Program Information
Initial Clinical Evaluation of the Stability of the Radixact MVCT Image Quality
U Robins*, T Romaguera , V Mishra , A Gutierrez , Miami Cancer Institute, Miami, FL
Presentations
TU-RPM-GePD-J(B)-5 (Tuesday, August 1, 2017) 3:45 PM - 4:15 PM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: The Radixact radiotherapy system is the latest remodeled version of the tomotherapy unit. Initial clinical evaluations of select dosimetric and imaging parameters have yet to be studied. The purpose of this study was to characterize the image quality and assess the stability of the MVCT of the Radixact.
Methods: A cylindrical solid-water phantom (Cheese Phantom) with known density plug inserts and a high contrast resolution plug was used. Scans were obtained with three different pitches; fine, normal and coarse. Image quality analysis was performed in the ImageJ software platform. Specifically, the noise level, uniformity, spatial resolution and HU stability were studied. The homogenous region of the phantom was used to evaluate the noise and uniformity parameters by placing ROIs in the four sectors and peripheral regions of the phantom. Care was taken to place each ROI in the same spot in the scan. Hard contrast resolution was assessed by detecting the row of visible holes in the hard contrast plug. HU stability was studied using the various known density plugs. The position of the plugs within the phantom was maintained during each scan.
Results: All of the image parameter evaluated showed good stability. The image noise and uniformity were consistent over time and within the three scan types. The image noise was 41HU and uniformity was 11HU and were within tolerances recommended by TG148. As for HU stability, a maximum of 9HU change was noted in the density plugs (range: 683-678HU) over the time evaluated. Hard contrast showed consistent detection and was clearly visible in all scans.
Conclusion: There was no significant statistical variation in the noise, uniformity, and HU stability over the 3 month evaluation period. The Radixact MVCT appears to show stable imaging parameters over the period evaluated.
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