Dosimetric Verification around High-density Materials for External Beam Radiotherapy.

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• Radiation treatment planning systems (RTPS) often lack accuracy in dose distribution calculations near high-density materials.
• The Acuros XB (AXB) algorithm, based on the linear Boltzmann transport equation, is a recent advancement for dose calculation.

Purpose of the Study:

• To evaluate the dose calculation accuracy of the AXB algorithm around high-density materials (titanium and stainless steel) using three X-ray energies.
• To compare AXB's accuracy against other RTPS algorithms (AAA, XVMC) and Monte Carlo (MC) simulations using EBT3 measurements.

Main Methods:

• Inserted titanium and stainless steel into a water-equivalent phantom and measured depth dose using EBT3 film.
• Created a virtual phantom in RTPS, calculating dose distributions with AXB, AAA, XVMC, and MC.
• Compared calculated doses with measured values.

Main Results:

• AXB demonstrated dose calculation accuracy comparable to MC and EBT3 measurements on the exit side of high-density materials.
• AXB underestimated dose by up to 30% at the plane of incidence due to limitations in estimating backscatter effects.

Conclusions:

• The Acuros XB algorithm offers improved accuracy for dose calculations near high-density materials in RTPS compared to traditional algorithms.
• Further refinement of AXB may be needed to fully account for backscatter phenomena for enhanced accuracy at the point of incidence.