A system and method for interactive therapy and diagnosis of a human or animalcomprising at least one first radiation source for emission of a diagnosticradiation, at least one second radiation source for emission of a therapeuticradiation, and at least one radiation conductor adapted to conduct radiationto a tumour site at or in said human or animal. A non-mechanical operationmode selector directs the therapeutic radiation and/or the diagnosticradiation to the tumour site through the radiation conductors. The operationmode selector means is preferably a non-mechanical optical switch and/or anoptical combiner. The system may be used for interactive interstitialphotodynamic tumour therapy.
