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Table 1 Challenges in the conventional micro-CT characterization

From: Micro-CT – a digital 3D microstructural voyage into scaffolds: a systematic review of the reported methods and results

Challenge Potential solution Reference
Artifacts and noise. Detailed in Table 1 of Ref. [162] [162, 164, 169, 170]
Soft tissue characterization is not as easy as a dry-state porous scaffold. Using contrast agents or high-atomic-number element probes can help. [28,29,30,31,32]
Operator-determined acquisition parameters may affect the results. Parameters should be optimized during the preliminary study. [13]
Harsh acquisitions may damage/alter the sample/tissue (for example, discoloring of a biomaterial or tumorigenesis in animals); and radiation exposure of animals in live animal studies, lethal dose 50/30 (both ethical and scientific considerations). Long scans (either due to very low rotation step, frame averaging, or long exposure time) should be avoided, and/or X-ray energy could be decreased. [11, 159,160,161]
Comparing micro-CT results of different studies is not easy if the used parameters are not identical. There is a need to establish a protocol with determined values for parameters. [13]
Issues with very dense/thick samples resulting in a dataset of almost only black images. This is because there will be no contrast since no X-ray can pass; however, use of a filter may resolve the problem, but it may greatly increase the acquisition time. The sample can be cut to its smaller representative volume. If it is not possible, then another instrument could be used such as a scanning electron microscope.  
Issues with very thin/light samples or a hydrogel, then no contrast will be obtained (this gives a dataset of images with very low contrast). Contrast agents can be used. [29,30,31,32]
A limited volume of sample that can be analyzed at once (the images have a certain number of pixels with a certain size of a pixel). Display matrix size and/or pixel size can be adapted. The representative portion of the sample can be pre-determined.  
Overlaps in gray-scale values in multi-material samples (i.e., scaffold-bone explants or composites). Advanced segmentation protocol can be used. [171]
Considerations on the maintenance and sharing of micro-CT data. During the preliminary study, the duration of the micro-CT characterization and the disc space requirements can be estimated. [13]