Paweł Turek

The influence of change in slice thickness on the accuracy of reconstruction of cranium geometry.

The article presents a comparative study of change in slice thickness on the accuracy of reconstruction of cranium geometry. Research was performed on 10 different patients. Digital Imaging and Communications in Medicine data were obtained on the Siemens Somatom Sensation Open 40 scanner. At the stage of reconstruction, the same parameters were utilized, while only slice thickness was changed. Modeling with voxel dimensions of 0.4 mm × 0.4 mm × 2.4 mm was chosen as the gold standard over the modeling approach comprising voxel dimensions of 0.4 mm × 0.4 mm × 4.8 mm. The influence of layer thickness on the accuracy of cranium geometry is very similar for the 10 presented patients. The average results show a distribution with a positive skew and kurtosis. The value of skewness is 0.284 (small asymmetry) and kurtosis is 3.746 (a distribution more peaked). Based on 95% confidence, the changes in layer thickness from 2.4 to 4.8 mm generated errors reconstructing the geometry of the cranium by 0.516 mm ± 1.345 mm. The presented research highlights new opportunities to control deviations at the stage of data processing and modeling geometry of the cranium.

Analysis of the geometry reconstruction accuracy of the anatomical structure using industrial tomography and laser head

Reverse engineering is a process that allows to recreate the geometry of an existing object [1,2]. It is used in many fields, including in medicine. The geometry of the anatomical structure model can be reconstructed in two ways in which the measurements are performed on the living body or outside it. Using the medical path, it is possible to reconstruct the geometry of anatomical structures [3,4] and to make surgical templates [5] and ready implants [6]. The nonmedical path is mainly a supplement to the medical path. Coordinated measuring systems used in this path are mainly used to verify the accuracy of models used in the medical industry [7], as well as to design orthoses stabilizing joints [8]. Each stage of the medical and non-medical path influences the accuracy of the reconstruction of the models geometry. One of the key steps is the acquisition of data the appropriate selection of the system, parameters and measurement strategy determines the quality of the obtained data [9,10]. The stage of data processing usually starts with the process of digital filtration, consisting in removing the noise found in 2D images (in the case of a medical path) and point clouds (in the case of a non-medical path). After filtration, a full model geometry is obtained, however, in the case of a medical path, the segmentation process is additionally performed. It is used to isolate the anatomical structure from 2D images through the use of various methods, based mainly on edge detection and identification of image areas that are characterized by some common features [11]. In both reconstruction methods, the reconstructed geometry is usually triangulated, leading to a faceted surface that requires additional editing, including the reversal of normal vectors and the removal of holes between triangles [11]. The finished model, represented by the faceted surface, can be manufactured using various additive techniques [12, 13]. Further modeling is also possible, consisting in covering the polygonal mesh with elementary surfaces [14]. The obtained model can be exported using various CAD data exchange formats, such as *.iges or *.step, or it can be used to execute a machining program on computer numerical controlled machines [15].

Measurements of the blade’s fir tree slots profile deviation on conturograph

* Dr hab. inż Jan Burek, prof. PRz (jburek@prz.edu.pl), mgr inż. Jarosław Buk (jbuk@prz.edu.pl), mgr inż. Marcin Płodzień (plodzień@prz.edu.pl), mgr inż. Paweł Turek (pturek@prz.edu.pl), mgr inż. Marcin Sałata (msalata@prz.edu.pl) – Katedra Technik Wytwarzania i Automatyzacji, Wydział Budowy Maszyn i Lotnictwa, Politechnika Rzeszowska Pomiar odchyłki profilu zamka łopatki wirnika na konturografie