Is a Single Respiratory Correlated 4D-CT Study Sufficient for Evaluation of Breathing Motion?
- Department of Radiation Oncology, Julius-Maximilians University of Wuerzburg, Wuerzburg (Germany)
Purpose: Respiratory correlated computed tomography has been shown to be effective for evaluation of breathing-induced motion of pulmonary tumors. This study investigated whether a single four-dimensional CT study (4D-CT) is representative and sufficient for treatment planning in stereotactic body radiotherapy (SBRT). Methods and Materials: Four repeated helical 4D-CT studies were acquired every 10 min for 10 patients with 14 pulmonary metastases. Patients remained immobilized in a stereotactic body frame (SBF) for 30 min; abdominal compression was applied to seven patients. Using amplitude based sorting, eight phases equally distributed over the breathing cycle were reconstructed for each 4D-CT study. Tumor position was defined in a total of 406 CT series and variability of breathing motion and mean tumor position were evaluated. Results: Peak-to-peak tumor motion was 9.9 mm {+-} 6.8 mm (mean {+-} standard deviation) and 9.0 mm {+-} 7.4 mm at time point 0 min (t{sub 0}) and t{sub 30}, respectively. In one patient with poor pulmonary function, continuous increase of breathing motion from 17.4 mm at t{sub 0} to 28.3 mm at t{sub 30} was seen. In five and two lesions, respectively, a drift of the mean tumor position greater than 3 mm and 5 mm was observed. A borderline significance was calculated for larger tumor position variability in midventilation phases compared with peak-ventilation phases of the breathing cycle (p = 0.08). Conclusion: Treatment planning based on a single 4D-CT study is reliable for the majority of patients. Increased intrafractional uncertainties were seen for patients with poor pulmonary function and with tumors located in the lower lobe.
- OSTI ID:
- 20951577
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 67, Issue 5; Other Information: DOI: 10.1016/j.ijrobp.2006.11.025; PII: S0360-3016(06)03519-X; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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