In vivo absorption spectroscopy of tumor sensitizers with femtosecond white light

Klinteberg, Claes af; Pifferi, Antonio; Andersson‐Engels, Stefan; Cubeddu, Rinaldo; Svanberg, Sune

doi:10.1364/ao.44.002213

Cited by 25 publications

(12 citation statements)

References 31 publications

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“…Consulting the literature, it can be found that this assumption is not fully warranted. 17,19,20 In particular, the absorption coefficient depends on the degree of blood oxygenation and amount of liquid water, and would tend to increase the absorption at 935 nm, as compared to 760 nm. The scattering coefficient could be expected to be the same within about 10%.…”

Section: Discussionmentioning

confidence: 99%

“…It can be assumed that the scattering properties are approximately the same for the two different wavelengths used. 19,20 However, the absorption coefficient may be different mostly depending on the degree of oxygenation of the blood and liquid water absorption. 17,19 If the same volume has been sampled for the two wavelengths, the ratio between the L eq values for oxygen and water vapor could provide information on the oxygen concentration inside the sinuses, since the water vapor concentration is always the maximum possible concentration at the given temperature ͑thermostated to about 37°C and 100% humidity in the cavities͒.…”

Section: Maxillary Sinus Studymentioning

confidence: 99%

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Gas monitoring in human sinuses using tunable diode laser spectroscopy

et al. 2007

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Gas monitoring in human sinuses using tunable diode laser spectroscopyPersson, Linda; Andersson, Mats; Lewander, Märta; Svanberg, Katarina; Svanberg, Sune General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract. 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. Gas monitoring in human sinuses

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Section: Discussionmentioning

confidence: 99%

Section: Maxillary Sinus Studymentioning

confidence: 99%

Gas monitoring in human sinuses using tunable diode laser spectroscopy

et al. 2007

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“…In order to further elucidate the interplay between scattering and absorption, time-resolved measurements of the photon history in the wood for the two wavelengths would provide independent information on the scattering of the material and the liquid water contents. Such measurements can be performed using white light [6,9], capturing the full spectrum, or employing a number of pulsed diode lasers selected at appropriate wavelengths [24]. …”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…A recent example on the determination of tumor sensitizer concentration in vivo is given in Ref. [9].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic studies of wood-drying processes

Andersson¹,

Persson²,

Sjöholm³

et al. 2006

Opt. Express

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By the use of wavelength-modulation diode laser spectroscopy, water vapor and oxygen are detected in scattering media nonintrusively, at 980 nm and 760 nm, respectively. The technique demonstrated is based on the fact that free gases have extremely sharp absorption structures in comparison with the broad features of bulk material. Water vapor and oxygen measurements have been performed during the drying process of wood.The results suggest that the demonstrated technique can give information about the drying process of wood to complement that of commercially available moisture meters. In particular, the time when all the free water has evaporated from the wood can be readily identified by a strong falloff in the water vapor signal accompanied by the reaching of a high-level plateau in the molecular oxygen signal. Furthermore, the same point is identified in the differential optical absorption signal for liquid water, with a sharp increase by an order of magnitude in the ratio of the signal intensities at 980 nm and 760 nm.

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“…Theory shows, that the absorption and scattering coefficients of the sample can be determined separately in such experiments. Following early demonstrations of spectroscopy of this kind [10,11], we reported on concentration measurements of tumour sensitizers in living tissue [12].…”

Section: Broad-band Spectroscopy In Scattering Mediamentioning

confidence: 99%

<title>Gas in scattering media absorption spectroscopy - GASMAS</title>

Svanberg

2008

SPIE Proceedings

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An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. GASMAS combines narrow-band diode-laser spectroscopy with diffuse media optical propagation. While solids and liquids have broad absorption features, free gas in pores and cavities in the material is characterized by sharp spectral signatures, typically 10,000 times sharper than those of the host material. Many applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, allowing propagation. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities have been studied. Transport of gas in porous media can readily be studied by first immersing the material in, e.g., pure nitrogen, and then observing the rate at which normal air, containing oxygen, reinvades the material. The conductance of the sinus connective passages can be measured in this way by flushing the nasal cavity with nitrogen. Also other dynamic processes such as drying of materials can be studied. The techniques have also been extended to remote-sensing applications (LIDAR-GASMAS).

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In vivo absorption spectroscopy of tumor sensitizers with femtosecond white light

Cited by 25 publications

References 31 publications

Gas monitoring in human sinuses using tunable diode laser spectroscopy

Gas monitoring in human sinuses using tunable diode laser spectroscopy

Spectroscopic studies of wood-drying processes

<title>Gas in scattering media absorption spectroscopy - GASMAS</title>

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