| 1. |
- Andersson-Engels, Stefan, et al.
(författare)
-
Clinical fluorescence imaging
- 2008
-
Ingår i: Lasers in Medicine.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 2. |
- Andersson, Mats, et al.
(författare)
-
Laser spectroscopy of gas in scattering media at scales ranging from kilometers to millimeters
- 2007
-
Ingår i: Laser Physics. - 1054-660X. ; 17:7, s. 893-902
-
Tidskriftsartikel (refereegranskat)abstract
- Free gases are characterized by their narrow line width, and they can conveniently be studied by laser spectroscopy. The present paper discusses the monitoring of such ambient pressure gases, which are dispersed in scattering media such as aerosol-laden atmospheres, solids, or liquids. Atmospheric work basically constitutes the well-known field of differential absorption lidar (DIAL), while the study of free gas in solids and liquids was initiated more recently under the name of GASMAS (GAs in Scattering Media Absorption Spectroscopy). We discuss the connections between the two techniques, which are extensively used in our labortory. Thus, we span the field from trace-gas mapping of gases in the lower atmosphere to gas studies in construction materials, food products, and the human body. We show that the basic ideas are very similar, while the spatial and temporal scales vary greatly.
|
|
| 3. |
- Bendsoe, Niels, et al.
(författare)
-
Fluorescence monitoring of a topically applied liposomal temoporfin formulation and photodynamic therapy of nonpigmented skin malignancies.
- 2007
-
Ingår i: Journal of Environmental Pathology and Toxicology. - 2162-6537. ; 26:2, s. 117-126
-
Tidskriftsartikel (refereegranskat)abstract
- Meso-tetra(hydroxyphenyl)chlorin (mTHPC) (INN: Temoporfin) is a potent photodynamically active substance in clinical use today. Usually, the substance is given systemically and a known drawback with this administration route is a prolonged skin light sensitization. For the first time to our knowledge, a liposomal Temoporfin gel formulation for topical application was studied in connection with photodynamic therapy (PDT) of nonpigmented skin malignancies in humans. Intervals of 4 hr between drug administration and light irradiation were used. Sensitizer distribution within tumor and surrounding normal skin was investigated by means of point monitoring and imaging fluorescence spectroscopy before, during, and after PDT, showing high tumor selectivity. Furthermore, the bleaching of Temoporfin was studied during the PDT procedure by monitoring the fluorescence following excitation by using a therapeutic light. A 30−35% light-induced photometabolization was shown. No pain occurred during or after treatment. It was also observed that the treated area did not show any swollen tissue or reddening, as is often seen in PDT using topical δ-aminolevulinic acid. On controlling the patients one week after treatment, healing progress was observed in several patients and no complications were registered.
|
|
| 4. |
- Johansson, Ann, et al.
(författare)
-
In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors
- 2006
-
Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- A system for interstitial photodynamic therapy is used in the treatment of thick skin tumors. The system allows simultaneous measurements of light fluence rate, sensitizer fluorescence, and tissue oxygen saturation by using the same fibers as for therapeutic light delivery. Results from ten tumor treatments using delta-aminolevulinic acid (ALA)-induced protoporphyrin IX show a significant, treatment-induced increase in tissue absorption at the therapeutic wavelength, and rapid sensitizer photobleaching. The changes in oxy- and deoxyhemoglobin content are monitored by means of near-infrared spectroscopy, revealing a varying tissue oxygenation and significant changes in blood volume during treatment. These changes are consistent with the temporal profiles of the light fluence rate at the therapeutic wavelength actually measured. We therefore propose the observed absorption increase to be due to treatment-induced deoxygenation in combination with changes in blood concentration within the treated volume. A higher rate of initial photobleaching is found to correlate with a less pronounced increase in tissue absorption. Based on the measured signals, we propose how real-time treatment supervision and feedback can be implemented. Simultaneous study of the fluence rate, sensitizer fluorescence, and local tissue oxygen saturation level may contribute to the understanding of the threshold dose for photodynamic therapy. (c) 2006 Society of Photo-Optical Instrumentation Engineers.
|
|
| 5. |
- Johansson, Ann, et al.
(författare)
-
Influence of treatment-induced changes in tussue absorption on treatment volume during interstitial photodynamic therapy
- 2006
-
Ingår i: Medical Laser Application. - : Elsevier BV. - 1615-1615. ; 21, s. 261-261
-
Tidskriftsartikel (refereegranskat)abstract
- Interstitial photodynamic therapy on thick skin lesions has been shown to induce changes in tissue light transmission as a direct consequence of variations in total blood volume and oxygen saturation. A finite element method was used in order to simulate the fluence rate distribution and total light dose throughout the target tissue for two cases. The first case constitutes a pre-treatment model where the tissue optical properties are assumed constant during the entire treatment. The second situation takes into account observed changes in tissue light transmission, small deviations in fiber insertion depth and a few cases of almost complete loss of source fiber output power possibly as a result of blood accumulation in front of the fiber tip. The pre- and post-treatment models from six clinical treatments are compared in terms of simulated treatment volumes. We conclude that real-time monitoring of the delivered fluence is necessary in order to ascertain a pre-determined light dose to the target tissue. Finally, we speculate on how to also include the sensitizer fluorescence level and tissue oxygenation in the real-time treatment feedback.
|
|
| 6. |
- Johansson, Ann, et al.
(författare)
-
Interstitial photodynamic therapy for primary prostate cancer incorporating realtime treatment dosimetry
- 2007
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6427, s. 4270-4270
-
Konferensbidrag (refereegranskat)abstract
- Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue necrosis and decrease in prostate specific antigen (PSA). Research groups report on large variations in treatment response, possibly due to biological variations in tissue composition and shortterm response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue that incorporates realtime treatment feedback is being developed. The treatment protocol consists of two parts. The first part incorporates the pre-treatment plan with ultrasound investigations, providing the geometry for the prostate gland and surrounding risk organs, an iterative random-search algorithm to determine near-optimal fiber positions within the reconstructed geometry and a Block-Cimmino optimization algorithm for predicting individual fiber irradiation times. During the second part, the therapeutic light delivery is combined with measurements of the light transmission signals between the optical fibers, thus monitoring the tissue effective attenuation coefficient by means of spatially resolved spectroscopy. These data are then used as input for repeated runs of the Block-Cimmino optimization algorithm. Thus, the irradiation times for individual fibers are updated throughout the treatment in order to compensate for the influence of changes in tissue composition on the light distribution at the therapeutic wavelength.
|
|
| 7. |
- Johansson, Ann, et al.
(författare)
-
System for integrated interstitial photodynamic therapy and dosimetric monitoring
- 2005
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5689:1, s. 130-140
-
Konferensbidrag (refereegranskat)abstract
- Photodynamic therapy for the treatment of cancer relies on the presence of light, sensitizer and oxygen. By monitoring these three parameters during the treatment a better understanding and treatment control could possibly be achieved. Here we present data from in vivo treatments of solid skin tumors using an instrument for interstitial photodynamic therapy with integrated dosimetric monitoring. By using intra-tumoral ALA-administration and interstitial light delivery solid tumors are targeted. The same fibers are used for measuring the fluence rate at the treatment wavelength, the sensitizer fluorescence and the local blood oxygen saturation during the treatment. The data presented is based on 10 treatments in 8 patients with thick basal cell carcinomas. The fluence rate measurements at 635 nm indicate a major treatment induced absorption increase, leading to a limited light penetration at the treatment wavelength. This leads to a far from optimal treatment since the absorption increase prevents peripheral tumor regions from being fully treated. An interactive treatment has been implemented assisting the physician in delivering the correct light dose. The absorption increase can be compensated for by either prolonging the treatment time or increasing the output power of each individual treatment fiber. The other parameters of importance, i.e. the sensitizer fluorescence at 705 nm and the local blood oxygen saturation, are monitored in order to get an estimate of the amount of photobleaching and oxygen consumption. Based on the oxygen saturation signal, a fractionized irradiation can be introduced in order to allow for a re-oxygenation of the tissue
|
|
| 8. |
- Lewander, Märta, et al.
(författare)
-
Clinical system for non-invasive in situ monitoring of gases in the human paranasal sinuses
- 2009
-
Ingår i: Optics Express. - 1094-4087. ; 17:13, s. 10849-10863
-
Tidskriftsartikel (refereegranskat)abstract
- We present a portable system for non-invasive, simultaneous sensing of molecular oxygen (O-2) and water vapor (H2O) in the human paranasal cavities. The system is based on high-resolution tunable diode laser spectroscopy (TDLAS) and digital wavelength modulation spectroscopy (dWMS). Since optical interference and non-ideal tuning of the diode lasers render signal processing complex, we focus on Fourier analysis of dWMS signals and procedures for removal of background signals. Clinical data are presented, and exhibit a significant improvement in signal-to-noise with respect to earlier work. The in situ detection limit, in terms of absorption fraction, is about 5 x 10(-5) for oxygen and 5 x 10(-4) for water vapor, but varies between patients due to differences in light attenuation. In addition, we discuss the use of water vapor as a reference in quantification of in situ oxygen concentration in detail. In particular, light propagation aspects are investigated by employing photon time-of-flight spectroscopy. (C) 2009 Optical Society of America
|
|
| 9. |
- Persson, Linda, et al.
(författare)
-
Gas monitoring in human sinuses using tunable diode laser spectroscopy
- 2007
-
Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 12:5
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 10. |
- Persson, Linda, et al.
(författare)
-
Human sinus studies using Monte Carlo simulations and diode laser gas absorption spectroscopy
- 2006
-
Ingår i: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials. - 0780397738 ; , s. 84-87
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate the possibility of non-intrusive in-vivo human sinus studies by diode laser gas absorption spectroscopy. Molecular oxygen in tissue-l ike phantoms were investigated in a practical backscattering detection geometry for frontal sinus studies both experimentally and numerically using the Monte Carlo concept, implemented in the Advanced Systems Analysis Program (ASAP (TM)) software. Light was launched into and detected from the forehead on a health volunteer. A model representing the frontal sinus measurements was implemented in ASAP (TM) and studied. The results from the experiments and the simulations show a good agreement for both the tissue-like phantom measurements and the measurements of the healthy volunteer. Preliminary data from human maxillary sinus measurements are also shown. The results are promising and suggest further development of this technique for sinuses studies.
|
|
