Positioning accuracy of a new image-guided radiotherapy system

Purpose: To evaluate the accuracy of the patient-positioning function of a newly developed image-guided radiotherapy system, the MHI-TM2000 (Mitsubishi Heavy Industries, Ltd., Japan). Methods: The isocenter positions prescribed by the lasers, MV treatment beam, and image guidance systems (kV X-ray i...

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Published in:Medical physics (Lancaster) Vol. 38; no. 5; pp. 2535 - 2541
Main Authors: Miyabe, Yuki, Sawada, Akira, Takayama, Kenji, Kaneko, Shuji, Mizowaki, Takashi, Kokubo, Masaki, Hiraoka, Masahiro
Format: Journal Article
Language:English
Published: United States American Association of Physicists in Medicine 01.05.2011
Subjects:
Cameras
Computed radiography
Computed tomography
Computer-Aided Design
computerised tomography
Cone beam computed tomography
Cone-beam CT
diagnostic radiography
Equipment Design
Equipment Failure Analysis - methods
image fusion
Image guided radiation therapy
image reconstruction
Image sensors
Image-guided radiotherapy (IGRT)
Infrared detectors
kV X-ray image
medical image processing
Medical imaging
Medical X‐ray imaging
phantoms
position measurement
Positioning accuracy
radiation therapy
Radiotherapy, Computer-Assisted - instrumentation
Radiotherapy, Conformal - methods
Reconstruction
Robotics
Therapeutic applications, including brachytherapy
Tomography, X-Ray Computed - instrumentation
X‐ray imaging
Cone-beam CT
Image-guided radiotherapy (IGRT)
Positioning accuracy
image fusion
kV X-ray image
ISSN:0094-2405, 2473-4209
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Summary:Purpose: To evaluate the accuracy of the patient-positioning function of a newly developed image-guided radiotherapy system, the MHI-TM2000 (Mitsubishi Heavy Industries, Ltd., Japan). Methods: The isocenter positions prescribed by the lasers, MV treatment beam, and image guidance systems (kV X-ray image and kV-CBCT) were calculated using a cube phantom with a 10-mm-diameter steel ball fixed to the center of the phantom. Then, their location discrepancies were estimated. In addition, to verify the scale and orientation of the coordinate axes of the kV X-ray imaging system, positional measurements were repeated with the phantom placed at 50 mm off-isocenter along the vertical, longitudinal, and lateral directions, respectively. Further, image fusions of an anthropomorphic phantom image and the corresponding image translated by a pre-determined amount were performed. Results: The isocenter alignment among the coordinate systems was coincident within 0.5 mm in translation for the vertical, longitudinal, and lateral axes, respectively. The geometrical errors at 50 mm off-isocenter for kV X-ray images and CBCT were within 0.2 mm and 1.0 mm, respectively. The image fusion errors were within 1.0 mm in translation and 1.0° in rotation, respectively. No significant difference in the image fusion accuracy was observed between the chest and pelvis phantoms. Conclusions: The isocenter alignment among the coordinate systems was performed with high accuracy. Furthermore, the automatic image fusion function achieved sufficient patient positioning accuracy and precision for image-guided radiotherapy.
Bibliography:Telephone: +81‐75‐751‐4215; Fax: +81‐75‐771‐9749.
Department of Radiation Oncology and Image‐applied Therapy, Kyoto University Graduate School of Medicine, 54 Shogoin‐Kawaharacho, Sakyo, Kyoto 606‐8507, Japan. Electronic mail
asawada@kuhp.kyoto‐u.ac.jp
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ISSN:0094-2405
2473-4209
DOI:10.1118/1.3578607