Internal-external correlation investigations of respiratory induced motion of lung tumors
- Department of Radiation Oncology, Division of Medical Physics, Dana-Farber/Brigham and Women's Cancer Center and Harvard Medical School, 75 Francis Street, Boston, Massachusetts 02115 (United States) and Department of Radiation Oncology, University of California, San Diego Moores Cancer Center, 3855 Health Sciences Dr. 0843, La Jolla, California 92093-0843 (United States)
In gated radiation therapy procedures, the lung tumor position is used directly (by implanted radiopaque markers) or indirectly (by external surrogate methods) to decrease the volume of irradiated healthy tissue. Due to a risk of pneumothorax, many clinics do not implant fiducials, and the gated treatment is primarily based on a respiratory induced external signal. The external surrogate method relies upon the assumption that the internal tumor motion is well correlated with the external respiratory induced motion, and that this correlation is constant in time. Using a set of data that contains synchronous internal and external motion traces, we have developed a dynamic data analysis technique to study the internal-external correlation, and to quantitatively estimate its underlying time behavior. The work presented here quantifies the time dependent behavior of the correlation between external respiratory signals and lung implanted fiducial motion. The corresponding amplitude mismatch is also reported for the lung patients studied. The information obtained can be used to improve the accuracy of tumor tracking. For the ten patients in this study, the SI internal-external motion is well correlated, with small time shifts and corresponding amplitude mismatches. Although the AP internal-external motion reveals larger time shifts than along the SI direction, the corresponding amplitude mismatches are below 5 mm.
- OSTI ID:
- 21032806
- Journal Information:
- Medical Physics, Vol. 34, Issue 10; Other Information: DOI: 10.1118/1.2779941; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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