KEYWORDS: Monte Carlo methods, Photons, Scattering, Sensors, Backscatter, Optical properties, Computer simulations, Data modeling, Signal detection, Reflection
We investigate the feasibility of using diode laser gas spectroscopy for sinusitis diagnostics. We simulate light propagation using the Monte Carlo concept, as implemented by the Advanced Systems Analysis Program (ASAPTM) software. Simulations and experimental data are compared for a model based on two scattering bodies representing human tissue, with an air gap in-between representing the sinus cavity. Simulations are also performed to investigate the detection geometries used in the experiments, as well as the influence of the optical properties of the scattering bodies. Finally, we explore the possibility of performing imaging measurements of the sinuses. Results suggest that a diagnostic technique complementary to already existing ones could be developed.
We demonstrate a novel nonintrusive technique based on tunable diode laser absorption spectroscopy to investigate human sinuses in vivo. The technique relies on the fact that free gases have spectral imprints that are about 10.000 times sharper than spectral structures of the surrounding tissue. Two gases are detected; molecular oxygen at 760 nm and water vapor at 935 nm. Light is launched fiber optically into the tissue in close proximity to the particular maxillary sinus under study. When investigating the frontal sinuses, the fiber is positioned onto the caudal part of the frontal bone. Multiply scattered light in both cases is detected externally by a handheld probe. Molecular oxygen is detected in the maxillary sinuses on 11 volunteers, of which one had constantly recurring sinus problems. Significant oxygen absorption imprint differences can be observed between different volunteers and also left-right asymmetries. Water vapor can also be detected, and by normalizing the oxygen signal on the water vapor signal, the sinus oxygen concentration can be assessed. Gas exchange between the sinuses and the nasal cavity is also successfully demonstrated by flushing nitrogen through the nostril. Advantages over current ventilation assessment methods using ionizing radiation are pointed out.
We demonstrate a novel non-intrusive technique based on tunable diode laser absorption spectroscopy to investigate
human maxillary sinuses in vivo. The technique relies on the fact that free gases have much sharper
absorption features (typical a few GHz) than the surrounding tissue. Molecular oxygen was detected at 760 nm.
Volunteers have been investigated by injecting near-infrared light fibre-optically in contact with the palate inside
the mouth. The multiply scattered light was detected externally by a handheld probe on and around the cheek
bone. A significant signal difference in oxygen imprint was observed when comparing volunteers with widely
different anamnesis regarding maxillary sinus status. Control measurements through the hand and through the
cheek below the cheekbone were also performed to investigate any possible oxygen offset in the setup. These
provided a consistently non-detectable signal level. The passages between the nasal cavity and the maxillary
sinuses were also non-intrusively optically studied, to the best of our knowledge for the first time. These measurements
provide information on the channel conductivity which may prove useful in facial sinus diagnostics.
The results suggest that a clinical trial together with an ear-nose-throat (ENT) clinic should be carried out to
investigate the clinical use of the new technique.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.