Abstract
PURPOSE: This study aimed to evaluate a novel technological platform, Taichi Pro-which integrates a 6 MV flattening filterfree linear accelerator with a 18 source Rotating Gamma System (RGS) to generate steep dose gradients via multisource focused γ-rays and noncoplanar arcs-for precision radiotherapy in prostate cancer. The work provides evidence to support the clinical adoption of hybridmodality radiotherapy devices. METHODS: Fifteen prostate cancer patients were enrolled. For each patient, a dual-modality Taichi Pro plan (RGS focused on the planning gross tumor volume (PGTV) + Linac covering the planning target volume (PTV)) and a Halcyon photon plan (three-arc VMAT) were designed while maintaining clinically tolerable dose to organs at risk (OAR). Comparative assessments included planning target volume (PTV and PGTV) metrics (D(95%), D(mean), homogeneity index HI, conformity index CI), OAR doses (rectum V(40)/V(60)/D(2cc), bladder V(40), testis D(2cc), etc.) and delivery efficiency to evaluate the ability to escalate target dose while sparing adjacent OARs. RESULTS: All plans met institutional clinical constraints. Taichi Pro significantly increased PGTV D(mean) (79.48 Gy ± 1.75 Gy) compared to Halcyon (73.25 Gy ± 0.55 24 Gy, P < 0.001) and D(max) (122.74 Gy ± 8.69 Gy) compared to Halcyon (76.15 Gy ± 0.79 Gy, P < 0.001), albeit poorer homogeneity (HI: 0.50 ± 0.09 for Taichi Pro vs. 0.06 ± 0.01 for Halcyon, though within clinically acceptable limits). Taichi Pro significantly reduced rectum V(60) (3.97% ± 3.25% vs. Halcyon 7.46% ± 4.78%, P = 0.016), and D(2cc) (61.61 Gy ± 5.01 Gy vs. Halcyon 65.29 Gy ± 4.52 Gy, P = 0.040). Taichi Pro also significantly reduced testis D(2cc) (2.39 ± 1.99 Gy) compared to (3.17 Gy ± 1.40 Gy, P = 0.006). Halcyon demonstrated significantly shorter beam-on time (1.81 ± 0.23 minutes vs. 5.05 ± 1.59 minutes for Taichi Pro, P < 0.001). CONCLUSION: Utilizing the steep dose gradient characteristic of the RGS, the Taichi Pro dual-modality system effectively achieved target dose escalation while simultaneously improving sparing of adjacent OARs. This approach holds the potential for enhancing patient treatment outcomes and quality of life.