| 1. |
- Spinelli, L., et al.
(författare)
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Determination of reference values for optical properties of liquid phantoms based on Intralipid and India ink
- 2014
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Ingår i: Biomedical Optics Express. - : Optical Society of America. - 2156-7085. ; 5:7, s. 2037-2053
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Tidskriftsartikel (refereegranskat)abstract
- A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at near-infrared (NIR) wavelengths. Nine research laboratories from six countries adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values at three NIR wavelengths for the intrinsic absorption coefficient of India ink and the intrinsic reduced scattering coefficient of Intralipid-20% were determined with an uncertainty of about 2% or better, depending on the wavelength considered, and 1%, respectively. Even if in this study we focused on particular batches of India ink and Intralipid, the reference values determined here represent a solid and useful starting point for preparing diffusive liquid phantoms with accurately defined optical properties. Furthermore, due to the ready availability, low cost, long-term stability and batch-to-batch reproducibility of these compounds, they provide a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment. Finally, the collaborative work presented here demonstrates that the accuracy level attained in this work for optical properties of diffusive phantoms is reliable.
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| 2. |
- Pifferi, A, et al.
(författare)
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Multi-distance optical characterization of the female breast by time-resolved diffuse spectroscopy
- 2003
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Ingår i: PHOTON MIGRATION AND DIFFUSE-LIGHT IMAGING. - : SPIE. - 1996-756X .- 0277-786X. - 0819450081 ; 5138, s. 6-11
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Konferensbidrag (refereegranskat)abstract
- Two systems for time-resolved diffuse spectroscopy were used for the optical characterization of the female breast in 4 volunteers. A first system was a compact laser diode instrument operated at 660 and 785 nm, while the second one was a broadband laboratory set-up based on mode-locked lasers tunable in the 610-1000 nm range. Measurements were obtained both in transmittance and in reflectance geometry at 5 inter-fiber distances ranging from I to 4 cm at different locations on the breast. Distinct spectral features both in absorption and in scattering were observed among the 4 volunteers, and for each subject between reflectance and transmittance measurements. These differences are correlated with the abundance of the glandular tissue and blood absorption. Upon increasing, the inter-fiber distance in reflectance, deeper tissue structures were investigated, generally resulting in higher water contribution.
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| 3. |
- Pifferi, A, et al.
(författare)
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Performance assessment of photon migration instruments: the MEDPHOT protocol
- 2005
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Ingår i: Applied Optics. - 2155-3165. ; 44:11, s. 2104-2114
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Tidskriftsartikel (refereegranskat)abstract
- We propose a comprehensive protocol for the performance assessment of photon migration instruments. The protocol has been developed within the European Thematic Network MEDPHOT (optical methods for medical diagnosis and monitoring of diseases) and is based on five criteria: accuracy, linearity, noise, stability, and reproducibility. This protocol was applied to a total of 8 instruments with a set of 32 phantoms, covering a wide range of optical properties.
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| 4. |
- Pifferi, A, et al.
(författare)
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Spectroscopic time-resolved diffuse reflectance and transmittance measurements of the female breast at different interfiber distances
- 2004
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668. ; 9:6, s. 1143-1151
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Tidskriftsartikel (refereegranskat)abstract
- The first, to our knowledge, in-vivo broadband spectro-scopic characterization of breast tissue using different interfiber distances as well as transmittance measurements is presented. Absorption and scattering properties are measured on six healthy subjects, using time-resolved diffuse spectroscopy and an inverse model based on the diffusion equation. Waveiength-tunable picosecond-pulse-lasers and time-correlated single-photon counting detection are employed, enabling fully spectroscopic measurements in the range 610 to 1040 nm. Characterization of the absorption and reduced scattering coefficients of breast tissue is made with the aim of investigating individual variations, as well as variations due to different measurement geometries. Diffuse reflectance measurements at different interfiber distances (2, 3, and 4 cm) are performed, as well as measurements in transmittance mode, meaning that different sampling volumes are involved. The results show a large variation in the absorption and scattering properties depending on the subject, correlating mainly with the water versus lipid content of the breast. Intra-subject variations, due to different interfiber distances or transmittance modes, correlate with the known structures of the breast, but these variations are small compared to the subject-to-subject variation. The intrasubject variations are larger for the scattering data than the absorption data; this is consistent with different spatial localization of the measurements of these parameters, which is explained by the photon migration theory. (C) 2004 Society of Photo-Optical Instrumentation Engineers.
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| 5. |
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| 6. |
- Svanberg, Sune, et al.
(författare)
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Generation, characterization, and medical utilization of laser-produced emission continua
- 2000
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Ingår i: Laser and Particle Beams. - 0263-0346. ; 18:3, s. 563-570
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Tidskriftsartikel (refereegranskat)abstract
- Intense continua of electromagnetic radiation of very brief duration are formed in the interaction of focused ultra-short terawatt laser pulses with matter. Two different kinds of experiments, which have been performed utilizing the Lund 10 Hz titanium-doped sapphire terawatt laser system are being described, where visible radiation and X-rays, respectively, have been generated. Focusing into water leads to the generation of a light continuum through self-phase modulation. The propagation of the light through tissue was studied addressing questions related to optical mammography and specific chromophore absorption. When terawatt laser pulses are focused onto a solid target with high nuclear charge Z, intense X-ray radiation of few ps duration and with energies exceeding hundreds of keV is emitted. Biomedical applications of this radiation are described, including differential absorption and gated-viewing imaging.
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| 7. |
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| 8. |
- af Klinteberg, C, et al.
(författare)
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In vivo absorption spectroscopy of tumor sensitizers with femtosecond white light
- 2005
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Ingår i: Applied Optics. - 2155-3165. ; 44:11, s. 2213-2220
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Tidskriftsartikel (refereegranskat)abstract
- A system based on a femtosecond white-light continuum and a streak camera was used for recordings of the in vivo absorption spectra of the tumor-seeking agent disulphonated aluminum phthalocyanine. Measurements for different drug doses were performed on tumor tissue (muscle-implanted adenocarcinoma) and normal muscle tissue in rats. It was found that the shape of the spectrum is tissue dependent. The peak of the absorption spectrum is blueshifted in tumor tissue as compared with the muscle. Thus the contrast in the drug-related absorption can be altered by up to a factor of 2 from the primary drug molecular-concentration contrast between normal muscle and tumor by the proper selection of the illumination wavelength.
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| 9. |
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| 10. |
- Gratz, M, et al.
(författare)
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Time-gated imaging in radiology: Theoretical and experimental studies
- 1996
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X. ; 2:4, s. 1041-1048
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Tidskriftsartikel (refereegranskat)abstract
- Novel short-pulse X-ray sources, e.g., laser-produced plasmas, offer new approaches to the solution of the scatter-reduction problem in X-ray imaging, by the use of time-gated detection techniques. Monte Carlo simulations are used to estimate the scatter-reduction performance of time-gated imaging techniques within a range of X-ray energies, gating times and tissue parameters, Significant improvements can be achieved for thick tissues combined with high photon energies, Experimental studies on water phantoms are performed using a laser-produced plasma X-ray source. Problems arising on the technical realization are discussed.
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