SU-F-J-53: A 3D Printed Phantom for the Use of Daily Quality Assurance Alignment Tests




To discuss experiences and results for a 3D printed QA phantom used for daily alignment purposes for a six degrees-of-freedom (6DoF) table


A 3D model was created using a fused deposition modeling (FDM) printer using free online computer-aided design (CAD) software. The model has been under use for daily QA alignment tests for a 6DoF couch. An aligned and angled baseplate were also printed in order to introduce known angles for 6DoF corrections during image-guidance. Unique registration contours were created on the faces of the phantom in order to achieve a better cone-beam computed tomography (CBCT) match using an auto-registration algorithm. A BB was also introduced at the center of the phantom in order to deliver an integrated daily Winston-Lutz (WL) test. Translational, rotational, and WL results were tabulated over one month.


The ’honeycomb’ structure of the print was apparent in the EPID images for the WL test, which affected the results of the analysis software. This was fixed by inserting a cube made of polyoxymethylene within the 3D phantom that encompass the BB. Auto-registration results for the three translational and three rotational from a known offset to the BB isocenter consistently fell within 1 mm and 0.2°, respectively. WL tests resulted in an average of 0.71 ± 0.14 mm.


3D printed models allow for accurate builds that can be customized to a variety of clinical needs. Results from translational, rotational, and WL show consistent results over a month's time. Given its relatively cheap and streamlined workflow, 3D printing could be implemented into any clinic looking to create customized phantoms.