- 作者：Kenneth Poels ; Tom Depuydt ; Dirk Verellen ; Benedikt Engels ; Christine Collen ; Steffen Heinrich ; Michael Duchateau ; Truus Reynders ; Katrien Leysen ; Marlies Boussaer ; Femke Steenbeke ; Koen Tournel ; Thierry Gevaert ; Guy Storme ; Mark De Ridder
- 关键词：Dynamic tumor tracking ; Intra-fraction treatment verification ; kV/MV fluoroscopy
- 刊名：Radiotherapy and Oncology
- 出版年：December, 2013
- 年：2013
- 卷：109
- 期：3
- 页码：469-474
- 全文大小：889 K
Background and purpose
For dynamic tracking of moving tumors, robust intra-fraction verification was required, to assure that tumor motion was properly managed during the course of radiotherapy. A dual-modality verification system, consisting of an on-board orthogonal kV and planar MV imaging device, was validated and applied retrospectively to patient data.Methods and materials
Real-time tumor tracking (RTTT) was managed by applying PAN and TILT angular corrections to the therapeutic beam using a gimbaled linac. In this study, orthogonal X-ray imaging and MV EPID fluoroscopy was acquired simultaneously. The tracking beam position was derived from respectively real-time gimbals log files and the detected field outline on EPID. For both imaging modalities, the moving target was localized by detection of an implanted fiducial. The dual-modality tracking verification was validated against a high-precision optical camera in phantom experiments and applied to clinical tracking data from a liver and two lung cancer patients.
Results
Both verification modalities showed a high accuracy (<0.3 mm) during validation on phantom. Marker detection on EPID was influenced by low image contrast. For the clinical cases, gimbaled tracking showed a 90th percentile error (E90) of 3.45 (liver), 2.44 (lung A) and 3.40 mm (lung B) based on EPID fluoroscopy and good agreement with XR-log file data by an E90 of 3.13, 1.92 and 3.33 mm, respectively, during beam on.
Conclusion
Dual-modality verification was successfully implemented, offering the possibility of detailed reporting on RTTT performance.