Photon interaction parameters of dosimetric interest in bone

Area of Science:

• Medical Physics
• Radiological Physics
• Biophysics

Background:

• Accurate characterization of bone's interaction with photons is crucial for medical imaging and radiation therapy.
• Understanding effective atomic number (Zeff) and electron density (Nel) is key to simulating bone tissue and developing substitutes.

Purpose of the Study:

• To compute and analyze the effective atomic numbers (Zeff) and electron densities (Nel) of cortical and compact bone for various photon interactions.
• To calculate bone's computed tomography (CT) numbers and kerma values relative to air.
• To assess the utility of these computed parameters for bone substitute material selection and radiation dose evaluation.

Main Methods:

• Utilized the WinXCom software to compute molecular, atomic, and electronic cross-sections for photon interactions from 1 keV to 100 GeV.
• Calculated effective atomic numbers for photon energy absorption (ZPEAeff) using mass energy absorption coefficients (1 keV-20 MeV).
• Determined kerma values relative to air and computed tomography (CT) numbers for bone.

Main Results:

• Presented graphical representations of Zeff and Nel variations with energy for different photon interactions.
• Provided computed Zeff, Nel, ZPEAeff, kerma ratios, and CT numbers for bone.
• Demonstrated the energy-dependent nature of these parameters across the investigated spectrum.

Conclusions:

• The computed Zeff and Nel values are valuable for selecting appropriate composite materials as bone substitutes.
• Estimated mass energy absorption coefficients can inform dose evaluation and survival fraction calculations for bone.
• The data facilitates the simulation of bone tissue and the development of advanced radiological applications.