Characterization of the optical properties of color pastes for the design of optical phantoms mimicking biological tissue

• Published in: Journal of biophotonics Vol. 12; no. 4; pp. e201800300 - n/a
• Main Authors: Tomm, Natasha, Ahnen, Linda, Isler, Helene, Kleiser, Stefan, Karen, Tanja, Ostojic, Daniel, Wolf, Martin, Scholkmann, Felix
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH & Co. KGaA 01.04.2019; Wiley Subscription Services, Inc
• Subjects: Biological properties; Color; Dyes; Fabrication; Infrared spectroscopy; inverse adding‐doubling (IAD); Medical electronics; Mimicry; near‐infrared spectroscopy (NIRS); optical phantoms; Optical properties; Oximetry; Oxygenation; Pastes; Quality assessment; Quality control; Silicones; Spectrum analysis; Tissues; UV/VIS spectroscopy; Wavelengths; oximetry; near-infrared spectroscopy (NIRS); optical phantoms; UV/VIS spectroscopy; inverse adding-doubling (IAD)
• ISSN: 1864-063X; 1864-0648
• DOI: 10.1002/jbio.201800300

Clinicians need a way to rapidly and reliably test the correct functioning of near‐infrared spectroscopy (NIRS)–based oximeters. Therefore, optical phantoms for quality assessment of NIRS oximeters are needed. The fabrication of such phantoms that mimic the optical properties of biological tissue in the NIR range represents a challenge. To enable their development, the aim was to characterize the absorption and scattering spectra of different dyes. The optical properties of silicone SILPURAN 2420 with 11 color pastes of type ELASTOSIL were measured in the 500 to 1000 nm range by a spectrometer with an integrating sphere. In addition, two commercial frequency‐domain NIRS devices, the ISS OxiplexTS and the ISS Imagent, were used to assess the optical properties at specific wavelengths. The evaluated colors present mostly features in the visible range below 650 nm, but two colors include peaks in the near‐infrared region, simulating low tissue oxygenation values. These colors were used to create an optical phantom, which matched the designed StO2 value within an error of only 4%. This set of dyes already enables simulating many different spectra, thus achieving a first step on the way to a long‐term stable comparison and validation method. To validate the correct functioning of near‐infrared spectroscopy–based oximeters, optical phantoms are necessary. We developed a new approach to create optical phantoms with specific oxygenation values based on combining 11 color pastes for coloring the phantom. We managed to create a phantom that matched the designed oxygenation value within an error of only 4%.