Simplified "on-couch" daily quality assurance procedure for CT simulators

Area of Science:

• Medical Physics
• Radiation Oncology
• Imaging Technology

Background:

• Current computed tomography (CT) quality assurance (QA) protocols for radiation oncology simulators require removing the couch top and using separate tools for imaging and laser QA.
• This multi-step process is time-consuming, labor-intensive, and increases the risk of accidents.
• A need exists for a more efficient and integrated QA solution for CT simulators.

Purpose of the Study:

• To develop and evaluate a novel, comprehensive daily QA phantom and program for CT simulators.
• To enable simultaneous localization-laser and imaging QA on a flat couch top using a single tool.
• To assess the impact of the couch top on CT image quality.

Main Methods:

• A commercial CT QA phantom was modified with adjustable legs and integrated metric scales for laser alignment.
• The modified phantom was used for both CT imaging QA and localization-laser QA on flat couch tops.
• Five different CT scanners from two manufacturers were tested to evaluate the phantom's performance and couch effects on image quality.

Main Results:

• The modified phantom successfully integrated laser and imaging QA into a single, efficient process.
• The presence of the couch top altered CT number uniformity but did not affect visual image resolution.
• Couch-specific and scanner-specific effects on image quality were observed, with variations within 3 Hounsfield Units for a carbon fiber couch, which can be incorporated into QA criteria.

Conclusions:

• The developed QA program and phantom provide a more thorough QA process for CT simulators.
• This integrated approach significantly reduces the time and effort required for daily QA procedures.
• The findings support the implementation of this streamlined QA method in radiation oncology settings.