Main Session
Sep 28
PQA 01 - Radiation and Cancer Physics, Sarcoma and Cutaneous Tumors

2057 - Bragg Peak Modulation in Ion Therapy Using a Mesh-Stacked Porous Structure: A Preliminary Study

02:30pm - 04:00pm PT
Hall F
Screen: 5
POSTER

Presenter(s)

Sixue Dong, PhD - Fudan University Shanghai Cancer Center, Shanghai, DC

S. Dong1, J. Wang1, Y. Sheng2, W. Hu1, and Z. Zhang3; 1Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, Shanghai, China, 2Shanghai Proton and Heavy Ion Center, Shanghai, Shanghai, China, 3Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China

Purpose/Objective(s): This study aims to develop and evaluate a mesh-stacked porous structure (MPS) for broadening Bragg peaks to enhance the efficiency and conformality of ion beam radiotherapy.

Materials/Methods: The MPS was fabricated with several (5~45) layers using both regular and random stacking techniques (Figure 1). The mesh dimension was 10 cm × 10 cm, each grid layer consisted of a line width, thickness, and spacing of 0.1 mm, 0.1 mm, and 0.5 mm, respectively. Monte Carlo simulations using the FLUKA code were performed to model the transport of a 196 MeV/u carbon ion beam and a 105 MeV proton beam through the MPS. Uncertainty of modulation power (Pmod) at different beam entrance positions and beam fluence homogeneity were analyzed. Additionally, the clinical application was assessed in treatment plans for nasopharyngeal cancer (NPC, 63 Gy in 21 fractions), lung cancer (77 Gy in 22 fractions), and prostate cancer (70.4 Gy in 16 fractions).

Results: The MPS broadened Bragg peaks by up to 2.95 mm for carbon ions and 1.73 mm for protons. MPS with 10 layers with regular stacking was sufficient to reduce the uncertainty of Pmod to 5% at various beam entry positions. A 30-layer MPS achieved proton/carbon-ion beam fluence homogeneity <3% within 18 cm of air transport. Compared to ripple filters (RiFi), the MPS reduced proton beam spot sizes by 0.91 mm. Take the comparison of NPC plans as an example (Figure 2), the MPS shortened treatment times by 37% (213 s) and reduced the maximum brainstem dose by 3.28 Gy (7.5%).

Conclusion: The MPS with regular stacking effectively broadens Bragg peaks with stable Pmod, superior fluence homogeneity, and reduced lateral scattering. Its clinical application potential includes improved efficiency and dose conformality, particularly for treatments requiring proximity to the patient.