Seminar Announcement: Gamma Knife Radiosurgery Basics: a Physicist's Prospective (Valeriy V. Kostyuchenko)

Department of Mathematics and Statistics

Department of Physics and Engineering Physics

Seminar Announcement

Title: Gamma Knife Radiosurgery Basics: a Physicist's Prospective

When: Tuesday October 25 2016 @ 3:30 PM

Where: Physics Building Room 103 

Guest Speaker: Valeriy V. Kostyuchenko, Medical Physicist
Gamma Knife Centre,
Burdenko Neurosurgery Institute, Moscow, Russia

Abstract: In this talk we will start from some aspects of radiation physics, discuss interaction
of radiation with matter, the means of generating radiation, and how all this allows
us to deliver large doses of radiation deep inside the matter. Then we will discuss radiobiological
questions, that is, how radiation inuences biological tissues – the DNA damage,
chromosome aberrations, and the role of oxygen. Mathematical models, such as Linear-
Quadratic Model (LQM) of cell damage, allow us to make some calculations of biological
eects and dene a fractionation scheme using the Biological Eective Dose (BED)
concept. Fractionation is commonly used in the conventional radiation therapy (RT), due to
the fact that tumors and normal tissues respond to the radiation dierently. In particular,
there is a so-called therapeutic gap between the probability curves of tumor control (TCP)
and complications in normal tissues (NTCP). But a modern technique which began with
Radiosurgery (RS) introduced by Lars Leksell in 1951 and was realized in the Gamma Knife
since 1967, and later also in other units, suggests another possibility – conformal/stereotactic
irradiation. First introduced for brain treatments (Stereotactic RS - SRS), and intended
for functional disorders, it quickly became common for tumor and AVM treatment, and has
now expanded to the spine and other localizations through the Image Guided Technology
(IGRT), respiratory synchronization, and so on. This eld is called Stereotactic Body RT
(SBRT) or Stereotactic Ablative RT (SAbR). This direction has a dierent, “surgical”, perhaps a
simpler view on the problem, compared to radio oncology (with less importance of fractionation
but necessity to account for systemic eects – blood supply, immune reaction,
etc.). This approach, more practically ecient due to high dose technique, becomes
increasingly popular, partly moving towards RT, and partly superseding it through the
hypo fractionation methods.

Due to their knowledge of fundamental science and versatility, medical physicists are key
specialists in the applied principally interdisciplinary RT eld. In a clinical setting, a medical
physicist routinely executes dosimetry testing and treatment planning, but also in many
cases denes the future of RT. First RT devices were developed by clinical engineers themselves,
and only later became manufactured by large companies like Philips, Varian, Elekta,
etc. Later, the same path, from a "physics art" to industry, was traced by computer treatment
planning. What is the present state and the future of the “physics art” in this area? We
will try to address this question.