2005 Fiscal Year Final Research Report Summary
Development of real-time tracking radiotherapy method and its clinical application
| Project/Area Number |
15390355
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | Tohoku University |
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Principal Investigator |
TAKAI Yoshihiro Tohoku University, School of Medicine, Radiological Technology, Professor, 医学部, 教授 (50107653)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Shogo Tohoku University, Graduate School of Medicine, Radiation Oncology., Professor, 大学院・医学系研究科, 教授 (60158194)
NEMOTO Kenji Tohoku University, Graduate School of Medicine, Radiation Oncology., Associate Professor, 大学院・医学系研究科, 助教授 (10208291)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Stereotactic Radiotherapy / Tumor tracking / Amorphous silicon X-ray sensor / Tracking radiotherapy / Gantry mounted fluoroscopy / Image-guided radiotherapy / Prostate cancer / Intensity modulated radiotherapy |
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| Research Abstract |
We have developed to mount two sets of X-ray fluoroscopy with amorphous silicon X-ray sensors on the gantry of Clinac EX23 for image-guided radiotherapy as a cooperative work with Varian Medical Systems company. A new software for real-time tracking of a fiducial marker in a tumor using images obtained by the fluoroscopic system on the gantry of Linac. In this software, the color of a rectangle square for tracking a marker turns green when the marker tracking is successful, and once it fails to track the marker, the color turns red and the size of the square get bigger. Thus the condition of the tracking can be monitored at real time. The 3D coordinates of the fiducial marker can be calculated using this tracking system, and the coordinates is displayed simultaneously. In the treatment of intensity modulated radiotherapy (IMRT) for prostate cancer, intra- and inter-fractional errors were evaluated by this system. Motion of the prostate more than 1 mm was found in 33 % of all fractions of dose delivery, and re-positionings of the patients of these cases were done so that all cases can be treated with less than 1mm positioning error. In IMRT for prostate cancer, dose painting method to reduce the dose around the urethra became possible by using our new image-guided devices. We have treated 67 patients so far. Among them, the whole prostates were treated with 80Gy/40fr in 24 patients (no dose reduction group), and 5% dose reduction around the urethra was done in 43 patients. The rates of grade 1 acute adverse effect of GU tract were 46% (11/24) and 28% (12/43) for no dose reduction group and dose reduction group, respectively.
This new device and system developed by this research was found to be very useful for image guided radiotherapy which is very important technology to increase the local control rate and to reduce normal tissue damage.
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