| 摘要 |
The invention relates to a projection data acquisition apparatus (14) for acquiring projection data for being used for reconstructing a computed tomography image. In acquisition intervals projection data are acquired only at certain acquisition rotational positions of a radiation source (2) relative to an object, wherein an acquisition rotational position of a current acquisition interval divides a largest non-acquisition angular region covering rotational positions, at which projection data have not already been acquired, into two smaller non-acquisition angular regions. Because of this acquisition of the projection data, after each acquisition interval the acquisition rotational positions, at which projection data have been acquired already, are relatively homogeneously distributed. This allows for an improved image quality of a computed tomography image which is reconstructed based on the acquired projection data. |
| 主权项 |
1. A projection data acquisition apparatus for acquiring projection data of an object, wherein the projection data acquisition apparatus comprises:
a radiation source generating radiation for traversing the object, a detector for detecting the radiation after having traversed the object and for generating the projection data based on the detected radiation, a moving unit for moving the radiation source and the object relative to each other, wherein the movement includes several rotations of the radiation source around the object, a control unit for controlling the radiation source and the moving unit such that: in acquisition intervals projection data are acquired only at certain acquisition rotational positions of the radiation source elative to the object, wherein an acquisition rotational position of a current acquisition interval divides a largest non-acquisition angular region covering rotational positions, at which projection data have not already been acquired, into two smaller non-acquisition angular regions, the angular distances between acquisition rotational positions of an n-th acquisition interval are equal to the angular distances between acquisition rotational positions of an (n−1)-th acquisition interval, wherein the angular distances between acquisition rotational positions of an acquisition interval are equal to a k-th Fibonacci number, wherein the rotational positions of an acquisition interval are consecutively numbered and an angular distance between rotational positions is defined by the difference between the rotational positions in terms of their numbers, and the first acquisition rotational position of the n-th acquisition interval is equal to (n times the (k−1)-th Fibonacci number) modulo the k-th Fibonacci number, wherein the rotational positions of an acquisition interval are consecutively numbered starting from zero. |
