Comparing imaging techniques

An imaging technique is suitable when it produces enough detail for the task and can be used conveniently and safely for the person being imaged. The technique that produces the finest detail is not necessarily the best choice in every situation.

Image resolution

Spatial resolution describes how well an image distinguishes two close features as separate. If the features are too close together for the technique to resolve them, they may appear as one feature rather than two.

A technique that can distinguish features at a smaller minimum separation has better spatial resolution. For a particular task, the image needs enough resolution to show the features being examined; detail beyond that requirement may not outweigh other disadvantages.

Convenience and safety

Convenience concerns the practical demands of obtaining an image. These include how quickly the image can be obtained, whether the equipment is available, and what preparation the person needs. A technique may be less suitable if it takes too long or the required equipment is not readily available.

Safety concerns the risks of the procedure. These depend on both the technique and the person being imaged. For example, exposure to ionising radiation carries a risk, so that risk must be considered alongside the benefit of obtaining the image.

Weighing the criteria

A comparison considers resolution, convenience and safety together for the situation. A technique with the best resolution may be less suitable if another technique provides enough detail while being quicker, more accessible or safer for the person concerned.