The Feasibility and Efficiency of Volumetric Modulated Arc Therapy-Based Breath Control Stereotactic Body Radiotherapy for Liver Tumors.

There are strong evidences showing the promising oncologic results of stereotactic body radiotherapy for liver tumors. This study aims to investigate the feasibility, plan quality, and delivery efficiency of image-guided volumetric modulated arc therapy-based voluntary deep exhale breath-holding technique in the stereotactic body radiotherapy for liver tumors. Treatment was planned using volumetric modulated arc therapy with 2 modified partial arc and replanned using intensity modulated radiation therapy technique for comparison. Dosimetric parameters were calculated for plan quality assessment. Quality assurance studies included both point and multiple planar dose verifications. Daily cone beam computed tomography imaging was used to measure and correct positional errors for target volumes and critical structures immediately prior to and during treatment delivery. Total monitor units and delivery times were also evaluated. No significant dosimetric difference was found between volumetric-modulated arc therapy and conventional intensity modulated radiation therapy plans. Both techniques were able to minimize doses to organs at risk including normal liver, kidneys, spinal cord, and stomach. However, the average monitor units with volumetric-modulated arc therapy were significantly lower (29.2%) than those with intensity modulated radiation therapy (P = .012). The average beam-on time in volumetric-modulated arc therapy plans was 22.2% shorter than that in intensity modulated radiation therapy plans. In conclusion, it is feasible to utilize volumetric modulated arc therapy in the treatment planning of stereotactic body radiotherapy for liver tumors under breath control mode. In comparison to conventional intensity modulated radiation therapy plans, volumetric modulated arc therapy plans are of high efficiency with less monitor units, shorter beam-on time, tolerable intrafractional errors as well as better dosimetrics, meriting further investigations, and clinical evaluations.