OAPT C O N F E R E N C E
25 - 27 May 2006		 Perimeter Institute

 

Pedro Goldman

Fast Optimization of the Radiation Therapy of Tumours
- the Impossible Possible

We could have named this talk "the many uses of a physicist". Although the talk will concentrate on the optimization of the radiation treatment of tumours, I will emphasize the opportunities available to physicists outside the realm of hard core physics and in particular in the field of Medical Physics. Another title could have been "the mystery of the negative intensities". The story goes as follows: the new standard for the radiation therapy of tumours is based on the delivery of hundreds or thousands of thin beams of radiation (or beamlets) incident from multiple directions. A crucial problem in radiation therapy is to optimize these thousand of beamlets so that the dose distribution is uniform inside the tumours and small inside organs at risk. A system of linear algebraic equations will handle this quickly but it is impossible to use: it results in negative beams! - Proofs of the impossibility of such a solution have been given. Instead we are forced to search numerically the optimal intensities, taking long computation times and yielding sometimes incorrect results. A fast optimization algorithm is crucial not only for the design of good radiation treatment plans but also to be able to re-adapt the daily application of the treatment in real-time. Our new solution made the impossible (a linear method) possible on physical grounds, delivering excellent dose distributions in times orders of magnitude shorter than present search methods.

Biography

Born in 1948 in Buenos Aires, Argentina, married to Ursula Trescases, and a member of a very loving family of four.

S. P. Goldman Received his B.Sc. Hon. in Physics at the TECHNION in Israel (1975), majoring in General Relativity and Cosmology under the tutelage of Prof. Nathan Rosen. Completed an M.Sc. in General Relativity at the University of Windsor (1977) under Prof. E. Glass and Ph.D. in Relativistic Atomic Physics under the supervision of Prof. Gordon Drake (1981). The Ph.D. dissertation solved a long standing problem in the field, opening the doors to a wide variety of relativistic and Quantum Electrodynamic Calculations - this work, on the avoidance of relativistic variational collapse, is now known as the Drake-Goldman theorem. Since then S. P. Goldman has produced ground-working work in a variety of fields. His work in relativistic calculations for many-electron atoms and diatomic molecules, done while being a Visiting Research Fellow at the Harvard-Smithsonian Observatory, led to a prestigious invitation to write a chapter for a book in honour of Alexander Dalgarno. His work on very accurate calculations for atoms in strong magnetic fields broke an impasse and became a standard source in the "Atomic, Molecular and Optical Physics Handbook". His work on extremely accurate calculations of Quantum Electrodynamic energy corrections led, in collaboration with G. W. F. Drake, to the most accurate calculations of the energy levels of Helium including relativistic and QED effects which, in conjunction with current experimental results, are crucial to the determination of fundamental constants and to the examination of fundamental theories.

His most recent work in Medical Physics has already produced results that have revolutionized the optimization of the radiation therapy of tumours. The University of Western Ontario in conjunction with the London Regional Cancer Program, has filed an international patent on this technique.

S. P. Goldman has had as well a strong dedication to teaching. He has been in the UWO teaching roll of honour each year since its inception, earning student evaluations above 90% each year in all his courses. He has as well received numerous medals in teaching including National Awards and has had a medal created in his name by the Student Council of the Faculty of Music at UWO. He has been as well a driving force behind the Division of Physics Education of the Canadian Association of Physicists, which he has chaired in the past and is presently chairing again.


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