Dose distribution for a 32P-impregnated coronary stent: Comparison of theoretical calculations and measurements with radiochromic film

Abstract

Purpose : Restenosis, caused by proliferation of smooth-muscle cells, limits the efficacy of catheter-based revascular of coronary arteries. Irradiation has been shown to growth of smooth-muscle cells in vitro and to prevent restenosis in animal models following stent placement. An intraarterial source of 32P, a pure β mitter with a half-life of 14.28 days and a 90% range in water of 3.6 mm, is almost ideal for irradiating just arterial wall without exposing any other part of the patients' heart or any organs, while posing minimal hazards to medical personnel. Two types of previously developed coronary stent impregnated with 32P were investigated. This study aimed to calculate and measure the dose outside of two types of 32P-impregnated β-emitting coronary stents under conditions closely simulating clinical use. Methods and Materials : The dose distributions in water surrounding these stents were calculated using a convolution method and measured by exposing radiochromic film in a solid-water phantom. Results : Experimental results were in excellent agreement with theoretical calculations. Conclusions : Radiochromic dosimetry can be used to measure the dose distribution around a β-emitting intraarterial stent at distances as smal as 0.1 mm from the stent surface. A simple cylindrical shell model is adequate for calculating the dose at points farther than 0.5 mm from the stent surface.