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Estimation of focal and extra-focal radiation profiles based on Gaussian modeling in medical linear accelerators

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Abstract

The X-ray source or focal radiation is one of the factors that can degrade the conformal field edge in stereotactic body radiotherapy. For that reason, it is very important to estimate the total focal radiation profiles of linear accelerators, which consists of X-ray focal-spot radiation and extra-focal radiation profiles. Our purpose in this study was to propose an experimental method for estimating the focal-spot and extra-focal radiation profiles of linear accelerators based on triple Gaussian functions. We measured the total X-ray focal radiation profiles of the accelerators by moving a slit in conjunction with a photon field p-type silicon diode. The slit width was changed so that the extra-focal radiation could be optimally included in the total focal radiation. The total focal radiation profiles of an accelerator at 4-MV and 10-MV energies were approximated with a combination of triple Gaussian functions, which correspond to the focal-spot radiation, extra-focal radiation, and radiation transmitted through the slit assembly. As a result, the ratios of the Gaussian peak value of the extra-focal radiation to that of the focal spot for 4 and 10 MV were 0.077 and 0.159, respectively. The peak widths of the focal-spot and extra-focal radiation profiles were 0.57 and 25.0 mm for 4 MV, respectively, and 0.60 and 22.0 mm for 10 MV, respectively. We concluded that the proposed focal radiation profile model based on the triple Gaussian functions may be feasible for estimating the X-ray focal-spot and extra-focal radiation profiles.

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Acknowledgments

The authors thank Mr. Kazuharu Nishitani and Mr. Tokuhiro Hayashi for assistance in measurements of the total focal radiation profile.

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Authors and Affiliations

  1. Department of Radiology, Kyushu University Hospital at Beppu, Tsurumihara Tsurumi, Beppu, Oita, 874-0838, Japan

    Shigeo Anai, Katsumasa Nakamura, Hideki Yoshikawa & Satoshi Yoshidome

  2. Department of Applied Quantum Physics and Nuclear Engineering, Graduate school of Engineering, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan

    Shigeo Anai & Nobuo Ikeda

  3. Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan

    Hidetaka Arimura

  4. Department of Health Sciences, School of Medicine, Kumamoto University, 4-24-1 Kuonji, Kumamoto, 862-0976, Japan

    Fujio Araki

  5. Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan

    Takaomi Matsuki

  6. Department of Heavy Particle Therapy and Radiation Oncology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan

    Yoshiyuki Shioyama

  7. Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan

    Hiroshi Honda

  8. Division of Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan

    Hidetaka Arimura

Authors
  1. Shigeo Anai
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  2. Hidetaka Arimura
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  3. Katsumasa Nakamura
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  4. Fujio Araki
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  5. Takaomi Matsuki
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  6. Hideki Yoshikawa
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  7. Satoshi Yoshidome
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  8. Yoshiyuki Shioyama
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  9. Hiroshi Honda
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  10. Nobuo Ikeda
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Corresponding author

Correspondence to Hidetaka Arimura.

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Anai, S., Arimura, H., Nakamura, K. et al. Estimation of focal and extra-focal radiation profiles based on Gaussian modeling in medical linear accelerators. Radiol Phys Technol 4, 173–179 (2011). https://doi.org/10.1007/s12194-011-0118-1

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  • DOI: https://doi.org/10.1007/s12194-011-0118-1

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