Mesh test object angle and dead line visibility
A custom made 43 x 43 cm mesh test object has been imaged on a direct-digital radiographic detector with a known single broken vertical pixel line. A Leeds Test Objects MS4 mesh test object was also imaged. The detector has a pixel pitch of 0.139 mm.
The MS4 mesh has a nominal aperture size of 0.50 mm and a nominal wire diameter of 0.31 mm (data from Leeds Test Objects SFS set specification sheet). A paper that includes the use of the MS4 mesh to show defective detector lines can be found here: https://link.springer.com/article/10.1007/s10278-008-9109-0.
The custom test object contains a #36 mesh with an aperture of 0.48 mm and a wire diameter of 0.22 mm (data from The Mesh Company website). It should be noted that other mesh companies are available, such as BOPP.
The test objects were exposed using 50 kVp, 3 mAs and a focus to detector distance of approximately 1.5 m.
The custom mesh was imaged at five different angles to the detector pixel matrix: 0, 3, 14, 28 and 49 degrees. The MS4 was imaged at approximately 45 degrees to the detector pixel matrix. 100 % crops from each image are shown below. The broken vertical line can be seen running down the centre of each image. Each of the five custom mesh crops are for the same window level and width. The MS4 crop uses a different window level and width to provide good visibility of the broken line. Broken line is visible in each image, but presents differently depending on the angle of the mesh.