Evaluation of Homemade Ballistic Gelatin Phantoms as a Low-Cost Alternative to Commercial-Grade Phantoms in Medical Education

Cost limitations of commercial-grade ultrasound phantoms often prevent ultrasound education from being incorporated into medical curricula (Bahner et al., Acad Med. 89:1681–6, 2014). While production of homemade agar gelatin phantoms to offset costs has been well documented, use of ballistic gelatin has only recently been described (Domenico et al., J Ultrasound. 11 (4):135-42, 2008; Zerth et al., J Emerg Med. 43:1066-9, 2012; Chao et al., J Emerg Med. 45:240-3, 2013; Shobeiri et al., J Ultrasound Med. 32:1393-6, 2013; Woywodt et al., Clin Nephrol. 79:241-5, 2013; Zeiler et al., Can J Neurol Sci. 40:225-9, 2013; Hunt et al., Eur J Radiol. 82:594-600, 2013; Lo et al., Emerg Med J. 29:738-41, 2012; Li et al., J Ultrasound Med. 30:263-72, 2011; Morrow and Broder, J Emerg Med. 49 (3):313-7, 2015). There exists a critical need for learner evaluation of homemade ballistic gelatin phantoms (BGPs) and their comparison to commercial-grade phantoms to better inform BGP introduction into medical education. The primary aim of this study is to describe survey-based evaluation of homemade BGPs and commercial-grade Blue PhantomsTM by medical students. The secondary aim is to compare image quality of BGPs and Blue PhantomsTM. Described are construction of BGPs and introduction in voluntary ultrasound training sessions offered to 61 first through fourth-year medical students. The evaluation and success of this model are reported. Students reported that versatility of homemade BGPs surpassed that of commercially available phantoms (4.52 ± 0.71) and that they felt more confident in their ultrasound skills after the session (4.82 ± 0.37). Side-by-side evaluation of images generated using BGPs and Blue PhantomsTM had comparable simulated vessel shape and echogenicity, adding objective assessment to subjective survey-based results. Training sessions were enabled by low-cost homemade BGPs at $4 vs $400+ cost of commercial-grade phantoms, a 100-fold reduction in cost. As students found BGPs and Blue PhantomsTM comparable, the results of this study can equip other institutions struggling with costs of incorporating ultrasound into their medical curricula with not only a cost-effective solution but also a learner-validated one.