[PEPPo] Demonstration of momentum cooling to enhance the potential of cancer treatment with proton therapy

[Jay Benesch]

Wedge used to reduce momentum spread, as for muons.  Something to think 
about for secondary electron/positron collection?   I'll have to think 
some more about what wedge material would suit.




https://www.nature.com/articles/s41567-023-02115-2

In recent years, there has been a considerable push towards ultrahigh 
dose rates in proton therapy to effectively utilize motion mitigation 
strategies and potentially increase the sparing of healthy tissue 
through the so-called FLASH effect. However, in cyclotron-based proton 
therapy facilities, it is difficult to reach ultrahigh dose rates for 
low-energy beams. The main reason for this lies in the large momentum 
spread that such beams have after reducing their energy to levels 
required for proton therapy, incurring large losses in conventionally 
used momentum or energy selection slits. Here we propose momentum 
cooling by using a wedge in the energy selection system (instead of a 
slit) to reduce the momentum spread of the beam without introducing 
substantial beam losses. We demonstrate this concept in our eye 
treatment beamline and obtain a factor of two higher transmission, which 
could eventually halve the treatment delivery time. Furthermore, we show 
that with a gantry design incorporating this feature, we can achieve 
almost a factor of 100 higher transmission for a 70 MeV beam compared 
with conventional cyclotron-based facilities. This concept could enhance 
the potential of proton therapy by opening up possibilities of treating 
new indications and reducing the cost.