(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose
To laser cut foam based on a scanned template, automate electron cutout fabrication and improve their accuracy.
Methods
A 3D printed frame was designed to hold the acrylic plate on which the desired electron field was drawn by the physician. The frame has four corner markers, one 5 cm scale and a pair of orientation notches. The corner markers were used as deformation references to correct the cutout shape to the normal projection direction. The image was scaled based on the template. The plates in the frame could be either scanned with a flatbed scanner, or photographed with a camera. Our software then imported the image, corrected the scale, perspective, and orientation using computer vision and converted it to CNC g-code for automatic fabrication by the laser cutter.
Results
The geometric accuracy was verified with predefined shape samples in different sizes of square cuts. The scale disagreement was determined to be around 0.25 and 0.5 mm in x- and y-directions. This asymmetric error came from the rectangular laser lens design. The average material cutting loss was around 0.5 mm which was taken into account when generating the cutting path in g-code. The cutting path was also modified to allow for heat dissipation. The fabricated foam block was then set on the acrylic plate with the alignment frame replaced by the cutout tray, and the Cerrobend poured.
Conclusion
Our automated electron cutout fabrication can improve the clinical workflow and provides submillimeter accuracy. Anyone can easily place the acrylic plate on the scanner and start the process. The laser cutter can be installed and operate alone under the fume hood or with any air filtration system without a user present. The automatically digitized block shape will allow for uploading to systems for output calculations and verification of the electron cone size.
Keywords
Electron Therapy, Quality Assurance, Computer Vision
Taxonomy
TH- External Beam- Electrons: General (most aspects)
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