[Radiation side effects of neutron and photon therapy of soft tissue sarcomas. Results of a 4-year pilot study]. / Strahlennebenwirkungen einer Neutronen- und Photonentherapie von Weichteilsarkomen. Ergebnisse einer vierjährigen Pilotstudie.

Within the frame of a four-year pilot study, 41 soft tissue sarcomas were treated with neutrons (31 patients), photons (3 patients), or a combination of both radiations (7 patients). All three patients submitted to relatively high neutrons doses (N + gamma) of 19 Gy showed marked radiogenic side effects. A relatively high percentage of radiogenic side effects (4/11) was observed after a total dose of 18 Gy, too. However, doses of 16 to 17 Gy did not cause any severe troubles. After doses below 16 Gy, the local recurrence rate is relatively high.

The three-dimensional dose distribution of 125I seeds in tissue.

The radiation treatment of brain tumours with 125I seeds requires a precise knowledge of the entire three-dimensional dose distribution of the seed. Assuming a point source distribution modified by an anisotropic factor, the absorbed energy is calculated and compared with measurements obtained using 7LiF thermoluminescence dosemeters. The measurements are carried out in air and in Mix-D. A mean relative difference of 5% is found between calculation and measurement of the dose perpendicular to the seed axis. It is concluded that the entire three-dimensional distribution of absorbed dose in tissue can be determined by a simple formula, which enables the calculation of absorbed dose at any point of interest with an uncertainty of 6%.

Combined use of stereotaxic CT and angiography for brain biopsies and stereotaxic irradiation.

A Riechert Mundinger stereotaxic device was modified to enable artifact-free computed tomographic (CT) scanning with the stereotaxic frame attached to the patient's head. A localization system was developed allowing determination of the XYZ coordinates of the target point directly from the CT cut. Angiography was performed intraoperatively with the stereotaxic frame attached. Coronal and sagittal CT reconstructions were enlarged to the radiographic magnification to allow direct comparison with angiography. CT offered optimum localization of the target, whereas angiography determined the safest approach. Computer programs were developed to enable three-dimensional radiotherapy planning. 125I seeds were implanted for treatment of low-grade gliomas and solid craniopharyngiomas. Yttrium-90 was applied in cystic craniopharyngiomas. Intracavitary rhenium-186 application was abandoned because of frequent cyst recurrence and leakage from the cyst.

Biological dosimetry by chromosome aberration scoring with parallel image processing with the Heidelberg POLYP Polyprocessor system.

Chromosome aberrations in human peripheral blood are recognized parameters of cellular damage and are used as indicators of exposure to ionizing radiation. In order to reach the low dose range, up to 10,000 metaphase cells each consisting of 46 chromosomes have to be analysed for each radiation exposed person. In order to perform this task within reasonable time limits the application of the Heidelberg POLYP Polyprocessor is considered. The POLYP consists of a number of processor modules and several global memory modules which are interconnected by a multi-common-bus for parallel data transfers and a multiple synchronization bus for processor/task-scheduling. The system is designed for handling large amounts of data in real time as is typical for image processing applications.

Stereotactic computer tomography with a modified Riechert-Mundinger device as the basis for integrated stereotactic neuroradiological investigations.

For stereotactic biopsy, intracavitary and interstitial irradiation of intracranial tumours, stereotactic CT investigations are of utmost importance. Target-points within a tumour as well as the tumour-outlines have to be transferred precisely from transverse and longitudinal CT sections to stereotactic X-ray images. For this purpose, the stereotactic apparatus of Riechert and Mundinger has been equipped with a fixation system of carbon fibre and a measuring phantoma of plexiglass with embedded steel wires allowing stereotactic CT scanning without artefacts. The stereotactic coordinates (x, y, z) of any target point can be taken directly from transverse CT images with high accuracy. The tumour outlines can be transferred to the stereotactic coordinate system from longitudinal CT reconstructions using special computer programmes. Precise transfer is possible if the CT investigation is performed stereotactically.

Direct visualization of intracranial tumours in stereotactic and angiographic films by computer calculation of longitudinal CT-sections: a new method for stereotactic localization of tumour outlines.

A new method for the direct transformation not only of a target point, but also of the whole tumour outlines from sagittal, coronal, and oblique computer calculated CT-reconstructions to stereotactic X-ray films of any scale is presented. The role of this method in the stereotactic therapy of intracranial tumours and the possibilities which are thus provided are discussed.