A challenge and solution for automatic thin slice thickness measurements on images of the Catphan phantom.


This study proposes a method for automatically measuring the thickness of thin slices on images of the Catphan phantom.
Methods:
In the proposed method, the angle of the phantom's orientation was determined based on the relative coordinates of the four hole objects in the phantom. After the angle of the wires were determined, the profiles of pixel values across the wire objects were constructed. Finally, their full widths at half maximum (FWHMs) were determined and multiplied by tan 23o to obtain the slice thicknesses of the images. The results of the proposed method were compared to a previous method, which used the Hough transform to obtain the phantom's orientation. We used slice thicknesses ranging from 0.8 mm to 5.0 mm, and phantom angles from 0o to 10o.
Results:
Our proposed method detected the angle of the phantom accurately in the thin slice thickness, while a previous method did not accurately detect the angle. The results of the slice thickness using this method were slightly higher compared to the previous method. However, the results of the two methods did not differ significantly (p-value > 0.05) with the largest difference is 7.9 % at a slice thickness of 5 mm. Using different angles, the proposed method detected the angle more accurately. Again, the slice thicknesses were not significantly different from the previous method (p-value > 0.05) with the largest difference of 8.8 % at an angle of 6o.
Conclusion:
The proposed method for measuring the thickness of thin slices in an image of the Catphan phantom, based on the relative coordinates of the four hole objects in the phantom, outperformed a previous method based on the Hough transform.&#xD.