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2 2022

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Automation of slice thickness measurements in computed tomography images of AAPM CT performance phantom using a non-rotational method

Ximenes Angelita D., Anam Choirul, Hidayanto Eko, Naufal Ariij, Rukmana Dito A., Dougherty Geoff

Polish Journal of Medical Physics and Engineering

2022

Vol. 28, Iss. 3

133--138

Purpose: The current study proposes a method for automatically measuring slice thickness using a non-rotational method on the middle stair object of the AAPM CT performance phantom image. Method: The AAPM CT performance phantom was scanned by a GE Healthcare 128-slice CT scanner with nominal slice thicknesses of 0.625, 1.25, 2.5, 3.75, 5, 7.5 and 10 mm. The automated slice thickness was measured as the full width at half maximum (FWHM) of the profile of the middle stair object using a non-rotational method. The non-rotational method avoided rotating the image of the phantom. Instead, the lines to make the profiles were automatically rotated to confirm the stair’s location and rotation. The results of this non-rotational method were compared with those from a previous rotational method. Results: The slice thicknesses from the non-rotational method were 1.55, 1.86, 3.27, 4.86, 6.58, 7.57, and 9.66 mm for nominal slice thicknesses of 0.625, 1.25, 2.4, 3.75, 5, 7.5, and 10 mm, respectively. By comparison, the slice thicknesses from the rotational method were 1.53, 1.87, 3.32, 4.98, 6.77, 7.75, and 9.80 mm, respectively. The results of the non- rotational method were slightly lower (i.e. 0.25%) than the results of the rotational method for each nominal slice thickness, except for the smallest slice thickness. Conclusions: An alternative algorithm using a non-rotational method to measure the slice thickness of the middle stair object in the AAPM CT performance phantom was successfully implemented. The slice thicknesses from the non- rotational method results were slightly lower than the rotational method results for each nominal slice thickness, except at the smallest nominal slice thickness (0.625 mm).

Experimental study on dynamic stability of rubber-cement composites by SHPB and high-speed slicing

Yang Rongzhou, Xu Ying, Chen Pei Yuan

Archives of Civil Engineering

2022

Vol. 68, nr 1

319--334

Improper disposal of waste tires will not only bring environmental impact and safety risks but also cause a serious waste of resources. In the field of civil engineering materials, waste tire particles are used as a substitute for non-renewable aggregates to produce flexible rubber-cement composites (RCC). To explore the high-speed slicing stability of RCC, this test took normal cement mortar (NCM) and rubber cement mortar (RCM) as research objects. The SHPB tests with the same impact energy level and the high-speed slicing tests with a slice thickness range of about 1.4 mm ~ 4.4 mm were carried out. The results showed that NCM and RCM showed different stability differences in the process of high-speed slicing. In the case of ensuring the integrity of the slice, the minimum thickness of the slice can be better decreased with the increase of the rubber content. Finally, from the perspectives of split Hopkinson pressure bar (SHPB) test results and mesoscopic structure states, the essential reason for ensuring the stability of high-speed slicing lied in the improvement of rubber particles (dominant role) and pores on material deformation and flexible energy dissipation.