I did not say that we are in an access crisis, I think you misunderstood my point.
The US likely has more than enough proton centers and we do not have access issues in Europe to treat what makes most sense with protons.
The problem with protons is the cost.
If you are going to spend hundreds of millions to build a facility and need millions per year to keep it running, you will have to treat prostates and breasts to pay it off. Because those are the cases, with which most of the radoncs make their money. Little effort, yet high pay.
5 prostate proton patients indirectly pay for 1 medulloblastoma proton treatment for a 5 year old.
So, if we are able to get proton solutions that are cheap, both in installation and operation, we may end up treating stuff which may make more sense. And that is where the S250 may fill a gap. If it costs 15 millions to set up, 1 million per year to operate and you can put it in an old department without having to build a new vault, then a center which now has 3-4 linacs and is thinking of swapping one of their C-arm linacs for a cyberknife, may actually buy one S250. The price likely has to come down more, I think the sweet spot is around the MR-linac or fully upgraded Cyberknife price, roughly worth two C-arm Linacs.
Have any of you seen a proton treatment for repeat RT of a bone met, which has already had considerable dose to the cord or perhaps a repeat RT for a nasty rectal cancer recurrence where the plexus and the small bowel are troublesome for photons? I haven‘t.
Because those treatments generally do not pay well, regardless if it‘s photons or protons.
It‘s a bit like the MR Linac argument. Many centers used/use those machines to treat prostate, where the clinical benefit is likely small (we‘ve been over Mirage). There‘s a reason those machines were not running 24/7 with NSCLC SBRT (where data is also compelling) or pancreas.