Beam therapy in 3D format

Algorithms and programs being developed by scientists from the Moscow Physics Engineering Institute and the Keldysh Institute of Applied Mathematics RAS with the support of the International Science and Technology Centre will help oncologists to accurately and rapidly calculate an optimal dose of radiation. Then, they will be able to determine the direction and intensity of radioactive flows so as to have maximum harmful effect on the tumour with minimum irradiation of healthy tissue, and all within a few minutes.

Unfortunately humans are not yet aware of totally safe means to fight malignant tumours. In the final analysis all resources that kill a tumour cause varying degrees of harm to healthy cells; they destroy the tissues of the heart, kidneys, testicles and so on. Sometimes the most effective kind of therapy and, strange though it may seem, the least harmful to the patient, is the so-called optimal beam therapy, in the course of which the dose required to treat the tumour is received by the tumour itself, while the patient’s remaining organs and tissues receive a minimum dose load.

Naturally the developers of the beam therapy apparatus are doing their utmost to optimize where possible the dose distribution and, to do this, to increase the accuracy of its calculation. In an ideal situation a beam is required which would hit the tumour directly and which would rapidly weaken beyond its outer limits. But is it possible to calculate in advance the parameters of the beam in such a way so as to pre-plan the radiation dose throughout its path in the patient’s organism? Our body after all is not an ideal homogeneous environment; knowing the laws of interaction of it with one or another form of radiation, it would be easy to calculate the dose in each point of the organism during the course of the irradiation. Skin, bone, muscle: as such all tissue types interact with radiation in their own way, not to mention the fact that the human body surface itself is nothing if not irregular.

It is clear that only a computer is able to resolve such a non-uniform task as the planning of remote beam therapy. In principle methods already exist in other applied fields to calculate the spread of radiation effects and the algorithms and programs required to solve other tasks. Under their direct application to resolve tasks in radiation therapy planning, they ensure high precision but are so difficult to implement that it would take one PC not minutes but tens of hours to solve such a task. It is understood that such terms are unacceptable for the purposes of practical medicine.

So, what are the project authors proposing? The fact is that they have considerable and very successful experience behind them in solving similar problems for calculations related to nuclear reactors and the protection of nuclear installations. To reduce the calculation time with three-dimensional systems, they were able to divide the total time and, accordingly, the calculation time between several computers, having taught the computers to exchange information between themselves. In other words they developed programs to transfer to multiprocessor technologies and to parallelize calculations.

It is this experience that the authors propose to use in order to facilitate the calculation of parameters of radiation beams that are required for optimal irradiation of a specific point in the patient’s body.

“To compute the radiation dose a patient will receive in the course of a procedure, in each point in their body, we have developed a principally new computational algorithm, based on a combination of Monte-Carlo methods and a discrete ordinates method,” explains Project Manager Alexander Kryanev. “This set up differs from all those before, not only in a reduction in the time required to model the trajectory of radiating particles, but also in that it uses a new class for estimating the radiation dose. The essence of the set up is fairly complicated, although the result is understood by all: it has been possible to reduce calculation time by orders of magnitude. And as the new algorithm, by way of its features, can almost completely parallelize calculations, all calculations of the doses in the radiation volume can be performed in just a few minutes.”

As a result the authors hope to develop a remote beam therapy complex to rapidly and accurately plan optimal irradiation on computers with parallel architecture. Then the authors intend to test their complex in a clinic of the Russian Federation Oncology Centre. In their turn oncologists and patients hope that the researchers will have the requisite conditions in place to create such a complex. There is no doubt that the scientists are equipped with the knowledge and experience required.