Revision 1

Accepted · first revision · record

Title: Conformal FLASH delivery to deep-seated tumours
Plain: Fast dose is easy to produce near the skin but hard to shape around a deep tumour. The accelerator and delivery physics for doing both at once is unsettled.
Precise: Design and demonstrate a delivery scheme giving a conformal dose distribution to a target at 10 to 20 cm depth with mean dose rate above 4000 rad/s over the whole target and delivery under 200 ms. Candidate routes: very-high-energy electrons at 100 to 250 MeV with magnetic scanning or focusing, transmission or Bragg-peak proton beams with ridge filters, and multi-source photon arrays. An answer is a validated design with measured dose rate, conformality and delivery time.
Settled by: Measured three-dimensional dose and dose-rate maps in a phantom meeting target conformality and the dose-rate criterion simultaneously.
Kind: well-posed
Answer type: mechanism
References: (empty)
Literature status: open
Status note: Proton transmission FLASH has been used in clinical trials, but conformal deep delivery at full dose rate was still a design problem in 2025.
Posed since: 2018