SYSTEMS FOR LIGHT APPLICATION AND DOSIMETRY IN PHOTODYNAMIC THERAPY

Successful photodynamic therapy requires homogeneous irradiation and l ight detection for dosimetry. Light delivery devices and detectors for treatment of spherical and cylindrical hollow organs have been develo ped. For photodynamic therapy of multifocal superficial bladder tumour s a catheter with an isotropic emitter is centred by a balloon. Light which is backscattered from the tissue surface is used for on-line dos imetry. The irradiation and dosimetry concept has been proven by compu ter simulations for a non-spherical bladder shape. Larynx, bronchi, oe sophagus and cervix have been irradiated by devices adapted to the sha pe of the organ. The light distribution is homogenized by multiple bac kscattering from a nearly white layer in contact with tissue, a promis ing method also for hollow organs with irregular geometry. The homogen eity of the light distribution as well as the dosimetry have been impr oved by the devices to be presented.