Automated procedure for slice thickness verification of computed tomography images: Variations of slice thickness, position from iso‐center, and reconstruction filter

Abstract

Purpose: The purpose of this study is to automate the slice thickness verification on the AAPM CT performance phantom and validate it for variations of slice thickness, position from iso-center, and reconstruction filter.Methods: An automatic procedure for slice thickness verification on AAPM CT performance phantom was developed using MATLAB R2015b. The stair object image within the phantom was segmented, and the middle stair object was located. Its angle was determined using the Hough transformation, and the image was rotated accordingly. The profile through this object was obtained, and its full-width of half maximum (FWHM) was automatically measured. The FWHM indicated the slice thickness of the image. The automated procedure was applied with variations in three independent parameters, i.e., the slice thickness, the distance from the phantom to the iso-center, and the reconstruction filter. The automated results were compared to manual measurements made using electronic calipers.Results: The differences of the automated results from the nominal slice thicknesses were within 1.0 mm. The automated results are comparable to those from manual approach (i.e., the difference of both is within 12%). The automatic procedure accurately obtained slice thickness even when the phantom was moved from the iso-center position by up to 4 cm above and 4 cm below the iso-center. The automated results were similar (to within 0.1 mm) for various reconstruction filters. Conclusions:We successfully developed an automated procedure of slice thickness verification and confirmed that the automated procedure provided accurate results.It provided an easy and effective method of determining slice thickness.

Root canal length estimated by cone-beam computed tomography at different slice thicknesses, dedicated endodontic software, or measured by an electronic apex locator

“…Most often, a thicker slice increases the contrast of the image and might provide better identification of the volume of interest 12 . However, previous studies have investigated the optimal slice thickness for different purposes and the results have not been consistent 11 – 16 . These studies used the same platform as in the present study 18 – 20 ; however, only one mentioned a slice thickness of 1 mm for CBCT measurements 18 .…”

“…CBCT scans depend on many parameters, such as voxel size, field of view, electric current intensity, reconstruction algorithm, beam collimation and slide thickness 11 . Slice thickness affects the resolution of the image, leading to an impact on the accuracy of measurements 11 . The slice thickness is inversely proportional to image noise and decreasing the slice thickness increases the latter 14 .…”

“…Slice thickness is an important factor in CBCT, along with voxel size, field of view and the reconstruction algorithm 11 . Slice thickness with a larger voxel size improves the contrast of images, facilitates the identification of anatomical structures and affects the accuracy of the measurement of certain distances 11 , 12 .…”

“…Slice thickness is an important factor in CBCT, along with voxel size, field of view and the reconstruction algorithm 11 . Slice thickness with a larger voxel size improves the contrast of images, facilitates the identification of anatomical structures and affects the accuracy of the measurement of certain distances 11 , 12 . Some studies have shown effects of slice thickness on the accuracy of specific issues, such as linear measurements of titanium pins, implant sites, occlusal caries, intact buccal cortical plates, or different devices 12 – 16 .…”

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

“…13 Sofiyatun et al 13 proposed an algorithm to measure slice thickness using the AAPM CT performance phantom automatically. The method was then evaluated for variations of reconstruction filter and distance from the iso-center by Lasiyah et al 14 Results were less than 1.0 mm different from the nominal slice thickness under a variety of conditions (i.e. slice thickness, distance to iso-center, angle of rotation, and filter).…”