in a planar manner in a rotation plane, wherein the rotation plane is perpendicular to the axis of rotation, - wherein the additional structure has a holding structure, wherein the holding structure is configured to accommodate the collimator plate in a detachable manner, - wherein the X-ray source and the X-ray detector are fastened to the additional structure in such a manner that they are arranged at a fixed position relative to one another and, between the X-ray source and the X-ray detector in the region of the axis of rotation, there is an examination region, in which a patient or a body part of a patient can be arranged, - wherein the collimator plate is fastened in a detachable manner to the additional structure, between the X-ray source and the examination region, in such a manner that the collimator plate can be detached from the additional structure as such, - wherein the collimator plate, between the X-ray source and the examination region, is accommodated in the holding structure in a detachable manner and fastened to the holding structure such that the collimator plate can be detached from the holding structure as such, characterised in that the additional structure is embodied in one piece and as a cast part, and the holding structure protrudes substantially perpendicularly in relation to the rotation plane relative to the annular rotating frame, wherein the holding structure is a constituent part of the additional structure. - wherein the CT system comprises a base structure, an additional structure, an X-ray source, an X-ray detector and a collimator plate, - wherein the additional structure is mounted on the base structure such that it can be rotated, so that the additional structure can be rotated relative to the base structure about an axis of rotation, - wherein the additional structure has an annular rotating frame, which extends in a planar manner in a rotation plane, wherein the rotation plane is perpendicular to the axis of rotation, - wherein the additional structure has a holding structure, wherein the holding structure is configured to accommodate the collimator plate in a detachable manner, - wherein the X-ray source and the X-ray detector are fastened to the additional structure in such a manner that they are arranged at a fixed position relative to one another and, between the X-ray source and the X-ray detector in the region of the axis of rotation, there is an examination region, in which a patient or a body part of a patient can be arranged, - wherein the collimator plate is fastened in a detachable manner to the additional structure, between the X-ray source and the examination region, in such a manner that the collimator plate can be detached from the additional structure as such, - wherein the collimator plate, between the X-ray source and the examination region, is accommodated in the holding structure in a detachable manner and fastened to the holding structure such that the collimator plate can be detached from the holding structure as such,