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KMID : 1164220140260010083
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Journal of Korean Society for Radiotherapeutic Technology
2014 Volume.26 No. 1 p.83 ~ p.89
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Compare to Evaluate the Imaging dose of MVCT and CBCT
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Yoon Bo-Reum
Hong Mi-Ran
Ahn Jong-Ho
Song Gi-Won
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Abstract
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Purpose : In case of the intensity modulated radiation therapy (IMRT) using Tomotherapy and linear accelerator (Linac), it was
to compare and to evaluate the imaging dose of MVCT and CBCT that were performed daily for the correct set up of the
patient.
Materials and Methods : The human body model Phantom (Anderson rando Phantom, USA) was divided into the three parts
as Head, Thorax, pelvis, and after GafChromic EBT3 film cut to the size of 0.5x0.5 cm2.in the center of the recording area were
situated on the ant, post, left, and right surface of the phantom and 2cm in depth from the ant, post, left, right, and center
surface of the phantom, the surface dose and inner dose were measured repeatedly three times, respectively, using the
tomotherapy (Hi Art) and the OBI of NovalisTx. The measured film calculated the output value by RIP version6.0 and then the
average value of the dose was calculated by the one-way analysis of variance.
Results : Using the human body model phantom, the results of MVCT and CBCT performance were that measurements of
MVCT inner dose were showed 15.43cGy ± 6.05 in the head, 16.62cGy ± 3.08 in the thorax, 16.81cGy ± 5.24 in the pelvis,
and measurements of CBCT inner dose were showed 13.28 ± 3.68 in the head, from 13.66 ± 4.04 in the thorax, 15.52 ±
3.52 in the pelvis. The measurements of surface dose were showed in case of MVCT performance, 11.64 ± 4.05 in the head,
12.16 ± 4.38 in the thorax, 12.05 ± 2.71 in the pelvis, and in case of CBCT performance, 14.59 ± 3.51 in the head, 15.82 ±
2.89 in the thorax, 17.48 ± 2.80 in the pelvis, respectively.
Conclusion : In case of Inner dose, the MVCT using MV energy showed higher than the CBCT using kV energy at 1.16 times
in the head, at 1.22 times in the thorax, at 1.08 times in the pelvis, and in case of surface dose, the CBCT was higher than
MVCT, at 1.25 times in the head, at 1.30 times in the thorax, at 1.45 times in the pelvis. Imaging dose was a small amount
compared to the therapeutic dose but it was thought to affect partially to normal tissue because it was done in daily schedule.
However, IMRT treatment was necessarily parallel with the IGRT treatment through the image-guide to minimize errors between
planned and actual treatment. Thus, to minimize imaging dose that the patients receive, when planning the treatment, it should
be set up a treatment plan considering imaging dose, or it must be performed by minimizing the scan range when shooting
MVCT.
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KEYWORD
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MVCT, CBCT, Imaging dose
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