  Ultrasound tomography generally struggles to reconstruct high-contrast and/or
extended-range problems. A prime example is site-specific in-vivo bone imaging,
crucial for accurately assessing the risk of life-threatening fractures, which
are preventable given accurate diagnosis and treatment. In this type of
problem, two main obstacles arise: (a) an external region prohibits access to
the region of interest (ROI), and (b) high contrast exists between the two
regions. These challenges impede existing algorithms -- including bent-ray
tomography (BRT), known for its robustness, speed, and reasonable short-range
resolution. We propose Virtual Extended-Range Tomography (VERT), which tackles
these challenges through (a) placement of virtual transducers directly on the
ROI, facilitating (b) rapid initialisation before BRT inversion. In-silico
validation against BRT with and without a-priori information shows superior
resolution and robustness -- while maintaining or even improving speed. These
improvements are drastic where the external region is much larger than the ROI.
Additional validation against the practically impossible -- BRT directly on the
ROI -- demonstrates that VERT is approaching the resolution limit. The
capability to solve high-contrast extended-range tomography problems without
prior knowledge about the ROI's interior has many implications. VERT has the
potential to unlock site-specific in-vivo bone imaging for assessing fracture
risk, potentially saving millions of lives globally. In other applications,
VERT may replace classical BRT to yield improvements in resolution, robustness
and speed -- especially where the ROI does not cover the entire imaging array.
For even higher resolution, VERT offers a reliable starting background to
complement algorithms with less robustness and high computational costs.
