Development of a Methodology to Assess the Image Quality of the ExacTracTM Localization System Using the PIPSproTM Software and Unfors RaySafe Xi R/F Detector
D Stanley*, N Papanikolaou, A Gutierrez, University of Texas HSC SA, San Antonio, TXSU-E-T-123 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To develop a methodology of assessing and evaluating the consistency of the spatial resolution, dose, energy, noise, contrast, and geometrical accuracy of the BrainLab ExacTrac™ system.
Methods:A device was constructed to hold the QCkV-1 Phantom firmly and reproducibly against the face of the flat panel detectors. Two image sets per detector were acquired using the ExacTrac present console setting--Cranial Standard. The two image sets were analyzed in PIPSpro™ and the following metrics were recorded: spatial resolution (f30, f40, f50), noise and Contrast-to-Noise Ratio. Geometrical image accuracy was evaluated by assessing the length of QCkV-1. Dose and kVp were recorded using the Unfors RaySafe Xi R/F Detector. The kVp and dose were evaluated for the following: Cranial (80kV,80mA,80ms), Thorax (120kV,160mA,160ms), Abdomen (120kV,160mA,130ms) and Pelvis(120kV,160mA,160ms).
Results:With regards to spatial resolution, the mean values of the f30, f40 and f50 for the left detector were, 1.39±0.09, 1.24±0.10 and 1.15±0.07 respectively, while the right detector were 1.38±0.07, 1.22±0.08 and 1.13±0.10, respectively. Mean CNR for the left and right detectors was 114±10 and 116±13, respectively. For geometrical accuracy, both detectors had a measured image length of the QCkV-1 of 218.8±0.3mm. The left detector showed dose measurements of 1.37±0.01 mGy (CS), 12.56±0.03 mGy (TS), 10.08±0.04 mGy (AS) and 12.58±0.05 mGy (PS) while the right detector showed 1.27±0.01 mGy (CS), 11.48±0.03 mGy (TS), 9.21±0.04 mGy (AS) and 11.50±0.04 mGy (PS), respectively. For energy, the left detector had kVp readings of 81.2±0.3 (CS), 121.1±0.4 (TS), 121.0±0.3 (AS) and 121.0±0.3 (PS) and the right detector had 79.9±0.1 (CS), 117.2±0.2 (TS), 117.2±0.2 (AS) and 117.2±0.2 (PS).
Conclusion:A methodology was developed to assess the basic image quality parameters recommended by TG-142 for the ExacTrac™ system. The ExacTrac system shows a consistent dose, kVp, spatial resolution, CNR and geometrical accuracy for each detector over the evaluated timeframe.