Anode angle

Last revised by Matt Skalski on 6 Aug 2021

The anode angle refers to the angle the target surface of the anode sits at in relation to the vertical. 

Most x-ray tubes have an anode angle of 12-15 degrees but greater or lesser angles can also be used depending on the application. The degree of angulation of the anode affects the effective focal spot length (not the width) and forms part of the line focus principle. The effect that the angle has on the effective focal spot length can be calculated by the following equation:

f = F x sinθ 


f = effective focal spot length

F = actual focal spot length

θ  = anode angle

The smaller the effective focal spot size the better spatial resolution produced but limits the size of the usable x-ray field. 

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