Strahlentherapie最新文献

Therac 15-Saturne is a linear accelerator for photon and electron radiation with a double scattering screen system. It has proved its worth during more than three years of clinical use. The dosimetric data of both kinds of radiation correspond to the international requirements for modern therapy units. The trimmer system for electron radiation is equipped with a continuous field size adjustment device for the whole range of field sizes. Thus a fast and precise adjustment is possible without any changing of tubes.

66 patients with malignant primary liver-tumors and liver-metastases from different histologic types were treated by radiotherapy between 1970 and 1984. Five patients had primary tumors and 61 metastases. The desired dose was 2400 cGy within three weeks, several patients received yet higher doses. In 45 cases radiation treatment was combined with a simultaneously or sequentially delivered polychemotherapy. The median survival of the expired was five months, nine patients survived one year. Three patients are alive more than one, five and seven years, their history is reported. Radiotherapy is either alone or in combination with chemotherapy an effective method for palliation in liver malignancies. In a few cases even longer lasting survival times are possible.

For checks and service an online monitoring-system consisting of 10 Si-photoelements will be described. It allows a very simple and fast control of field flatness in therapy-accelerators.

The different techniques and radioisotopes for the intracavitary remote-controlled afterloading therapy of the carcinoma of the cervix are discussed. Single or multi-channel applicators including sector-shielding are characterized. A modified 3-channel-applicator offers beside the well known advantages, the possibility to irradiate a vaginal infiltration and the cervix simultaneously and guarantees a definite distance to rectum and bladder and allows an improved representation on localisation-films. Extended tumor-invasion requires beside the intracavitary therapy an additional percutaneous irradiation. Depending on the theoretical approach, intracavitary or percutaneous therapy is predominant. The complex 3-dimensional intracavitary isodose distribution and the locally different fractionation has to be considered by matching the intracavitary and percutaneous therapy. The biological effect of different fractionations arising from the abrupt intracavitary isodose decrease, enlarged penumbra regions behind wedge-filters or slow decreasing isodoses from moving-field irradiations have to be taken into consideration.

The importance of bone scintigraphy for the classification of stages of lymphogranulomatosis is judged differently, the indications in literature are not unanimous. The high sensitivity of this method is uncontested, but it is said to be not very reliable in the exclusion of a bone manifestation because of its low specificness. Bone scintigraphy demonstrates a disturbance in bone metabolism; in clinical examination this has to be checked by X-ray view in order to exclude not tumor-induced reasons for the increased or decreased concentration. In a prospective study we have investigated if this combined radiologic approach allows to use scintigraphy in the classification of stages. Four out of 23 patients in stage I showed a tumor-suspicious scintigram which was confirmed by X-ray examination within 1 1/2 years in two patients. One quarter of 133 patients in stage II and III had a pathologic scintigram. In 34 out of 36 patients who could be followed up, this was confirmed later on by an X-ray finding in the same site. 15 out of 36 patients in stage III with initially normal scintigram showed a conversion to a tumor-suspicious scan during the later course of the disease. The tumor-suspicious scintigraphy found at the time of classification of stages has been confirmed later on by X-ray examination in 91% of our series. So, scintigraphy may be considered to be valuable for the classification of stages. Furthermore the conformity of tumor-suspicious scintigram and bone marrow biopsy was investigated. Whereas in 62% of patients with M+ a bone manifestation could be demonstrated by scintigraphy, only 46% of patients with scintigraphic 0+ showed a histologic manifestation in bone marrow. Consequently, bone scintigraphy cannot be used to demonstrate or to exclude a manifestation in bone marrow. As the metabolism is modified by therapy in case of a demonstrated bone manifestation, scintigraphy should be a sensitive parameter in these cases, too, for an early indication of response to cytostatic treatment. The scintigram became normal in 46 patients coming to a complete remission; eight out of nine patients the scintigraphic findings of whom became worse were non-responders. Five out of twelve patients with unchanged scintigram came to a remission. A normalizing scintigram indicates a response to therapy, whereas a deterioration suggests a non-response. Bone scintigraphy can also be used to judge the success of a cytostatic therapy.

Recent developments in computer technology enable the use of direct measured data without complex calculations for the isodose generation of electron fields of a 42 MeV Betatron. To reduce the time necessary for measuring the isodose data, different procedures to measure and generate electron matrices are investigated. Different methods to reduce the amount of data necessary for the isodose-generation are introduced. Under certain circumstances isodose data for numerous field sizes can be generated from a set of data of one field with sufficient accuracy.

The results of NMR tomography obtained hitherto in the imaging of malignant tumors are presented in order to show that this new method is of great importance for radiotherapy. A quantification of radiotherapy and chemotherapy seems possible with the aid of NMR diagnosis, as vital and necrotic tumors zones as well as radiation effects in the tumor and in sound tissue can be visualized.

The short-term afterloading therapy (AL-ST) with high dose rates (DR) and remote control prevents the risk of a radiation exposure of the staff, facilitates the optimization of the dose distribution in space, makes the treatment easier for patients and hospital, and allows a considerable increase of the treatment capacity without additional need of staff or capital. AL-ST works with another dose distribution in time than the conventional brachytherapy, so a higher fractionation of high-dose-rate afterloading is substituted for the classical protraction of low-dose-rate brachytherapy. 2072 patients with gynecologic tumors were treated by AL-ST between 1974 and 1983. 1762 out of them (964 carcinomas of the cervix, 677 carcinomas of the body, and 121 vaginal tumors, metastases and urethral carcinomas) could be checked up for at least twelve months up to more than five years, which allowed an evaluation with regard to recurrence-free survival rate, local absence of tumors, and side effects. The five-year survival rates obtained by primary and post-operative AL-ST are compared to historical control groups of our own hospital and to the international results. The results, related to the stages, are at least equivalent; several groups show a statistically significant improvement compared to conventional brachytherapy. The incidence of early and late reactions in bladder and rectum showed a statistically significant decrease after AL-ST and was dependent on the dose in a statistically highly significant manner (p = 0.001). In addition to the well-known advantages of AL-ST, the following may be mentioned: 1. The intracavitary application was made without general anaesthesia, only with sedation by drugs, which prevented the primary treatment mortality. 2. An ambulatory treatment was possible in about 40% of the cases due to the time-sparing and patient-sparing method--the advantages are evident. 3. The therapeutic efficacy is increased and the risk of side effects in bladder and rectum is decreased by the better radiobiologic (same DR) and dosimetric adaption of AL-ST and percutaneous high-voltage therapy.