LhARA radiobiology; meeting: 27Nov25; 14:00 BST

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

Attended: EM, JMcG, CW, DA, AFr, TP, AG, MB, MH, JP, RW, CD

Meeting Notes

1. Minutes and actions:

2. Laser: RW
   

• RW: Explanation of the laser problem and the fix
  • That problem seems permanently fixed.

3. RCF: AFR, DA, CD
   

• Calibration
  • Rotation Issue
  • Rotating the films in the scanner can cause a ~30% change to the mean dose in a particular case. More generally causes a substantial difference.
  • Can combat by rotating the films each time we scan and always selecting the orientation that gives the highest mean pixel count
• Calculating Dose per Shot, Variation and Dose delivered to Cells
  • From RCF, average dose per shot of 0.61±0.25Gy (More data to be analysed)
  • Hard to spot a variation day to day
  • Variation in one showed a change after 8 films had been irradiated. Need to analyse the shots to get a better understanding of what this is
    • Robbie's suggestion is a defocussing laser spot effect
• Flatness and Uniformity of Dose
  • Average CV: 15.1±2.5%
  • Average Flatness in X: 26.4±5.5%
  • Average Flatness in Y: 29.6±4.7%
  • Beam is too non-uniform still
• Sim comparison
  • CV: 17%
  • Moving the Copper closer would bring CV down to 9% and the mean dose would also fall by 45%

4. Bio: EM, JP
   

• EM: Summary of Experiment

Dry Run

• Seeding density test

FaDu gave a plating efficiency of 40?%

• Marie Boyd update
  • Comet analysis

Alive dead stain can be done after a couple of hours? That depends on the dose received to how to wait

• Collect pellets and do a western blot test for a rough idea
  • Could not tell between a 2 and 4Gy

H2X -There is a way to select cells from all the same area. Though there is the issue that there are not enough cells then.

• IF might give an idea of hotspots
• x-ray irradiate with a known dose to do a comparison
• Marie will do a comet assay
• Plan for staining and delivery back to Birmingham

• Move things to Marie's lab
• Can also do some control irradiations at Marie's as well

• From the colonies, no growth in the controls either
• Microscope is not great, so Marie can take their one to SCAPA
• Could be the microscope that means cannot see any cells
• Marie can do the staining check on Friday but will do on Monday
• The cells were dried out by 50%, incubator felt very hot and humid. Put a thermometer in it to check

5. Future:
   

• Current Problems:
  • Clear Communication of Requirements
  • RCF to Dose Procedure
    • Alfredo and Diaza are piecing together a protocol document to standardise how we complete this procedure
    • The rotation issue is taken into account
    • Diaza in favour of scanning at lower resolution to speed it up
  • Uniformity not good enough
    • Place the Copper scatterer closer
    • Results need to analysed
  • Shot-to-shot variation
    • Include a piece of RCF in front of the cells (Ideally delaminated but not possible to calibrate before the next visit)
      • Need to sim what the LET would be for our energy range into the cells with the RCF in place
    • Longer-term investigate an on-beam diagnostic
    • Another option is to find a correlation between the RCF mean dose and one of the laser diagnostics that the team already gathers

• Discussion of when to use the rollover days
  • Plan to use Wednesday, Thursday and Friday next week
  • If good, then use the 3 days to do more cell irradiations
    • Emma will send the dishes up tomorrow
  • If not work on more beam diagnostics and improving it to complete cell irradiations, tackling either uniformity or shot-to-shot variation

• IPAC abstract submission?
  • No takers and a belief that we should wait until we have a slam dunk result
  • Note: LhARA will have a general submission that will mention PoPLaR
• Book a longer discussion to analyse all the results and define a plan for the future
  • Not discussed

6. DoNM

• 11th Dec

7. AoB

• Congratulations Dr Melia!!!

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