Radiological Physics and Technology

, Volume 5, Issue 2, pp 248–269

Reconsideration of the Iwasaki–Waggener iterative perturbation method for reconstructing high-energy X-ray spectra

  • Akira Iwasaki
  • Shigenobu Kimura
  • Kohji Sutoh
  • Kazuo Kamimura
  • Makoto Sasamori
  • Morio Seino
  • Fumio Komai
  • Singo Terashima
  • Mamoru Kubota
  • Yuichiro Narita
  • Yoichiro Hosokawa
  • Masanori Miyazawa
Article

DOI: 10.1007/s12194-012-0160-7

Cite this article as:
Iwasaki, A., Kimura, S., Sutoh, K. et al. Radiol Phys Technol (2012) 5: 248. doi:10.1007/s12194-012-0160-7
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Abstract

We have reviewed applicable ranges for attenuating media and off-axis distances regarding the high-energy X-ray spectra reconstructed via the Iwasaki–Waggener iterative perturbation method for 4–20 MV X-ray beams. Sets of in-air relative transmission data used for reconstruction of spectra were calculated for low- and high-Z attenuators (acrylic and lead, respectively) by use of a functional spectral formula. More accurate sets of spectra could be reconstructed by dividing the off-axis distances of R = 0–20 cm into two series of R = 0–10 cm and R = 10–20 cm, and by taking into account the radiation attenuation and scatter in the buildup cap of the dosimeter. We also incorporated in the reconstructed spectra an adjustment factor (fadjust ≈ 1) that is determined by the attenuating medium, the acceleration voltage, and the set of off-axis distances. This resulted in calculated in-air relative transmission data to within ±2 % deviation for the low-Z attenuators water, acrylic, and aluminum (Al) with 0–50 cm thicknesses and R = 0–20 cm; data to within ±3 % deviation were obtained for high-Z attenuators such as iron (Fe), copper (Cu), silver (Ag), tungsten (W), platinum (Pt), gold (Au), lead (Pb), thorium (Th), and uranium (U) having thicknesses of 0–10 cm and R = 0–20 cm. By taking into account the radiation attenuation and scatter in the buildup cap, we could analyze the in-air chamber response along a line perpendicular to the isocenter axis.

Keywords

High-energy X-ray spectra Discrete X-ray spectra Iterative perturbation technique Transmission analysis Buildup cap In-air chamber response 

Copyright information

© Japanese Society of Radiological Technology and Japan Society of Medical Physics 2012

Authors and Affiliations

  • Akira Iwasaki
    • 1
  • Shigenobu Kimura
    • 2
  • Kohji Sutoh
    • 2
  • Kazuo Kamimura
    • 2
  • Makoto Sasamori
    • 3
  • Morio Seino
    • 4
  • Fumio Komai
    • 4
  • Singo Terashima
    • 6
  • Mamoru Kubota
    • 6
  • Yuichiro Narita
    • 5
  • Yoichiro Hosokawa
    • 6
  • Masanori Miyazawa
    • 7
  1. 1.HirosakiJapan
  2. 2.Department of RadiologyAomori City HospitalAomoriJapan
  3. 3.Department of RadiologyMisawa City HospitalMisawaJapan
  4. 4.Department of RadiologyHirosaki University HospitalHirosakiJapan
  5. 5.Graduate School of Medicine and School of MedicineHirosaki UniversityHirosakiJapan
  6. 6.Graduate School of Health SciencesHirosaki UniversityHirosakiJapan
  7. 7.Technology of Radiotherapy CorporationTokyoJapan

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