LhARA radiobiology; meeting: 30Oct25; 14:00 BST

ZOOM: ​https://imperial-ac-uk.zoom.us/j/98220889714?pwd=SM90vOF7BKSXoU3mD9q7OwBQo4IVB3.1

Attended: CW, KL, HO, AFr, MH, ND, CD, BT

Meeting Notes

1. Minutes and actions:

• RW: Fine-tune installation of cell carousel
  • Done
• CD/DA/Afr: Find final beam setup with gold foil
  • Done
• EM/JMcG/DA/more visitors: Complete the online training indicated by Mark
  • Stands
• CW/RW: Turn on and clean the water in the incubators
  • Stands
• CW: Contact Marie Boyd
  • Done Waiting
• RW: Add lip to RCF holder
  • Done
• KL/CD: Get RCF cut
  • Done

2. Strathclyde: BT, ED, RW
   

• Beamline update:
  • Missing pulses were traced to a failed power supply. New power supply gives an increase in energy. The increase in power was sufficient to move one of the system outside its linear range and compromise operation. There are ND filters in the system to correct for this and once the problem was identified and located, the level of filtering was corrected and the team were able to produce a good focal spot at close on Tuesday. On Wednesday, the quads were placed in the beamline and we saw proton focus. Today (Thursday), the quads were moved as close to the source as possible, and an increase in proton flux was seen. A z-scan has also been performed, waiting for resutls.
• Dose Rate Update:
  • Slides
  • Calvin's sim produced ~1Gy. The RCF dose calculated by Nick peaked at 7Gy in the distribution. Tony produced a number of 2000Gy. Believe this must be a normalisation issue. Possibly a confusion of N vs E compared with dN/dE vs E
  • Clarify the problem to Tony so that he can calculate a more accurate dose per pulse
  • Will always have an issue with background subtraction that can cause a large variation in the calculated dose
  • Could remove some uncertainty by many RCF shots
  • Clear we need a faster way to calculate dose from the RCF

3. Simulation CD, DA, AFr:
   

• Results indicated quads are best placed as close to the source as possible and as close to each other as possible. The gold foil should be at the tube entrance, and the cell dish should be as close to the vacuum window as possible. The importance of these reduces in the order of them being stated here.
• However, fear with the statistics used in the optimisation causing the noise to dominate and uniformity being lost to noise.
• Can improve the sims by reducing the bin sizes.
  • Slides
• Alfredo simulation results
  • Indicated that a run with higher stats still looks uniform
• Highlighted an important issue, that in sim we can optimise number of protons against number of bins, there is a real world limit to these values in the number of protons per pulse and the area of a cell nucleus (110um^2).
  • Calculate the average proton to proton distance in simulation.

4. BioPrep EM, JP:
   

• Tick off items on checklist
  • Incubator update - Double
  • Consumables ordered - Waiting for delivery
  • Waste stream - Sorted
  • Microscope - camera not needed
  • Hoods serviced - Check anything else needs doing to them? No
  • Ice machine - Sorted
• Plan for staining finalised
• Marie Boyd update

5. Beam Diagnostics KL, CD:
   

• RCF update
  • Cut and brought to SCAPA
  • Fits in the holder
• Real-time beam diagnostic update
  • Lanex with a hole ready to go
  • Lanex also placed behind the cell dish

6. DoNM

• Next Week: 13th Nov

7. AoB

• Visitors complete the online training indicated by Mark
  • Tick off: EM (Done), Afr, DA, JMcG, CD
• Link to the run sheet: ​https://docs.google.com/spreadsheets/d/13vkixxNBZX42WFtxw7_MFJTU-gc06J19N8zpTcMKFys/edit?usp=sharing

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