Optical measurements on tissue at visible and near infrared (NIR) wavelengths are inherently non-invasive, with a potentially high information content. Then, photon propagation through diffusing media like tissues has been investigated in depth for biomedical applications. As optical technologies are being developed towards clinical applications, the assessment of the reliability of the recovered information is an essential issue. Various protocols for the performance standardization assessment of optical instruments have been proposed. For the implementation of standardized procedures, however, the definition of reliable tissue-like phantoms is needed. A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at NIR wavelengths. Nine worldwide spread research laboratories adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common circulating samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values for the intrinsic reduced scattering coefficient of Intralipid and the intrinsic absorption coefficient of India ink were determined with an uncertainty of about 1% for Intralipid and 2% for ink, at three NIR wavelengths. Availability, low cost, long-term stability of these compounds and the batch-to-batch reproducibility of Intralipid make them the preferable choice to prepare diffusive liquid phantoms with accurately known optical properties. This provides a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment.
Optical properties of tissue-like phantoms based on Intralipid and India ink accurately assessed by means of a multi-center study
L Spinelli;A Farina;A Pifferi;R Cubeddu;
2013
Abstract
Optical measurements on tissue at visible and near infrared (NIR) wavelengths are inherently non-invasive, with a potentially high information content. Then, photon propagation through diffusing media like tissues has been investigated in depth for biomedical applications. As optical technologies are being developed towards clinical applications, the assessment of the reliability of the recovered information is an essential issue. Various protocols for the performance standardization assessment of optical instruments have been proposed. For the implementation of standardized procedures, however, the definition of reliable tissue-like phantoms is needed. A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at NIR wavelengths. Nine worldwide spread research laboratories adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common circulating samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values for the intrinsic reduced scattering coefficient of Intralipid and the intrinsic absorption coefficient of India ink were determined with an uncertainty of about 1% for Intralipid and 2% for ink, at three NIR wavelengths. Availability, low cost, long-term stability of these compounds and the batch-to-batch reproducibility of Intralipid make them the preferable choice to prepare diffusive liquid phantoms with accurately known optical properties. This provides a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
