| 1. |
- Larsson, Jim, et al.
(författare)
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A 3-D printed phantom for optical techniques in medicine
- 2017
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Ingår i: CLEO: Applications and Technology, CLEO_AT 2017. - 9781943580279 ; Part F43-CLEO_AT 2017
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Konferensbidrag (refereegranskat)abstract
- Development of optical techniques in medical applications can be difficult due to limited access to realistic phantoms. Here a 3-D printed model based on CT-images of the thorax of an infant is developed and tested.
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| 2. |
- Larsson, Jim, et al.
(författare)
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Comparison of dermal vs internal light administration in human lungs using the TDLAS-GASMAS technique—Phantom studies
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen and water vapor content, in the lungs of a 3D-printed phantom model based on CT-images of a preterm infant, is evaluated using Tunable Diode Laser Absorption Spectroscopy (TDLAS) in Gas in Scattering Media Absorption Spectroscopy (GASMAS), that is, the TDLAS-GASMAS technique. Oxygen gas is detected through an absorption line near 764 nm and water vapor through an absorption line near 820 nm. A model with a lung containing interior structure is compared to a model with a hollow lung. Compared to the model with the hollow lung, both the mean absorption path length and the transmitted intensity are found to be lower for the model with the structured lung. A new approach, where laser light is delivered internally into the model through an optical fiber, is compared to dermal light administration, that is, illumination onto the skin, for the model with structure inside the lung. The internal light administration generally resulted in larger gas absorption, and higher signal-to-noise ratios, compared to the dermal light administration. The results from the phantom measurements show great promise for the internal illumination approach and a natural next step would be to investigate it further in clinical studies.
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| 3. |
- Larsson, Jim, et al.
(författare)
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Development of a 3-dimensional tissue lung phantom of a preterm infant for optical measurements of oxygen—Laser-detector position considerations
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- There is a need to further improve the clinical care of our most vulnerable patients—preterm infants. Novel diagnostic and treatment tools facilitate such advances. Here, we evaluate a potential percutaneous optical monitoring tool to assess the oxygen and water vapor content in the lungs of preterm babies. The aim is to prepare for further clinical studies by gaining a detailed understanding of how the measured light intensity and gas absorption signal behave for different possible geometries of light delivery and receiver. Such an experimental evaluation is conducted for the first time utilizing a specially developed 3-dimensional-printed optical phantom based on a geometry model obtained from computer tomography images of the thorax (chest) of a 1700-g premature infant. The measurements yield reliable signals for source–detector distances up to about 50 mm, with stronger gas absorption signals at long separations and positions related to the lower part of the lung, consistent with a larger relative volume of this. The limitations of this study include the omission of scattering tissue within the lungs and that similar optical properties are used for the wavelengths employed for the 2 gases, yielding no indication on the optimal wavelength pair to use.
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| 4. |
- Liao, Peilang, et al.
(författare)
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Computer simulation analysis of source-detector position for percutaneously measured O2-gas signal in a three-dimensional preterm infant lung
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Further improvements in the clinical care of our most vulnerable patients-preterm infants-are needed. Novel diagnostic and surveillance tools facilitate such advances. The GASMAS technique has shown potential to become a tool to, noninvasively, monitor gas in the lungs of preterm infants, by placing a laser source and a detector on the chest wall skin. It is believed that this technology will become a valuable clinical diagnostic tool for monitoring the lung function of these patients. Today, the technology is, for this application, in an early stage and further investigations are needed. In the present study, a three-dimensional computer model of the thorax of an infant is constructed, from a set of CT images. Light transport simulations are performed to provide information about the position dependence of the laser- and detector probe on the thorax of the infant. The result of the simulations, based on the study method and the specified model used in this work, indicates that measurement geometries in front and on the side of the lung are favorable in order to obtain a good gas absorption signal.
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| 5. |
- Lundin, Patrik, et al.
(författare)
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Noninvasive monitoring of gas in the lungs and intestines of newborn infants using diode lasers: feasibility study.
- 2013
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Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 18:12
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT. Preterm newborn infants have a high morbidity rate. The most frequently affected organs where free gas is involved are the lungs and intestines. In respiratory distress syndrome, both hyperexpanded and atelectatic (collapsed) areas occur, and in necrotizing enterocolitis, intramural gas may appear in the intestine. Today, these conditions are diagnosed with x-ray radiography. A bed-side, rapid, nonintrusive, and gas-specific technique for in vivo gas sensing would improve diagnosis. We report the use of noninvasive laser spectroscopy, for the first time, to assess gas content in the lungs and intestines of three full-term infants. Water vapor and oxygen were studied with two low-power diode lasers, illuminating the skin and detecting light a few centimeters away. Water vapor was easily detected in the intestines and was also observed in the lungs. The relatively thick chest walls of the infants prevented detection of the weaker oxygen signal in this study. However, results from a previous phantom study, together with scaling of the results presented here to the typical chest-wall thickness of preterm infants, suggest that oxygen also should be detectable in their lungs.
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| 6. |
- Svensson, Tomas, et al.
(författare)
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Disordered, strongly scattering porous materials as miniature multipass gas cells
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:14
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the interaction of light and gas in strongly scattering nano- and macroporous media. Manufacturing and structural characterization of ZrO2, Al2O3 and TiO2 ceramics with different pore sizes, measurements of optical properties using photon time-of-flight spectroscopy, and high-resolution laser spectroscopy of O 2 at 760 nm are reported. We show that extreme light scattering can be utilized to realize miniature spectroscopic gas cells. Path length enhancement factors up to 750 are reached (5.4 m path through gas for light transmitted through a 7 mm ZrO2 with 49% porosity and 115 nm pores). © 2011 American Physical Society.
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| 7. |
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| 8. |
- Xu, Can, et al.
(författare)
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Wall-collision line broadening of molecular oxygen within nanoporous materials
- 2011
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947 .- 1094-1622. ; 84:4
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Tidskriftsartikel (refereegranskat)abstract
- Wall-collision broadening of near-infrared absorption lines of molecular oxygen confined in nanoporous zirconia is studied by employing high-resolution diode-laser spectroscopy. The broadening is studied for pores of different sizes under a range of pressures, providing new insights on how wall collisions and intermolecular collisions influence the total spectroscopic line profile. The pressure series show that wall-collision broadening is relatively more prominent under reduced pressures, enabling sensitive means to probe pore sizes of porous materials. In addition, we show that the total wall-collision-broadened profile strongly deviates from a Voigt profile and that wall-collision broadening exhibits an additive-like behavior to the pressure and Doppler broadening.
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