Virtual Library
Start Your Search
K. Li
Author of
-
+
P2.05 - Poster Session with Presenters Present (ID 463)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
-
+
P2.05-048 - Directional Characteristics of Motion Marker in CBCT for Target Localization for Lung Stereotactic Body Radiotherapy (SBRT) (ID 6243)
14:30 - 14:30 | Author(s): K. Li
- Abstract
Background:
Fiducial marker has been an effective and intuitive way to localize motion target for lung Stereotactic Body Radiotherapy (SBRT). However, due to the complexity for motion target imaging, the optimal target localization strategy still need to be developed to improve the efficiency and effectiveness of the clinical procedure. In this study, the golden marker moving in different directions was characterized in Conebeam CT images for optimal localization application.
Methods:
A Visicoil linear fiducial marker was selected for this study. The length and diameter of the marker were 5mm and 1mm. The motion was generated by Real Time Position Management (RPM) phantom from Varian Medical System. The motion was simulated to be about 2.3 seconds breathing period and about 1cm amplitude and phantom was positioned at three directions along the anterior-posterior (AP), left-right (LR), and In-Out (IO) of the couch. The CBCT images were taken in Truebeam On-board Imaging System. And targets were defined by auto-contouring with Hounsfield Unit(HU) setting from minus 900 to positive 4000 in Eclipse treatment planning system. The targets were post-processed with keeping the largest part, and converted to high resolution segment. Their characteristics were described by shape, volume, center of the volume and volume pixel information, which were attained by MIM Software.
Results:
In this CBCT study, for the given the contouring technique, the volumes of Visicoil fiducial maker were 0.28cc, 0.35cc, and 0.27cc as moving along AP, IO and LR direction. They were corresponding to 143%, 163% and 236% of the static volume. The maximum HUs inside each moving target were 3395, 343 and 3097, which were 49 %, 13% and 44% of those inside the static marker volumes. The center distances between the moving and static targets were 0.63cm in average with standard deviation at 0.02cm.
Conclusion:
When golden makers are applied for localization of treatment target in Lung SBRT, the geometric distance can be reflected in accurate level submillimeter; however, the directional motions could generate large HU difference, which is possibly a challenge to distinguish the boundary of moving tumor. And resolution limit around region of marker should be further investigated to understand the difference between marker tracking or soft tissue localization techniques
