LhARA ionacoustic dose profiling meeting: 01Sep21; 09:00 BST

Notes

JM 08/09/2021

Present: Jeff Bamber, Ben Cox, Ken Long, John Matheson

1. Introduction, notes and actions of previous meeting: All
   Actions:
   • JB – circulate long version of GC proposal
     • Stands. KL will check if he has it on his disc.
   • All – read GC proposal in preparation for discussions next week
     • Stands.
   • KL – simulations of proton beams in water => dose maps
     • Done: but not posted ... a sample at 15MeV was produced. Will be added to Anthea's page
   • BC – acoustic simulations from dose maps, aim to demonstrate sufficient acoustic pressures for successful use of available transducers
     • Stands.

2. Discussion
   To get a handle on the acoustic signal from the LhARA Stage 1 beam Ken is running GEANT simulations. These will be an input for Ben’s acoustic simulations. We need to have a plan for the proof of principle setup, which may partially be based on material to be circulated by Jamie on what has already been shown in the literature. We need something believable on the timescale of a few weeks – Ken and Ben will meet again on Friday to take the simulations forward, hopefully putting some numbers on the acoustic frequencies and pressures of the low energy beam by next meeting (15/09/21). The GEANT simulations use typically 1E4 protons, to give reasonably smooth distributions, whilst the expected LhARA pulse is 1E9 protons. Other facilities where we might test will be considered individually. If there is a threshold on detectability of the acoustic signal, that tells us what minimum beam intensity would be needed to perform a given experiment. Jeff believes he can probably estimate well enough but would like to see the simulation results to confirm.

WRT finishing SmartPhantom, RAL can provide circa £2K which seems reasonable for consumables, etc. Scintillating fibre, carbon fibre supports, tooling for winding all exist at IC and could be shipped back to RAL. Liam Cooper at RAL has previous experience on this – John to talk to Liam. John and Ken to talk at RAL tomorrow. John had received an e-mail from Richard Smith (RAL Manufacturing Facility) and it looks like technical effort could be available if it can be paid for. There is a possibility of some limited money being available via Fergus Wilson (RAL PPD). John to follow up.

Jeff asked about the spatial resolution of the fibre planes and whether they offered single photon detection. Ken replied that they were to use 250 micron fibre and were only intended to be a cheap and cheerful way of profiling the beam, to be thrown away in case of radiation damage. Readout is via cheap CMOS camera. Single photon detection is well understood but expensive.

Jeff will try to write something for next week’s meeting, to share plans with other WPs. He confirmed that Emma Harris will take on some of his role if needed. Emma’s experience is in image guidance for adaptive radiotherapy and she is already involved in a European project which contains an element of ion acoustic imaging.

Last week there was a discussion about contact with AVO ​https://www.avoplc.com/en-gb/ and Tony Price will follow up. AVO could give us access to suitable test beams and may have their own interest in ion acoustic imaging.

3. AOB: All
   Dealt with above.

Actions:

• KL – circulate long version of GC proposal
• JG – circulate literature on existing lab ion acoustic imaging setups
• KL, BC meet to discuss putting the parts of the simulation together to get the acoustic pressure for the low energy beam
• JM, KL meet at RAL to discuss taking forward the SmartPhantom. JM talk to Liam Cooper, Fergus Wilson.
• JB to connect KL with Emma Harris and prepare some slides for next week if possible

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