Author: Christopher J. Mart, Inna V. McGowin 👨🔬
Affiliation: Medical University of South Carolina 🌍
Purpose: Electron treatments are prone to setup variations and uncertainties due to absence of imaging or surface guided alignment. Patient setup relies on daily marking and visual verification. A 3D-printed template to enable faster and more accurate patient positioning, to reduce targeting uncertainties and to avoid tattoos or permanent marking on the patient’s skin.
Methods: A surface contour created in the treatment planning system to represent patient’s skin around the target. This contour is expanded above the skin by 2-3mm and converted to 3D volumetric template to fit the skin like a glove. Multiple aids can be added to the template to show locations of target, CAX, shielding, or other points-of-interest. This custom template is 3D-printed with PLA and verified prior to clinical use. After the patient setup is established, the template is removed, and treatment can proceed per plan.
Results: Four templates were created, tested and used in our clinic so far. These four cases showed improvement in both setup speed and reproducibility, especially for a challenging case with three targets. Physician’s target markings on treatment day 1 were compared to the location identified by the template and all cases agreed within 1-3mm. Setup time was reduced due to the faster target delineation and field alignment using the template in place of markings on the patient’s skin. Furthermore, patient time on the table and physician time in the vault were reduced.
Conclusion: This novel 3D-printed patient specific template assists with more precise target location, improves alignment, reduces time on the machine and avoids any permanent markings on the skin. With physician approval, the template can be used daily for setup and target verification by therapists. The template needs appropriate topography features to ensure correct fit, thus may not be suitable for sites such as abdomen or extremities.