Photon field quantities and units for kernel based radiation therapy planning and treatment optimization.

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Computational Physics

Background:

• Traditional radiation quantities and units for energy deposition kernels lack consistency.
• Existing methods for calculating energy deposition may not be optimal for treatment planning.

Purpose of the Study:

• To establish consistent radiation quantities and units for energy deposition kernels.
• To generalize concepts like mass stopping power and mass attenuation coefficients.
• To improve the accuracy of radiation dose calculations in medical applications.

Main Methods:

• Defining energy deposition kernels h(r) as the quotient of mean specific energy imparted to incident radiant energy.
• Utilizing the point energy deposition kernel h(p) as a fundamental building block.
• Expressing irradiation density f(r) in terms of incident radiant energy per unit volume.
• Relating kernel density to the divergence of incident unattenuated vectorial energy fluence.

Main Results:

• Kernels are presented as generalizations of mass stopping and attenuation coefficients, detailing energy deposition spatial distribution.
• Irradiation density f(r) is shown to act as an irradiation density for vectorial energy fluence.
• A method is derived to determine incident energy fluence directly from irradiation density for treatment planning.
• Maximal calculational accuracy is achieved in the target volume due to localized irradiation density.

Conclusions:

• The proposed definitions provide a consistent framework for radiation quantities and units in energy deposition.
• The method offers improved accuracy for radiation dose calculations, particularly in targeted treatment areas.
• This approach facilitates direct determination of required incident energy fluence for external radiation sources in treatment realization.