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Recently, LINAC-based radiotherapy equipment are being developed by combining with imaging devices such as CT or MRI, so that it is possible to precisely focus high dose radiation on tumor tissues while minimizing the normal tissue damage. In order to place the diagnostic and treatment devices simultaneously in a confined space, constraints related to interference and volume between the subsystems must be considered. To meet these requirements, the size and weight of the LINAC system need to be reduced, which can be achieved by applying X-band technology. For the purpose of use in IMRT based on image guided radiotherapy, we developed a 9.3 GHz X-band medical LINAC using side-coupled structure. The LINAC is designed to have the accelerating field strength of 16.8 MV/m, and the beam current transmission efficiency of 26 % at the end of accelerating cell when the supplied RF power is at 1.7 MW. Therefore, it can accelerate the electron beam up to 6.2 MeV with having about 90 mA beam current. We plan to carry out the performance test using beam diagnostics system and X-ray measurement system, and the details of design and experimental results of LINAC will be described in this paper., Proceedings of the 29\textsuperscript{th} Linear Accelerator Conf., LINAC2018, Beijing, China

Current advances in radiotherapy are based on the precise imaging techniques, and there is a pressing need for the development of techniques that are capable of visualizing cancer tissues in real time in conjunction with radiotherapy. Indeed, the image-guided radiotherapy systems in which conventional diagnostic tools such as CT and MRI are combined with the linear accelerator (LINAC)-based radiotherapy have been extensively studied. In this work, we mounted 9.3GHz X-band LINAC designed by KERI on the 360 degree-rotatable O-arm system, which allows efficient integration of a diagnostic tool with a radiotherapy equipment. After mounting, the X-ray profile and percentage depth dose were measured by following the quality assurance using the AAPM TG-51,142 protocol. The beam profile symmetry was estimated to be 10².4% with ±3% tolerance. The X-ray dose was also measured by rotating the O-arm to confirm the stability of the mounted X-band LINAC. As a result, the standard deviation of the X-ray dose was shown to be 0.016 while rotating. Therefore, we demonstrate the feasibility of our O-arm X-band LINAC system for use in highly effective radiotherapy with simultaneous CT image guidance., Proceedings of the 29\textsuperscript{th} Linear Accelerator Conf., LINAC2018, Beijing, China

Using the nonlinear interaction between the high power laser and the plasma, we can generate strong acceleration field, called the laser wake field acceleration. The plasma density is very crucial to generate high energy electron. In this work, we studied the effect of the plasma density structure on the accelerated electron energy. We used 20 TW, 40 fs laser system to generate the plasma wakefield. A gas jet was used as a target. The plasma density was controlled by the back pressure of the gas nozzle and measured by the interferometer. The accelerated electron energy was measured using the electron energy spectrometer with 0.5 T magnet. The bunch charge was measured integrated charge transformer (ICT). When the plasma density is uniform, 2×10¹⁹ cm⁻³ we can generate 200 MeV electron beam with bunch charge 33 pC. The electron beam divergence was less than 5 degree. If there exists the downward density tramp, the electron energy is only 50 MeV. The PIC simulation also indicates that if there is density ramp structure, the electron is not accelerated well. In this presentation, the overall experimental and simulation results are presented., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan