Radio-opaque isotropic fiber optic probes for in vivo photodynamic therapy dosimetry

When measuring laser light distribution in tissue during photodynamic therapy, accurate determination of the position of the monitoring probes is vital. For this purpose, computerized tomographic scanning has been incorporated into our treatment routine. Different mixtures of barium sulphate powder and an opaque dental sealant were used in the construction of probes which could be imaged on a computerized tomographic scan. These were tested for radio- opacity, isotropy and strength, and a mixture of 27% barium sulphate powder and 73% opaque dental sealant was found to be suitable.