Room: Exhibit Hall
Purpose: To establish and recommend a quality assurance program for 4-dimensional CT scan protocols on a helical 4D CT scanner.
Methods: Anzai AZ-733V respiratory phantom was used in this study. The settings were set to normal and resp. modes with repetition rates at 15 rpm and 10 rpm. Helical scan, AIP (average intensity projection) and MIP (maximum intensity projection) were generated from 4D-CT scans with phase-based sorting into 10 phases with Siemens syngo software. In our study, 1 cm and 5 cm peak-to-peak amplitude with 2 second, 4 second and 10 second breathing cycle were tested. The Siemens Somatom definition AS 4D scan protocols, i.e. 6 rpm, 9 rpm, and 12 rpm, were tested. 2 different types of sensor cells (deep and standard) inserted into the Anzai belt was used as the patient breathing signal sensor. Coherence of breathing signal detection, object volumes, lengths along the motion direction from AIPs and MIPs and motion movies were analyzed in this study.
Results: A time course study was performed with the test listed above and recorded in an excel sheet with the values of each settings with the same object. A time course chart was plotted and we found that the quality assurance of 4D CT is important and needed to be done regularly. Under the condition that CT scanner is under contract to be performed periodic maintenance quarterly, we recommend 4D-CT QA should be performed annually in order to catch some unexpected signal drift of respiratory signal detection. AIPs and MIPs image analyses showed steady HUs prediction.
Conclusion: A comprehensive a quality assurance program for 4-dimensional CT scan protocols on a helical 4D CT scanner is established and we recommend performing this test annually.