Is model-based dose calculation based on cone-beam computed tomography suitable for adaptive treatment planning in...

Area of Science:

• Medical Physics
• Radiotherapy
• Imaging Technology

Background:

• Model-based dose calculation is gaining traction in brachytherapy.
• Accurate tissue composition data is crucial for these calculations.

Purpose of the Study:

• To evaluate modern cone-beam computed tomography (CBCT) against conventional computed tomography (CT) for model-based dose calculations.
• To assess the suitability of CBCT for brachytherapy dose calculations.

Main Methods:

• Phantom studies compared CT numbers and electron densities from CBCT and CT scanners.
• Dose calculations (TG-43, ACEuniform, ACECT#) were performed on CT and CBCT datasets.
• Interfractional implant variations were estimated by comparing planning CTs and control CBCTs.

Main Results:

• No significant difference in dose parameters between ACEuniform and ACECT# calculations using CT versus CBCT.
• Small, partly significant dosimetric deviations (<10 cGy/fraction) between model-based calculations and TG-43.
• Interfractional dosimetric variations exceeded differences between dose calculation methods.

Conclusions:

• Model-based dose calculation using CBCT is feasible for brachytherapy.
• Further investigation into differences between model-based calculations and TG-43 is warranted.
• Treatment quality assurance is essential due to significant interfractional variations.