4 Notes
1. The CT device should have the option of using lower acceleration voltage than conventional ones (about 70 vs 120 kV), in
order to obtain a higher predominance of the photoelectric
effect and a higher dependence on the atomic number.
2. It is recommended the maximum width of the coil possible and
the maximum number of turns according to the dimensions of
the dewar, in order to ensure a better heat exchange between
the liquid nitrogen and the nitrogen gas.
3. The dimensions of the polystyrene tube must be the maximum
allowed to fit inside the CT bed; in our case the outer diameter
must be lower than 60 mm. The total length of the polystyrene
tube is the length needed from the copper coil to the cryochamber described below, in our case, about 700 mm. It is also
necessary the use of connectors for the joining of different
tubes (e.g., the cooper coil and the polystyrene tube, which
have a different diameter).
4. It is recommended to test containers of different materials in
order to find out the interaction in the images. We selected the
following materials after our tests: polypropylene (PP), polyethylene (PE), and polystyrene (PS).
5. We used these following materials depending on the sample to
analyze: 2 mL cryovials (for ovarian tissues), 200 μL microplates (for solutions of different CPA concentrations), and
20 and 50 mL vials (for bigger samples, e.g., rabbit kidneys).
6. In order to get a centered image and the same position for all
the samples to image, it is recommended to use a holder for the
sample. Remember the holder must be made of an X-ray
transparent material (e.g., polystyrene) and must fit inside the
cryochamber (see Fig. 2).
7. According to our NanoCT device, the maximum length to get
a single rotation of the CT gantry is 37 mm (z-axis); so
depending on the sample, you will need more than one
rotation.
8. With these parameters and considering a selected area to image
shorter than 37 mm (z-axis), the total time acquisition is 3 min.
This time is relevant when imaging cryopreserved samples,
since the temperature must be kept below the glass transition
temperature for the entire duration of the measurement. Nevertheless, other parameters could be used according to the
desired spatial resolution.
9. Our NanoCT device achieves a spatial resolution up to 50 μm,
although the higher the spatial resolution, the greater the
noise. It is important to keep in mind the signal-to-noise
ratio (SNR), which is relevant in imaging techniques.
328
Ariadna Corral et al.
1. The CT device should have the option of using lower acceleration voltage than conventional ones (about 70 vs 120 kV), in
order to obtain a higher predominance of the photoelectric
effect and a higher dependence on the atomic number.
2. It is recommended the maximum width of the coil possible and
the maximum number of turns according to the dimensions of
the dewar, in order to ensure a better heat exchange between
the liquid nitrogen and the nitrogen gas.
3. The dimensions of the polystyrene tube must be the maximum
allowed to fit inside the CT bed; in our case the outer diameter
must be lower than 60 mm. The total length of the polystyrene
tube is the length needed from the copper coil to the cryochamber described below, in our case, about 700 mm. It is also
necessary the use of connectors for the joining of different
tubes (e.g., the cooper coil and the polystyrene tube, which
have a different diameter).
4. It is recommended to test containers of different materials in
order to find out the interaction in the images. We selected the
following materials after our tests: polypropylene (PP), polyethylene (PE), and polystyrene (PS).
5. We used these following materials depending on the sample to
analyze: 2 mL cryovials (for ovarian tissues), 200 μL microplates (for solutions of different CPA concentrations), and
20 and 50 mL vials (for bigger samples, e.g., rabbit kidneys).
6. In order to get a centered image and the same position for all
the samples to image, it is recommended to use a holder for the
sample. Remember the holder must be made of an X-ray
transparent material (e.g., polystyrene) and must fit inside the
cryochamber (see Fig. 2).
7. According to our NanoCT device, the maximum length to get
a single rotation of the CT gantry is 37 mm (z-axis); so
depending on the sample, you will need more than one
rotation.
8. With these parameters and considering a selected area to image
shorter than 37 mm (z-axis), the total time acquisition is 3 min.
This time is relevant when imaging cryopreserved samples,
since the temperature must be kept below the glass transition
temperature for the entire duration of the measurement. Nevertheless, other parameters could be used according to the
desired spatial resolution.
9. Our NanoCT device achieves a spatial resolution up to 50 μm,
although the higher the spatial resolution, the greater the
noise. It is important to keep in mind the signal-to-noise
ratio (SNR), which is relevant in imaging techniques.
328
Ariadna Corral et al.