# Low-Cost and Easily Fabricated Ultrasound-Guided Breast Phantom for Breast Biopsy Training
###### Abstract
developed a gelatin-agar-based breast phantom that could closely mimic the acoustic properties and density of real breast tissues [25]. The same authors later suggested dispersing safflower oil in solid aqueous gelatin to allow elastography in a gelatin-agar-based breast phantom [26]. The method combined oil, gelatin and agar to fabricate the glandular tissue, fat tissue, skin and [PERSON]'s ligaments. The difference in [PERSON]'s modulus between normal and abnormal breast tissues was mimicked by adjusting the proportions of the oil and gelatin. [PERSON] et al. proposed another gelatin-agar-based phantom that could reproduce the acoustic and elastic properties of fat tissue, glandular tissue, fibrous tissue and carcinoma [27]. We also found a type of tissue-mimicking material for ultrasound-guided breast biopsy training that used paraffin-gel wax. [PERSON] et al. developed a paraffin-gel wax-based phantom embedded with cyst and tumor models [28]. Another group of studies developed polyvinyl chloride (PVC)-based phantoms. A two-layered breast phantom (breast fat and mixed fatty-fibroglandular tissue) was developed using customizable PVC plastisol formulations that could mimic the acoustic and optical properties of different breast tissues [29]. Besides, a multi-layered breast phantom [30] was built using a custom PVC plastisol formulation to simulate fat, fibroglandular tissue and blood vessels with tissue realistic acoustic and optical properties. The phantom also included embedded tumors that were modeled as clusters of small blood vessels and skin that was mimicked using a silicon layer. Finally, PVC-based material was used to mimic the glandular breast tissue and the 3D printing technique was used to construct a custom-designed breast phantom mold and the embedded inserts (microcalcifications, fiber lesions and tumors with different sizes) [31]. A silicone-based breast phantom was constructed with components emulating a breast parenchyma/chest wall (silicone rubber mixed with agricultural grade silicone oil), epidermis (mesh fabric layer applied with silicone rubber), areola/nipple (epidermis mixture and a silicone baby bottle nipple as the mold) and a tumor (marble) [32]. Commercial products of breast phantom for practicing ultrasound needle biopsy are professionally made and can contain different types of lesions [33; 34; 35]. However, they are mainly developed for ultrasound imaging and may not provide realistic haptic feedback. None of these products contains a fat tissue layer to simulate the multi-layer structure of the human breast. More importantly, the commercial phantom products are unaffordable (more than USD 150 per set) for most hospitals as a training tool and are not available in all countries. A comprehensive analysis of the aforementioned tissue-mimicking phantoms is provided in Table 1. Turkey and chicken breast phantoms are cheap (about USD 15) and can be obtained easily [14; 15]. While acquiring turkey/chicken breasts is simple, extra steps, such as cleaning and thawing, can be troublesome and not user friendly. Gelatin-based phantoms are also easy to prepare and cheap (less than USD 20) [12; 16; 17; 18; 19; 20; 21; 22; 23; 24]. This type of phantoms is currently not well studied in terms of its tunability of acoustic and mechanical properties and a way to make it a multilayer structure. Gelatin-agar- [25; 26; 27], paraffin-gel wax- [28], PVC- [29; 30; 31] and silicone rubber-based [32] phantoms are considered as more advanced types of phantoms that can closely resemble acoustic and mechanical properties of human tissues. These phantoms are adjustable in terms of acoustic and mechanical properties and capable of being made in a multilayer structure. The gelatin-agar based phantoms were also shown to mimic various types of lesions [25; 26; 27].