On the statistics and risks of fiducial migration in the CyberKnife treatment of liver cancer tumors

Abstract

Purpose: To gather statistics about the probability of fiducial migration during the process of treating liver tumor with CyberKnife and analyze the risks brought by fiducial migration. Methods: Between March 2011 and June 2012, 552 patients of liver tumors accepted CyberKnife treatment in the Oncology Radiotherapy Center, among whom the youngest was 21 years old and the oldest was 78. In total, 2378 fiducial markers were implanted in patients, at least 2 fiducials per patient, at most 9 fiducials per patient, and on average, 4.37 fiducials are implanted per patient. We gathered statistics about the fiducial migration before and during the treatment, got the number of cases with fiducial migration and the number of migrated fiducials in these two situations, and studied the risks brought by the migration according to fiducial tracking principle. Results: 78 of the 552 patients had fiducial migration, with a migration probability of 14.13 %; 93 of the 2378 implanted fiducials migrated, with a migration probability of 3.91 %. Before the treatment, 47 patients had fiducial migration, taking 8.51 % of the total; 58 fiducials migrated, taking 2.44 % of the total; during the treatment, 31 patients (5.62 %) had 35 fiducials (1.47 %) migrated. Conclusion: The problem of fiducial migration before treatment, which results in the reduction of trackable fiducials, could be resolved by a re-implantation. If fiducials migrate to other organs before treatment, the selection of fiducials used for tracking may be affected, so we need to recognize them carefully. If fiducials migrate during the treatment, the safety and accuracy of treatment may be influenced, and then CT localization shall be implemented when necessary. No matter fiducial migration happens before or during the treatment, we should take measures proactively to avoid influencing the safety and accuracy of radiotherapy. © Springer Science+Business Media Dordrecht 2014.