Table 1.
FLASH radiotherapy (FLASH-RT) challenges
| General |
| Accurate dose monitoring and delivery at ultra-high dose rates Technologies, which can provide FLASH dose-rate radiation that can reach majority of tumours lying at depth of 10–20 cm in the body, eg. very high-energy electron (VHEE) beams [33], laser particle accelerators [34], pluri-directional high-energy agile scanning electronic radiotherapy (PHASER) [25] |
| Dosimetry |
| Detectors able to measure online the beam fluence at FLASH dose-rate Detailed simulations and modeling of the detector behavior in environment proper for FLASH-RT Recombination effect, saturation, and sensor linearity with dose-rate Calibration and quality assurance tools Precise beam characteristic tools: verification of machine output, dose delivered per pulse, and dose-rate in real-time, pulse duration, interval, and overall irradiation time Full pencil beam scanning for proton beam-based FLASH-RT |
| Radiobiology and clinical practice |
| Detail relationship on how FLASH effect varies with LET and oxygen concentration Experimental proofs for distinction of oxygen level between normal and malignant tissue allowing its quantification Treatment planning systems utilising FLASH radiotherapy planning Immune factors in both normal and tumor tissues exposed to FLASH-RT Mechanisms of DNA damage response and immune response after FLASH-RT Clinical study when beams able to reach 10–20 cm in a body are available |
LET — linear energy transfer