Effective atomic numbers and electron densities of some human tissues and dosimetric materials for mean energies of various radiation sources relevant to radiotherapy and medical applications

摘要

Effective atomic numbers, Z_(eff), and electron densities, n_(eff), are convenient parameters used to characterise the radiation response of a multi-element material in many technical and medical applications. Accurate values of these physical parameters provide essential data in medical physics. In the present study, the effective atomic numbers and electron densities have been calculated for some human tissues and dosimetric materials such as Adipose Tissue (ICRU-44), Bone Cortical (ICRU-44), Brain Grey/White Matter (ICRU-44), Breast Tissue (ICRU-44), Lung Tissue (ICRU-44), Soft Tissue (ICRU-44), LiF TLD-100H, TLD-100, Water, Borosilicate Glass, PAG (Gel Dosimeter), Fricke (Gel Dosimeter) and OSL (Aluminium Oxide) using mean photon energies, E_m, of various radiation sources. The used radiation sources are Pd-103, Tc-99, Ra-226,1-131, lr-192, Co-60, 30kVp, 40kVp, 50kVp (Intrabeam, Carl Zeiss Meditec) and 6 MV (Mohan-6 MV) sources. The E_m values were then used to calculate Z_(eff)-and n_(eff) of the tissues and dosimetric materials for various radiation sources. Different calculation methods for Z_(eff) such as the direct method, the interpolation method and AutQ-Z_(eff) computer program were used and agreements and disagreements between the used methods have been presented and discussed. It has been observed that at higher E_m values agreement is quite satisfactory (Dif. < 5%) between the adopted methods.