Program Information
Commissioning a Multislice CT Scanner for X-Ray CT Polymer Gel Dosimetry
H Johnston1,2*, M Hilts1,3 , A Jirasek1 , (1) University of Victoria, Victoria, BC, (2) UT Southwestern Medical Center, Dallas, TX, (3) BC Cancer Agency, Kelowna, BC
Presentations
SU-E-T-70 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose: To commission a multislice computed tomography (CT) scanner for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD).
Methods: Commissioning was performed for a 16-slice CT scanner using images acquired through a 1L cylinder filled with water. Additional images were collected using a single slice machine for comparison purposes. The variability in CT number associated with the anode heel effect was evaluated and used to define a new slice-by-slice background image subtraction technique. Image quality was assessed for the multislice system by comparing image noise and uniformity to that of the single slice machine. The consistency in CT number across slices acquired simultaneously using the multislice detector array was also evaluated. Finally, the variability in CT number due to increasing x-ray tube load was measured for the multislice scanner and compared to the tube load effects observed on the single slice machine.
Results: Slice-by-slice background subtraction effectively removes the variability in CT number across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image quality for the multislice machine was found to be comparable to that of the single slice scanner. Further study showed CT number was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thickness examined. In addition, the multislice system was found to eliminate variations in CT number due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to imaging a large volume using a single slice scanner.
Conclusion: A multislice CT scanner has been commissioning for CT PGD, allowing images of an entire dose distribution to be acquired in a matter of minutes.
Funding Support, Disclosures, and Conflict of Interest: Funding support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC).
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