Dose calculation of 142Pr microspheres as a potential treatment for arteriovenous malformations.

Arteriovenous malformation (AVM), especially cryptic AVM, can cause highly variable cerebral neurological defects. Injection of 142Pr microspheres into arteries feeding an AVM in order to simulate radio-embolism has been proposed as a novel treatment method. To investigate optimization of radiation dose to the clinically important arterial wall area, preliminary dosimetric studies have been performed. Monte Carlo calculations were performed for simulated arteries filled with microspheres packed by random packing. Arterial radii from 0.05 mm to 3 mm and microsphere radii from 0.01 mm to 0.7 mm were used in the simulation. For constant arterial size, dose varied significantly with microspheres radius. Inter-arterial effect was also simulated using simplified geometry. For the inter-arterial sites, the dose rate was calculated between two arteries of the same size parallel to each other. The dose increased significantly for large arteries (>1 mm radius) filled with large microspheres (>0.3 mm radius). The dose increase between small arteries (<0.3 mm radius) was not as significant as that between large arteries. Overall results indicate that arterial size and microsphere size significantly affect the dose profile. This factor should be taken into account in future clinical applications.