Flash radiation therapy

Flash radiation therapy

• 1.
  FLASH Radiation Therapy Basics andclinical translation
• 2.
  History & Preclinicalapplication • Described by Town et al (1967) first • Applied to tumours first (Favaudon & Vozenin et al: 2015-16) • Bourhis et al (2019): first patient treatment • Preclinical application • 28, 31, 34 Gray delivered to pig skin in a volume of <10 cc (2.6 cm diameter): No necrosis seen at 9 months as compared to conventional therapy • 31 Gray delivered to approx. 120 cc: No necrosis
• 4.
  Physical parameters: FLASHEffects • Dose rate: >40 Gray/sec (possible); >100-150 Gray/sec (likely) • Reproducible effect • Dose / pulse (> 1.5 Gy & few pulses) • Dose rate in the pulse (>= 106 Gy /s) • Overall time (< 100 ms) • Dose/fraction • Begins to show up at >10 Gray/fraction • No dose limiting effect observed in animal models between 25-41 Gray • Radiation type • Most reproducible with electrons • Ongoing work on X-rays and protons
• 5.
  Biological effect • Completeoxygen depletion in cells: well oxygenated normal tissues are spared • Difference in redox biology of the oxygen metabolism • Different immune effect (less cytokine release: less normal tissue damage) • Differential gene expression induced by FLASH
• 7.
  Optimizing therapeutic outcome
• 8.
  Advantages over conventionaltherapy • Better normal tissue sparing: 25-30% • Fewer fractions of treatment (1-3): compliance and QOL • Ultra short treatment times (ms): No intrafraction motion management
• 9.
  Challenges ahead • Modificationof existing LINAC to match physical parameters • Modified VARIAN Linac at Standford • Modified ELEKTA Linac at Lund university, Sweden • Lausanne University Hospital, the eRT6 Oriatron (5.6 MeV, electron linac, PMB, Peynier France):First patient treated with this • Pluridirectional High-energy Agile Scanning Electronic Radiotherapy (PHASER): Under evaluation • Development of FLASH VHEE (very high energy electrons); X-Ray and proton systems • Quality assurance and dosimetric verification • Robust dose monitoring and stopping system • Evolution of dose fractionation schedules for clinical routine use