Systems for light application and dosimetry in photodynamic therapy.

Successful photodynamic therapy requires homogeneous irradiation and light detection for dosimetry. Light delivery devices and detectors for treatment of spherical and cylindrical hollow organs have been developed. For photodynamic therapy of multifocal superficial bladder tumours a catheter with an isotropic emitter is centred by a balloon. Light which is backscattered from the tissue surface is used for on-line dosimetry. The irradiation and dosimetry concept has been proven by computer simulations for a non-spherical bladder shape. Larynx, bronchi, oesophagus and cervix have been irradiated by devices adapted to the shape of the organ. The light distribution is homogenized by multiple backscattering from a nearly white layer in contact with tissue, a promising method also for hollow organs with irregular geometry. The homogeneity of the light distribution as well as the dosimetry have been improved by the devices to be presented.