ESTRO 36 Abstract Book

S314 ESTRO 36 _______________________________________________________________________________________________

2 Princess Margaret Cancer Centre, Radiation Medicine Department, Toronto, Canada Over the past two decades, radiation therapy treatment has rapidly changed. Since 2000, Computed tomography (CT) scans have been used for the definition and delineation of target volumes by radiation oncologists. Treatment planning platforms have advanced from 2D to 3D, as well as radiotherapy techniques from 2D conventional approaches to 3D conformal radiotherapy (3D-CRT). Moreover, in just one decade Intensity Modulated Radiotherapy (IMRT) and rotational therapy (Volumetric Modulated Arc Therapy (VMAT), TomoTherapy) have made their appearance. CT simulation is often accompanied by MR simulation or MR fusion for radiotherapy planning purposes and over the next few years, the use of Magnetic Resonance Imaging (MRI) accelerators will become more widespread providing new insights and opportunities. Online megavoltage and/or kilovoltage Imaging before and during radiation treatment is allowing for localization of the target volume to deliver the prescribed dose as accurately as possible. Each step in the radiation treatment process, from CT to treatment delivery needs to be precise, ensuring the optimal treatment is achieved. In this debate we will focus on this precision, discussing if we have found the highest level of precision in radiation treatment. Topics for debate will include: -Modern planning and delivery systems have optimised target coverage. -Online Cone Beam CT/MR guidance has maximised precision in the preparation of the radiation therapy treatment -MR/CT imaging during radiotherapy delivery has optimised the precision and accuracy of radiation treatment delivery -The precision of highly conformal treatment techniques has resulted in improved clinical outcomes with reduced radiotherapy related side effects.