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Author Matsumura, Akihiko ♦ Yusa, Ken ♦ Kanai, Tatsuaki ♦ Ohno, Tatsuya ♦ Nakano, Takashi ♦ Mizota, Manabu
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ ALGORITHMS ♦ BEAM MONITORS ♦ BEAM PRODUCTION ♦ CALIBRATION ♦ CARBON IONS ♦ HEAVY IONS ♦ ION BEAMS ♦ PHANTOMS ♦ QUALITY ASSURANCE ♦ RADIATION DOSE DISTRIBUTIONS ♦ RADIATION DOSES ♦ RADIOTHERAPY
Abstract Purpose: A conventional broad beam method is applied to carbon ion radiotherapy at Gunma University Heavy Ion Medical Center. According to this method, accelerated carbon ions are scattered by various beam line devices to form 3D dose distribution. The physical dose per monitor unit (d/MU) at the isocenter, therefore, depends on beam line parameters and should be calibrated by a measurement in clinical practice. This study aims to develop a calculation algorithm for d/MU using beam line parameters. Methods: Two major factors, the range shifter dependence and the field aperture effect, are measured via PinPoint chamber in a water phantom, which is an identical setup as that used for monitor calibration in clinical practice. An empirical monitor calibration method based on measurement results is developed using a simple algorithm utilizing a linear function and a double Gaussian pencil beam distribution to express the range shifter dependence and the field aperture effect. Results: The range shifter dependence and the field aperture effect are evaluated to have errors of 0.2% and 0.5%, respectively. The proposed method has successfully estimated d/MU with a difference of less than 1% with respect to the measurement results. Taking the measurement deviation of about 0.3% into account, this result is sufficiently accurate for clinical applications. Conclusions: An empirical procedure to estimate d/MU with a simple algorithm is established in this research. This procedure allows them to use the beam time for more treatments, quality assurances, and other research endeavors.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-09-15
Publisher Place United States
Journal Medical Physics
Volume Number 42
Issue Number 9


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