VIRTUOS – VIRTUal RadiOtherapy Simulator

Introduction

VIRTUOS is a virtual radiotherapy simulator, which was developed in our department as a research platform for scientific projects. Hence, VIRTUOS was the basis for a variety of research projects and was itself evolved and increased out of these research projects.

VIRTUOS is used for treatment planning at DKFZ Heidelberg since 1991 [1, 2, 3, 4]. Based on this technology it was possible to introduce three-dimensional treatment planning in clinical routine at the Radiological University Clinic in Heidelberg in the early nineties [3]. Due to its depth of functionality and various configurations we also have various national and international partners (e.g. Charite in Berlin, iThemba Labs in South Africa).

Therapy simulators are widely used in radiotherapy. The goal of therapy simulation is the evaluation and optimization of alternative treatment strategies before treatment, to find the optimal treatment plan for the patient. 

Radiotherapy Planning

A therapy simulator is an X-ray imaging device, with the same geometric properties as the linear accelerator used for therapy. This device allows the acquisition of images from that position where the radiation source will be during therapy. This way the therapist can verify the patient’s position and beam direction. Treatment simulation is one of a series of consecutive steps in radiotherapy planning. VIRTUOS is focused on issues, how the “visible” part of radiotherapy can be simulated, that means how individual three-dimensional patient models can be generated efficiently, how optimal parameter settings (irradiation directions, beam portals etc.) can be found and how it could be assured, that the treatment is done exactly as defined in the planning step. This way it is possible to minimize the dose in the surrounding healthy tissue and to take care of radio-sensitive structures. In addition it is possible, to pre-calculate the physical dose distribution exactly, based on this three-dimensional patient model. The pre-calculated dose distribution allows the comparison of alternative treatment strategies and the selection of an optimal plan.

Simulation of the dose deposition in the patient’s tissue is done by dedicated dose calculation algorithms. After dose calculation is performed VIRTUOS supplies various quantitative and qualitative methods to evaluate dose distributions and to compare and score concurrent plans. 

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References

[1] Bendl R (1991): Entwicklung und Implementation einer Benutzerschnittstelle zur virtuellen Strahlentherapiesimulation. Diplomarbeit Medizinische Informatik Universität Heidelberg / Fachhochschule Heilbronn

[2] Schlegel W, Pastyr O, Bortfeld T, Becker G, Schad L, Gademann G, Lorenz WJ (1992): Computer Systems and Mechanical Tools for Stereotactically Guided Conformation Therapy with Linear Accelerators. Int J. Radiation Oncology Biol. Phys. 24: 781-787

[3] Gademann G, Schlegel W, Bürkelbach J, Laier C, Behrens S, Brieger S, Wannenmacher M (1993): Dreidimensionale Bestrahlungsplanung – Untersuchungen zur klinischen Integration. Strahlentherapie und Onkologie 3: 159-167

[4] Höss A, Debus J, Bendl R, Engenhart-Cabillic R, Schlegel W (1995) Computerverfahren in der dreidimensionalen Strahlentherapieplanung. Radiologe 35: 583 - 586

People involved:
Rolf Bendl
Christian Bierstedt
Silvia Handlos
Kim Löpprich

Alumni:
Bernd Hemmer
Jan Rüppell
Sven Skobowski 

You want to know more? …. Get in touch with Prof. Dr. Rolf Bendl

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