Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds.

Here we describe methods for creating tissue-mimicking ultrasound phantoms based on patient anatomy using a soft material called gel wax. To recreate acoustically realistic tissue properties, two additives to gel wax were considered: paraffin wax to increase acoustic attenuation, and solid glass spheres to increase backscattering. The frequency dependence of ultrasound attenuation was well described with a power law over the measured range of 3-10 MHz. With the addition of paraffin wax in concentrations of 0 to 8 w/w%, attenuation varied from 0.72 to 2.91 dB cm-1 at 3 MHz and from 6.84 to 26.63 dB cm-1 at 10 MHz. With solid glass sphere concentrations in the range of 0.025-0.9 w/w%, acoustic backscattering consistent with a wide range of ultrasonic appearances was achieved. Native gel wax maintained its integrity during compressive deformations up to 60%; its Young's modulus was 17.4 ± 1.4 kPa. The gel wax with additives was shaped by melting and pouring it into 3D printed moulds. Three different phantoms were constructed: a nerve and vessel phantom for peripheral nerve blocks, a heart atrium phantom, and a placental phantom for minimally-invasive fetal interventions. In the first, nerves and vessels were represented as hyperechoic and hypoechoic tubular structures, respectively, in a homogeneous background. The second phantom comprised atria derived from an MRI scan of a patient with an intervening septum and adjoining vena cavae. The third comprised the chorionic surface of a placenta with superficial fetal vessels derived from an image of a post-partum human placenta. Gel wax is a material with widely tuneable ultrasound properties and mechanical characteristics that are well suited for creating patient-specific ultrasound phantoms in several clinical disciplines.

Driving Innovation in Low Resource Settings.

As of 2015, it was estimated that 400 million people lacked access to essential health services The Universal Health Coverage (UHC). Initiative aims to address this issue by delivering quality health service to people around the world whilst minimizing costs. Access to affordable medical technology is a cornerstone to this initiative. Consequently, the World Health Organisation (WHO) has developed the 'Compendium of Innovative Technologies for Low-Resource Settings' in order to highlight 127 innovations that could help to address these health issues. In low resource settings, the lack of reliable infrastructure can limit the success of medical devices, but it is clear that technology developed specifically for these settings, could have a more sustained impact. The 'Feasibility Tool' was designed by the WHOR to quantitatively analyse whether a medical device could be successfully implemented in a particular setting. The WHO has taken steps towards establishing criteria to encourage medical device innovation for appropriate and affordable technologies and local production of basic products, when feasible, in low resource settings. It is evident that encouraging this paradigms shift in our perception of medical technology development and manufacture will benefit healthcare systems around the world.