Spatial frequency domain imaging (SFDI) is a low-cost imaging technique
that maps absorption and reduced scattering coefficients, offering
improved contrast for important tissue structures such as tumours.
Practical SFDI systems must cope with various imaging geometries
including imaging planar samplesex vivo, imaging
inside tubular lumenin vivoe.g. for endoscopy, and
measuring tumours or polyps of varying morphology. There is a need for
a design and simulation tool to accelerate design of new SFDI systems
and simulate realistic performance under these scenarios. We present
such a system implemented using open-source 3D design and ray-tracing
softwareBlenderthat simulates media with realistic
absorption and scattering in a wide range of geometries. By usingBlender’sCycles ray-tracing engine, our
system simulates effects such as varying lighting, refractive index
changes, non-normal incidence, specular reflections and shadows,
enabling realistic evaluation of new designs. We first demonstrate
quantitative agreement between Monte-Carlo simulated absorption and
reduced scattering coefficients with those simulated from our Blender
system, achieving16%discrepancy in absorption coefficient
and18%in reduced scattering coefficient.
However, we then show that using an empirically derived look-up table
the errors reduce to1%and0.7%respectively. Next, we simulate SFDI
mapping of absorption, scattering and shape for simulated tumour
spheroids, demonstrating enhanced contrast. Finally we demonstrate
SFDI mapping inside a tubular lumen, which highlighted a important
design insight: custom look-up tables must be generated for different
longitudinal sections of the lumen. With this approach we achieved2%absorption error and2%scattering error. We anticipate our
simulation system will aid in the design of novel SFDI systems for key
biomedical applications.