Energy Absorption Buildup Factor in A Few Human Tissues and Tissues-Equivalent Plastic
Kerbala Journal of Medicine,
2014, Volume 7, Issue 1, Pages 1806-1817
Abstractلاackground: Energy absorption buildup factor inhuman tissuesare very importantfor the researchers working to help in estimating safe dose levels for radiotherapy patients and useful in radiation therapy, diagnostics, and dosimeters.
Aim: The mainemphasis has been focused on the dependence of energy absorption buildup factor on the incident photon energy, penetration depth and effectiveatomic number (Zeff )in the human tissues and tissues equivalent plastic.
Materials and Methods: Energy absorption buildup factor ina fewhumantissuessuch as skin, brain, striated muscle and compact bone as well as in tissue-equivalent plasticA-150 and bone- equivalent plasticB-100have been computedusing the five parameter geometric progression(G.P) fittingformula in the energy range of 0.015-15 MeV up to penetration depth 40 mfp. The half value layer (HVL) for selected tissues were also estimated.
Results & Discussion: The variation of energy absorption buildup factorfor selected tissueshas been studied as a function of incident photon energy, penetration depth and effective atomic number(Zeff).The energy absorption buildup factor increases with increasing photon energy and reaches a maximum value at gamma ray energy range(0.1-0.2MeV), then start decreasing further with the increasing photon energy. There is continuous increase in energy absorption buildup factor with increase in penetration depth.
Comparison of calculated energy absorption buildup factor with standard database from ANSI/ANS6.4.3-1991 (American National Standard, 1991)shows good agreements.
Conclusion:Variation in value of energy absorption buildup factor was due to dominance of different interaction processes in different energy regions and chemical compositions of thehuman tissues. In general, the energy absorption buildup factor is lower for compact bone and boneequivalent plastic B-100 at photon energy range (0.015- 1 MeV) .
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