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An Evaluation of the Effectiveness of Surgical Clips for Fiducial Tracking with the CyberKnife in Partial Breast Cancer Surgery

S AHN*, J Kim , S Lee , J Cho , Y Kim , Yonsei Cancer CenterSeoul


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: It is now common practice to insert gold fiducial markers into tumor sites during partial breast cancer surgery to improve the accuracy of treatment when using the CyberKnife® Synchrony Respiratory Tracking System. This paper evaluates the effectiveness of tracking surgical clips, which are similar in shape to gold fiducial markers, when using the CyberKnife®.

Methods: This study included 45 patients who each had four surgical clips implanted into the tumor site prior to radiotherapy to treat partial breast cancer. A total of 30 Gy in 5 fractions was prescribed for the planning target volume. All the patients received X-ray irradiation to calibrate their postures during radiotherapy. The effectiveness of the clips was evaluated by comparing the size and density of the gold fiducial markers and the surgical clips. Other analyses included the tracking failure rates of the surgical clips and changes in treatment times.

Results: The density of the surgical clips (1.95 g/cm3) was 10.8% lower than that of the gold fiducial markers (2.16 g/cm3) despite their similar size and thickness. The X-ray irradiation count was 76.6 ± 8.2 and the tracking failure rate 4.8 ± 1.2%. The average beam delivery time for the patients was 22.3 ± 3.2 minutes, while the average delay in treatment time due to tracking failure was 1.4 ± 0.6 minutes.

Conclusion: No problems occurred during tracking with the CyberKnife® when the surgical clips overlapped with the patients’ ribs because surgical clips have a lower density than gold fiducial markers. On the other hand, the clips could not be tracked when they overlapped with the spine, so they needed to be positioned carefully. Overall, the use of surgical clips in place of gold fiducial markers did not pose a significant problem when tracking tumors during radiotherapy with the CyberKnife®.


Stereotactic Radiosurgery, Radiation Therapy, Breast


TH- RT Interfraction motion management : X-ray projection/CBCT-based

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