Comparison of measurement methods with a mixed effects procedure accounting for replicated evaluations (COM3PARE):...

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Statistical Modeling

Background:

• Comparing imaging measurement devices, especially in image-guided radiotherapy (IGRT), is challenging due to the lack of gold standards and replicated measurements.
• The proliferation of IGRT devices necessitates a robust method to assess interchangeability between different imaging techniques.

Purpose of the Study:

• To evaluate the feasibility and utility of the Comparison of Measurement Methods with the Mixed Effects Procedure Accounting for Replicated Evaluations (COM3PARE) for IGRT method comparison.
• To assess agreement between cone beam CT (CBCT) and kilovoltage X-ray (KVX) imaging in head and neck cancer patient positional verification using COM3PARE.

Main Methods:

• Utilized a dataset of 100 paired coordinate measurements from head and neck cancer patients imaged with CBCT and KVX.
• Applied the COM3PARE methodology, based on linear mixed effects models, using SAS software to analyze bias, inter-method, intra-method, and overall agreement.
• Evaluated positional shifts in lateral (X), vertical (Y), and longitudinal (Z) dimensions.

Main Results:

• COM3PARE identified statistically significant differences in bias and inter-method agreement for the Z-axis between CBCT and KVX (p < 0.01).
• Statistically significant differences in intra-method and overall agreement were observed for both X and Z axes (p < 0.01).
• CBCT was preferred for X-axis positional verification, while KVX was preferred for superoinferior (Z-axis) alignment based on intra-method agreement.

Conclusions:

• The COM3PARE methodology proved feasible and useful for comparing IGRT methods in a head and neck cancer dataset.
• COM3PARE offers a flexible, robust, and standardized analytical approach for IGRT comparisons.
• A SAS script for COM3PARE is provided to facilitate its adoption in other clinical settings and for different IGRT platforms.