Photodynamic therapy (PDT) is known as a routine treatment method in which cell survival index like viability plotted versus ¹O₂ concentration or light fluence in the form of a curve. In this paper, a mathematical model was proposed with ability of generating a mirrored-sigmoid curve which seems to be fitted to any experimental data relating to cell viability, survival probability or any cellular index representing living conditions through adjusting three parameters. It was validated by showing an excellent curve fitting relatively with data obtained from cancerous lung cells under ALA-PDT process in vitro. 

It was tried to define the relations between model’s parameters and biological/clinical factors with the curve regions of plateau (at low doses; non- sensitive part), steep (high-sensitive part), and steady state (at high doses; low-sensitive part). It seems this model could be excellently fitted to any data presenting the cell-living index versus the killer agent in «any cancer therapy technique (e.g. radiotherapy)». Although this claim showed to be correct for PDT, different relevant data of other researchers should also be used for this model and other usual models too, in order to compare their fitness rates.

Laser interstitial hyperthermia is an actively developing direction in intracerebral tumor surgery. The paper presents thermal effects in polyacrylamide biophantoms with bovine albumin and citrated blood under laser irradiation at 970 nm and 1560 nm. For laser irradiation, a surgical two-wave apparatus manufactured by IRE Polis was used. The phantom was irradiated through a quartz optical fiber 400 µm in diameter with an end exit. The result of irradiation of the phantom was its coagulation zone, which was visualized with a FLUM-LL fluorescent organoscope. Thermometry was carried out with a FLIRONE PRO for IOS thermal imager and a T-8 digital thermograph based on a laptop with thermal sensors placed in a phantom. The use of irradiation with a power of not more than 2 W in the coagulation mode, with a total energy dose of up to 120 J, made it possible to achieve a smooth rise in temperature to 88.0 °C. The dimensions of the coagulation zone under irradiation with a wave of 1560 nm were always larger than under irradiation with a wave of 970 nm, although the difference was not statistically significant (p=0,41). Thus, the average coagulation spot area for 970 nm radiation was 43.2 (39.3 – 47.1) mm², and for 1560 nm – 99.4 (56.5-141.3) mm². With total irradiation with two waves, the coagulation zone was larger if the radiation power of 1560 nm prevailed. When irradiated with a wave of 970 nm, the coagulation zone partially propagates posteriorly from the tip of the optical fiber, and 1560 nm coagulates the phantom anteriorly. The results obtained are of practical importance for laser hyperthermia of intracerebral tumors.

In this experimental work the acute toxicity of a chemically modified derivative of the natural pigment chlorophyll a called monocationic chlorin e6, which is a promising photosensitizer (PS) for antimicrobial and antitumor photodynamic therapy, was studied using white rats. The advantages of the PS under investigation are an intense absorption in the long-wavelength region of the visible spectrum, a sufficiently high quantum yield of singlet oxygen generation, pronounced amphiphilic properties along with an appropriate solubility in water, and a high level of photocytotoxic- ity in relation to both malignant HeLa cells and antibiotic-resistant hospital strains of E. сoli bacteria., P. aerugenosa and others. It has been shown that the value of LD50 of the considered PS can be calculated as the value of 100 mg/kg. In the reproduced experimental model of acute toxicity, pathomorphological changes in the vital organs of laboratory animals indicate a pronounced vasopathic effect of the drug with the development of cerebral edema and respiratory distress syndrome, which have become the main signs of thanatogenesis.

There is a clinical report of successful oral intraluminal laser lithotripsy with subsequent lithoextraction of a large concretion of the common bile duct in a patient with choledocholithiasis and mechanical jaundice. For the intraluminar lithotripsy a tulium laser "Urolaz" was used with energy modes 0,025-0,05-0,1 J, up to a maximum of 0.5 J. The average power is 6-10 W. Laser exposure was carried out by pulses in an aqueous medium in order to prevent carbonation of the light guide and smoke. The effect of exposure to the concretion was manifested in its fragmentation and the formation of small particles without damage of the mucous membrane of the common bile duct. The total duration of the intervention was 45 minutes. The method is effective and safe, thus it avoids the need of endoscopic papillosphincterotomy and violation of the anatomical integrity and physiological function of the Oddi sphincter.