Publication

Topological methods for the comparison of structures using LDR-brachytherapy of the prostate as an example

Journal Paper/Review - Aug 21, 2009

Units
PubMed
Doi

Citation
Schiefer J, Roth J, Krusche B, Leippold T, Schmid H, Ries G, Plasswilm L, Seelentag W, Vontoggenburg F, Engeler D. Topological methods for the comparison of structures using LDR-brachytherapy of the prostate as an example. Physics in medicine and biology 2009; 54:4959-70.
Type
Journal Paper/Review (English)
Journal
Physics in medicine and biology 2009; 54
Publication Date
Aug 21, 2009
Issn Print
0031-9155
Pages
4959-70
Brief description/objective

The dose coverage of low dose rate (LDR)-brachytherapy for localized prostate cancer is monitored 4-6 weeks after intervention by contouring the prostate on computed tomography and/or magnetic resonance imaging sets. Dose parameters for the prostate (V100, D90 and D80) provide information on the treatment quality. Those depend strongly on the delineation of the prostate contours. We therefore systematically investigated the contouring process for 21 patients with five examiners. The prostate structures were compared with one another using topological procedures based on Boolean algebra. The coincidence number C(V) measures the agreement between a set of structures. The mutual coincidence C(i, j) measures the agreement between two structures i and j, and the mean coincidence C(i) compares a selected structure i with the remaining structures in a set. All coincidence parameters have a value of 1 for complete coincidence of contouring and 0 for complete absence. The five patients with the lowest C(V) values were discussed, and rules for contouring the prostate have been formulated. The contouring and assessment were repeated after 3 months for the same five patients. All coincidence parameters have been improved after instruction. This shows objectively that training resulted in more consistent contouring across examiners.