We present the commissioning and initial validation of Phoenix Plan, a GPU-accelerated treatment planning system (TPS) developed for raster-scanned carbon ion therapy delivered by the Heavy Ion Medical Machine (HIMM). Phoenix Plan employs a quintuple-Gaussian pencil beam model for physical dose calculation and incorporates a subspot-splitting algorithm to account for lateral heterogeneities. RBE-weighted dose is computed using a linear–quadratic model based on the mixed-beam approach. We implemented a physically-informed interpolation method for integrated depth dose (IDD) curves, allowing the dose engine to be commissioned from a sparse subset of measured energies. GPU acceleration is achieved through a precomputed water-equivalent depth texture-based framework, enabling rapid and scalable dose calculations. The system was validated against a range of physical and biological benchmarks. Comparisons between calculated and measured doses for spread-out Bragg peak (SOBP) plans showed agreement within 2.4 % in the target region and within 1 mm at distal fall-off. RBE-weighted doses at the SOBP centers were within 2 % of values reported in the literature, using a clinical factor of 1.38. Ten retrospective patient plans covering diverse anatomical sites achieved gamma passing rates above 95 % under both 3%/3 mm and 2%/3 mm criterion. The interpolation strategy reduced IDD measurement time from 41 h to 4.6 h without compromising accuracy. The beam modeling process was completed under five minutes. These results demonstrate that Phoenix Plan achieves accurate and efficient physical and biological dose calculation, supports streamlined commissioning workflows, and is ready for clinical deployment in conjunction with HIMM.
Xia et al. (Sun,) studied this question.