Image Guided Intensity Modulated Helical Radiation (Tomotherapy) Used as a Radiosurgical Tool

Abstract

Introduction: Tomotherapy (HT) is a Linear accelerator mounted on a Computerized Tomography (CT), it is helical in nature, its application implies a megavoltage CT image acquisition which is fused daily to the radiosurgical plan that has been done previously (Image Guided Intensity Modulated Radiosurgery). This technology is new worldwide; to our knowledge this is the first report of intracranial radiosurgery in Latinamerica with HT. We describe dose distribution in a small target, as well as normal case flow and our initial intracranial experience. Methods: For the analysis of irradiation of a small target (PTV), one 10 mm spherical (0.51cc volume) target was elaborated. The PTVs where placed in the isocenter and 100 mm above the isocenter, the PTV received a 6 Gy prescription to the 85% isodose line, with a maximum dose of 9.0 Gy and a minimum of 4.7 Gy. We describe normal patient flow and retrospectively report our early experience from February 2011 to August 2011of intracranial radiosurgical cases. Results: The results of our Quality Assurance (DQA) on phantom studies show a very conformal (CI) 1.14, and homogeneous (HI) 1.51 dose behavior with a fall-off to 50% with regards to PTV of 4.6 mm, thirteen patients had been treated receiving 36 radiosurgical sessions. Conclusions: Radiosurgery with HT, it is a highly conformal,homogeneous with steep dose falloff, comparable to other stereotactic radiosurgical (SRS) tools, it is non invasive and it usually is a very low time consumption technique.