Tissue-Mimicking Phantoms: From Imitating Human Tissue to Measurement Reliability: A Review of the Metrological Evaluation of Tissue-Mimicking Phantoms in Acoustic, Optical, and Photoacoustic Imaging

This review examines tissue-mimicking phantoms from a metrological perspective, emphasizing that their scientific value lies not in reproducing biological tissue itself, but in providing reliable, traceable, and uncertainty-characterized measurements for medical imaging systems. The paper reviews the current literature on acoustic, optical, and photoacoustic tissue-mimicking phantoms, discussing the physical properties required for different imaging modalities, fabrication methods, characterization techniques, measurement uncertainty, long-term stability, digital twin approaches, artificial intelligence, and population diversity. A conceptual metrological framework is proposed, highlighting that phantom development should extend beyond material fabrication to include characterization, uncertainty evaluation, traceability, inter-laboratory comparison, and reference value assignment. The review argues that the future of phantom research will increasingly depend on measurement reliability rather than on material realism alone. Keywords: tissue-mimicking phantom, metrology, ultrasound imaging, photoacoustic imaging, optical imaging, measurement uncertainty, traceability, digital twin, medical imaging.