Focal Spot Fluoro

Focal spot size, measured in mm. directs image quality to a large extent. The smaller the focal spot, the better the image resolution. However, it is important to consider the image matrix of the system. For example, a 1k x 1k matrix with 0.3mm focal spot will produce approximately the same resolution as a 0.6mm focal spot at object-to-image distances of 40cm or less. Therefore, in C-arm imaging with 1k x 1k matrix, the performance of a 0.6mm is equal to a 0.3mm.