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KMID : 1164220110230020109
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Journal of Korean Society for Radiotherapeutic Technology
2011 Volume.23 No. 2 p.109 ~ p.117
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Analysis on Longitudinal Dose according to Change of Field Width
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Jung Won-Seok
Baek Jong-Geal
Shin Ryung-Mi
Oh Byung-Cheon
Jo Jun-Young
Kim Gi-Chul
Choi Tae-Gu
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Abstract
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Purpose: To analyze the accuracy of tumor volume dose following field width change, to check the difference of dose change by using self-made moving car, and to evaluate practical delivery tumor dose when tomotherapy in the treatment of organ influenced by breathing.
Materials and Methods: By using self-made moving car, the difference of longitudinal movement (0.0 cm, 1.0 cm, 1.5 cm, 2.0 cm) was applied and compared calculated dose with measured dose according to change of field width (1.05 cm, 2.50 cm, 5.02 cm) and apprehended margin of error. Then done comparative analysis in degree of photosensitivity of DQA film measured by using Gafchromic EBT film. Dose profile and Gamma histogram were used to measure degree of photosensitivity of DQA film.
Results: When field width were 1.05 cm, 2.50 cm, 5.02 cm, margin of error of dose delivery coefficient was -2.00%, -0.39%, -2.55%. In dose profile of Gafchromic EBT film’s analysis, the movement of moving car had greater motion toward longitudinal direction and as field width was narrower, big error increased considerably at high dose part compared to calculated dose. The more field width was narrowed, gamma index had a large considerable influence of moving at gamma histogram.
Conclusion: We could check the difference of longitudinal dose of moving organ. In order to small field width and minimize organ moving due to breathing, it is thought to be needed to develop breathing control unit and fixation tool.
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KEYWORD
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moving car, field width, DQA (delivery quality assurance)
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