Radiobiologia, radiotherapia最新文献

The radiosensitizing effectiveness of 1-(2-hydroxy-3-methoxy-propyl)-2-chloro-4-nitroimidazole (P40) dependent on various fractionated schedules was tested in the rat solid tumor, rhabdomyosarcoma R 1. P40 combined conventional fractionation of gamma rays exerted no radiosensitizing effect measured as local control and growth delay as well. In contrary, the significant sensitization has been noticed when nontoxic doses of the nitroimidazole were combined with higher (3.7 Gy) doses of radiation. Low toxicity of P40 is encouraging for further experimental studies.

Results are presented applying an enteral nutrition by means of probes with Cosilat in complex therapy of patients with radiotherapeutic late effects of the colon. This nutrition was prescribed with the intention to gave the colon a functional recovery and to guarantee optimal conditions for repair of radiation injuries. Good results were seen in 27 of 28 patients (96.7%), the situation of one patient (3.3%) continued without any change. Cosilat has a high nutritive value, good organoleptic qualities and is digested well. In use complications did not appear.

In a retrospective investigation the remission rate was determined in roentgen picture for 264 male patients with bronchogenic carcinoma after intensive radiotherapy (target dose 56 Gy). Classification of roentgenologic remission was done in 3 groups (complete, partial, minimal/no remission). For each patient the pretherapeutic haemoglobin value was taken from casebook and clinical relevant limit concentrations for an anaemia were correlated with the classified remissions. The difference of regression frequency between complete and partial remission always can be secured statistically irrespectively of chosen limit, that is the anaemia has a provable influence on roentgenologic tumor reaction. To prove that the tumor value as a third variable is not responsible for that a covariant analysis was done. According to that the corrected mean haemoglobin values were 8.9 mmol/l for complete, 8.1 mmol/l for partial and 7.7 mmol/l for minimal/no remission. These differences of the mean values are significant in Newman-Keuls-test, the relation between initial haemoglobin value and remission type is provable independently of tumor volume. Also for bronchogenic carcinoma with that a dependence could be shown between haemoglobin concentration--and by this the oxygen supply of the tumor--and the reaction of the primary tumor after radiotherapy. From this we deduce the recommendation to treat anaemia before beginning of radiotherapy or to irradiate anaemic patients applying an effective sensitizer.

Influence of functions of cardiac pace-makers by ionizing radiation are represented, that is characterized in praxis relevant parameters as pulse duration and sensitivity in a special clear manner. For these parameters dose limits were defined in a phantom where tolerance ranges of pace-makers, guaranteed by producer, were over or underdosed. These dose values were different in dependence of installed electronic wiring diagrams. The radioresistance of pace-makers with Lewicki-wiring diagram (MCP 211 L) was higher than those with wiring diagram U 115. Measurings showed that the upper dose limits were greater than the known values with 60Co- and 9-MV-roentgen braking radiation and with that the complete programming and functional capacity of the pace-makers were conserved. The close cooperation of radiologists, physicists, cardiologists and technicians in the implantation clinic guarantees a good care for patients with pace-makers during radiotherapy without complications.

Dose-distributions in radiation fields are calculated for purpose of irradiation planning from measured depth dose and cross-distributions predominantly. Especially in electron fields the measuring effort is high to this, because these distributions have to be measured for all occurring irradiation parameters and in many different tissue depths. At the very least it can be shown for the 6...10 MeV electron radiation of the linear accelerator Neptun 10p that all required distributions can be calculated from each separately measured depth dose and cross-distribution. For this depth dose distribution and the measured border decrease of cross-distribution are tabulated and the abscissas are submitted to a linear transformation x' = k.x. In case of depth dose distribution the transformation factor k is dependent on electron energy only and in cross-distribution on tissue depth and source-surface-distance additionally.

The sensitivity vs. dose characteristics of two TL readers (Harshaw 2000 A + B and NHZ-203C) was compared both in the range of small doses (10 microGy to 100 mGy) as well as in the radiation therapy level by using individually calibrated LiF:Mg, Ti detectors manufactured in Poland. The performance of both systems can be predicted by a three parameter theoretical model. The very good reproducibility of the NHZ-203C reader (sigma/D = 0.6%) is important in radiation therapy while the high sensitivity (the lowest detectable dose limit = 3 S.D. of the background = 27 microGy) is useful for radiation protection measurements.

In therapy of plasmocytoma the radiotherapy has a well established place in addition to chemotherapy. At the Clinic and Policlinic for Radiology of the Medical Academy Erfurt 42 patients with a plasmocytoma were treated in the years 1967 to 1987, 38 of them were included into the presented study. In radiotherapy roentgen depth-therapy was used with total surface dose of 30 to 40 Gy as well as telecobalt therapy with TD of 40 to 50 Gy. 8 patients had a solitary plasmocytoma, in three times with extramedullary manifestation in mucosa of cheek and nose and in gingiva and five times with bone localisation. In 30 patients with a multiple plasmocytoma we irradiated 37 painful bone lesions; for 29 of these irradiated findings the patients stated painlessness or distinct mitigation. In two bone manifestations a pathological fracture existed additionally, in which a complete painlessness and a clear callus formation could be attained. 4 patients with an incomplete cross-section syndrome in consequence of vertebral destruction with extradural tumor spreading responded with clear mitigation and regression of paresis. Furthermore an infiltration into soft parts was diagnosed at 9 bone foci, that were reduced in part (6 infiltrations) or regressed completely (3 findings) after radiotherapy. Additionally to osseous manifestations an extramedullary tumor (peribronchial lymph-nodes, hypophysis) existed in 2 patients, that regressed completely after termination of radiotherapy. The following indications can be mentioned for radiotherapy in plasmocytoma: 1. Curative postoperative radiotherapy after exstirpation of a solitary extramedullary plasmocytoma, 2. Curative sole radiotherapy of a solitary extramedullary of medullary plasmocytoma after its histological proving.(ABSTRACT TRUNCATED AT 250 WORDS)

Male Wistar-H-rats were exposed monthly to a 60cobalt-source low dose whole body irradiation (0.25 Gy, total dose: 4.5 Gy). The glutathione disulphide:total glutathione ratio, the concentration of thiobarbituric acid-reactive substances and the activities of glutathione peroxidase and glutathione transferase in eight different organs and blood were analysed. The low dose irradiation is accompanied by distinct peroxidative changes in organs. These oxidative loadings occur in the small intestine, the spleen and the kidneys. The measurements of glutathione status and of thiobarbituric acid-reactive substances are proposed as sensitive parameters for low dose radiation induced changes.

The irradiation of tumors in thoracal area presupposes an exact irradiation planning including the lung to prevent therapy limiting dosage errors. With it the exact dimension and the density of the lung have to be known. It was investigated of which factors the lung density depends on and how they affect the dosage precision. Within the lung the density fluctuates considerably; these fluctuations are different from patient to patient and depend on age among other things. This age dependence can be represented by a regression straight line; with this the lung density of patients can be found out from age approximatively. Individual investigation of density from CT-sections can improve precision of dose calculation up to 4%. It has to pay attention to producing CT-sections with normal respiration and in such position as the later irradiation shall be done in.