Compact medical fluorosensor for minimally invasive tissue characterization

Klinteberg, Claes af; Andreasson, Markus; Sandström, Ola; Andersson‐Engels, Stefan; Svanberg, Sune

doi:10.1063/1.1867569

Cited by 24 publications

(19 citation statements)

References 43 publications

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“…22 A nitrogen laser pumped dye laser emits pulsed excitation light at 405 nm. After passing through a RG435 cut-off filter, fluorescent light between 450 and 800 nm is dispersed by a spectrometer and detected by an intensified and cooled charge-coupled device ͑CCD͒.…”

Section: Instrumentationmentioning

confidence: 99%

In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors

Johansson

Thompson

et al. 2006

J. Biomed. Opt.

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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 ␦-aminolevulinic acid ͑ALA͒-induced protoporphyrin IX show a significant, treatmentinduced 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. © 2006 Society of Photo-Optical Instrumentation Engineers.

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Section: Instrumentationmentioning

confidence: 99%

In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors

Johansson

Thompson

et al. 2006

J. Biomed. Opt.

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“…25 The fluorescence light from the sample was guided through a 600-m-core-diameter step-index fiber ͑N.A. ϭ 0.22͒ to a spectrometer and a cooled CCD camera (DH501-25U-01, Andor Technology, North- 22 ).…”

Section: E Fluorescence Measurementsmentioning

confidence: 99%

Fluorescence spectra provide information on the depth of fluorescent lesions in tissue

et al. 2005

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The fluorescence spectrum measured from a fluorophore in tissue is affected by the absorption and scattering properties of the tissue, as well as by the measurement geometry. We analyze this effect with Monte Carlo simulations and by measurements on phantoms. The spectral changes can be used to estimate the depth of a fluorescent lesion embedded in the tissue by measurement of the fluorescence signal in different wavelength bands. By taking the ratio between the signals at two wavelengths, we show that it is possible to determine the depth of the lesion. Simulations were performed and validated by measurements on a phantom in the wavelength range 815-930 nm. The depth of a fluorescing layer could be determined with 0.6-mm accuracy down to at least a depth of 10 mm. Monte Carlo simulations were also performed for different tissue types of various composition. The results indicate that depth estimation of a lesion should be possible with 2-3-mm accuracy, with no assumptions made about the optical properties, for a wide range of tissues.

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“…17 In the previous system 14 it was possible to measure the therapeutic light flux in the lesion but the system construction did not allow the measurements of other parameters. The sensitizer fluorescence was in that case assessed by using a separate fluorosensor 18,19 with a separate measurement fiber. The novel approach 20 reported in the present paper enables us to perform light flux as well as sensitizer fluorescence and oxygenation monitoring through the same fibers that deliver the therapeutic light.…”

Section: Introductionmentioning

confidence: 99%

Clinical system for interstitial photodynamic therapy with combined on-line dosimetry measurements

Thompson¹,

Johansson²,

Johansson³

et al. 2005

Appl. Opt.

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A system for interstitial photodynamic therapy with ␦-aminolaevulinic acid and multiple optical fibers has been developed. The system enables photodynamic treatment of large embedded tumor volumes and utilizes real-time measurements to allow on-line dosimetry. Important parameters such as light fluence rate, sensitizer fluorescence intensity, and changes in local blood oxygen saturation are measured with the same fibers that deliver the therapeutic light. Data from the first clinical treatments on nodular basal cell carcinomas indicate a major treatment-induced light absorption increase, rapid sensitizer photobleaching, and a relatively constant global tissue oxygen saturation level during the treatment.

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Compact medical fluorosensor for minimally invasive tissue characterization

Cited by 24 publications

References 43 publications

In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors

In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors

Fluorescence spectra provide information on the depth of fluorescent lesions in tissue

Clinical system for interstitial photodynamic therapy with combined on-line dosimetry measurements

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