Review of nine years of a 125-Iodine seeds prostate brachytherapy programme

In our hospital, 125-Iodine seeds permanent implantations commenced in January 2007 using Oncura/Amersham Model 6711 single seed deposition. Recently, in July 2015, this seed model has been replaced by the Isoseed 125.S06 (Bebig) model. 682 monotherapy patients have been implanted with Amersham seeds, 33 patients have received Bebig seeds to date. The aim of the study is (1) to evaluate the progression of the programme over time and (2) to compare the two models of seeds utilized. In an initial approach the dose level covering 90% of the US prostate volume, D90%, has been chosen as a quality parameter. Annual descriptive statistics have been calculated for D90% for the Amersham seeds for the years 2007–2014 as well as for the entire set of Bebig seed treatments. With a nominal prescription dose of 160 Gy, the annual average of D90% in 2007 of 150 Gy increases to a plateau value of about 170 Gy in the years 2011–2014. Over the entire time period the annual spread of D90%, expressed as an interquartile range, decreases from 40 Gy in 2007 to a plateau value of about 10 Gy (2011–2014). The Bebig seeds D90% mean value and interquartile range is comparable to the Amersham seed plateau data. The D90% data indicate that with progressing time the prostate brachytherapy dosimetry has improved. After the source model change, no differences in D90% have been observed. The data will be discussed with regard to user variability and treatment protocol changes.