Cerebral tissue oxygenation response to brain irradiation measured during clinical radiotherapy

Abstract

. Significance Cancer therapy treatments produce extensive changes in the physiological and morphological properties of tissues, which are also individual dependent. Currently, a key challenge involves developing more tailored cancer therapy, and consequently, individual biological response measurement during therapy, such as tumor hypoxia, is of high interest. This is the first time human cerebral haemodynamics and cerebral tissue oxygenation index (TOI) changes were measured during the irradiation in clinical radiotherapy and functional near-infrared spectroscopy (fNIRS) technique was demonstrated as a feasible technique for clinical use in radiotherapy, based on 34 online patient measurements. Aim Our aim is to develop predictive biomarkers and noninvasive real-time methods to establish the effect of radiotherapy during treatment as well as to optimize radiotherapy dose planning for individual patients. In particular, fNIRS-based technique could offer an effective and clinically feasible online technique for continuous monitoring of brain tissue hypoxia and responses to chemo- and radiotherapy, which involves modulating tumor oxygenation to increase or decrease tumor hypoxia. We aim to show that fNIRS is feasible for repeatability measuring in patient radiotherapy, the temporal alterations of tissue oxygenation induced by radiation. Approach Fiber optics setup using multiwavelength fNIRS was built and combined with a medical linear accelerator to measure cerebral tissue oxygenation changes during the whole-brain radiotherapy treatment, where the radiation dose is given in whole brain area only preventing dosage to eyes. Correlation of temporal alterations in cerebral haemodynamics and TOI response to brain irradiation was quantified. Results Online fNIRS patient measurement of cerebral haemodynamics during clinical brain radiotherapy is feasible in clinical environment, and results based on 34 patient measurements show strong temporal alterations in cerebral haemodynamics and decrease in TOI during brain irradiation and confirmed the repeatability. Our proof-of-concept study shows evidently that irradiation causes characteristic immediate changes in brain tissue oxygenation. Conclusions In particular, TOI seems to be a sensitive parameter to observe the tissue effects of radiotherapy. Monitoring the real-time interactions between the subjected radiation dose and corresponding haemodynamic effects may provide important tool for the researchers and clinicians in the field of radiotherapy. Eventually, presented fNIRS technique could be used for improving dose planning and safety control for individual patients.

Carbon Ions for Hypoxic Tumors: Are We Making the Most of Them?

“…Secondly, painting techniques require non-invasive hypoxia imaging tools with high temporal and spatial resolutions. A wide range of techniques has been proposed for this purpose, ranging from more conventional PET- and MRI-based approaches to recently proposed alternatives such as Cherenkov-excited phosphorescence [ 135 ] and functional near-infrared spectroscopy [ 136 ]. However, the information obtained with any of these methods is still not considered reliable enough for treatment planning [ 90 , 137 , 138 ].…”

Tissue optical clearing for fNIRS studies in radiotherapy

“…In a potential step toward personalized brain radiotherapy, we are using functional near-infrared spectroscopy (fNIRS) to measure from patients in real-time tissue oxygenation changes caused by radiotherapy [1]. The measurement principle of fNIRS is based on wavelength-dependent absorption.…”