Image-guided volumetric-modulated arc therapy of total body irradiation: An efficient workflow from simulation to delivery.

Introduction: Using multi-isocenter volumetric-modulated arc therapy (VMAT) for total body irradiation (TBI) may improve dose uniformity and vulnerable tissue protection compared with classical whole-body field technique. Two drawbacks limit its application: (1) VMAT-TBI planning is time consuming; (2) VMAT-TBI plans are sensitive to patient positioning uncertainties due to beam matching. This study presents a robust planning technique with image-guided delivery to improve dose delivery accuracy. In addition, a streamlined sim-to-treat workflow with automatic scripts is proposed to reduce planning time.

Materials: Twenty-five patients were included in this study. Patients were scanned in supine head-first and feet-first directions. An automatic workflow was used to (1) create a whole-body CT by registering two CT scans, (2) contour lungs, kidneys, and planning target volume (PTV), (3) divide PTV into multiple sub-targets for planning, and (4) place isocenters. Treatment planning included feathered AP/PA beams for legs/feet and VMAT for the body. VMAT-TBI was evaluated for plan quality, planning/delivery time, and setup accuracy using image guidance.

Results: VMAT-TBI planning time can be reduced to a day with automatic scripts. Treatment time took around an hour per fraction. VMAT-TBI improved dose coverage (PTV V100 increased from 76.8 ± 10.5 to 88.5 ± 2.6; p < 0.001) and reduced lung dose (lung mean dose reduced from 10.8 ± 0.7 Gy to 9.4 ± 0.8 Gy, p < 0.001) compared with classic AP/PA technique.

Conclusion: A VMAT-TBI sim-to-treat workflow with robust planning and image-guided delivery was proposed. VMAT-TBI improved the plan quality compared with classical whole-body field techniques.