A Novel Strategy for Soft Tissue Sarcoma Lattice Radiotherapy: Integrating X-Ray andγ-Ray Technologies to Optimize Dose Delivery

Background: The TaiChi radiotherapy platform is an innovative system integrating linear accelerator (LINAC) and Gamma Knife technologies, approved by both NMPA and FDA. This hybrid design enables bimodal (X-ray and γ-ray) radiation delivery, offering enhanced flexibility for treatment planning and dose delivery. This study quantitatively evaluates its dosimetric performance for lattice radiotherapy (LRT) in soft tissue sarcoma (STS), specifically comparing its dose escalation potential and normal tissue sparing to conventional C-arm LINAC. Methods: A dosimetric analysis was conducted on 10 STS cases. The treatment combined LRT (15Gy single fraction to spherical vertices within the Gross tumor volume (GTV) ) with conventionally fractionated external beam radiotherapy (50Gy/25F to the planning target volume (PTV)). TaiChi utilized its dual-modality capability, employing γ-ray focusing for vertex dose escalation and optimizing the LINAC for conventional coverage. Plans were compared on high-dose vertex coverage, dose fall-off, and organ-at-risk (OAR) sparing. Results: TaiChi demonstrated superior dosimetric performance across all evaluated parameters. For vertex coverage, TaiChi achieved significantly higher D _mean (18.87 ± 0.46Gy vs. 16.66 ± 0.85Gy, p < 0.0001) and D _0.5cc (25.15 ± 0.39Gy vs. 18.90 ± 0.44Gy, p < 0.0001). Dose gradient analysis revealed steeper fall-off with TaiChi, evidenced by higher GTV D ₁₀ /D ₉₀ values (5.93 ± 0.84 vs 3.40 ± 0.92, p < 0.0001) and reduced margin doses (3.95 ± 0.48Gy vs 4.87 ± 0.41Gy, p < 0.0001). Importantly, these improvements were achieved while maintaining or reducing OAR exposure, with statistically significant reductions in maximum doses to nerves and bones ( p < 0.05). Conclusion: The TaiChi platform's innovative integration of LINAC and Gamma Knife technologies provides distinct dosimetric advantages for STS LRT, enabling superior dose escalation to high-dose vertex regions while maintaining steep dose gradients and effective normal tissue sparing.These capabilities position TaiChi as a promising platform for advancing LRT applications.