Abstract

A system has been developed for in vivomonitoring and control of light dose rate and dose during whole bladder wall photodynamic therapy (PDT). Through a modified cystoscope three transparent plastic catheters (1-mm i.d.) can be introduced into the bladder cavity and unfolded into three directions, ~120° apart, along the bladder wall. Into each catheter a miniature isotropic light dosimetry probe is inserted. The fibers of these probes are connected to an electronic readout system with displays for energy fluence rate and integrated light dose. The cystoscope also admits an isotropic light source connected to a laser for irradiation. The readings of the three light dosimetry probes are used to optimize the position of the light source in the optical center of the bladder and to monitor its position during treatment. The uniformity of the irradiation across the bladder wall can also be checked and adjusted. Measurements in vivoconfirm that the true energy fluence rate at the bladder wall is 5–6 times the irradiance of unscattered light (wavelength, 625–630 nm). Measurements during treatment show that controlling the light source position by intravesical ultrasound does not guarantee a uniform light dose distribution across the bladder wall.

© 1988 Optical Society of America