Assessing respiratory motion effects after breathing training on hybrid and IMRT plans in hypofractionated breast radiotherapy.
[PURPOSE] This study aimed to evaluate the dosimetric impact of respiratory motion after breathing training on Hybrid and IMRT plans in hypofractionated breast radiotherapy, using 4D-CT and deformable
APA
Hou L, Yan G, Yao S (2026). Assessing respiratory motion effects after breathing training on hybrid and IMRT plans in hypofractionated breast radiotherapy.. Radiation oncology (London, England), 21(1). https://doi.org/10.1186/s13014-026-02821-0
MLA
Hou L, et al.. "Assessing respiratory motion effects after breathing training on hybrid and IMRT plans in hypofractionated breast radiotherapy.." Radiation oncology (London, England), vol. 21, no. 1, 2026.
PMID
41803865
Abstract
[PURPOSE] This study aimed to evaluate the dosimetric impact of respiratory motion after breathing training on Hybrid and IMRT plans in hypofractionated breast radiotherapy, using 4D-CT and deformable dose accumulation.
[METHODS] Twenty-two postoperative breast cancer patients treated under free breathing underwent both 3D-CT and 4D-CT scanning after abdominal breathing training. Original Hybrid (O_HY) and IMRT (O_IM) plans were generated on 3D-CT. Each plan was mapped onto the ten 4D-CT phases and recalculated. Deformable image registration was applied to accumulate phase-specific doses onto the original 3D-CT, generating motion-inclusive deformed Hybrid (D_HY) and IMRT (D_IM) plans. Respiratory motion amplitudes of the chest wall and liver were quantified. Dosimetric parameters of targets and OARs were evaluated and compared.
[RESULTS] After breathing training, respiratory motion amplitudes were 13.2 ± 4.6 mm for the liver and 1.54 ± 0.85 mm for the chest wall. Both techniques achieved good target coverage in the original plans, with comparable hotspot, homogeneity, and conformity. Hybrid plans provided superior OAR sparing, particularly in the low-dose regions. After deformable dose accumulation, target coverage exhibited only minor decreases: PTV_V decreased by 2.5% for Hybrid and 2.1% for IMRT. PTV_D remained largely unchanged, and HI/CI deteriorated only slightly. OAR dose variations were minimal, with no significant differences except for a lower Breast_D in the IMRT plan. Respiratory motion showed no meaningful correlations with most dosimetric parameters, except for weak correlations between liver motion and PTV_V and a significant correlation with Breast_D in the IMRT plan.
[CONCLUSIONS] In this cohort, chest wall motion amplitude after breathing training remained within 3.1 mm. Under these conditions, Hybrid and IMRT plans demonstrate comparable target dose robustness, while Hybrid achieves superior OAR sparing, particularly in the low-dose region. Based on this comparison, Hybrid planning may be considered a favorable option relative to IMRT for hypofractionated whole-breast irradiation under free breathing.
[SUPPLEMENTARY INFORMATION] The online version contains supplementary material available at 10.1186/s13014-026-02821-0.
[METHODS] Twenty-two postoperative breast cancer patients treated under free breathing underwent both 3D-CT and 4D-CT scanning after abdominal breathing training. Original Hybrid (O_HY) and IMRT (O_IM) plans were generated on 3D-CT. Each plan was mapped onto the ten 4D-CT phases and recalculated. Deformable image registration was applied to accumulate phase-specific doses onto the original 3D-CT, generating motion-inclusive deformed Hybrid (D_HY) and IMRT (D_IM) plans. Respiratory motion amplitudes of the chest wall and liver were quantified. Dosimetric parameters of targets and OARs were evaluated and compared.
[RESULTS] After breathing training, respiratory motion amplitudes were 13.2 ± 4.6 mm for the liver and 1.54 ± 0.85 mm for the chest wall. Both techniques achieved good target coverage in the original plans, with comparable hotspot, homogeneity, and conformity. Hybrid plans provided superior OAR sparing, particularly in the low-dose regions. After deformable dose accumulation, target coverage exhibited only minor decreases: PTV_V decreased by 2.5% for Hybrid and 2.1% for IMRT. PTV_D remained largely unchanged, and HI/CI deteriorated only slightly. OAR dose variations were minimal, with no significant differences except for a lower Breast_D in the IMRT plan. Respiratory motion showed no meaningful correlations with most dosimetric parameters, except for weak correlations between liver motion and PTV_V and a significant correlation with Breast_D in the IMRT plan.
[CONCLUSIONS] In this cohort, chest wall motion amplitude after breathing training remained within 3.1 mm. Under these conditions, Hybrid and IMRT plans demonstrate comparable target dose robustness, while Hybrid achieves superior OAR sparing, particularly in the low-dose region. Based on this comparison, Hybrid planning may be considered a favorable option relative to IMRT for hypofractionated whole-breast irradiation under free breathing.
[SUPPLEMENTARY INFORMATION] The online version contains supplementary material available at 10.1186/s13014-026-02821-0.