Near-Infrared Spectroscopic Study Towards Clinical Radiotherapy Treatment Monitoring

Abstract

This study used near-infrared spectroscopy to monitor dynamic spectral effects to radiotherapy aiming to monitor spectral response for clinical radiotherapy. Twenty-four patients with total fractions of 96 measurements were measured to evaluate the dynamic spectral status of radiotherapy response. Dynamic responses from absorbance measurement were found to be associated with effects of induced radiation to skin and it linearly correlates to the dose given. Whereas significantly no response was found in ex vivo samples. A spectrometer was used in near infrared range between 650 nm and 1100 nm wavelength in absorbance mode. The absorbance spectral dynamics were measured using one light source-detector probe attached to the forehead in human patients and chicken samples to compare their responses to irradiation. The absorbance measurements of the forehead (skin) show absorbance increase throughout the spectra during irradiation in patients and confirmed with repeatability whereas in corresponding irradiation of ex vivo chicken samples, no absorbance changes were detected. Since spectral range of 650 nm–950 nm is dominantly affected by hemodynamical changes in tissue this indicates the oxygenation of blood in patients is strongly affected by irradiation. Furthermore, the irradiation caused absorbance changes also between 950 nm to 1100 nm range which is dominated by water in tissue, however in ex vivo chicken no visible effects of irradiation were detected in this range either.