TITLE:
An Integrated Simulation System Based on Digital Human Phantom for 4D Radiation Therapy of Lung Cancer
AUTHORS:
Jing Cai, You Zhang, Irina Vergalasova, Fan Zhang, W. Paul Segars, Fang-Fang Yin
KEYWORDS:
Lung Cancer, Digital Human Phantom, Motion Management, 4D Radiation Therapy
JOURNAL NAME:
Journal of Cancer Therapy,
Vol.5 No.8,
July
7,
2014
ABSTRACT:
Purpose: To develop and
test an integrated simulation system based on the digital Extended Cardio Torso
(XCAT) phantom for 4-dimensional (4D) radiation therapy of lung cancer.
Methods: A computer program was developed to facilitate the characterization
and implementation of the XCAT phantom for 4D radiation therapy applications.
To verify that patient-specific motion trajectories are reproducible with the
XCAT phantom, motion trajectories of the diaphragm and chest were extracted
from previously acquired MRI scans of five subjects and were imported into the
XCAT phantom. The input versus the measured trajectories was compared.
Simulation methods of 4D-CT and 4D-cone-beam CT (CBCT) based on the XCAT
phantom were developed and tested for regular and irregular respiratory
patterns. Simulation of 4D dose delivery was illustrated in a simulated lung
stereotactic-body radiation therapy (SBRT) case based on the XCAT phantom.
Dosimetric comparison was performed between the planned dose and simulated
delivered dose. Result: The overall mean (±standard deviation) difference in
motion amplitude between the input and measured trajectories was 1.19 (±0.79)
mm for the XCAT phantoms with voxel size of 2 mm. 4D-CT and 4D-CBCT images
simulated based on the XCAT phantom were validated using regular respiratory
patterns and tested for irregular respiratory patterns. Comparison between
simulated 4D dose delivery and planned dose for the lung SBRT case showed
comparable results in all dosimetric matrices: the relative differences were
0.3%, 4.0%, 0%, and 2.8%, respectively, for max cord dose, max esophagus dose,
mean heart dose, and V20Gy of the lungs. 97.5% of planning target volume (PTV)
received prescription dose in the simulated 4D delivery, as compared to 95% of
PTV received prescription dose in the plan. Conclusion: We developed an
integrated simulation system based on the XCAT digital phantom and illustrated
its utility in 4D radiation therapy of lung cancer. This simulation system is
potentially a useful tool for quality control and development of imaging and
treatment techniques for 4D radiation therapy of lung cancer.