Tissue Mimicking Phantoms for Biomedical Optics: A Systematic Review of Inverse Adding–Doubling Characterization and Clinical Relevance

Tissue mimicking phantoms are essential for calibration and clinical translation of biophotonic techniques. Although the inverse adding-doubling (IAD) method is widely regarded as a reference standard for determining absorption and reduced scattering coefficients, significant inter-laboratory variability persists due to differences in integrating-sphere configurations, loss-compensation strategies, and model assumptions. This PRISMA-guided review (2015-2025) analyzes 10 experimental studies and proposes a unified comparison framework based on scattering power-law parameters a , b (a,b) to relate phantom fabrication to clinically relevant optical targets. Nonlinear regression of continuous μ s ' λ μₛ^(λ ) spectra shows that selected PVC plastisol formulations reproduce dermal-like scattering slopes and that the power-law model provides consistent spectral descriptions ( R ¯ 2 = 0.98 R̄²=0.98 ). By linking measurement methodology, spectral fitting, and mapping in a , b (a,b) space, this work provides a practical framework to interpret variability and guide development of tissue-equivalent phantoms for reliable calibration of biophotonic devices.