open access
Retrospective assessment of a single fiducial marker tracking regimen with robotic stereotactic body radiation therapy for liver tumours
open access
Abstract
Aim
To investigate tumour motion tracking uncertainties in the CyberKnife Synchrony system with single fiducial marker in liver tumours.
Background
In the fiducial-based CyberKnife real-time tumour motion tracking system, multiple fiducial markers are generally used to enable translation and rotation corrections during tracking. However, sometimes a single fiducial marker is employed when rotation corrections are not estimated during treatment.
Materials and methods
Data were analysed for 32 patients with liver tumours where one fiducial marker was implanted. Four-dimensional computed tomography (CT) scans were performed to determine the internal target volume (ITV). Before the first treatment fraction, the CT scans were repeated and the marker migration was determined. Log files generated by the Synchrony system were obtained after each treatment and the correlation model errors were calculated. Intra-fractional spine rotations were examined on the spine alignment images before and after each treatment.
Results
The mean (standard deviation) ITV margin was 4.1 (2.3)mm, which correlated weakly with the distance between the fiducial marker and the tumour. The mean migration distance of the marker was 1.5 (0.7)mm. The overall mean correlation model error was 1.03 (0.37)mm in the radial direction. The overall mean spine rotations were 0.27° (0.31), 0.25° (0.22), and 0.23° (0.26) for roll, pitch, and yaw, respectively. The treatment time was moderately associated with the correlation model errors and weakly related to spine rotation in the roll and yaw planes.
Conclusions
More caution and an additional safety margins are required when tracking a single fiducial marker.
Abstract
Aim
To investigate tumour motion tracking uncertainties in the CyberKnife Synchrony system with single fiducial marker in liver tumours.
Background
In the fiducial-based CyberKnife real-time tumour motion tracking system, multiple fiducial markers are generally used to enable translation and rotation corrections during tracking. However, sometimes a single fiducial marker is employed when rotation corrections are not estimated during treatment.
Materials and methods
Data were analysed for 32 patients with liver tumours where one fiducial marker was implanted. Four-dimensional computed tomography (CT) scans were performed to determine the internal target volume (ITV). Before the first treatment fraction, the CT scans were repeated and the marker migration was determined. Log files generated by the Synchrony system were obtained after each treatment and the correlation model errors were calculated. Intra-fractional spine rotations were examined on the spine alignment images before and after each treatment.
Results
The mean (standard deviation) ITV margin was 4.1 (2.3)mm, which correlated weakly with the distance between the fiducial marker and the tumour. The mean migration distance of the marker was 1.5 (0.7)mm. The overall mean correlation model error was 1.03 (0.37)mm in the radial direction. The overall mean spine rotations were 0.27° (0.31), 0.25° (0.22), and 0.23° (0.26) for roll, pitch, and yaw, respectively. The treatment time was moderately associated with the correlation model errors and weakly related to spine rotation in the roll and yaw planes.
Conclusions
More caution and an additional safety margins are required when tracking a single fiducial marker.
Keywords
CyberKnife; Synchrony system; Fiducial marker tracking; Liver tumour; AP; CTV; GTV; LED; ITV; LR; PTV; SBRT; SD; SI; XST
About this articleTitle
Retrospective assessment of a single fiducial marker tracking regimen with robotic stereotactic body radiation therapy for liver tumours
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
383-391
Published online
2019-07-01
DOI
10.1016/j.rpor.2019.06.001
Bibliographic record
Rep Pract Oncol Radiother 2019;24(4):383-391.
Keywords
CyberKnife
Synchrony system
Fiducial marker tracking
Liver tumour
AP
CTV
GTV
LED
ITV
LR
PTV
SBRT
SD
SI
XST
Authors
Masao Nakayama
Kazuyuki Uehara
Hideki Nishimura
Shuhei Tamura
Yoshiki Munetomo
Shinji Tsudou
Hiroshi Mayahara
Naritoshi Mukumoto
Moshi Geso
Ryohei Sasaki