Proton Calorimetry/Meetings/2025/02/04
Minutes for UCL Proton Beam Therapy Group Meetings, 4th February
Present
Joe Bateman, Sonia Escribano, Simon Jolly, Raffaella Radogna (via Teams), Kirsty Hall (from Hamamatsu)
- Discussion with Kirsty Hall from Hamamatsu about photodiode arrays for scintillating fibre array to allow for better integration with QuARC.
- Kirsty to investigate two possible routes for going forward:
- Possibility of having on board DDC or way of connecting S13885-128 photodiode array to DDC board.
- Possibility of having surface mounted photodiodes (such as S12859-021) shrunk to a smaller size so that pixel pitch is comparable with 0.5mm fibre diameter.
- Also will look into questions Raffy has a about current experience with S13885-128 photodiode array, i.e.:
- If observed response at saturation (e.g., decreasing signal rather than plateau or charge sharing among neighbours) is expected
- How response of individual photodiodes within array vary and how to characterise this.
Raffaella Radogna
- Discussed with Bari mech eng Producing second prototype with resin material harry suggested - use inventor files (should be able to open fusion) will share with them once harry has finished with the fusion file
- Produce 2 new prototypes (frame + fibres + screws etc) and have one sent here
- Beam test in Trento
- ~5s per beam
- 10 beam deliveries each for CONV and UHDR calibrations (but may only need 8)
- Background measurement at FSR for 12.5pC acquisition and for for FLASH
- Happy to cut out as many pristine Bragg peaks as necessary to keep within FLASH time limits at Trento
- I.e. 1 minute = 12 Bragg peaks at ~5s per measurements
- Or Bragg peaks at lower measurement time per FLASH Bragg peak (i.e. <5 s)
- Spot scanning at CONV dose rates
- Potentially WET measurement of fibres at next UCLH if using giraffe on new QuARC electronics
Sonia Escribano
- Looking at new calibration method - now works with txt file that is generated with calibration values
- Problem with calibration
- Need calibRMS - need separate file with these values?
- Important for the fit
- Include rms beneath calibration coefficients
- How do we save name of header file for calibration file
- Include in header file which files were used to generate calibration coefficients
- Need calibRMS - need separate file with these values?
- In new file structure maybe have new file directory for background data, i.e. calibration, background, date
- For now do it manually
- New calibration and fitting procedure
- generate calibration txt files using shoot throughs
- Apply calibration values generates calibrated txt with every single measurement
- Fit data averaged at 25 Hz -read calibrated data and fit at desired frequency (default 25hz)
- Things for new experiment
- Raw data = 160*8 (hex length and 8 modules)
- Calibration: 4 calibration_i files
- Calibrate data
- Initially split the raw data in two files for each Bragg peak
- Messaged harry about scintillators waiting to hear from John and Wayne but still hasn't sent them scintillator sheets yet
- Simon and Sonia to check final design on fusion
- How do you ensure consistency between modules if there's difference in coupling etc
- Take Manchester data and do shoot-through calibration in current way then apply it to one of the shoot-through calibration files and see how it looks for each module (i.e. treat each module independently)
- Need to find a way to scale to dose in each of the modules
Joe Bateman
- Re-did simulations in TOPAS (ongoing) and FRED with adjusted input beam size from DICOM for 3x3 and 5x5 cm box fields
- Calculated new input beam size as: σ_P = (σ_iso × (SAD - d)) / SAD Where:
- σ_P is spot size at position P
- σ_iso is spot size from DICOM (at isocenter)
- SAD is virtual source-axis distance
- d is distance from isocenter to position P
- Using d as 10 cm upstream from phantom surface
- Calculated new input beam size as: σ_P = (σ_iso × (SAD - d)) / SAD Where:
- Resulting shape looks more characteristic of TPS distribution.