Tumor dose specification of I-125 seed implants

Abstract

A new calculation procedure for interstitial implants with I-125 seeds is presented. The total activity of I-125 seeds required to deliver a net minimum dose of 1 Gy is also given as a function of implant volume for various seed spacings. This will permit clinicians to prescribe a specific dose for patients as a primary or boost treatment. Elongation and shape corrections are studied. Discussions and comparisons with other dosimetric calculations such as "matched" peripheral dose, average minimum dose, and minimum peripheral dose are made. The results indicate that for a fixed total activity the net minimum dose is relatively insensitive to variations in seed spacing and individual seed activity.