S1914
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
and knowledge-based optimization employing overlap volume histograms [2] and overlap-z-histograms [3] for dose prediction. Both APs and MPs used two coplanar full arcs and a prescription dose of 50.4Gy in 1.8Gy per fraction. Plan evaluation included PTV coverage, OAR doses, and plan complexity metrics such as monitor units (MUs), modulation complexity score (MCS), and leaf travel (LT) [4]. The MCS quantifies the shape and intensity variation of the radiation fields, where lower values indicate stronger modulation and higher complexity. LT represents the total movement of the MLC leaves during irradiation, with greater motion reflecting higher plan complexity. Statistical analysis between APs and MPs was performed using the Wilcoxon signed-rank test at 5% significance level. Results: Table 1 summarizes all dosimetric and complexity metrics, and Figure 1 visualizes the corresponding distributions. APs achieved comparable PTV coverage (CAP=95.04±1.37% vs. CMP=95.29±2.28%, p=0.184) with slightly improved homogeneity (HIAP=0.1088±0.0138 vs. HIMP=0.1143±0.0219, p=0.028). Lung dose metrics showed significant advantages for APs: the mean total lung dose decreased from 11.60±3.10Gy (MP) to 11.12±2.97 Gy (AP) (p<0.001), and V ₂₀ Gy from 17.42±6.60% to 16.51±6.18% (p<0.001). Significant reductions were also found for the spinal cord (D0.5cc,=26.96±3.65Gy (AP) vs. 27.92±4.79Gy (MP), p=0.046) and esophagus (D0.01cc=49.74±4.45Gy (AP) vs. 50.48±3.04Gy (MP), p=0.003). Regarding plan complexity, APs required fewer monitor units (612±115 vs. 681±183, p=0.023) and exhibited shorter leaf travel (350±125mm vs. 377±143mm, p=0.009), while MCS remained comparable (p=0.257).
Conclusion: The UKER-ATP software consistently generated high- quality VMAT plans for lung tumors. Compared with manual planning, it achieved modest reductions in lung dose while maintaining comparable target coverage and plan complexity. Even small lung dose reductions may help limit cumulative exposure during boost irradiation. Overall, UKER-ATP improves planning efficiency and consistency without compromising plan quality. References: [1] Brand J et al. (2025). Automated radiotherapy planning for volumetric modulated arc therapy in lung cancer. J Appl Clin Med Phys 26, e70297. https://doi.org/10.1002/acm2.70297[2] Wu B et al. (2009). Patient geometry-driven information retrieval for IMRT treatment plan quality control. Med Phys 36, 5497–5505. https://doi.org/10.1118/1.3253464[3] Brand J et al. (2025). An extension to the OVH concept for knowledge-based dose volume histogram prediction in lung tumor volumetric-modulated arc therapy. J Appl Clin Med Phys 26, e70090. https://doi.org/10.1002/acm2.70090[4] Masi L et al. (2013). Impact of plan parameters on the dosimetric accuracy of volumetric modulated arc therapy. Med Phys 40, 071718. https://doi.org/10.1118/1.4810969 Keywords: Automated Treatment Planning, VMAT, Lung Cancer Digital Poster 3034 Minimizing bowel bag dosage via dedicated treatment planningfor patients with rectal cancer Erik Almhagen 1,2 , Karin Bünte 1 , Alexander Valdman 3,2 1 Department of Nuclear Medicine and Medical Physics, Karolinska Univerity Hospital, Stockholm, Sweden. 2 Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden. 3 Department of Radiation Oncology, Karolinska Univerity Hospital, Stockholm, Sweden
Made with FlippingBook - Share PDF online