Gamma-ray buildup factor and radiation absorbed dose enhancement at tissue-bone interfaces

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Superficial radiotherapy can cause dose perturbations at tissue interfaces, particularly near bone.
• Understanding these perturbations is crucial for accurate dose delivery in clinical practice.

Purpose of the Study:

• To estimate absorbed dose distribution in bone and muscle tissues at various photon energies.
• To investigate the impact of tissue-bone interfaces on radiation dose during superficial radiotherapy.

Main Methods:

• Computed energy absorption buildup factor using the (GP) fitting method.
• Simulated a multilayer tissue matrix with bone and muscle layers.
• Analyzed photon energies ranging from 0.05 to 1.333 MeV.

Main Results:

• Observed dose enhancement limited to a few millimeters from the tissue/bone interface.
• Found dose variations to be significant only at low photon energies (< 0.06 MeV).
• Dose variations were insignificant at higher photon energies.

Conclusions:

• Dose enhancement at tissue-bone interfaces during superficial radiotherapy is localized and energy-dependent.
• Accurate dosimetry requires consideration of interface effects, especially at lower photon energies.