SU-E-I-20: Comprehensive Quality Assurance Test of Second Generation Toshiba Aquilion Large Bore CT Simulator Based On AAPM TG-66 Recommendations

Authors


Abstract

Purpose:

AAPM radiation therapy committee task group No. 66 (TG-66) published a report which described a general approach to CT simulator QA. The report outlines the testing procedures and specifications for the evaluation of patient dose, radiation safety, electromechanical components, and image quality for a CT simulator. The purpose of this study is to thoroughly evaluate the performance of a second generation Toshiba Aquilion Large Bore CT simulator with 90 cm bore size (Toshiba, Nasu, JP) based on the TG-66 criteria. The testing procedures and results from this study provide baselines for a routine QA program.

Methods:

Different measurements and analysis were performed including CTDIvol measurements, alignment and orientation of gantry lasers, orientation of the tabletop with respect to the imaging plane, table movement and indexing accuracy, Scanogram location accuracy, high contrast spatial resolution, low contrast resolution, field uniformity, CT number accuracy, mA linearity and mA reproducibility using a number of different phantoms and measuring devices, such as CTDI phantom, ACR image quality phantom, TG-66 laser QA phantom, pencil ion chamber (Fluke Victoreen) and electrometer (RTI Solidose 400).

Results:

The CTDI measurements were within 20% of the console displayed values. The alignment and orientation for both gantry laser and tabletop, as well as the table movement and indexing and scanogram location accuracy were within 2mm as specified in TG66. The spatial resolution, low contrast resolution, field uniformity and CT number accuracy were all within ACR's recommended limits. The mA linearity and reproducibility were both well below the TG66 threshold.

Conclusion:

The 90 cm bore size second generation Toshiba Aquilion Large Bore CT simulator that comes with 70 cm true FOV can consistently meet various clinical needs. The results demonstrated that this simulator complies with the TG-66 protocol in all aspects including electromechanical component, radiation safety component, and image quality component.

Employee of Toshiba America Medical Systems

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