Characteristics of Scattered Rays Depending on the Use of a Flattening Filter

선속평탄 여과판 사용 유무에 따른 산란선 특성

  • Received : 2016.01.03
  • Accepted : 2016.01.30
  • Published : 2016.01.30


This Study aims at measuring scattered rays depending on the use of a flattening filter when radiation is irradiated using a linear accelerator. measurement of the scattered rays, an ionization chamber was used, and the energy of the irradiated radiation was 6 MV and 10 MV. The ionization chamber was located at the spot 15 cm, 25 cm, 35 cm and 45 cm far away from the center of gantry rotation, and the scattered rays were measured according to whether a flattening filter was used or not and to the distance. As the result of investigation of 100 cGy about each energy, when the flattening filter was not used with 6 MV, it occurred at a low level of 65%, and with 10 MV at that of 55%. In other words, it's been concluded that when a flattening filter is not used for radiation dose of the parts around the critical organ, scattered rays generate in a small quantity, and it's a useful way to decrease the stochastic effect of radiation.


flattening filter;linear accelerator;scattered ray


  1. D. J. Pizzarello and R. L. Witcofski, Medical radiation biology, 2nd Ed., Lea & Febiger, Philadelphia, p p. 52-62, 1982.
  2. P. Ash, "The influence of radiation on fertility in man," British Journal of Radiology, Vol. 53, pp. 271-278, 1980.
  3. B. A. Fraass and J. van de Geijn, "Peripheral dose from megavoltage beams," Medical Physics, Vol. 10, pp. 809-818, 1983.
  4. P. F. O'Brien, B. A. Gillies, M. Schwartz, C. Young and P. Davey, "Radiosurgery with unflattened 6-MV photon beams," Medical Physics. Vol. 18, No. 3, pp.519-521, 1991.
  5. S. F. Kry, O. N. Vassiliev and R. Mohan, "Out-of-field photon dose following removal of the flattening filter from a medical accelerator," Physics Medical Biology, Vol. 55, No. 8, pp. 2155-2166, 2010.
  6. S. F. Kry, U. Titt, F. Ponisch, et al, "Reduced neutron production through use of a flattening-filter-free accelerator", International Journal of Radiation Oncology Biology Physics, Vol. 68, No. 4, pp. 1260-1264, 2007.
  7. F. H. Attix, F. Lopez, S. Owolabi and B. R. Paliwal, "Electron contamination in gamma-ray beams," Medical Physics, Vol. 10, No. 3, pp. 301-306, 1983.
  8. P. L. Petti, M. S. Goodman, T. A. Gabriel and R. Mohan, "Investigation of buildup dose from electron contamination of clinical photon beams," Medical Physics, Vol. 10, No. 1, pp. 18-24, 1983.
  9. C. C. Ling, M. C. Schell, S. N. Rustgi, "Magnetic a nalysis of the radiation components of a 10 MV photon beam," Medical Physics, Vol. 9, No. 1, pp. 20-26, 1982.
  10. M. A. Kim, Y. D. Kwon, J. Y. Je, "A study on the interior structure and scattered radiation measurement of radiotherapy room," Journal of the Korean Society of Radiology, Vol. 3, No. 3, pp. 194, 2012.
  11. J. T. Parsons, C. R. Fitzerald, C. IanHood, "The effects of irradiation on the eye and optic nerve," International Journal of Radiation Oncology Biology Physics, Vol. 9, No. 3, pp. 609-622, 1983.