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Evaluation of the Device-Less 4D CT

J Fan

J Fan1*, X Chen2 , Q Xu3 , T Lin1 , J Liu1 , L Jin1 , L Wang1 , R Price1 , C Ma1 , (1) Fox Chase Cancer Center, Philadelphia, PA, (2) Penn Medicine Virtua Cancer Program, Voorhees, NJ, (3) MD Anderson Cancer Center at Cooper, Mt Laurel, NJ


SU-I-GPD-J-60 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: 4D-CT scan has been widely used in radiation therapy simulation to help identify treatment targets. A standard 4D-CT scan acquires in Cine clusters with multiple acquisitions along the z-axis. Then sorting software sort the images based on the breathing phases using signals recorded via an external respiratory gating device. The GE smart device-less 4D-CT (DL-4DCT) is the first commercial available system that do image sorting based on the measurements of the lung, body and air area and density without external marker. The purpose of this study is to evaluate the 4D quality from device-less sorting and compare results to standard 4D scans.

Methods: 20 patients including 10 lungs and 10 abdomens were included in the study. All patients received the standard 4DCT using the Varian RPM. Those cine CT data were also submitted to the DL-4DCT sorting software. Two sets of 4D images were generated from the standard 4D and the DL-4D, respectively. The DL-4DCT image quality was assessed in reference to standard 4DCT. Using maximum intensity projection (MIP) images, the ITVs of the standard 4DCT and DL-4DCT were compared.

Results: The DL-4DCT was able to produce the 4DCT images on all 20 cases. The ITVs determined on the 10 lung patients with DL-4DCT were averaged about 5.2% smaller than the ITVs with standard 4DCT. This translates to less than 1 mm difference in ITV dimensions, which is clinically insignificant comparing to the 5-6 mm PTV margin used. However, much larger differences were identified in abdominal cases. The ITV volume varies from -17.2% to 23.1%.

Conclusion: The Device-less 4DCT was promising in generating 4D-CT images without a respiratory monitoring device for most lung patients. The differences found in the abdominal cases need to be further investigated to find out which one is more appropriate for clinical use.

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