Utilization rate of gold fiducial markers and reasons for abandonment in CyberKnife stereotactic body radiation therapy

Abstract

Objective To investigate the utilization rate of gold fiducial markers and reasons for abandonment of gold fiducial markers in the CyberKnife VSI System, and to provide reference data for implantation of gold fiducial markers and radiotherapy planning. Methods From March to August, 2017, a total of 47 patients had gold fiducial markers implanted or pasted. In those patients, 42 patients had gold fiducial markers implanted, including 32 receiving computed tomography (CT)-guided 3D-printing coplanar template assisted implantation, 1 receiving CT-guided 3D-printing non-coplanar template assisted implantation, 1 receiving CT-guided implantation, and 8 receiving ultrasound-guided implantation. A total of 44 patients received the CyberKnife treatment, including 2 patients who failed to use gold fiducial markers and were treated with spine tracking instead and 3 patients missing the treatment for other reasons. The numbers of utilized and abandoned gold fiducial markers were recorded for calculation of the utilization and abandonment rates. The reasons for abandonment of gold fiducial markers were analyzed and classified. Results A total of 134 gold fiducial markers were implanted into or pasted to the 44 patients. In all the gold fiducial markers, 111 were utilized and 23 abandoned, yielding a utilization rate of 82.8% and an abandonment rate of 17.2%.The reasons for abandonment of gold fiducial markers included large rigidity error (26.1%), unqualified implanted fold fiducial markers (17.4%), displacement of gold fiducial markers (26.1%), and others (30.4%). Conclusions Compared with the CT-guided or ultrasound-guided implantation of gold fiducial markers, the CT-guided 3D-printing coplanar or non-coplanar template assisted implantation of gold fiducial markers requires only two puncture needles for each implantation and implants two gold fiducial markers by a single needle, which reduces the number of puncture needles, risk of puncture-induced injury, and incidence of complications after implantation. Not all the gold fiducial markers implanted by a variety of ways will be utilized. Some gold fiducial markers will be abandoned for different reasons, which should be taken into account during implantation of gold fiducial markers. Key words: Neoplasms/stereotactic radiotherapy; CyberKnife; Fiducial markers; Qualified rate