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KMID : 0357520160390020171
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Journal of Radiological Science and Technology
2016 Volume.39 No. 2 p.171 ~ p.176
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Comparison of Horizontal and Vertical Noise Power Spectrum in Measurements by Using Various Electronic Portal Imaging Devices in Radiation Therapy
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Kim Ki-Won
Choi Kwan-Woo
Jeong Hoi-Woun
Jang Seo-Goo
Kwon Kyung-Tae
Son Soon-Yong
Son Jin-Hyun
Min Jung-Whan
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Abstract
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The quality assurance (QA) is very important for diagnostic field and radiation therapy field to evaluate the characteristic of devices. The purpose of this study was to compare different NPS methodologies results which are measuring NPS with regard to horizontal and vertical directions by using megavoltage X-ray energies. The NPS evaluation methods were applied to the International Electro-technical Commission standard (IEC 62220-1). The electronic portal imaging devices (EPID) devices such as Siemens BEAMVIEWPLUS, Elekta iViewGT and Varian ClinacR iX aS1000 were used. NPS data were expressed by corresponding each frequency about average of noise value corresponding the each frequency, and NPS were evaluated quantitatively by totaling up the noise values of average frequency which are on horizontal and vertical directions. In NPS results for Elekta iViewGT, NPS of horizontal and vertical by using 4 methods were indicated
the difference of 3~5% between horizontal and vertical direction. In the results of Siemens BEAMVIEWPLUS and Varian ClinacR iX aS1000, the NPS of horizontal and vertical direction were indicated the difference of 15% when averaging the whole values. This study were evaluated the NPS of each devices by totaling up the noise values of average frequency
which are on horizontal and vertical directions suggesting the quantitative evaluation method using the data.
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KEYWORD
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Noise power spectrum (NPS), Electronic portal imaging device (EPID), Quality assurance (QA)
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