Absorbed dose determination for interstitial 125I boost therapy

Abstract

125I implants are being used to boost external beam treatments of unresectable pancreas and lung tumors [human]. Calculations of the 125I activity required to achieve a specific average peripheral dose are presented as a function of the average tumor dimension for spherical, ellipsoidal, and cylindrical implants. Both uniform and random seed spacings are investigated. The results indicate that the average peripheral dose is relatively insensitive to the seed distribution as well as to the seed activity. The average tumor dose is typically 20% greater than the average peripheral dose.