Program Information
Isocenter Verification of a Compact Rotating Gantry for Carbon Ion Therapy
n saotome*, T Furukawa , Y Saraya , K Mizushima , Y Hara , r tansho , t Shirai , K Noda , National Institutes for Quantum and Radiological Science and Technology, Chiba, Chiba
Presentations
SU-I-GPD-T-146 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: At the National Institute of Radiological Sciences (NIRS), we have been commissioning the rotating- gantry system for the carbon-ion radiotherapy in 2015. It is world’s first rotating-gantry with super-conducting magnet and achieved a more compact, lighter rotating gantry than the typical gantry. During the commissioning of the rotating gantry, we adjusted the beam position using a steel sphere located at isocenter and verified the accuracy using a scintillation screen and CCD system. We employ the digital QA system to verify the geometrical accuracy easily and quickly.
Methods: The 300 ton rotating gantry can deliver carbon ions having 430 MeV/u to the isocenter over 360 degrees, having the capability of performing three-dimensional scanning irradiation. the mechanical isocenter was verified using the laser tracker system. To verify the coincidence of the isocenter for irradiation system and the patient positioning system, we used a steel sphere located at isocenter. As a part of the verifying of the treatment beam position, scintillation screen viewed by a CCD camera mounted on the gantry downstream of the sphere. Total 201energy carbon beams with that were in the range from 48 to 430 MeV/u were measured sequentially. A starshot test was also performed to verify the gantry angle and beam direction visually using a scintillator block and a CCD camera. For the starshot test, 13 beam energy were selected.
Results: From the result of the test using a sphere, the maximum displacement of the beam position was within 0.5mm at all gantry angles. The gantry starshot shows accuracy of the gantry angle was less than 0.5 degree.
Conclusion: The isocentricity of the compact super-conducting rotating gantry for carbon ion therapy dedicated to the highly precise treatment were within 1mm. Two of digital measurement system brought high-efficient beam adjusting and commissioning.
Contact Email: