Program Information
A Formulation of 4D Treatment Planning for Tumour Tracking Volumetric Modulated Arc Therapy for Lung Cancer
Michael L M Cheung1,2*, Louis K Y Lee1, Anthony T C Chan1,2 (1) Prince of Wales Hospital, Hong Kong (2) The Chinese University of Hong Kong
Presentations
TU-G-CAMPUS-J-11 (Tuesday, July 14, 2015) 5:30 PM - 6:00 PM Room: Exhibit Hall
Purpose:
To develop a formulation for 4D treatment planning for a tumour tracking volumetric modulated arc therapy treatment (VMAT) plan for lung cancer.
Methods:
A VMAT plan was optimized based on a reference phase of the 4DCT of a lung cancer patient. The PTV was generated from the GTV of the reference phase. The collimator angle was set to 90 degrees such that the MLC travels along superior-inferior direction which is the main component of movement of a lung tumour. Then, each control point of the VMAT plan was assigned to a particular phase of the 4DCT in chronological order. The MLC positions of each control point were shifted according to the position of the tumour centroid of its assigned phase to form a tumour tracking VMAT plan. The control points of the same phase were grouped to form a pseudo VMAT plan for that particular phase. Dose calculation was performed for each pseudo VMAT plan on the corresponding phase of the 4DCT. The CTs of all phases were registered to the reference phase CT according to the displacement of the tumour centroid. The individual dose distributions of the pseudo VMAT plans were summed up and displayed on the reference phase of the 4DCT. A control VMAT plan was optimized based on a PTV generated from the ITV of all phases and compared with the tumour tracking VMAT plan.
Results:
Both plans achieved >95% volume coverage at the prescription dose level (96% for the tumour tracking plan and 97% for the control plan). But the normal lung volume irradiated at the prescription dose level was 39% less for the tumour tracking plan than the control plan.
Conclusion:
A formulation of 4D treatment planning for tumour tracking VMAT plans for lung cancer was developed.
Contact Email: