Program Information
Analysis of Image Quality in CBCT QA Using a Treatment Planning System
M Xu1*, (1) Radiation Oncology Physics, Cancer Center, Cadence Health, Warrenville, IL
Presentations
SU-E-J-26 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose: The objective of this study is to propose an alternative QA technique that analyzes imaging quality(IQ) in CBCT-QA processing.
Methods: A catphan phantom was used to take CT imaging data set that were imported into a treatment planning system - Eclipse. The image quality was analyzed in terms of in-slice geometry resolution, Hounsfield numbers(HU) accuracy, mean-slice thickness, edge-to-center uniformity, low contrast resolution, and high contrast spatial resolution in Eclipse workstation. The CBCT-QA was also analyzed by OBI-workstation and a commercial software. Comparison was made to evaluation feasibility in a TPS environment.
Results: The analysis of IQ was conducted in Eclipse v10.0 TPS. In-slice geometric resolution was measured between 2-rods in section CTP404 and repeated for all 4 rods with the difference between expected and measured values less than +/-0.1 cm. For HU, the difference between expected and measured values in HU was found much less than +/-40. Mean slice thickness measured by a distance on the wire proportional to scanner increment multiplying by a factor of 0.42. After repeating measurements to 4 wires, the average difference between expected and measured values was less +/-0.124 mm in slice thickness. HU uniformity was measured in section CTP486 with the tolerance less than +/-40 HU. Low contrast resolution in section CTP515 and high contrast resolution in section CTP528 were found to be 7 disks in diameter of 4 mm and 6 lp/cm, respectively. Eclipse TPS results indicated a good agreement to those obtained in OBI workstation and ImagePro software for major parameters.
Conclusion: An analysis of IQ was proposed as an alternative CBCT QA processing. Based upon measured data assessment, proposed method was accurate and consistent to IQ evaluation and TG142 guideline. The approach was to utilize TPS resource which can be valuable to re-planning, verification, and delivery in adaptive therapy.
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