Author: David Chighvinadze, Lisa Czaplicki, Jeremy D. Donaghue, Lama K. Muhieddine Mossolly 👨🔬
Affiliation: Cleveland Clinic Sandusky, Cleveland Clinic Strongsville, Cleveland Clinic Fairview 🌍
Purpose:
Current electron block generation requires manual cutting of stryofoam and placement for pouring of the block which can lead to possible miscutting of blocks, and non-accurate rotations compared to the treatment plan. A process was developed that uses 3D printing to reproduce the block more accurately and then making sure that orientation is correct.
Methods:
The block coordinate data was removed from the DICOM RTplan using Pydicom. The coordinate points were then scaled appropriately for block location (0.95) and sent programmatically to OpenSCAD to generate a block aperture that was 3 cm thickness. This thickness was chosen so that a weight could be placed to hold the block in place. This block had both an orientation mark, and alignment holes that would align with a generated 3D printed base plate.
Results:
Initial testing was done with PLA. When a lower infill percentage was used (30%) the block crumpled. When infill was set to 100% (solid) the block still warped to an extent that made it impossible to remove the 3D printed block to determine how much of a difference there was. It was established that the warping was because the melting point of PLA was lower than Cerrobend. Once it was determined that PETG’s melting point was higher, a 100% infill was used. Initial testing started with square cutouts used for commissioning. All blocks were generated accurately. Subsequent patient specific blocks were also found to be accurate.
Conclusion:
Generating 3D printed blocks for electron block generation can be done, but it is important to use PETG due to its higher melting point, and 100% infill (solid) setting should also be used. Removal of the block from the cerrobend cutout can be a bit difficult, so a coating on the 3D printed block may help ease this.