Purpose: We propose a novel workflow that utilizes a couple of emerging and certainly innovative technologies of direction modulated brachytherapy (DMBT) tandem applicator along with rapid 3D printing for a patient-specific template augmented for a further improvement in dosimetric conformity and needle positioning accuracy.
Methods: The proposed workflow consists of three steps to produce an optimized needle configuration with a DMBT tandem. The first step is composed of pre-and each inter-fraction MR imaging to acquire high-risk CTV and delineate the vaginal space for creating the patient-specific template. The second step includes the two-step inverse optimization to (1) determine optimal needle numbers and needle paths and (2) perform volume optimization with DMBT tandem and needle paths. The final step includes rapid 3D printing and QA. This process is iterative and the 3D printed template may be re-optimized using the patient’s latest imaging.
Results: We present a highly adaptable workflow and utilized it for a retrospective patient case. A conformal plan with optimal needle tracks and DMBT tandem was created, and a 3D vaginal template with the tandem and needle tracks was printed. A dosimetric planning comparison is provided to illustrate the additional plan quality improvement achievable with the proposed novel two-step optimization and 3D printing workflow. Radiation Oncology departments with access to MRI and 3D printers can implement this process to reduce inter and intra-fractional needle placement uncertainties.
Conclusion: The proposed workflow attempts to optimally utilize the rich anatomic information present in the daily MRI by the power and the flexibility of needle positioning offered through 3D printed tracks in combination with the DMBT tandem that allows superior intensity modulation over conventional tandems. The combination of the two technologies, and powered by the daily MRI, offers a truly adaptive workflow that generates the most conformal plans for each fraction.
Funding Support, Disclosures, and Conflict of Interest: The senior author has Varian funding for the project.