2293 - Feasibility Study of Functional MR Imaging Based Biologically Guided Lattice Radiotherapy
Presenter(s)
K. Yuan1,2, Y. Peng1, X. Zhou3, Y. Wang1, P. Xu1, X. Liao Sr1, X. Wang4, L. C. Orlandini1, and J. Lang1; 1Sichuan Cancer Hospital and Research Institute, University of Electronic Science and Technology of China, Chengdu, China, Chengdu, China, 2School of Physics, University of Electronic Science and Technology of China, Chengdu, China, 3School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China, 4Sichuan Cancer Hospital and Research Institute, University of Electronic Science and Technology of China, Chengdu, China
Purpose/Objective(s): Lattice radiotherapy (LRT) could effectively treat bulky tumors. However, current LRT plans typically do not account for patient-specific tumor characteristics. Parallelly, low-ADC regions derived from diffusion-weighted MR Imaging (DWI) representing high cellular density and rapidly proliferating. Dose escalation to these regions could improve tumor control. This study proposes an ADC-based spatial arrangement strategy to achieve biologically guided lattice radiotherapy (BG-LRT).
Materials/Methods: Sixteen patients with bulky tumors (>6cm) were retrospectively studied. DWI images were acquired within 3 days of simulation CT. BG-LRT plans were designed by placing high-dose LRT regions focused on low-ADC regions. BG-LRT was compared with hexagonal close-packed lattice radiotherapy (HCP-LRT). All plans were prescribed a total dose of 60 Gy in the lattice regions and GTV dose of 20 Gy, delivered in five fractions. Treatment plans were evaluated using the peak valley dose ratio (PVDR) and ablation dose ratio (ADR) within the GTV. The regions below a certain ADC percentile within the GTV (R_ADC10-R_ADC50) and dose to organs at risk (OARs) were compared between BG-LRT and HCP-LRT.
Results: The average values (PVDR, ADR) of BG-LRT and HCP-LRT are (2.7, 2.4) and (2.4, 1.5), respectively. The ADR within R_ADC10, R_ADC20, R_ADC30, R_ADC40, and R_ADC50 are also considerably higher in BG-LRT than HCP-LRT. There are negligible difference in Dmeans of the heart, stomach, esophagus, kidneys, livers, duodenum, and Dmax of the spinal cord. However, the lens, eyes, and optic nerve Dmax are memorably lower in BG-LRT, while brainstem and chiasm Dmax are drastically lower in HCP-LRT (p<0.05). Plan optimization time, delivery time, MU, and gamma pass rate ratio showed ignorable differences between BG-LRT and HCP-LRT.
Conclusion: The proposed BG-LRT technique enhances the PVDR and ADR in the GTV, also the ADR in the low-ADC regions while retaining low OAR doses. This novel strategy potentially improving tumor control rates, and it offers a promising approach to LRT planning.