Quality assurance for non-invasive patient fixation during stereotactic convergent beam irradiation.

Using a non-invasive mask this patient fixation system for stereotactic radiotherapy allows one to perform fractionated irradiation. Measuring the statistical quantities of patient motion and positioning uncertainties and calculating its effect on a spherically symmetric dose distribution showed that there is no severe disadvantage in most cases. Only if small field-size, excentric target volume localisation and extreme proximity to an organ at risk coincides have the statistical effects to be taken into account. The greatest measured standard deviation for positioning uncertainty was 2.3 mm. Its effect on the dose distribution with a field size of 9.1 mm increases the diameter of the 80% isodose to about 115%.

[A device for rapid and reliable loading, with reduced radiation exposure, of Hodt applicators with Au-198 seeds]. / Vorrichtung zur schnellen, sicheren und strahlenbelastungsreduzierten Beladung von Hodt-Applikatoren mit Au-198-Seeds.

Thanks to the improved devices at the Royal Marsden gun the loading time for gold seeds has been reduced by about one third as well as the radiation exposure has been reduced to about one tenth, due to the fact that the fingers are not so long close to the seeds. The reliability and the manageability has been improved, too.

[Radiotherapy of esophageal cancer--indications, methods and attainable results]. / Strahlentherapie des Oesophaguskarzinoms--Indikation, Methodik und erzielbare Ergebnisse.

From 1965-1985, in the Department of Radiotherapy of the University Hospital of Freiburg 226 patients with esophageal carcinoma have been treated with primary radiotherapy at a sufficient tumor dose - 138 of them with curative and 66 patients with palliative intention. With curative irradiation the survival rates between 1 at 5 years were 28.6%, 14.1%, 8.2%, 5.8% and 3.5%. To palliative indication the 1 year survival rate was 10.4%, none of these patients reached the two years' limit. Apparently relevant prognostic factors are: length of history, overall state of health, histologic classification, tumor stage, state of clinical remission, localization of the tumor. Our findings were compared with observations between 1965 and 1985. This paper deals with the problems of pre- and post-therapeutic irradiation, in combination with chemotherapy. Indications for radiotherapy, definition of the target volume and the different techniques of radiation planning and performance are discussed, especially with reference to comparison of stimulator- and CT-assisted radiation planning. We demonstrate the possibilities of rotation therapy with an electronically controlled diaphragm device developed in our department.

[Stent implantation as a palliative measure in an inoperable bronchial tumor. Initial experiences with an endoscopically implanted stent]. / Stentimplantation als Palliativmassnahme beim inoperablen Bronchialtumor. Erste Erfahrungen über eine endoskopisch implantierte Stentapplikation.

Imminent asphyxia due to tracheal or bronchial compression by inoperable tumors in the mediastinum and the central bronchi is serious, particularly if alternative treatments, i.e., radiation or chemotherapy, have been exhausted. For that reason, stents of different diameters and lengths were developed that could be dilated. With the patient under general anesthesia these stents can be introduced into the stenotic bronchus or trachea through a rigid bronchoscope. The appropriate stent is mounted on a 3-mm balloon catheter, which is inflated after the stent is in the correct position. Positioning is done under direct bronchoscopic and fluoroscopic control. After deflation of the balloon, the stent maintains its cross-sectional shape and keeps the airway open. The first clinical application was in a 53-year-old patient with end-stage small-cell carcinoma. The patient had had a relapse after combined chemo- and radiotherapy and had severe stridor. Stent insertion led to a significant relief of symptoms. The second patient, a 53-year-old woman who suffered from collapse of the bronchus caused by a radionecrosis, was treated by the same method. Nine months later, ventilation is excellent in the left lung, and the patient can tolerate the stent without any clinical symptoms. A 69-year-old woman suffered from a tracheal carcinoma with severe tracheal stenosis. It was possible to maintain the stability of the collapsed tracheal wall by insertion of a tracheal stent. This new technique can provide good palliative treatment and is sometimes even the main therapy in such cases.

Clinical application of percutaneous transluminal angioscopy. Comparison of findings in percutaneous transluminal angioplasty, thrombolysis, thrombus-extraction and stent-application.

Since the introduction of ultrathin angioendoscopes into clinical application, it has been possible to subject the findings of conventional or digital angiography to objective verification. In dogs and in patients, this new angioscopic method for visualization of arteries without surgical intervention has been carried out. The approach is transfemoral. Endoscopy is combined with angiography and, when indicated, percutaneous transluminal angioplasty (PTA), thrombolysis, thrombus extraction and insertion of a new type of stent. An ultrathin endoscope with an outer diameter of 1.6 mm and a working channel of 0.35 mm is used. Guidewires, contrast media and drugs for local thrombolysis can be employed through this channel. The endoscope is placed in the region of interest under fluoroscopy and direct visualization is obtained by using 0.9% NaCl for decreasing blood flow. Image recording is achieved by video or high-speed camera. With this method, the intraluminal events of dilatation, recanalization, local lysis, stent application and thrombus extraction can be visualized.

[Equipment for rapid and reliable perineal implantation of I-125 seeds in prostatic cancer with reduced radiation exposure]. / Vorrichtung zur schnellen, sicheren und strahlenbelastungsreduzierten perinealen Implantation von J-125-Seeds beim Prostatakarzinom.

The aim of an implantation of iodine seeds into the prostate controlled by ultrasound is reached by means of the equipment presented in this paper. The method, allowing to implant the seeds according to the therapy plan, has been developed above all in order to reduce the radiation exposure to the physicist, the radiotherapist and the surgeon.

[Individual field shaping in rotational irradiation]. / Individuelle Feldformung bei der Rotationsbestrahlung.

At the Radiotherapy Department of the University Hospital of Freiburg i.Br., an additional diaphragm controlled by an electronic system in dependence on the angles was developed for the optimization of irradiation planning, i.e. administration of the therapeutically necessary dose to the target volume and, at the same time, sparing of risk organs.