| 1. |
- Stenberg, M, et al.
(författare)
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Interstitial photodynamic therapy - diagnostic measurements and treatment in rat malignant experimental tumours
- 2000
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Ingår i: OPTICAL BIOPSY AND TISSUE OPTICS. - : SPIE. - 1996-756X .- 0277-786X. - 0819438170 ; 4161:32, s. 151-157
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Konferensbidrag (refereegranskat)abstract
- A recently developed multiple fibre system for treating malignant tumours with interstitial photodynamic therapy was used in studies on rats with colon adenocarcinoma inoculated into the muscles of the hind legs. The animals were intraperitonially administrated delta -aminolevulinic acid (ALA), which is metabolised to protoporphyrin IX (PpIX) in the tissue. The treatment system consists of a laser light source, a beam-splitting system dividing the light into three or six output fibres and a dosimetry programme calculating the optimal fibre position within the tumour as well as the treatment time needed to obtain a given threshold value of the light dose. One aim of the study was to compare the treatment outcome with the modelled dosimetry predictions. Tumour reduction was examined three days post treatment. A volume decrease was found in 85\% of the treated tumours. The mean volume reduction was 44\%, with one tumour completely disappearing. Histopathological examination three days post treatment showed substantial necrotic parts which, however, to a smaller extent were present also for non-treated tumours. These results indicated that the tumours have been under treated and the light dose has to be increased. Measurements of the build-up and photo-induced bleaching of PpIX using laser-induced fluorescence were also performed during the experiments.
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| 2. |
- Andersson-Engels, Stefan, et al.
(författare)
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Integrated system for interstitial photodynamic therapy
- 2003
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5142, s. 42-49
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Konferensbidrag (refereegranskat)abstract
- A novel photodynamic therapy system based on interstitial illumination using multiple fibres is under development. The aim with this system is to enable treatment of large tumour volumes and also to utilise real-time measurements to allow on-line dosimetry. Important dosimetric parameters to measure are light fluence rate, sensitizer fluorescence intensity and local blood oxygenation. A construction which allows all functions to be readily performed with a single system is presented. We believe that interstitial PDT utilising this technique may be attractive in many clinical situations.
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| 3. |
- Andersson-Engels, Stefan, et al.
(författare)
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Integrated system for interstitial photodynamic therapy
- 2002
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Ingår i: Advanced Optical Devices, Technologies, and Medical Applications. - : SPIE. - 0277-786X .- 1996-756X. ; 5123, s. 293-302
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Konferensbidrag (refereegranskat)abstract
- To develop PDT beyond treatment of thin superficial tumours, to also be an efficient treatment alternative for deeply located and/or thick tumours, a system based on interstitial illumination using multiple fibres has been developed. Conditions that could benefit from such a treatment modality are for instance malignant brain tumours and tumours in the oral cavity. In interstitial PDT one needs to use multiple fibres for light delivery in order to allow treatments of tumours larger than a few millimetres in diameter. Our system consists of a laser light source, a beam-splitting system dividing the light into three or six output fibres and a custom-made dosimetry programme. The concept is then to use these fibres not only for delivering the treatment light but also to measure parameters of interest for the treatment outcome. The fluence rate of the light emitted by each fibre is measured at the positions of the other fibre tips. From these results the light dose at all positions could be recalculated. Changes in optical properties as well as bleaching and concentration of the photosensitizer during the treatment could be monitored and compensated for in the dosimetry. Tumours have been treated both in experimental studies and in patients with thick superficial Basal Cell Carcinomas. Almost all treated skin lesions responded with complete response.
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| 4. |
- Jensen, LK, et al.
(författare)
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Optical coherence tomography in clinical examination of non-pigmented skin malignancies
- 2003
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Ingår i: OPTICAL COHERENCE TOMOGRAPHY AND COHERENCE TECHNIQUES. - : SPIE. - 0277-786X .- 1996-756X. - 0819450103 ; 5140, s. 160-160
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Konferensbidrag (refereegranskat)abstract
- Optical coherence tomography (OCT) images of basal cell carcinomas (BCCs) have been acquired using a compact handheld probe with an integrated video camera allowing the OCT images to be correlated to a skin surface image. In general the healthy tissue of the skin has an obvious stratified structure, whereas the cancerous tissue shows a more homogenous structure. Thus it was demonstrated that it is possible to distinguish BCCs from healthy tissue by means of OCT. Furthermore different histological types of BCC were identified. Comparison of OCT images taken prior to and immediately after photodynamic therapy clearly shows the tissue response to the treatment, and indicates local oedema in the treated area.
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| 5. |
- Johansson, Ann, et al.
(författare)
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mTHPC pharmacokinetics following topical administration
- 2006
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Ingår i: Optical Diagnostics and Sensing VI. - : SPIE. - 1996-756X .- 0277-786X. ; 6094, s. 940-940
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Konferensbidrag (refereegranskat)abstract
- Measurements of concentration of sensitizers for photodynamic therapy can provide important information in the dosimetry planning and can also give input to the optimal time for treatment. There has been skepticism towards fluorescence techniques for this purpose, as the signal depends on the fluorescence yield and optical properties of the tissue. Absorption based techniques, lack on the other hand, often the sensitivity required for many sensitizers with relative weak absorption in a wavelength region where hemoglobin absorption is dominant. A direct comparison between absorption and fluorescence techniques for measuring mTHPC concentration after topical application on hairless SKH-1 mice bearing skin carcinomas has been performed. 20 μl/cm2 of m-THPC thermogel (0.5 mg m-THPC/ml) were applied on normal and tumor area and the concentration of mTHPC was measured at 4 and 6 hours after drug application by two methods: 1. A fluorescence imaging system capturing images at two wavelengths (500 and 650 nm) following 405 nm excitation. Signals from different regions of interest were averaged and the intensity ratio at 650 to 500 was calculated. 2. A diffuse reflectance spectroscopy system with a fiber separation of 2 mm, providing the absorbance at 652 nm. Both systems provided consistent results related to the photosensitizer concentration. The methods show a remarkable difference in the concentration of photosensitizer in normal skin and tumor. No significant difference in mTHPC concentration in tumor could be observed between the 4 and 6h groups after drug application.
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| 6. |
- Johansson, Ann, et al.
(författare)
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System for integrated interstitial photodynamic therapy and dosimetric monitoring
- 2005
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5689:1, s. 130-140
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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
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| 7. |
- Lundin, Patrik, et al.
(författare)
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Non-invasive gas monitoring in newborn infants using diode laser absorption spectroscopy: A case study
- 2012
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Ingår i: Optical Diagnostics and Sensing XII: Toward Point-of-Care Diagnostics; and Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurement of Tissue IV. - : SPIE. - 1996-756X .- 0277-786X. ; 8229
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Konferensbidrag (refereegranskat)abstract
- Non-invasive diode laser spectroscopy was, for the first time, used to assess gas content in the intestines and the lungs of a new-born, 4 kg, baby. Two gases, water vapor and oxygen, were studied with two low-power tunable diode lasers, illuminating the surface skin tissue and detecting the diffusely emerging light a few centimeters away. The light, having penetrated into the tissue, had experienced absorption by gas located in the lungs and in the intestines. Very distinct water vapor signals were obtained from the intestines while imprint from oxygen was lacking, as expected. Detectable, but minor, signals of water vapor were also obtained from the lungs, illuminating the armpit area and detecting below the collar bone. Water vapor signals were seen but again oxygen signals were lacking, now due to the difficulties of penetration of the oxygen probing light into the lungs of this full-term baby. Ultra-sound images were obtained both from the lungs and from the stomach of the baby. Based on dimensions and our experimental findings, we conclude, that for early pre-term babies, also oxygen should be detectable in the lungs, in addition to intestine and lung detection of water vapor. The present paper focuses on the studies of the intestines while the lung studies will be covered in a forthcoming paper.
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| 8. |
- Persson, Linda, et al.
(författare)
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Non-intrusive optical study of gas and its exchange in human maxillary sinuses - art. no. 662804
- 2007
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Ingår i: Diagnostic Optical Spectroscopy in Biomedicine IV. - : SPIE. - 1996-756X .- 0277-786X. ; 6628, s. 62804-62804
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 9. |
- Samsöe Andersen, Eva, et al.
(författare)
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A novel diode laser system for photodynamic therapy
- 2001
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Ingår i: LASER-TISSUE INTERACTIONS, THERAPEUTIC APPLICATIONS, AND PHOTODYNAMIC THERAPY. - : SPIE. - 0277-786X .- 1996-756X. - 0819441473 ; 4433:33, s. 134-139
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Konferensbidrag (refereegranskat)abstract
- In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system provides an almost diffraction limited output which is efficiently coupled into a 50 mum core diameter fiber. The optical power transmitted through the fiber is increased by a factor of six when the feedback is applied to the diode laser. 85 percent of the power from the freely running laser diode is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through tile fiber scales linearly with the power of the laser diode. which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50 mum core diameter fiber. The system is compact, portable, stable, and easy to operate.
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| 10. |
- Svanberg, Katarina
(författare)
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Diagnostics and treatment of human malignant tumours using laser based techniques
- 2002
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 5226, s. 387-393
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Konferensbidrag (refereegranskat)abstract
- Laser-induced fluorescence is a technique for optical tissue characterisation. It has a real-time capability and as the excitation light and the fluorescence emission are transmitted through optical fibres the technique is compatible to various kinds of endoscopes for hollow organ investigation. The tissue fluorescence itself with the emission from the endogenous chromophores or enhanced with exogenously administered tumour seeking agents are employed. Contrast functions are beeing developed for optimal tumour demarcation. Photodynamic therapy is a selective therapy for certain types of malignancies. In particular the topical application of a sensitising agent has been employed for human skin malignancies. Clinical examples are both from the detection and the treatment side.
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