Program Information
Radcal Solid State Multisensor 1-Shot Half Value Layer Evaluation
C Layfield*, V Garcia , W Wang , University of Oklahoma Health Science Center, Oklahoma City, OK
Presentations
TU-C3-GePD-I-3 (Tuesday, August 1, 2017) 10:30 AM - 11:00 AM Room: Imaging ePoster Lounge
Purpose: The accuracy of 1-shot Half-Value-Layer (HVL) measurement by Radcal Solid State Multisensor (Radcal AGMS-DM+ Diag-Mam) is evaluated under different conditions: exposure to the multisensor, multisensor to focal spot distance, multisensor location in the X-ray field, and the rotation of the multisensor itself. The 1-shot HVL measurement is also compared to the HVL measurement using the traditional method.
Methods: Firstly, we evaluated the 1-shot HVL while rotating the multisensor to 8 different angles, each separated by 45 degrees (0, 45, 90, …, 315 degrees). Secondly, when the exposure to the multisensor is below 150mR, the measured 1-shot HVL decreased with decreasing exposure to the multisensor. The measured 1-shot HVL was 2% to 4% lower than the HVL from the traditional method for 60kVp to 120kVp. Thirdly, the 1-shot HVL was measured using different source to multisensor/detector distances (SDD) ranging from 75cm to 183cm. The measured 1-shot HVL increased up to 1.6% with increasing the SDD, making it closer to the HVL from the traditional method. Fourthly, when moving the multisensor from the cathode side to the anode side, the anode filtration caused a 50% increase in the measured HVL. Moving the detector away from the center of the field, in the direction perpendicular to the A/C direction, resulted in a decrease in the measured HVL of up to 5.3%.
Results: The measured 1-shot HVL decreased up to 5.6% with decreasing exposure from 600mR to 6mR at 120kVp. Using a larger SDD, up to at least 183cm, increased the accuracy of the 1-shot HVL measurement. An interaction angle of 90 degrees gave more accurate readings.
Conclusion: For more accurate measurements, the multisensor should be positioned at the center of the X-ray field with a SDD of 183cm and 300mR multisensor exposure. The orientation of the multisensor does not affect the measurement.
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