Toshiro Tsubouchi became fascinated by radiotherapy when he stumbled across it online, as a master’s student in quantum engineering in Nagoya, Japan. “It was very interesting and surprising to me that radiation could be so useful in treating cancer,” says Tsubouchi, originally from Kyoto. Eight years later, he is a physicist at the Osaka Heavy Ion Therapy Centre.

Particle therapy uses protons and heavier ions to deliver a sharp spike of dose at a certain depth in the body; which is defined by the particles’ energy, as compared to the gradual drop-off provided by photons in conventional radiotherapy.  Consequently, tumours can be more precisely targeted, reducing side effects.

As it is a brand-new facility, it’s an exciting time at Tsubouchi’s centre, which uses a 17 m diameter synchrotron to accelerate carbon ions to therapeutic energies. The centre will begin treating patients this month, and once they arrive, Tsubouchi will focus on planning and checking patients’ treatments and routine checks of the beamlines.

Tsubouchi joined the centre in April following a PhD at Osaka University. While his thesis focused on photons, he pursued his interest in particles as a side project, investigating grid therapy – research that he hopes to continue in his new job. The technique uses a comb-like array of narrow beams, instead of a conventional solid beam, to reduce the dose to healthy tissue further still.

Both projects were theoretical, using Monte Carlo simulations. The chance for Tsubouchi to grow his programming skills is now paying dividends in his job. “Sometimes the data we want to analyse are not suitable for commercial software. In that case we need to write the programs ourselves.”