[CT-guided manual afterloading with 198-gold seeds in intracerebral tumors]. / CT-gestütztes manuelles Afterloading mit 198-Gold-Seeds bei intrazerebralen Tumoren.

Interstitial brachytherapy of intracerebral tumours was stimulated through the introduction of computed tomography and afterloading technique. Biopsies for their histologic verification as well as the stereotactic implantation of plastic tubes and adjusted to the extent of the tumour can be carried out with a high degree of exactitude by means of CT-supported localization and puncture. The small-sized 198-gold seeds are then introduced according to the manual afterloading technique and remain in situ until the planned dose in the target volume of 50 Gy is achieved. Report on our manual afterloading brachytherapy in high-grade astrocytomas III and IV and in adenomas of the hypophysis. Indications of the diagnostic and therapeutic procedure, irradiation planning, calculation of the dose and discussion of our tentative clinical experience are explained.

[Automatic adaptation of stationary field dose distributions to the individual geometry of the patient. I: Calculation of dose distributions]. / Automatische Anpassung von Stehfelddosisverteilungen an die individuelle Patientengeometrie. Teil I: Bewertung von Dosisverteilungen.

In radiotherapy approved standard irradiation techniques are available for almost all tumor localizations that has to be adapted to individual anatomic situations with the concrete particular case. A possibility is shown that allows an anatomic adaptation of four types of parameters for four coplanar irradiation fields in maximum with permissible expenditure of time. During the dose adaptation process the estimation of the separate dose distribution is done for the target area and for risk organs according to given criteria by an added measure function value that is calculated from measure function values for the areas to be estimated.

[Automatic adaptation of stationary field dose distributions to the individual geometry of the patient. II: A model for adaptation of dose distributions]. / Automatische Anpassung von Stehfelddosisverteilungen an die individuelle Patientengeometrie. Teil II: Modell zur Anpassung von Dosisverteilungen.

Starting point for automatic adaptation of a dose distribution is a starting variant which parameters values are fixed as a matter of experience. On base of this starting variant a limited number of variants is produced and the "quality" of the attained dose distribution in each case is expressed by an added measure function value. A gradual improvement of adaptation of dose distribution to individual geometry of patients is done by pointed search of new parameter values for field breadths, field beginning points, field weights, and field insolation directions.

[Automatic adaptation of stationary field dose distributions to the individual geometry of the patient. III: Practical application]. / Automatische Anpassung von Stehfelddosisverteilungen an die individuelle Patientengeometrie. Teil III: Praktische Anwendung.

For the concrete case of a central bronchial carcinoma the method, explained in parts I and II, is applied for an automatic dose adaptation. In result a dose distribution is found which has a better adaptation of target area isodoses opposite the starting variant and results in a lower exposure of risk regions altogether.

[Questions of accuracy when using "not therapy-specific" computer systems for irradiation planning (author's transl)]. / Zu Fragen der Genauigkeit beim Einsatz "nichttherapiespezifischer" Computersysteme für die Bestrahlungsplanung.

The conditions were examined under which little and medium computer systems not having been primarily developed for radiotherapy can be used in order to make sufficiently precise calculations of dose distributions. The adapted accuracy of the principal factors influencing the dose distribution renders possible a time-saving calculation of several dose distributions and a final calculation. By comparison with a reference calculation made as accurately as possible, the isodose curve shows only little deviations. The following factors were examined in order to find out an eventual influence exerted upon an isodose displacement: number of scan points in the cross-section, correction of the oblique ray incidence, inhomogeneities, dissociations of the rotation field. To our opinion, the isodose displacements found for a dose calculation with adapted accuracy are acceptable when related to influencing factors depending on the individual patients.

[Wood's alloy, a material suitable for quick production of individualized shielding blocks in the mantle technique (author's transl)]. / Die Legierung nach Wood, ein geeignetes Material zur schnellen Herstellung von individuellen Abschirmblöcken für dei Manteltechnik

The extended radiation therapy of lymphogranulomatosis by means of the mantle technique requires individualized focussed satelittes. The production of such individualized, ray divergences considering "lead mantles", however, needs some technical expenditure and causes loss of time. Using Wood's alloy, which has a shielding capacity similar to lead but is well and easily workable because of its low melting point, it is possible to obtain individually adjusted shielding blocks by casting.