Calibration of Spectral Imaging Devices With Oxygenation-Controlled Phantoms: Introducing a Simple Gel-Based Hemoglobin Model

Abstract

An optical phantom model with stable oxygen saturation (StO2) and optical properties (OPs) is the key for quick and accurate calibration of spectral imaging devices. Toward this goal, we have developed gel-based phantoms using Agarose, polystyrene microsphere, purified hemoglobin, and yeast. Theoretical values of OPs were calculated by applying Beer Lambert law and Mie theory whereas a robust fitting algorithm was used to extract StO2. Stability of OPs and StO2 in the phantoms was validated experimentally over a period of 2 weeks and the effect of pre-heating at 65 • C degrees on StO2 was observed. Multi-spectral imaging (750, 780, 850, and 945 nm) of the phantoms were also performed on the FDA-approved commercial system to demonstrate the utility of the phantoms.

Noninvasive hemoglobin sensing and imaging: optical tools for disease diagnosis

“…For example, several devices simulate the circulatory system and finger using pumps to mimic the pulsatile flow of arterial blood and venous blood. 12 , 151 – 155 The system is then sealed off, and the oxygenation of the blood can be controlled by varying the oxygen content of the system. Alternatives include electrical simulators that emit light from an LED corresponding to the light detected by the sensor to mimic the light transmitted in a typical finger.…”

Fabrication and characterization of multi-biomarker optimized tissue-mimicking phantoms for multi-modal optical spectroscopy

“…3,5,8 Such base materials also allow the control of the water fraction and can be cast in different shapes including thin sheets to mimic skin tissue. 12,13 These phantoms can be refrigerated to maintain their optical properties and minimize the evaporation of water, increasing their shelf-life. The mechanical properties of these phantoms can also be tuned as desired for some specific applications.…”

Spectral characterization of liquid hemoglobin phantoms with varying oxygenation states

“…Also gel phantoms are able to mimic living tissue regulating SO 2 with a yeast suspension. 7 If blood is observed with the naked eye, arterial blood appears as bright red and venous blood as dark red. This difference in color can be quantified noninvasively using diffuse reflectance spectroscopy.…”

“…Others have compiled original measured data of others into useful average spectral data sets. 7,11,[13][14][15][16][17][18] Most common tabulated data sets used for hemoglobin absorption values are those of Zijlstra et al 16 and Prahl. 17 These two tabulated data sets display subtle differences with relative deviations in shape up to 10%.…”