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KMID : 0357520100330030261
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Journal of Radiological Science and Technology
2010 Volume.33 No. 3 p.261 ~ p.268
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Comparison of Experimental and Radiation Therapy Planning (RTP) Dose Distributions on Air Cavity
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Kim Yon-Lae
Suh Tae-Suk
Ko Shin-Gwan
Lee Jeong-Woo
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Abstract
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This study is compared that the dose distribution by experimentation and radiation therapy planning (RTP) when the air cavity region was treated high energy photon. The dose measurements were performed with a 6 MV photon beam of linear accelerator. The polystyrene and self made acyl phantom were similar to tissue density of the human body. A parallel plate chamber was connected to an electrometer. The measurement setup was SCD (Source Chamber Distance) 100 cm and the distance of surface from air cavity was 3 cm. Absorbed dose of interface were measured by area and height. The percent depth dose were measured presence and absence of air cavity, depth according to a ratio of field size and air cavity size. The dose distribution on planning was expressed to do the inhomogeneity correction. As the area of air cavity was increased, the absorbed dose were gradually reduced. It was slightly increased, when the height of air cavity was changed from 0 cm to 0.5 cm. After the point, dose was decreased. In case of presence of air cavity, dose after distal air cavity interface was more great than absence of air cavity. The rebuild up by field size and area of air cavity occurred for field size, , and , with fixed on area of air cavity, . But it didn’t occur at field size. On the contrary, the field size was fixed on , rebuild up occurred in area of air cavity, , . but, it did not occur for air cavity, , . All of the radiation therapy planning were not occurred rebuild up. It was required to pay attention to treat tumor in air cavity because the dose distribution of planning was different from the dose distribution of patient.
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KEYWORD
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air cavity, dose distribution, inhomogeneity correction, rebuild up
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