Monte Carlo simulation of a novel medical linac concept for highly conformal x-ray FLASH cancer radiotherapy
摘要
A growing body of pre-clinical research has demonstrated the potential of ultra-high dose-rate (UHDR) radiotherapy to reduce normal tissue toxicity while maintaining tumor control. However, owing to a wide range of technical difficulties, no existing x-ray systems are capable of highly conformal UHDR radiotherapy to humans. In this work, we designed and simulated a novel x-ray UHDR system representing a next-generation solution for rapid and highly conformal treatment delivery. This system comprises 16 stationary beamlines employing a new class of highly efficient linear accelerator to generate 12 MeV electron beams electromagnetically steered onto a bremsstrahlung target, a collimator with channels to create a divergent array of x-ray beamlets, and a translating patient couch. The system design was tuned to maximize the dose rate while minimizing beam penumbra and cross-channel leakage. A simulation framework was developed to facilitate iteration of machine parameters during optimization. A treatment plan for a case of locally advanced lung cancer was generated using an in-house optimizer to assess the capabilities of the x-ray UHDR system. Individual beamlets of 10, 15, and 20-mm in size can produce isocenter dose rates of 17.3, 18.7, and 19.7-Gy/mAs and cross-channel leakage of 2.3, 1.9, and