192Ir brachytherapy sources in Belgian hospitals

To treat some types of cancer, radionuclide sources are implanted into the patient to deliver high doses of radiation to a limited volume of tissue. Ir-192 is one of the most common isotopes used in brachytherapy. Medical physicists are responsible for the accuracy of the absorbed dose in the treated volume of the patient. The dose is prescribed by the physician. In brachytherapy the dose distribution produced by homogeneous linear Ir sources is well known. The Belgian Hospital Physicist Association describes here its work related to some of the main problems in brachytherapy, namely a survey of the characteristics of the sources; homogeneity and source strength measurements with commercially available radionuclide calibrators and linear activity meters; and the determination of the required accuracy on the homogeneity of the wires derived from analysis of calculated dose distributions produced by inhomogeneous sources.