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<p>Anatomical changes during adjuvant radiotherapy (RT) for post-operative oral cavity squamous cell carcinoma (OCSCC) have greater dosimetric effects with highly conformal techniques, thereby necessitating plan adaptation. We compared conventional adaptive RT (cART) with deformable image registration (DIR)-based ART (dART). Post-operative OCSCC patients receiving adjuvant RT with a ≥ 5&#xa0;mm change in skin contour on cone beam computed tomography (CBCT) were enrolled. After re-simulation, planning CT (pCT) and extended CBCT were imported into Velocity<sup>®</sup> to generate a synthetic CT (sCT) using DIR. Separate plans were created on the re-simulation CT (rCT) and sCT. The initial plan he was also projected onto the sCT anatomy and compared with the original plan on the pCT. Geometric (volume, Dice similarity coefficient [DSC], mean distance to agreement [MDA]) and dosimetric (mean dose, dose-volume histogram [DVH]) differences were evaluated between rCT- and sCT-based plans. Twenty-five patients were prospectively enrolled. Based on DSC and MDA, DIR showed acceptable geometric accuracy for all structures except the spinal cord (DSC = 0.75). Compared to pCT, most structures had significant volume reduction on sCT, except the low-risk planning target volume (PTV<sub>LR</sub>) (<i>p</i> = 0.14) and the larynx (increased, <i>p</i> = 0.04). Projection of the initial plan onto sCT revealed significant loss in PTV<sub>LR</sub> coverage (V<sub>95%</sub> <i>p</i> = 0.001; D<sub>98%</sub> <i>p</i> = 0.01) and a non-significant loss for the high-risk PTV (PTV<sub>HR</sub>). Organs at risk (OARs) doses increased non-significantly, except for the mandible (<i>p</i> = 0.007). Comparison of rCT and sCT volumes showed a 3.7% increases in PTV<sub>HR</sub> (<i>p</i> = 0.009) and 5.7% in PTV<sub>LR</sub> (<i>p</i> = 0.049), with non-significant OAR volume increases (2.4%–6.3%) except for the larynx (decreased). DVH comparison showed non-significant dose reductions to the parotids (0.6%), the mandible (0.5%), and the larynx (5.8%), but slight increases for the spinal cord (2.6%) and its planning organ at risk volume (PRV) (3.7%). Target coverage was significantly lower with sCT-based plans (PTV<sub>HR</sub> V<sub>95%</sub> by 3.2%, D<sub>98%</sub> by 3.8%, PTV<sub>LR</sub> V<sub>95%</sub> by 4.1% and D<sub>98%</sub> by 4.3%). dART improved OAR sparing but was compromised in a few target coverage parameters. Further enhancement of DIR accuracy is needed. Currently, DIR is primarily used in ART for dose accumulation to assess the need for plan adaptation.</p>

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Evaluation of deformable image registration vs offline adaptive replanning in post-op oral cavity cancer treated with volumetric modulated Arc therapy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月24日

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  • Shubham Dokania,
  • Ashutosh Mukherji,
  • Sambit S. Nanda,
  • Sanju Sanju,
  • Pritam Mondal,
  • Ninad H. Patil,
  • Ajay S. Krishnan,
  • Ajay Choubey

摘要

Anatomical changes during adjuvant radiotherapy (RT) for post-operative oral cavity squamous cell carcinoma (OCSCC) have greater dosimetric effects with highly conformal techniques, thereby necessitating plan adaptation. We compared conventional adaptive RT (cART) with deformable image registration (DIR)-based ART (dART). Post-operative OCSCC patients receiving adjuvant RT with a ≥ 5 mm change in skin contour on cone beam computed tomography (CBCT) were enrolled. After re-simulation, planning CT (pCT) and extended CBCT were imported into Velocity® to generate a synthetic CT (sCT) using DIR. Separate plans were created on the re-simulation CT (rCT) and sCT. The initial plan he was also projected onto the sCT anatomy and compared with the original plan on the pCT. Geometric (volume, Dice similarity coefficient [DSC], mean distance to agreement [MDA]) and dosimetric (mean dose, dose-volume histogram [DVH]) differences were evaluated between rCT- and sCT-based plans. Twenty-five patients were prospectively enrolled. Based on DSC and MDA, DIR showed acceptable geometric accuracy for all structures except the spinal cord (DSC = 0.75). Compared to pCT, most structures had significant volume reduction on sCT, except the low-risk planning target volume (PTVLR) (p = 0.14) and the larynx (increased, p = 0.04). Projection of the initial plan onto sCT revealed significant loss in PTVLR coverage (V95% p = 0.001; D98% p = 0.01) and a non-significant loss for the high-risk PTV (PTVHR). Organs at risk (OARs) doses increased non-significantly, except for the mandible (p = 0.007). Comparison of rCT and sCT volumes showed a 3.7% increases in PTVHR (p = 0.009) and 5.7% in PTVLR (p = 0.049), with non-significant OAR volume increases (2.4%–6.3%) except for the larynx (decreased). DVH comparison showed non-significant dose reductions to the parotids (0.6%), the mandible (0.5%), and the larynx (5.8%), but slight increases for the spinal cord (2.6%) and its planning organ at risk volume (PRV) (3.7%). Target coverage was significantly lower with sCT-based plans (PTVHR V95% by 3.2%, D98% by 3.8%, PTVLR V95% by 4.1% and D98% by 4.3%). dART improved OAR sparing but was compromised in a few target coverage parameters. Further enhancement of DIR accuracy is needed. Currently, DIR is primarily used in ART for dose accumulation to assess the need for plan adaptation.