| Id |
Subject |
Object |
Predicate |
Lexical cue |
| T407 |
0-10 |
Sentence |
denotes |
Resolution |
| T408 |
11-142 |
Sentence |
denotes |
Resolution estimates are challenging for tissue reconstructions due to the absence of sharp edges or features of well defined size. |
| T409 |
143-213 |
Sentence |
denotes |
Here, we follow the approach known as Fourier-shell correlation (FSC). |
| T410 |
214-377 |
Sentence |
denotes |
Accordingly, an upper bound for the resolution is be obtained in the following way: the CT scan is split into two, and from each half a 3D volume is reconstructed. |
| T411 |
378-557 |
Sentence |
denotes |
After registry, that is, mutual alignment of the volumes, the correlation between the two independent reconstructions in Fourier space is plotted as function of spatial frequency. |
| T412 |
558-713 |
Sentence |
denotes |
This correlation must not necessarily reflect the pure system resolution, but instead the range of spatial frequencies over which the results are reliable. |
| T413 |
714-838 |
Sentence |
denotes |
As such it is not only affected by the system resolution but also by the sample contrast and the noise of the specific scan. |
| T414 |
839-1011 |
Sentence |
denotes |
Further, it represents an average over all structures, not taking into account that features with stronger/weaker contrast can correspondingly show higher/lower resolution. |
| T415 |
1012-1103 |
Sentence |
denotes |
Here the Fourier operation for FSC was implemented with a Kaiser-Bessel window of 7 pixels. |
| T416 |
1104-1249 |
Sentence |
denotes |
For the parallel-beam data, a central volume of 650 × 650 × 650 voxels was correlated, for the cone-beam data a volume of 685 × 680 × 250 voxels. |
| T417 |
1250-1384 |
Sentence |
denotes |
These sub-volumes were selected to obtain the average values for the tissue while minimizing contributions from paraffin-filled holes. |
| T418 |
1385-1441 |
Sentence |
denotes |
The correlation curves are shown in Appendix 2—figure 1. |
| T419 |
1442-1565 |
Sentence |
denotes |
The intersection of the curve with the half-bit threshold yields the resolution estimate, indicated with dashed black line. |
| T420 |
1566-1710 |
Sentence |
denotes |
Correspondingly, a half-period resolution of 0.71μm and 0.39μm (or better) is obtained for the parallel and cone beam dataset, respectively. |
| T421 |
1711-1921 |
Sentence |
denotes |
However, since the splitted dataset resulted in only 721 angles for the reconstruction, i.e. the resolution estimate is severely affected by under-sampling artifacts, and hence can only serve as an upper bound. |
| T422 |
1922-1967 |
Sentence |
denotes |
Appendix 2—figure 1 illustrates the analysis. |
| T423 |
1968-1988 |
Sentence |
denotes |
Appendix 2—figure 1. |
| T424 |
1990-2054 |
Sentence |
denotes |
Quantification of the 3D-resolution for the example of sample V. |
| T425 |
2055-2164 |
Sentence |
denotes |
FSC analysis was carried out for two independent reconstructions, each from half the projections of the scan. |
