The new challenges in radiation therapy.

Together with surgery and chemotherapy, radiation therapy is one of the main pillars in combating cancer. More than half of all cancer patients will be treated by radiation therapy in one or more stages of their disease. Radiation therapy is not merely effective, but compared to the other treatment modalities, extremely cost-effective. With risk of oversimplification, it can be stated that progress in high precision photon beam techniques have resulted in less toxicity by their ability to decrease the unwanted dose outside the tumour volume and initiate new paradigms of aggressive treatment doses to increase the tumour control probabilities. Modern radiation therapy is developing in several parallel tracks and in general individual solutions are being proposed for particular problems, usually based on upgrading existing equipment. Inevitably, this approach leads to sub-optimal solutions and compromises. The VERO System is designed (not an adaptation of existing equipment) to be an all-in-one solution to solve the new challenges in radiation therapy.

The VERO system: all-in-one solution.

The VERO system is developed for adaptive and high-precision conformal arc therapy with high-energy photons (6 MV) in combination with state-of-the-art image-guidance. The real-time imaging possibilities together with the pan-and-tilt assembly of the linear accelerator (linac) allows for real-time and respiratory synchronized tumour tracking. The system is based on an O-ring structure offering an extremely high mechanical precision of 0.5 mm. The pan-and-tilt linac and collimating assembly is a gimbals-based mechanism designed to anticipate tumour mobility during treatment (real-time tumour tracking!). In addition, the gimbals mechanism is able to correct for small mechanical deviation or gravity effects resulting in an increased precision in dose delivery to 0.1 mm. Image-guidance and feedback is provided with an on-board dual X-ray/detector system allowing both fluoroscopic imaging (assessment of real-time tumour motion) as well as cone-beam CT reconstruction (3D reconstruction of patient anatomy). An additional flat panel detector mounted in-line with the treatment beam distal to the patient, is designed for megavolt cone-beam CT reconstruction with the actual treatment beam, real-time tracking of implanted markers with the treatment beam, as well as in-vivo dosimetry based on dose transmission measurements. Accurate patient positioning is provided with a robotic treatment couch allowing 6 degrees-of-freedom in patient set-up (3 translations – 3 rotations). The patient’s position is continuously monitored and the robotic couch is controlled in real-time utilizing an infrared tracking device.

The VERO System: implementation of new treatment approaches

The VERO System is an ideal platform to investigate both biological relevant dose distributions as well as dose escalation studies. The system incorporates state-of-the-art imaging modalities, both volumetric (kV CT and MV CT) as well as kV fluoroscopy for 3D and real-time assessment of tumour localization. In addition, the 2D collimating system mounted on a ring-based gantry via a gimbals-mechanism allows for high precision dose delivery using intensity-modulated arc therapy as well as tracking mobile tumours in real-time. None of these features have been incorporated simultaneously into one treatment machine to date. The multi-functional approach of VERO System is not only a world-premiere, but it also represents an optimal platform to challenge the multiple facets of cancer. The system will enable a safe and clinical implementation of new treatment approaches in radiation oncology.