Standardization of scan protocols for RT CT simulator from different vendors using quantitative image quality...

Area of Science:

• Medical Physics
• Radiology
• Imaging Technology

Background:

• Standardizing computed tomography (CT) simulation protocols across different vendors is crucial for consistent radiotherapy planning.
• Vendor-specific iterative reconstruction (IR) methods and dose levels can significantly impact image quality (IQ).

Purpose of the Study:

• To assess the feasibility of standardizing RT simulation CT scanner protocols between vendors using target-based IQ metrics.
• To establish a phantom-based method for evaluating and comparing IQ across different CT scanners and reconstruction algorithms.

Main Methods:

• A phantom study was conducted using CT scanners from different vendors (Philips, Siemens) with varying CTDIvol and iterative reconstruction (IR) levels (iDose, IMR, SAFIRE).
• Image quality metrics including noise, texture (noise power spectrum), contrast, contrast-to-noise ratio (CNR), and low contrast detectability (d') were quantified.
• The area under the curve (AUC) of the receiver operating characteristic curve for d' was calculated to compare performance.

Main Results:

• Significant IQ changes were observed with model-based iterative reconstruction (IMR).
• iDose and SAFIRE showed low to moderate IQ ratio changes, with SAFIRE-2 in the Siemens scanner closely matching the reference body protocol.
• The Siemens scanner generally performed better than the Philips scanner in matching protocols, particularly in the body protocol.

Conclusions:

• Target-based IQ metrics are effective for evaluating CT scanner performance and operations in a phantom setting.
• This methodology can serve as a reference for converting clinical CT simulation protocols between different vendor scanners.