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KMID : 1164220150270010001
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Journal of Korean Society for Radiotherapeutic Technology
2015 Volume.27 No. 1 p.1 ~ p.11
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Imaging dose evaluations on Image Guided Radiation Therapy
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Hwang Seon-Bung
Kim Gi-Hwan
Kim Il-Hwan
Kim Woong
Im Hyeong-Seo
Han Su-Cheol
Gang Jin-Mook
Kim Jin-Ho
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Abstract
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Purpose : Evaluating absorbed dose related to 2D and 3D imaging confirmation devices.
Materials and Methods : According to the radiographic projection conditions, absorbed doses are measured that 3 glass
dosimeters attached to the centers of 0’, 90’, 180’and 270’in the head, thorax and abdomen each with Rando phantom are
used in field size 26.6x20, 15x15. In the same way, absorbed doses are measured for width 16cm and 10cm of CBCT each. OBI(version 1.5) system and calibrated glass dosimeters are used for the measurement.
Results : AP projection for 2D imaging check, In 0°degree absorbed doses measured in the head were 1.44±0.26 mGy with
the field size 26.6x20, 1.17±0.02 mGy with the field size 15x15. With the same method, absorbed doses in the thorax were
3.08±0.86 mGy to 0.57±0.02 mGy by reducing field size. In the abdomen, absorbed dose were reduced 8.19±0.54 mGy to
4.19±0.09 mGy. Finally according to the field size, absorbed doses has decreased by average 5~12%. With Lateral projection, absorbed doses showed average 5~8% decrease. CBCT for 3D imaging check, CBDI in the head were 4.39±0.11 mGy to 3.99±0.13 mGy by reducing the width 16cm to 10cm. In the same way in thorax the absorbed dose were reduced 34.88±0.93(10.48±0.09) mGy to 31.01±0.3(9.30±0.09) mGy and 35.99±1.86 mGy to 32.27±1.35 mGy in the abdomen. With variation of width 16cm and 10cm, they showed 8~11% decrease.
Conclusion : By means of reducing 2D field size, absorbed dose were decreased average 5~12% in 3D width size 8~11%. So that it is necessary for radiation therapists to recognize systematical management for absorbed dose for Imaging confirmation. and also for frequent CBCT, it is considered whether or not prescribed dose for RT refer to imaging dose.
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KEYWORD
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Image Guided Radiation Therapy(IGRT), Imaging Dose, Glass dosimeter, CBDI(Cone Beam Dose Index)
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