Multi-material 3D Printing in Brachytherapy– Prototyping Teaching Tools

Abstract

The utilization of brachytherapy for cervical cancer has been declining, resulting in worsening survival. To improve resident confidence in performing of intracavitary and interstitial HDR brachytherapy procedures, an educational multi-material modular 3D printed gynecologic pelvic phantom training kit simulating both normal and pathological conditions has been developed. The implementation of this phantom in resident education is intended to allow for a more thorough and comprehensive training in tandem and ovoid and needle insertions. CT and MR scans from 50 patients with locally advanced cervical cancer were analyzed. Dimensions of the uterine bodies and canals were measured from the T2 weighted MRI images. These measurements were used to construct four model uteri based off of averages and standard deviations. The vaginal canal was constructed based on standard gynecological speculum dimensions. Individual STL files were imported into Autodesk Meshmixer and manipulated to include features such as hollowed out cavities and canals to allow for applicator placement. Modular components of the phantom were designed and integrated into patient anatomy using CAD 3DShapr. Five HRCTVs were extracted from patient scans to be incorporated into the uterine body. Elasticity properties of tissues were used to calculate appropriate flexible and rigid shore values (0-100) to assign to each anatomical structure for multi-material printing. Average dimensions and SD from the 50-patient study are presented in Table 1 for the anatomical structures considered. The finalized prototype kit consists of three anteverted uteri based on the smallest, the average, and the largest dimensions from our patient set. The fourth uterus is retroverted and uses average dimensions. Clip-on HRCTV attachments expanding outside of the uterine body are included to mimic different pathology. Color staining with different shore values within the uterus was done to represent internal HRCTVs. All uterus bodies and the vaginal canal were printed using Agilus (shore 30A) in clear as a means of evaluation for tandem/ovoid and needle placement. The rectum and HRCTVs were printed using a blend of polymers that allow for variable stiffness (Vero and Agilus, shore 70A and 40A respectively). The bladder was printed using pure Agilus (shore 30A). A multi-material modular 3D printed pelvic phantom training kit simulating normal and cervix pathological conditions has been developed for practicing tandem and ovoid insertions. This tool may be used to help address a gap in decreased resident confidence in performing brachytherapy procedures.Tabled 1Abstract 2983; TableCanal Length [cm]Canal Width [cm]Body Length [cm]Body Width (top) [cm]Body Width (midpoint) [cm]Canal Angle [deg]U15.810.345.812.023.1519.1U26.230.427.872.744.4527.6U37.630.3439.933.455.7436.1U4*6.230.427.872.744.4527.6∗Retroverted Open table in a new tab