Spatial resolution (CT)

Last revised by Mateusz Wilczek on 8 Dec 2023

Spatial resolution in CT is the ability to distinguish between object or structures that differ in density.

A high spatial resolution is important for one to discriminate between structures that are located within a small proximity to each other. 

Factors affecting CT spatial resolution

  • field of view 

    • as the FOV increases so does the pixel size (assuming constant number of pixels), resulting in a decreased resolution

  • pixel size

    • the smaller the pixel size the higher the spatial resolution

  • focal spot size

    • a larger focal spot will decrease the resolution 

  • magnification 

    • increasing will decrease the resolution

  • motion of the patient 

  • pitch 

    • is inversely related to the resolution, the higher the pitch the lower the resolution 

  • kernel  

    • edge enhancement kernels will have a higher spatial resolution than soft tissue kernels, at the cost of more noise and therefore decreased contrast resolution

  • slice thickness 

    • the larger the slice thickness the lower the resolution

  • detector element (dexel) size 

    • increase in detector element size decreases resolution

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Cases and figures

  • Figure 1: CT window and algorithm effects
    Drag here to reorder.