Development and preclinical test of a 32P containing PEEK foil aiming at urethral stricture prevention by LDR brachytherapy

Purpose: Primary or recurrent urethral stenosis are a common clinical problem. The aim of this feasibility study was development and application test of a novel radioactive catheter for potential use in LDR brachytherapy to prevent urethral stenosis. Methods: A beta radiation emitting 32P-foil was developed and integrated in an indwelling catheter, which is usually inserted after surgical interventions in the urethra. Activity and dose distribution were measured after neutron activation of the 31P foil component with scintillation techniques as well as radiochromic films and compared to MC simulations. Practicability and radiation safety of this new applicator was tested on male rabbits, which underwent before catheter application a new method of stricture induction by radial laser light irradiation. Results: Measured dose distributions of catheters with 32P-foils were found in good agreement with MC simulations. Wash-out test confirmed the radioactive catheter setup to be inside the permitted limits of a sealed source. Strictures could be induced by laser light in all animals, surgically treated by slitting and irradiation with a 7-day dose of 15 Gy or 30 Gy without adverse radiation effects during 4 weeks observation time. Conclusions: This prove-of-concept study presents a save and technically uncomplicated approach of LDR brachytherapy intending to prevent urethral stenosis. The prescribed irradiation dose can be administered in a reproducible and precise manner using a urethral catheter as carrier of a beta radiating foil. The study duration of 63 days was too short for statistically significant stricture related conclusions. This approach may be considered for similar problems in other hallow organs.