Search results for "RADIATION"
showing 10 items of 5298 documents
Tumor tissue oxygenation as evaluated by computerized-po2-histography
1990
A computerized pO2 measurement system with a novel electrode motion pattern (Sigma-pO2-histography) was evaluated in vitro and in vivo. The system was found to be reliable in 0.9% saline and 10% hydroxyethylene starch solution and in fresh donor blood. Marked deviations were found in lipid and hemoglobin solutions and in fluorocarbon emulsions. Histograms obtained in rat liver, mouse muscle, and subcutis were similar to previously reported distributions. Direct comparison between Sigma-Eppendorf and self-constructed Whalen-type electrodes in hypoxic tumors gave similar results. A large series of measurements indicated that hypoxic and anoxic tissue areas were frequently found both in isogra…
MR Thermometry Data Correlate with Pathological Response for Soft Tissue Sarcoma of the Lower Extremity in a Single Center Analysis of Prospectively …
2020
Background: There is a strong biologic rationale for using locoregional hyperthermia in soft tissue sarcoma and a randomized trial reported significant improvements with hyperthermia. The aim of this study was to describe the opportunities of magnetic resonance (MR)-based thermometry in a cohort of soft tissue sarcoma patients undergoing combined radiotherapy and locoregional hyperthermia. Patients and Methods: For eleven evaluable patients, tumor volume (VTu) and a separate volume for temperature analysis with reliable temperature distribution (Vtherm) were contoured for every hyperthermia treatment (103 therapies). Temperature data were recorded for all tumors and were correlated with cli…
The Vascularization of Experimental and Human Primary Tumors: Comparative Morphometric and Morphologic Studies
1998
The importance of the blood vessel system in solid tumors has given rise to an increasing interest in this system as a direct target for tumor therapy, i.e. vascular targeting (Denekamp, 1984). Furthermore, its importance as a route for delivery of anticancer drugs (chemo- and immunotherapies) or photosensitizers (photodynamic laser therapy), as well as its modulatory influences on radiotherapy and hyperthermia — the former greatly depending on the amount of oxygen available, the latter on heat transfer — are evident. Numerous studies on the energy metabolism of solid tumors (Vaupel et al., 1987, 1989) have pointed out the functional importance of the blood vessel system and stress the need…
Blood Flow and Oxygen Supply to Human Mammary Carcinomas Transplanted into Nude Rats
1985
Tumor blood flow (TBF), by itself, greatly influences the efficiency of nonsurgical therapeutic modalities, especially chemotherapy and hyperthermia. Furthermore, TBF is one of the most important determinants of tumor tissue oxygenation in vivo, thus playing a relevant role in tumor growth kinetics and in the development of regressive changes. In addition, the oxygenation of tumor tissue strongly determines the efficiency of radiation therapy and to a certain extent, pharmacodynamics of some antiproliferative drugs. Despite the considerable information available for rodent tumor systems, there are only sporadic ireports on blood flow (Beaney et al., 1984, Johnson, 1976, Mantyla, 1979, Manty…
Vascular Meets of Localized Hyperthermia
2008
When hyperthermia is applied in vitro, no fundamental differences can be seen between the response to normal and tumor cells. In vivo however, selective damage of tumor cells can be achieved and this phenomenon can be largely attributed to a number of characteristic properties of the blood vessels within solid tumors. Changes in blood flow induced by hyperthermia can influence the response of a tumor to heat either by affecting the delivery of heat through changes in heat dissipation or by a modulation of the tumor microenvironment which may in turn affect the thermosensitivity of tumor cells. Studies in experimental and human tumors suggest however that an accurate prediction of changes in…
Enhanced effects of aminolaevulinic acid-based photodynamic therapy through local hyperthermia in rat tumours.
2003
The possibility of enhancing aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) by simultaneous application of localised hyperthermia (HT) was evaluated. Treatments of rat DS-sarcomas included: (i) control, (ii) ALA administration (375 mg kg(-1), i.p.), no illumination, (iii) 'nonthermal' illumination, (iv) ALA-PDT: that is, ALA administration, 'nonthermal' illumination, (v) localised HT, 43 degrees C, 60 min (vi) ALA-PDT+HT: ALA administration with full spectrum irradiation resulting in ALA-PDT and HT. Tumour volume was monitored for 90 days or until a target volume (3.5 ml) was reached. No differences were seen between the first three groups, with all tumours reaching the target …
Tumour tissue monitoring during photodynamic and hyperthermic treatment using bioimpedance spectroscopy.
2003
Electrical bioimpedance spectroscopy is a fast and relatively easily applicable method for tissue characterization. In the frequency range up to 10 MHz, current conduction through tissue is mainly determined by tissue structure, i.e. the extra- and intra-cellular compartments and the insulating cell membranes. Therefore, changes in the extra- and intra-cellular fluid volumes are reflected in the impedance spectra. Investigations of tumours (DS sarcoma, implanted on the hind foot dorsum of rats) during treatment with localized hyperthermia (HT), photodynamic therapy (PDT) and the combination of these two components were carried out using impedance spectroscopy in the frequency range of 37 Hz…
The influence of tumor blood flow and microenvironmental factors on the efficacy of radiation, drugs and localized hyperthermia.
1997
It is generally accepted that tumor blood flow, microcirculation, oxygen and nutrient supply, tissue pH distribution, and the bioenergetic status-factors which are usually closely linked and which define the so-called metabolic microenvironment--can markedly influence the therapeutic response of malignant tumors to conventional irradiation, chemotherapy, other nonsurgical treatment modalities, and the cell proliferation activity within tumors. Currently available information on the parameters defining the metabolic micromilieu in human tumors is presented in this review. According to these data, significant variations in these relevant factors are likely to occur between different locations…
Effect of hyperthermia on tumor blood flow.
1984
Differences in blood perfusion rates between tumors and normal tissue can be utilized to selectively heat many solid tumors. Blood flow in normal tissues is considerably increased at temperatures commonly applied during localized hyperthermia. In contrast, tumor blood flow may respond to localized heat typically in two different blood flow patterns: Flow may either decrease continuously with increasing exposure time and/or temperature or flow may exhibit a transient increase followed by a decline. A decrease in blood flow at high thermal doses can be observed in most of the tumors, whereas an increase in flow at low thermal doses seems to occur less frequently. The inhibition of blood flow …
Moderate hypofractionated helical tomotherapy for localized prostate cancer: preliminary report of an observational prospective study.
2019
Objective: To report preliminary findings of a phase II study exploring the clinical outcomes of moderate hypofractionated radiotherapy performed with helical tomotherapy (HT) using computed tomography–magnetic resonance imaging–based planning for localized prostate cancer. Methods: The phase II prospective study received ethics approval from our institutional ethics committee. A dose of 60 Gy/20 fractions for low–intermediate risk prostate cancer by means of HT was explored. Primary endpoints of the study were acute and late gastrointestinal (GI) and genitourinary (GU) toxicities. Secondary endpoints were quality of life and biochemical-free survival. Results: A total of 35 patients were i…