[Interstitial afterloading therapy. Principles, practical application and first clinical experiences]

The principle and practical application of an afterloading system for interstitial therapy is reported. The system works with a single Ir-192 source with high dose rate and achieves the optimum dose distribution by gradual displacement and variable position times. A specially developed computer program serves to calculate the stopping times of the source. The implantation is performed with hollow needles made of refined steel, which are held in parallel position by means of jigs fixed to the patient. 28 patients with 36 tumors have been treated. The dose was determined according to the experiences in gynecologic afterloading therapy with high dose rate sources and dosage prescriptions in teletherapy. The authors present the therapeutic results of this pilot study, discuss the new system and show practicable possibilities for further development.