A compact X-band backward traveling-wave accelerating structure

Lin, Xian-Cai; Zha, Hao; Shi, Jia-Ru; Gao, Qiang; Hu, Fang-Jun; Li, Qing-Zhu; Chen, Huai-Bi

doi:10.1007/s41365-024-01403-7

Optimizing focused very-high-energy electron beams for radiation therapy based on Monte Carlo simulation

An,

Zhang,

Dai

et al. 2024

Sci Rep

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A TOPAS-based optimization program has been developed to precisely concentrate the dose of focused very-high-energy electron (VHEE) beams on deep-seated targets. This is accomplished by optimizing the magnetic gradients, positions, and number of quadrupole magnets within TOPAS. Using only three quadrupole magnets, the program focuses 250 MeV VHEE beams to achieve a maximum dose position deeper than 17 cm, while maintaining entrance and exit doses within 25% and limiting the lateral dimensions to ≤ 1 cm at the maximum dose location. The linear relationship between the magnetic gradient of the last quadrupole magnet and the maximum dose position enables dose location adjustments through gradient variation. Multiple positions were validated in TOPAS with errors within 1%. The spread-out electron peak (SOEP) is achieved by combining two VHEE beams with different maximum dose positions using the differential evolution method, covering a target depth of 12–17 cm and attaining a dose flatness better than 99%. This pioneering program imposes constraints on entrance dose, exit dose, maximum dose position, and the lateral dimensions of dose deposition at the maximum dose position within phantom. This program may be a promising tool in the applications of focused VHEE in highly conformal treatment plans based on TOPAS. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-024-79187-4.

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Optimizing focused very-high-energy electron beams for radiation therapy based on Monte Carlo simulation

An,

Zhang,

Dai

et al. 2024

Preprint

0

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A TOPAS-based optimization program has been developed to precisely concentrate the dose of focused very-high-energy electron (VHEE) beams on deep-seated targets. This is accomplished by optimizing the magnetic gradients, positions, and number of quadrupole magnets within TOPAS. Using only three quadrupole magnets, the program focuses 250 MeV VHEE beams to achieve a maximum dose position deeper than 17 cm, while maintaining entrance and exit doses within 25% and limiting the lateral dimensions to ≤ 1 cm at the maximum dose location. The linear relationship between the magnetic gradient of the last quadrupole magnet and the maximum dose position enables dose location adjustments through gradient variation. Multiple positions were validated in TOPAS with errors within 1%. The spread-out electron peak (SOEP) is achieved by combining two VHEE beams with different maximum dose positions using the differential evolution method, covering a target depth of 12–17 cm and attaining a dose flatness better than 99%. This pioneering program imposes constraints on entrance dose, exit dose, maximum dose position, and the lateral dimensions of dose deposition at the maximum dose position within phantom. This program may be a promising tool in the applications of focused VHEE in highly conformal treatment plans based on TOPAS.

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Design, construction, and test of compact, distributed-charge, X-band accelerator systems that enable image-guided, VHEE FLASH radiotherapy

Barty,

Algots,

Amador

et al. 2024

Front. Phys.

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The design and optimization of laser-Compton x-ray systems based on compact distributed charge accelerator structures can enable micron-scale imaging of disease and the concomitant production of beams of Very High Energy Electrons (VHEEs) capable of producing FLASH-relevant dose rates (∼ 10 Gy in less than 100 ns). The physics of laser-Compton x-ray scattering ensures that the x-rays produced by this process follow exactly the trajectory of the electrons from which the x-rays were produced, thus providing a route to not only compact VHEE radiotherapy but also image-guided, VHEE FLASH radiotherapy. This manuscript will review the compact accelerator architecture considerations that simultaneously optimize the production of laser-Compton x-rays from the collision of energetic laser pulses with high energy electrons and the production of high-bunch-charge VHEEs. The primary keys to this optimization are use of X-band RF accelerator structures which have been demonstrated to operate with over 100 MeV/m acceleration gradients. The operation of these structures in a distributed charge mode in which each radiofrequency (RF) cycle of the drive RF pulse is filled with a low-charge, high-brightness electron bunch is enabled by the illumination of a high-brightness photogun with a train of UV laser pulses synchronized to the frequency of the underlying accelerator system. The UV pulse trains are created by a patented pulse synthesis approach which utilizes the RF clock of the accelerator to phase and amplitude modulate a narrow band continuous wave (CW) seed laser. In this way it is possible to produce up to 10 µA of average beam current from the accelerator. Such high current from a compact accelerator enables production of sufficient x rays via laser-Compton scattering for clinical imaging and does so from a machine of “clinical” footprint. At the same time, the production of 1,000 or greater individual micro-bunches per RF pulse enables > 10 nC of charge to be produced in a macrobunch of < 100 ns. The design, construction, and test of the 100-MeV class prototype system in Irvine, CA is also presented.

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A compact X-band backward traveling-wave accelerating structure

Cited by 3 publications

References 36 publications

Optimizing focused very-high-energy electron beams for radiation therapy based on Monte Carlo simulation

Optimizing focused very-high-energy electron beams for radiation therapy based on Monte Carlo simulation

Optimizing focused very-high-energy electron beams for radiation therapy based on Monte Carlo simulation

Design, construction, and test of compact, distributed-charge, X-band accelerator systems that enable image-guided, VHEE FLASH radiotherapy

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