Radiobiologia, radiotherapia最新文献

Radiation induced changes in the testicular RNA content of whole body irradiated Swiss albino mouse and their modification by a thiophosphate, WR-2721 were studied. Three different doses of gamma radiation were given for the purpose. The RNA content of the testis was found to be affected adversely after irradiation. It was observed that the drug inhibited the alterations in the RNA content to a significant extent. Degree of protection and possible mechanisms of action have been discussed.

Quantitative changes in nucleic acids and DNA synthesis in the bone marrow and blood were followed after a single neutron irradiation with the dose of 2 Gy alone and combined with subsequent continuous gamma irradiation up to accumulated dose of 6 Gy. The pattern of changes after neutron exposure was similar as after other kinds of ionizing radiation. Additional continuous gamma irradiation affected mainly the rate of regenerative processes.

Morphologic alterations were studied in rat bone marrow and spleen after wholebody neutron irradiation (2 Gy dose). Neutron irradiation causes damage of hemapoietic organs changing their morphological structure already in the first hours after irradiation. The damage is further intensified reaching its maximum on 3rd day. Recovery of the hemopoiesis in the bone marrow and spleen begins approximately on 5th day being complete by 15th to 21st day after irradiation. Continuous gamma irradiation for 10.5 days following single neutron irradiation (total accumulated dose of 6 Gy, daily input dose of 0.574 Gy) results in prolonged inhibition of the hemopoietic activity until termination of the irradiation. Reparation of the damaged bone marrow is seen only on about day 5 after cessation of continuous irradiation; this implies that continuous irradiation following neutron irradiation delays the onset of reparative processes by approximately 5 days. In the spleen reparation of erythropoiesis begins already during the irradiation.

Principles for prophylaxis, early diagnosis, therapy, and after-care of mammary carcinoma are discussed. With this basis interdisciplinarily co-ordinated recommendations are given for therapy and after-care, which have been elaborated by a group of specialists.

With 282 autopsied patients with bladder carcinoma, that were treated by combined operation and radiotherapy, conclusions are given for tendency in tumor spreading as well as for complications and late-effects of radiotherapy. In 24.5% of the cases tumor tissue was found within the bladder and in 30.5% of the cases within the minor pelvis. Metastases were found in 24.1% in iliac lymph-nodes, in 21.3% of the autopsy cases in abdominal lymph-nodes. Liver, lungs, bones, and kidneys are main organs for hematological metastasizing. Little or undifferentiated carcinomas and squamous cell carcinomas show a greater tendency to metastasize than highly and medium-differentiated ureteral carcinomas. The least radiotherapeutical complications and late-effects were found in a fractionation with daily 1.5 Gy and a total dose of 60 Gy (necrotising urocystitis 17.9%, proctitis 3.6%).

Not only in experiment on animal but also from analysis of clinical data important knowledges could be obtained in the last years, that deal with the course of biological processes in tumor and normal tissue during fractionated irradiation. In centre there are differences in the capacity for recovery from sublethal radiation injury and in repopulation. Chronically reacting normal tissues show a clearly higher repair capacity than tumors, that can be used for hyperfractionation with reduced single doses. With it higher attention must be given to repairing time yet, that the selective benefit is not endangered by incomplete recovery. On the other side clinical analyses have confirmed that the stem cell repopulation--going on in several tumor types, so e.g. in squamous cell carcinomas, during the time of conventional treatment--can make a considerable contribution to radioresistance. The actual level of knowledge justifies further clinical experiments with unconventional fractionation, especially with accelerated hyperfractionation.

From experiences in Rostock nasopharyngeal carcinomas are a domain of radiotherapy, whereas surgical measures can be used in lymph node metastases additionally. Carcinomas of the oropharynx need a balanced radiosurgical combination therapy, which has been done by sandwich-procedure in Rostock for 10 years. The value of an additional chemo- or immunotherapy needs further securing yet, as generally a prospective randomized study is suggested for all the country. Carcinomas of hypopharynx are treated in combination by operation of different dimension and after-irradiation.

In afterloading contact therapy of cervico-facial tumors the control of position of the applicator has a special importance. Especially this applies the contact therapy in epipharynx. By means of a phantom of synthetic material the application can be simulated in epipharynx and the position of the applicator can be shown by means of computer-assisted tomography in all three planes. Estimation of distances by computer-assisted tomography allows correction in position and also control of corrected applicator position. Compared to it the glass fibre endoscopy requires longer working time and the topographical orientation is rendered more difficult with the technique being available in the same manner as post-rhinoscopic endo-photographic documentation of findings.

Since 1982 79 patients with intracranial AVM's were irradiated at linear accelerator with 10 MV photons. Diagnosis, localization and therapy were done immobilizing the head for identical positioning. In a controlled study the therapy was done with fractionated irradiation up to 50 Gy in 25 fractions within 5 weeks or with 20 Gy in 4 fractions within 7 days. Complications, due to therapy, did not occur. Suffering from convulsion was not affected. Five patients have died, one patient got a hemorrhage 36 months later. The angiographical analysis of the first 25 patients until 30 months after radiotherapy gave complete obliterations and reduction of volume in more than 50% with minor AVM's. The result are not detrimental compared with a group after photon irradiation.