Focal Spot plugin

Author:

Giovanni Di Domenico (Giovanni.Di.Domenico[at]unife.it)
History:

2015/07/20: First version

2019/11/18: Second version

2025/04/30: Third version
Source: Focal_Spot.java
Installation:

Download Focal_Spot_v3_0.zip to the plugins folder and restart ImageJ or click Help>Update Menus.
Description:

This plugin permits the reconstruction of the X-ray focal spot by circular penumbra analysis.

[Dialog-1]

Angular Step: number of angular steps along which to calculate the focal spot projections (default 360).

Axis Offset: the offset of axis projection in pixels(default 32.5).

Filter Type: the filter used in backprojection reconstruction(default Ramp filter).

Filter Cutoff: the reconstruction filter cutoff (default and maximum value 0.5).

Filter Order: the reconstruction filter order for the butterworth filter(default value 1).

Circular Hole Diameter: the diameter of the hole used in the focal spot measurement in mm.

Detector Pixel Size: the size of detector pixel used in the focal spot measurement in mm.

Report: info about the reconstruction process.

The second version of plugin is able to perform the analysis on images with background value >> 0.0. The number of samples along the projection axis is 128. Additionally, it has been added a code fragment for evaluating the right offset value for the reconstruction.
Reconstruction of a simulated square focal spot.

Hole blurred by a square focal spot.

Roi for the calculation of hole center and radius.

Hole Radial Profiles.

Calculated sinogram.

Reconstructed Focal Spot.

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