Results can be considered in following steps:
Head CT data acquisition
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Regarding the phantom head positioning,
it should be noted that it is extremely important a good alignment and immobilization of phantom (figure 2).
A correct positioning leads to a CT image acquisition,
where a contour of anatomical structures,
providing a correct delineation of clinical volumes and organs of risk is easier for its delineation (Figure 2).
Head CT data post-processing
Using the head CT data,
and based on 3D Slicer® software,
it was possible to represent phantom´s head 3D views (Figure 4).
Performing the segmentation with a threshold of soft tissues,
and manipulating the grey scale to achieve a correct visualization and definition is very important to guaranty the correct adaptation of the object to be printed to the phantom morphology and “skin” surface.
The grayscale was manipulated to obtain a better view of the soft tissues,
allowing a correct delineation [8],
for which the threshold is one of the key points to the production process of a bio-model (Figure 4).
DICOM data format conversion to 3D printing compatible format (STL)
3D Slicer® software for DICOM file conversion to .stl format proved to be an effective tool for final object printing,
as far as the printed bio-models require conversion of DICOM images in virtual 3D surface models that are stored as .stl files [9].
At this phase,
a volume of information restricted to the area of interest to print was obtained with a reduced “ladder effect”,
ensuring higher precision and quality.
In Figure 5 it is represented the final 3D model.
3D printing of the developed object
Once the printing parameters were established the object was produced by AM.
The results are shown in in Figure 6 (phantom´s nose surface).
Head with AM nose mask: CT acquisition
For the analysis of the adjustment between the printed nose and the phantom surface,
a new CT was performed through the same protocol used in the first phase.
The acquired images showed the presence of air,
although minimal,
which reveals that it is necessary to improve the 3D Printing object parameters,
both in terms of geometry,
material and production (work ongoing),
being these preliminary results.
Current clinical practice in EBRT faces the same problem,
mainly in immobilization masks and bolus.