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[en] In the present study we used an ex-vivo human lung cancer model to compare temperature diffusion during thermal ablation using one laser fiber to that of a two-fiber approach. Furthermore, we examined whether there was a difference between temperature diffusion in normal lung tissue and tumor tissue during laser ablation. Materials and Methods: 48 resected lung specimens containing non-small cell lung cancer were connected to a perfusion/ventilation apparatus and treated with 1 (22 specimens, group 1) or, in a second experiment, with 1 (13 specimens, group 2) or 2 (13 specimens, group 3) laser fibers. During tumor ablation, temperatures were measured interstitially every 5 sec. Laser ablation was followed by the taking of samples of 13 specimens for histological examination. For comparison we performed laser ablation in 7 specimens with normal lung tissue. Results: Laser treatment and temperature control were technically feasible in all samples. Thirty min after starting laser ablation with 1 fiber, a temperature of 61±17 C was achieved in group 1 at a distance of 10 mm from the laser fiber and a temperature of 74±11 C was achieved in group 2 (p = 0.1). In the middle between two active laser fibers placed 20 mm apart, a temperature of 93±7 C was achieved. The temperature reached in normal lung tissue after 20 min of laser ablation was 77±15 C at a distance of 10 mm from the laser fiber. Conclusion: The ex-vivo model allowed performance of laser-induced thermal ablation in the perfused and ventilated lung. The use of two laser fibers increases the achieved temperatures significantly (p < 0.05). Temperatures reached in normal lung tissue were as high as in tumor tissue (p = 0.24). (orig.)
[en] Complete text of publication follows. Early detection of malignant transformation is a goal of modern medicine and to this end there is an impressive number of approaches from the scientific field that tries to identify early changes preceding malignant transformation in order to establish a correct diagnosis. This work aims is to combine the optical and biochemical techniques for identifying the changes in membrane dynamics of growth and development of experimental solid tumours. During the purpose has been used experimental Walker 256 carcinoma graft in Wistar rats, followed from day 7 up to day 24 from inoculation of tumour cells. Optical techniques were used fractalometry laser polarization in the preclinical diagnosis of pathological changes and degenerative-dystrophy of experimental tissue, and in terms of biochemical tumour tissue was determined the reaction of lipid peroxidation monitored by the malondialdehyde (MDA), the end product assays of reaction. In addition were followed also the total antioxidants as a response of the endogenous defences systems. The results indicate a rising profile of the processes investigated by the 14th day after tumour graft, following a decrease due to lack of substrate enzymatic reactions, specifically the double links of polyunsaturated fatty acids in the membranes change during tumour development. These data are consistent with the changes of the optical investigated parameters. It is shown that in all the cases the linear dichroism appears in bio tissues with the cancer disease the magnitude of which depends on the tumour growth of the cancer process development. The phenomenon of the linear dichroism formation has a selective character: maximum values Δ are observed in the area λ = 410 / 430 nm and in the area λ = 500 / 530 nm, for the wavelength λ < 750 nm Δ is almost zero or zero. The linear dichroism magnitude depends on the thickness of samples that's why at thicknesses d = 10 / 12 μm when the transmission is 80% and more, it doesn't become apparent at the measurements on the spherical photometer, in this case it is better to conduct the transmission investigation in the direct beam. As the linear dichroism is lacking for healthy tissues, then the obtained results can have diagnostic values with the purpose of detection and estimation of the stage of the cancer disease development.
[en] Methyl-11C-choline ([11C]choline) is a radiopharmaceutical used for oncological PET studies. We investigated the biodistribution and biokinetics of [11C]choline and provide estimates of radiation doses in humans. The distribution of [11C]choline was evaluated ex vivo in healthy rats (n=9) by measuring the radioactivity of excised organs, and in vivo in tumour-bearing rats (n=4) by PET. In addition to estimates of human radiation doses extrapolated from rat data, more accurate human radiation doses were calculated on the basis of PET imaging of patients with rheumatoid arthritis (n=6) primarily participating in a synovitis imaging project with [11C]choline. Dynamic data were acquired from the thorax and abdomen after injection of 423±11 MBq (mean±SD) of tracer. Following PET imaging, the radioactivity in voided urine was measured. The experimental human data were used for residence time estimations. Radiation doses were calculated with OLINDA/EXM. In rats, the radioactivity distributed mainly to the kidneys, lungs, liver and adrenal gland. The effective dose in a human adult of about 70 kg was 0.0044 mSv/MBq, which is equivalent to 2.0 mSv from 460 MBq of [11C]choline PET. The highest absorbed doses in humans were 0.021 mGy/MBq in the kidneys, 0.020 mGy/MBq in the liver and 0.029 mGy/MBq in the pancreas. Only 2.0% of injected radioactivity was excreted in the urine during the 1.5 h after injection. The absorbed radiation doses after administration of 460 MBq of [11C]choline were low. Except for the pancreas, biodistribution in the rat was in accordance with that in humans, but rat data may underestimate the effective dose, suggesting that clinical measurements are needed for a more detailed estimation. The observed effective doses suggest the feasibility of [11C]choline PET for human studies. (orig.)
[en] Fifteen women undergoing breast radiotherapy following wide local excision of an early stage breast cancer were submitted to repeated measurements of surface landmarks to check the reproducibility of patient positioning, and to portal imaging using a megavoltage imaging device. When the patient is being set-up the mean rise and fall of a lateral skin mark (tattoo) was within 4 mm in 95 observations of 15 patients. At the end of the lateral field exposure, mean displacement of the lateral tattoo was close to zero, with only 15/95 (16%) observations falling outside the range ±2mm. The daily measurements of lung thickness fell above and below the stimulated lung thickness, consistent with random fluctuations. Eighty-eight percent of lung thickness measurements were within ±5mm of the stimulator position. A tentative conclusion is made that more sophisticated immobilisation and imaging devices may be unnecessary for breast irradiation with a high degree of reproducibility. (author). 3 refs.; 5 figs
[en] Because of preliminary results and the ongoing controversy relative to whether radioiodinated fibrinogen accumulates in tumors in a passive manner like others proteins or is actively accumulated due to coagulation phenomena, studies in a murine tumor model were initiated. The results in concert with other investigations leave little doubt that accumulation of radioiodinated fibrinogen in this tumor model is an active process quite distinct from that of other proteins. It is reasonable to suggest that this accumulation is determined to a significant extent by a procoagulant factor whose behavior is similar to that of thrombin. Furthermore, the amount of accumulation of radioiodinated fibrinogen in this tumor model provides a rational basis for current clinical trials of highly iodinated I-123 fibrinogen in patients with cancer