Dosimetry of beta sources for cardiovascular brachytherapy

Abstract

Introduction

Over a period of the last ten years the application of ionizing radiation in the prevention of restenosis in cardiovascular diseases has become a treatment of choice. The aim of this study was the verification of procedures used for the determination of the activity and uniformity of a P-32 wire source used in brachytherapy of cardiovascular disease.

Materials and methods

Measurements of activity and uniformity were carried out for beta P-32 radioactive sources used in the Galileo afterloading system from Guidant. Measurements of activity were carried out with an ionization well chamber. Source homogeneity was measured with radiochromic films.

Results and discussion

The activity of the source determined on the basis of measurements with a well chamber agreed within 1.5% with the activity values provided by the manufacturer for each source. The results show that the activity distribution along the source length is homogeneous within ±5%. The dose rate fall-off as a function of the distance from the source axis measured with a radiochromic film is in good agreement with Monte Carlo calculations.

Conclusions

Measurements of the activity of P-32 sources with a dedicated well chamber confirm with high accuracy the results of activity measurements provided by the manufacturer. The methods of measurement of source activity and uniformity presented in this paper assure proper quality of treatment planning in cardiovascular brachytherapy.