Stereotactic external beam irradiation using a linear accelerator: the Washington University experience.

From February 1989 to December 1993, 139 patients with a variety of brain lesions were treated with stereotactic external beam irradiation using a 6MV linear accelerator. The largest group consisted of patients with recurrent brain metastases (n = 46). Twenty seven patients had malignant gliomas, most of which were recurrent. Several benign conditions were treated, including arteriovenous malformations (n = 27), acoustic neuromas (n = 9), meningiomas (n = 7), and pituitary adenomas (n = 2). Durable responses were seen in the majority of patients with transient, mild, side effects. This experience suggests that stereotactic external beam irradiation is a safe, reliable, and effective method for non-invasive treatment of selected patients with small, localized brain lesions.

Clinical system for simultaneous external superficial microwave hyperthermia and cobalt-60 radiation.

A system for simultaneous thermoradiotherapy was devised to investigate the possible benefits and/or complications of thermal radiosensitization in human superficial tumours. The system combines the well-known treatment modalities of external 915 MHz microwave hyperthermia and cobalt-60 teletherapy. Single waveguide applicators are utilized either attached to blocking trays, so that the gamma beam travels through a waveguide and into the patient (en face setup), or in a conventional way with the microwave propagation vector orthogonal to the gamma beam (orthogonal setup). With these setups a radiation fraction can be delivered in the middle of a 60-min, non-interrupted hyperthermia treatment. Temperatures and power level are remotely monitored and recorded outside the Cobalt room. Extensive measurements and testing showed that the operation of the hyperthermia system (generator, applicators, thermometry unit and temperature sensors) was not disrupted by irradiation and that the microwaves were confined to the treatment room and did not interfere with the operation of the Cobalt unit, of an adjacent linear accelerator or of an adjacent radiotherapy simulator. For the en face setup the dose distributions induced in solid water phantoms were uniform with the exception of a narrow (< 0.5 cm) region under the applicators' internal probes where 10-18% reduction exists. This dose defect is clinically smoothed using feathering techniques. The system has been successfully used without technical problems in 51 treatments in 15 patients (18 lesions) in a phase I/II clinical trial. An analysis of the thermal data showed that the temperature distributions achieved during simultaneous delivery have the same general characteristics of those achieved in conventional sequential hyperthermia with microwaves, and that the steady state distributions are maintained during the time of simultaneous irradiation. The tests performed in addition to the preliminary clinical experience clearly indicate that this type of combined therapy is technically feasible and safe. Here the system for simultaneous, external, superficial thermoradiotherapy and the implementation tests performed are described in detail. Preliminary clinical experience and results are also reported.

[On the value of drill biopsy in diagnosis of breast lesions (author's transl)]. / Untersuchungen über den Wert der Drillbiopsie in der Mammadiagnostik.

During a period of 30 months 216 drill biopsies of palpable breast lesions were carried out. By using this method sufficient tissue material for a histological examination could be acquired in all cases. Out of 106 cases, in which the histological results could exactly be proved by following excision biopsy or mastectomy, 87% were correctly diagnosed by drill biopsy. The reason for failure in all of the 14 false drill biopsy diagnoses was due to sampling error. Comparing the diagnostic results of the first 15 month after establishing the method, with the second half of the investigation period, a considerable improvement from 80% to 94% of correct diagnoses could be established. This improvement was based on increasing experience and routine. By means of drill biopsy, cosmetically and diagnostically disturbing scar formation could be avoided. Drill biopsy can be carried out in local anaesthesia and on outpatient basis as well. It is also suitable for frozen-section technique.