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Prostate Cancer
Volume 2011, Article ID 128360, 9 pages
Research Article

An NTCP Analysis of Urethral Complications from Low Doserate Mono- and Bi-Radionuclide Brachytherapy

1NAmur Research Institute for LIfe Sciences (NARILIS), Research Center for the Physics of Matter and Radiation (PMR-LARN), University of Namur (FUNDP), Rue de Bruxelles, 61, 5000 Namur, Belgium
2Department of Physics, Clatterbridge Center for Oncology, Clatterbridge Road Bebington, Merseyside CH63 4JY, UK

Received 13 January 2011; Accepted 2 May 2011

Academic Editor: M. J. Zelefsky

Copyright © 2011 V. E. Nuttens et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Urethral NTCP has been determined for three prostates implanted with seeds based on 125I (145 Gy), 103Pd (125 Gy), 131Cs (115 Gy), 103Pd-125I (145 Gy), or 103Pd-131Cs (115 Gy or 130 Gy). First, DU20, meaning that 20% of the urhral volume receive a dose of at least DU20, is converted into an I-125 LDR equivalent DU20 in order to use the urethral NTCP model. Second, the propagation of uncertainties through the steps in the NTCP calculation was assessed in order to identify the parameters responsible for large data uncertainties. Two sets of radiobiological parameters were studied. The NTCP results all fall in the 19%–23% range and are associated with large uncertainties, making the comparison difficult. Depending on the dataset chosen, the ranking of NTCP values among the six seed implants studied changes. Moreover, the large uncertainties on the fitting parameters of the urethral NTCP model result in large uncertainty on the NTCP value. In conclusion, the use of NTCP model for permanent brachytherapy is feasible but it is essential that the uncertainties on the parameters in the model be reduced.