• Title/Summary/Keyword: blocking correction

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Characteristics of 23 MV Photon Beam from a Mevatron KD 8067 Dual Energy Linear Accelerator (Mevatron KD 8067 선형가속기의 23 MV 광자선의 특성)

  • Kim, Ok-Bae;Choi, Tae-Jin;Kim, Young-Hoon
    • Radiation Oncology Journal
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    • v.8 no.1
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    • pp.115-124
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    • 1990
  • The characteristics of 23 MV photon beam have been presented with respect to clinical parameters of central axis depth dose, tissue-maxi mum ratios, scatter-maximum ratios, surface dose and scatter correction factors. The nominal accelerating potential was found to be $18.5\pm0.5$ MV on the central axis. The half-value layer (HVL) of this photon beam was measured with narrow beam geometry from central axis, and it has been showed the thickness of $24.5\;g/cm^2$. The tissue-maximum ratio values have been determined from measured percentage depth dose data. In our experimental dosimetry, the surface dose of maximum showed only $9.6\%$ of maximum dose at $10\times10\;cm^2$, 100 cm SSD, without blocking tray in. The TMR'S of $0\times0$ field size have been determined to get average $2.3\%$ uncertainties from three different methodis; are zero effective attenuation coefficient, non-ilnear least square fit of TMR's data and effective linear attenuation coefficient from the HVL of 23 MV photon beams of dual energy linear accelerator.

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