Figure 3.

(a) Schematic of the sample preparation and the experimental workflow for the example of the PTA stained sample. (i) Surgery: removing human pancreatic cancer tissue. (ii) Sectioning: a tissue piece of a few millimetre size was sectioned from the removed tissue. (iii) Fixation and staining: tissue piece was fixated and stained in a phosphotungstic acid (PTA) staining solution. (iv) Paraffin embedding: a tissue piece was embedded in paraffin. (v) Inhouse µ-CT: tomograms of the tissue sample within the paraffin block were acquired at our laboratory phase-contrast µ-CT instrument with an effective pixel size of 5.3 µm. (vi) 2D histology: tissue slides of 2.5 µm thickness were cut from the top, stained by H&E (hematoxylin and eosin), and imaged with a microscope. (vii) Punch biopsy: 1 mm punch biopsy was taken from the sample by using a needle of 1 mm diameter, inserted into a polyimide tube of 1 mm diameter and mounted on a brass pin. (viii) Synchrotron CT: tomograms of the punch biopsy were taken at the synchrotron endstation GINIX. (ix) 2D histology of punch biopsy: after the tomographic scans, histology slides were taken from the punch biopsy for validation purposes. (b) 3D volume rendering of Sample B (PTA stained), Dashed lines mark the reconstructed slice shown in (c). (c) Virtual slice of the reconstructed 3D volume of an X-ray tomogram acquired at the laboratory setup. The red circle indicates the position of the punch biopsy. (d) Image of the histological slide of the sample, stained with H&E, corresponding to the virtual slice in (c). The red circle indicates the position of the punch biopsy. Scale bars: (b), (c) and (d) 600 µm.