[Comparison of different methods for the determination of the energy dose distribution of enclosed Cs-137 afterloading sources].

A low-dose afterloading unit of the type "Curitron" with Cs-137 sources is available at the Radiologic Hospital of the Karl-Franzens-Universität of Graz. The available sources are between 4.2 cm and 9.1 cm long. The corresponding activities of the individual sources are at present between 117 mCi and 383 mCi. The energy dose distributions around the sources were measured by means of an automatic dose measuring equipment and an additionally developed water phantom. Based on the measurement results, three rapid algorithms were developed and introduced as program modules into the existing therapy planning system which is running under RSX in a minicomputer of the type PDP 11/34. These algorithms are compared with regard to their precision and calculating speed, and the results are presented in form of energy dose distributions.