@misc{oai:repo.qst.go.jp:00065485,
 author = {早乙女, 直也 and Haga, A. and Imae, T. and Kida, S. and Nakano, M. and Yamashita, H. and Nakagawa, K. and Ohtomo, K. and 早乙女 直也},
 month = {Jul},
 note = {Purpose
To verify the delivered four-dimensional (4D) dose distribution for the lung VMAT using in-treatment 4D cone-beam CT (CBCT) and LINAC log data. Material and methods
Three patients for lung stereotactic radiotherapy (SRT) were treated by single-arc volumetric modulated arc therapy (VMAT) created by SmartArc in Pinnacle v9.2 (Philips, USA).
Kilovoltage (kV) projection images were acquired during VMAT delivery using the x-ray volumetric imager, XVI (Elekta, UK). LINAC log data were also recorded via iCom interface (Elekta, UK). Subsequently, the iCom data format was converted to Pinnacle data format, thereby allowing Pinnacle to read actual MLC positions, jaw positions, gantry angles and MUs. These parameters were categorized into four groups according to patient’s respiratory phase. The patient respiratory phase was determined from kV-projection images by in-house phase recognizing software. By exporting these data back to Pinnacle, in-treatment dose distributions for each respiratory phase were obtained by combining calculated dose having a particular phase. The 4D CBCT were reconstructed by in-house program. The density in the structures on the CBCT was overridden by the average density in the corresponding structures on the planning CT for the dose calculation. The dose indexes, such as maximum, minimum, mean dose in the target were compared among the plan, in-treatment 3D calculation, and in-treatment 4D calculation.
Result
The day-to-day variation of the delivered dose was observed for all three patients. The maximum difference was 5.9% for the minimum dose in the target. Difference for the mean dose was found to be small (1.1% at maximum).
Conclusion
We have obtained in-treatment dose distribution for each of the different respiratory phases using in-treatment 4D CBCT and LINAC log data during
lung VMAT delivery. Our result indicate a small but significant dose difference between the 3D and 4D calculations for the case of large target traveling., American Association of Physicists in Medicine 56th annual meeting (AAPM2014)},
 title = {Delivered 4D Dose Calculation for Lung-VMAT Patients Using In-Treatment CBCT and LINAC Log Data},
 year = {2014}
}