Vaughn Betz

University of Toronto
Project Title: Fast and accurate biophotonic simulations for personalized photodynamic cancer therapy treatment planning
Industry Partners: IBM Canada Ltd.Theralase
Project Partner: Lothar Lilge
Platform: Agile Computing

Advanced Manufacturing Health

There are many medical uses of light, both for diagnostic purposes (medical imaging) and for treatment. We will build a very fast and accurate simulator of where light inserted with fiber optic probes travels within a person’s body; by using this simulator we can enable a promising new cancer therapy, among other medical applications. The key use of our light simulator in this project will be for photodynamic therapy (PDT), a promising new cancer therapy. It uses non-toxic light activated drugs (called a photosensitizer) which is harmless until it is activated by light of a certain wavelength; where activited the photosensitizer destroys cells.

Hence, if we can localize the light to a cancerous tumour, we can destroy it with minimal damage to surrounding healthy tissue and with fewer side effects and less cost than would be achieved with ionizing radiation therapy or surgery. PDT is used today to destroy “superficial” cancers, such as those on the skin where it is easy to localize the light to the tumour. PDT can also be used to destroy tumours within the body by inserting fiber optic probes through needles into the body.

The key challenge is that the light reflects, refracts and is absorbed in complex ways when it leaves the fiber, making it hard for a physican to determine where to place the fibers and whether the tumour will be completely destroyed. We aim to fill this gap by developing a fast and accurate simulator that can determine the light density throughout a person’s tissue that will result from a given fiber optic probe placement and light input intensity. To do so we will compute the path taken by hundreds of millions of simulated photons — a task so computationally intense that we will use an unconventional IBM computing platform that uses special programmable hardware to offload key calculations from the conventional processor. We believe that by doing so we can speed up the computation and reduce the power required by a factor of 60. This large speed up will allow us not just to simulate one probe placement but many possible light probe placements — we seek to return the best probe placement and the expected treatment results to the physician in less than an hour.

Overall this project will pave the way for a much-needed new, less invasive, more effective, and lower-cost cancer treatment. It will also use a new style of computation where special hardware does much of the computation, instead of a general purpose CPU, showing how such an approach can be used to make future computers faster and less power-hungry.