Exploring the Use of Raman Spectroscopy and Covariate-Adjusted Multivariate Analysis for the Detection of Irradiated Blood

Abstract

Biological dosimetry is a key technique for retrospective radiation dosimetry that provides individual estimates of absorbed dose of ionizing radiation, applicable for use in a large scale radiological/nuclear event. Current techniques for biodosimetry are labor intensive and time consuming and not high through-put. In this proof-of-concept study, we developed a new approach for detecting irradiated blood based on Raman spectroscopy of blood combined with multivariate analysis. Peripheral blood samples from 8 healthy male and female, anonymous donors, were exposed to either 5 Gy X ray radiation or unirradiated (0 Gy). At 3 h postirradiation, the blood was immediately frozen at –80°C. Raman spectra were measured from thawed blood using a portable spectrometer system. Data were preprocessed and analyzed using principal component analysis (PCA) to observe trends in the data, and by using partial least squares-discriminant analysis (PLS-DA) to build a model to discriminate between Raman spectra of control (0 Gy) and irradiated (5 Gy) blood. We found strong evidence of inter-donor variability in the form of donor-wise clustering of PCA scores corresponding to the control Raman spectra, in addition to the poor separation of PLS-DA scores associated with Raman intensities of 0 Gy vs. 5 Gy spectra. However, after adjustment for donor covariates using a linear mixed-effects model, we obtained a better separation between control and irradiated blood using PLS-DA. Evaluation of the coefficients of the PLS-DA loading vectors indicated radiation-induced changes in proteins, lipids and hemoglobin to be major contributors for this discrimination. This pilot study demonstrates the potential of application of Raman spectroscopy to support biodosimetry of blood and blood components.

Application of Raman spectroscopy and multivariate analysis to detect ionizing radiation-induced changes in blood plasma

“…Raman spectroscopy has shown promising potential to identify the effects of ionizing radiation in blood and blood components 6,7 . In a recent pilot study involving blood from 8 healthy donors, our work demonstrated the application of RS and multivariate analysis for the separation between 0 and 5 Gy irradiated whole blood 5 . The effects of ionizing radiation were shown to correspond to changes in the Raman intensity contributions from hemoglobin, proteins, and lipids, with the hemoglobin signal dominating the Raman spectrum.…”

“…However, it is technically challenging, labour-intensive, and time-consuming 2 . To address these limitations, many other techniques for determining absorbed radiation dose are currently being explored such as genomic 2,3 and automated cytogenic 4 techniques, as well as Raman spectroscopy 5,6 .…”