234 - Development and Comparative Evaluation of Low-Cost Gelatin-Agar and Silicone-Based Phantoms to Expand Access to Ultrasound-Guided Brachytherapy Training In Resource-Limited Settings

Purpose/Objective(s): Limited access to hands-on brachytherapy training remains a major barrier in low- and middle-income regions where commercial simulation phantoms are cost-prohibitive. We developed and compared three low-cost phantom models for ultrasound-guided interstitial brachytherapy and evaluated imaging feasibility, radiologic properties, and workshop implementation in a Latin American training program.

Materials/Methods: Three phantom versions were fabricated:

1. Prostate model: agar-based matrix (~12% gelatin, ~3% agar) with Shore 10A silicone prostate.
2. Cervical model (agar-based): agar subcutaneous tissue with Shore 10A silicone uterus.
3. Cervical model (silicone-rubber matrix): silicone-based tissues with variable densities.

Ultrasound feasibility was evaluated using biplanar transrectal probes (prostate) and convex transducers (gynecologic models).

Gynecologic phantoms underwent CT scanning for Hounsfield Unit (HU) comparison.

All models were implemented during a structured hands-on brachytherapy workshop. Post-course surveys assessed participant satisfaction and confidence.

Results: All phantom models permitted repeated needle insertion under real-time ultrasound guidance with clear visualization of target anatomy and acceptable needle artifact behavior. The prostate model allowed approximation of gland boundaries using biplanar transrectal ultrasound, while cervical models enabled identification of the endocervical canal and uterine contour during interstitial exercises.

CT analysis demonstrated comparable radiologic properties between agar and silicone gynecologic models (Table 1), with no clinically meaningful differences for training-based contouring or needle planning simulation.

Phantoms were successfully implemented in a structured hands-on workshop, where participants performed supervised insertion exercises. Post-course surveys demonstrated high satisfaction (>85% rated excellent) and significant improvement in self-reported procedural confidence.

Agar-based phantoms showed favorable tactile realism but structural degradation within approximately one month. Silicone-based matrices maintained integrity after repeated handling and multiple insertion sessions.

Conclusion: Low-cost gelatin–agar and silicone-based phantoms provide scalable training solutions for resource-constrained environments. While agar formulations are economical and effective for short-term workshops, silicone-rubber matrices offer improved longevity for sustainable brachytherapy training programs and may help reduce global disparities in procedural education.