Application Examples

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Equipment developed by BioSpec has been successfully applied in various biomedical and clinical applications including fluorescent tumor diagnostics and photodynamic therapy control, optical biopsy and blood oxygen saturation evaluation:

Photodynamic therapy (PDT) of cancer. PDT control.

Medical care of oncological diseases with the use of photosensitizers allows both diagnostics and treatment of cancerous tumors of intracavity organs and skin. More than 10000 successful cases of photodynamic therapy were carried out in the world. Our equipment is adapted to the use of Hematoporphyrin, ALA induced PP IX, phthalocyanines, chlorins, etc. as photosensitizers. The diagnostics is based on the fact that above mentioned drugs are selectively accumulated in malignant tumors (for example, accumulation of some phthalocyanines in cancerous tissues is 15 times higher than those in normal tissues). In this case spreading and localization of tumor is determined by intensive fluorescence. Calculation of difference in optical properties of biological tissues is carried out by normalization to the scattered laser line, used for excitation of fluorescence.

Spectral picture (Hematoporphyrin)
Example 1. Clinical observations of fluorescent spectra of skin tumor (patient A.) and various normal tissues. The photosensitizer (hematoporphyrin) has been injected intravenously in dose 2 mg/kg, accumulation time 24 hours.

For treatment the tumor is irradiated by laser light with a wavelength corresponding to the absorption maximum of the photosensitizer administered before. Control of photodynamic treatment consists in measuring of fluorescence intensity before, during and after irradiating.

Spectral picture (ALA)
Example 2. PDT with 5-ALA efficiency control using fluorescent measurements method. (Patient Y., cancer of stomach).

You may see in Example 2 that fluorescence intensity after PDT is declining to values adequate to normal contiguous tissues. Therefore further irradiating is pointless.


Optical biopsy

Measurements and analysis of scattering, absorption and fluorescence spectra of biological tissues of the patients during medical examinations, endoscopic or surgical treatment allow to carry out the following diagnostic techniques:
- differential diagnostics of cancer;
- diagnostics of internal organs blood supply;
- atherosclerosis diagnostics;
- diagnostics of transplanted tissues state.


The blood oxygen saturation measurements

Our equipment allows to carry out measurements of the blood oxygen saturation.

Oxygenation measurements. 1-st PDT session.
First PDT session (photosensitizer accumulation time 6 hours). An irreversible vessel damage is observed.

Oxygenation measurements. 2-nd PDT session.
Second PDT session (photosensitizer accumulation time 28 hours). The oxygen saturation is restored reversibly after switching off the laser.

Example 3. The influence of laser irradiation (85 mW/cm², 670 nm) on hemoglobin oxygen saturation in microcircular blood vessels of mice during photodynamic therapy with sulphanated aluminum phtalocyanine (Photesens) in injection dose 4 mg/kg. The dotted line represents the time dependence of the laser power.



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