Photon energy absorption and exposure buildup factors for deep penetration in human tissues

  • O. KadriEmail author
  • A. Alfuraih


Using photons in therapeutic and diagnostic medicine requires accurate computation of their attenuation coefficients in human tissues. The buildup factor, a multiplicative coefficient quantifying the ratio of scattered to primary photons, measures the degree of violation of the Beer–Lambert law. In this study, the gamma-ray isotropic point source buildup factors, specifically, the energy absorption buildup factor (EABF) and exposure buildup factor, are estimated. The computational methods used include the geometric progression fitting method and simulation using the Geant4 (version 10.4) Monte Carlo simulation toolkit. The buildup factors of 30 human tissues were evaluated in an energy range of 0.015–15 MeV for penetration depths up to 100 mean free paths (mfp). At all penetration depths, it was observed that the EABF seems to be independent of the mfp at a photon energy of 1.5 MeV and also independent of the equivalent atomic number (\(Z_{\text{eq}}\)) in the photon energy range of 1.5–15 MeV. However, the buildup factors were inversely proportional to \(Z_{\text{eq}}\) for energies below 1.5 MeV. Moreover, the Geant4 simulations of the EABF of water were in agreement with the available standard data. (The deviations were less than 5%.) The buildup factors evaluated in the present study could be useful for controlling human exposure to radiation.


Buildup factors Human tissues Geant4 GP fitting Gamma rays 

Supplementary material

41365_2019_701_MOESM1_ESM.xlsx (521 kb)
Supplementary material 1 (xlsx 521 KB)


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Copyright information

© China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society and Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Department of Radiological Sciences, College of Applied Medical SciencesKing Saud UniversityRiyadhSaudi Arabia
  2. 2.National Center for Nuclear Sciences and TechnologiesTunisTunisia

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