Program Information
CT Dose Measurements with Solid-State Probes
J Stickel*, B Lofton , Colorado Assn in Medical Phys (CAMP), Golden, CO
Presentations
WE-RAM2-GePD-I-5 (Wednesday, August 2, 2017) 10:00 AM - 10:30 AM Room: Imaging ePoster Lounge
Purpose: : CTDIvol is an essential CT dose parameter and is required by the ACR CT accreditation program. CTDIvol is required to be calculated based on measurements obtained using a CT ion chamber with environmental corrections and non-helical scanning. Solid-state point profile dosimetry has been introduced as an alternative to traditional measurements. It may provide a more efficient method of evaluating CTDIvol for helical scan protocols and may also be more accurate with no corrections needed. The goal here is to compare measurements using both solid-state and ion chamber measurement methods.
Methods: 2 measuring systems were used to determine CTDIvol. The first is the standard 100cm ion chamber with data taken in an axial mode. Standard calculations were done to calculate the CTDIvol. The second arrangement used the RTI Electronics Piranha measurement system equipped with a CT Dose Profiler. Measurements were made in helical scanning mode and software was used to determine the CTDIvol. The CTDIvol value displayed by the scanner was also recorded.
Results: Across manufacturers and models, the Dose Profiler could estimate the CTDIvol accurately when compared to the displayed CTDIvol and the standard CTDIvol method. The measurements were completed faster as a single scan rather than 6 measurements was made. The measurements from the Dose Profiler system showed less deviation from the scanner displayed numbers. Finally, the measurements with the dose profiler system provided a graphical display of the acquired dose that allows for a more complete understanding of the dose deposition.
Conclusion: The RTI Dose Profiler system can accurately measure the CTDIvol of a scanner in a single scan of the phantom. This provides both a quick assessment and more accurate measurement for large beam width scanners. These results will hopefully encourage accreditation bodies to consider allowing dosimetry to be performed using solid-state dose profilers.
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