Dosimetric comparison of lattice radiotherapy across three modern linear accelerator platforms

This study aimed to compare the dosimetric characteristics of lattice radiotherapy across different linear accelerator platforms (Versa HD, Halcyon, and NeuRT Aurora) and to evaluate the feasibility of its clinical application.

This study included ten patients with bulky tumors who were eligible for spatially fractionated radiotherapy, including five pelvic cases and five abdominal cases. For each patient, high-dose vertices were contoured within the gross tumor volume using a standardized method, followed by three independently designed treatment plans on the Versa HD, Halcyon, and NeuRT Aurora platforms. The prescribed dose was 2400 cGy in three fractions. Dosimetric evaluation of the target volume included vertex coverage, maximum dose, and the peak-to-valley dose ratio. In addition, a vertex-specific dose analysis was performed to quantify the number of vertices with a D95 of less than 2400 cGy. For organs at risk, the following dosimetric parameters were evaluated: the mean dose to the intra-lattice margin volume, the maximum dose to tissues located more than 2 cm from the vertices, and standard dosimetric parameters for the spinal cord, small bowel, colon, liver, stomach, lungs, and kidneys.

All plans demonstrated the characteristic dosimetric features of lattice radiotherapy by establishing alternating high-dose peaks and low-dose valleys within the target volume, while achieving effective protection of surrounding normal tissues without compromising target coverage. Among the three platforms, NeuRT Aurora demonstrated superior performance in dose gradient control and normal tissue protection. The mean peak-to-valley ratios were 6.4, 6.9, and 8.9 for the Versa HD, Halcyon, and NeuRT Aurora platforms, respectively. The maximum dose to tissues located more than 2 cm from the vertices was significantly lower in the NeuRT Aurora plans (1158.6 cGy) than in the Versa HD plans (1280.6 cGy) and Halcyon plans (1257.8 cGy). Consistent with this trend, the NeuRT Aurora plans were also associated with a lower mean dose to the intra-lattice margin volume (792.4 cGy) than the Versa HD (831.4 cGy) and Halcyon (845.7 cGy) plans. For all specific organs at risk, the evaluated dosimetric parameters remained within clinical tolerance limits across the three treatment platforms.

This study systematically evaluated lattice radiotherapy plans across three accelerator platforms. Although differences were observed in peak-to-valley ratios and organ-at-risk sparing, all plans met clinical requirements, confirming the overall feasibility of each platform.