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

Abstract

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 nearinfrared region, simulating low tissue oxygenation values. These colors were used to create an optical phantom, which matched the designed StO 2 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.

Development and Validation of Robust and Cost-Effective Liquid Heterogeneous Phantom for Time Domain Near-Infrared Optical Tomography

“…We produced silicone windows with specified optical properties according to a previously developed recipe [8]. We used Elastosil Vario40 (Wacker, Germany) instead of Silpuran 2420 (Wacker, Germany), because the latter is too soft for this task.…”

“…They also enable complex internal structures. These phantoms can be built of gelatin or agar [4], resin [5][6][7], or silicone [8]. At the same time, the 2 temporal stability is the drawback when a specific dynamic is required.…”

Multimodal imaging combining time-domain near-infrared optical tomography and continuous-wave fluorescence molecular tomography

“…Both material A and B are based on the silicone matrix (Silpuran 2420, Wacker, Germany). We achieved different levels of absorption by applying various mixtures of added ink [36]. Material A contains carbon black powder for absorption and white pigment (RAL 9010, Wacker, Germany) for scattering, whereas material B includes additional ink (RAL 6004, Wacker, Germany) to enhance the absorption.…”