ESTRO 36 Abstract Book

S413 ESTRO 36 _______________________________________________________________________________________________

difference between NFS and EFS was about 6% for 5 mm field size. Penumbra values were lower than 3 mm for field sizes up to 15 mm.

incorporated and accounted for in a customizable collision control. Software: A control software release has been developed featuring extended functions, simplified usage and platform independence.

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Figure 2 shows the phantom in a clinical setup. A static and a respiratory gated CT were performed. Respiration surrogates were acquired using the C-Rad Sentinel System. Furthermore, a Cone Beam CT mounted at a linear accelerator was obtained.

Conclusion Conclusions : CyberKnife OFs measured by Razor showed a high consistency among different centers and a comparable variability to data obtained by PTW-60017 routine detector. Comparison between Razor OFs and PTW-60017 measurements corrected by Monte Carlo indicated that correction factors for Razor should be smaller than for PTW-60017 down to 7.5 mm field size. EFS and penumbra measured over the four centers showed a good consistency confirming Razor as a good candidate for small beam relative dosimetry. PO-0779 New robotic phantom for evaluation of imaging and radiotherapy of moving structures H. Arenbeck 1 , L. Eichert 1 , G. Hürtgen 2 , K. Gester 2 , I. Brück 2 , N. Escobar-Corral 2 , M. Fleckenstein 1 , A. Stahl 3 , M.J. Eble 2 1 Boll Automation GmbH, Research and Development, Kleinwallstadt, Germany 2 RWTH Aachen University Hospital, Radiooncology and Radiotherapy, Aachen, Germany 3 RWTH Aachen University, III. Institute of Physics B, Aachen, Germany Purpose or Objective Four dimensional radiotherapy processes that allow an adaptation to intrafractional motion require increased accuracy of dose application while displaying increased technological and procedural complexity and thus multiplied sources of error. Consequentially, novel 4D phantoms are required that feature anthropomorphic structure and motion. In this work, a prototype of such phantom, which is fit for long term clinical service, is presented. Material and Methods The modular phantom architecture allows different static and moving human equivalent structures and dose measurement devices to be placed into the irradiated region. A new kind of parallel robot generates freely programmable motion in all Cartesian directions. The whole system is portable and features similar extension as a human. Concept, kinematics, construction and software of a previously presented evaluation model have been fundamentally refined. Results The new components of the robotic phantom are presented in figure 1. Major technological advancements with respect to the evaluation model are: • Robot: A novel kinematic structure has been found, which reduces the number of joints and increases stiffness of the mechanics. A fatigue endurable mechanical construction has been created. Rapid exchange of the Target core and inclusion of tethered measurement devices are now possible via the hollow end effector.

Figure 1: Structure of the robotic phantom

Figure 2: Results of medical imaging Conclusion

First applications of the phantom under clinical conditions and purposes revealed feasible physical properties, functional range and applicability. The platform technology of the phantom has reached prototype maturity and can be flexibly adapted to a broad range of clinical scenarios. For example, both little and high complexity of human equivalent structure and motion, both film and ion chamber dosimetry, both air and fluidic environments, optionally containing radioactive tracers, are supported. A unique feature of the phantom is its combination of the described high flexibility with practical feasibility, efficiency and robustness. Next, real time robot control capabilities will be extended and clinical long term studies will be performed. PO-0780 Feasibility study of beam monitoring system using AFCRS for proton pencil beam J.M. Son 1 , M.Y. KIM 2 , M.G. Yoon 3 , D.H. Shin 1 1 National Cancer Center, Proton therapy Center, Goyang-si- Gyeonggi-do, Korea Republic of 2 Dongnam Inst. Of Radiological & Medical Sciences, Research Center, Busan, Korea Republic of 3 Korea University, Bio-convergence engineering, Seoul, Korea Republic of

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Modularization: Body and Target can now be assembled manually and rapidly while ensuring an absolute positioning accuracy of < 0.1 mm. Third party phantom structures can be