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Improved Organ Sparing Using Auto-Planned Stanford Volumetric Modulated Arc Therapy for Total Body Irradiation (VMAT-TBI) Technique
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  • Nataliya Kovalchuk,
  • Nicholas Ngo,
  • Erik Blomain,
  • Eric Simiele,
  • Ignacio Romero,
  • Richard Hoppe,
  • Susan Hiniker
Nataliya Kovalchuk
Stanford University School of Medicine

Corresponding Author:[email protected]

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Nicholas Ngo
Stanford University School of Medicine
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Erik Blomain
Stanford University School of Medicine
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Eric Simiele
Stanford University School of Medicine
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Ignacio Romero
Stanford University School of Medicine
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Richard Hoppe
Stanford University School of Medicine
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Susan Hiniker
Stanford University School of Medicine
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Abstract

Purpose/Objectives: To evaluate dosimetric differences between auto-planned Volumetric Modulated Arc Therapy (VMAT) Total Body Irradiation (TBI) technique and 2D AP/PA TBI technique. Methods: Ten pediatric patients treated with VMAT-TBI on Varian c-arm linac were included in this study. VMAT-TBI plans were generated using our in-house developed and publicly shared auto-planning scripts. For each VMAT-TBI plan, a 2D AP/PA plan was created replicating the institution’s clinical setup with the patient positioned at extended SSD with a compensator to account for differences in patient thickness, 50%-transmission daily lung blocks and electron chest-wall boosts prescribed to 50% of the photon prescription. Clinically relevant metrics were analyzed and compared between the VMAT and 2D plans. Results: All VMAT-TBI plans achieved PTV D90%≥100% of prescription. VMAT-TBI PTV D90% significantly increased (6.2%±2.4%, p<0.001) compared to the 2D technique, whereas no differences were observed in global Dmax (p<0.2) and PTV V110% (p<0.4). Compared to the 2D plans, significant decreases in the Dmean to the lungs (-25.6%±11.5%, p<0.001) and lungs-1cm (-34.1%±10.1%, p<0.001) were observed with the VMAT plans. The VMAT technique also provided additional sparing to other organs: for 12Gy prescription, kidneys Dmean of 64.7%±3.3%; for 2Gy prescription, testes/ovaries (Dmean of 31.6%±10.7%), brain (Dmean of 74.8%±1.6%) and thyroid (Dmean of 72.5±3.5%). Conclusions: Superior lung sparing with improved target coverage and similar global Dmax were observed with the VMAT plans as compared to 2D plans. In addition, VMAT-TBI plans provided greater dose reductions in gonads, kidneys, brain, and thyroid.
09 May 2023Submitted to Pediatric Blood & Cancer
09 May 2023Submission Checks Completed
09 May 2023Assigned to Editor
10 May 2023Review(s) Completed, Editorial Evaluation Pending
10 May 2023Reviewer(s) Assigned
09 Jun 2023Editorial Decision: Revise Major
22 Jun 2023Submission Checks Completed
22 Jun 2023Assigned to Editor
22 Jun 20231st Revision Received
22 Jun 2023Review(s) Completed, Editorial Evaluation Pending
22 Jun 2023Reviewer(s) Assigned
06 Jul 2023Editorial Decision: Revise Minor
08 Jul 2023Submission Checks Completed
08 Jul 2023Assigned to Editor
08 Jul 20232nd Revision Received
08 Jul 2023Review(s) Completed, Editorial Evaluation Pending
08 Jul 2023Editorial Decision: Accept