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Radiation Therapy Application of a Novel Split-Filter Dual-Energy CT (DECT) to Improve Pancreas and Liver GTV Contrast

L Di Maso

L Di Maso*, J Huang , M Bassetti , L DeWerd , J Miller , University of Wisconsin-Madison, Madison, WI


SU-K-FS4-15 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: Four Seasons 4

Purpose: Tumor delineation using conventional CT images can be a challenge in areas such as the pancreas and liver where contrast between the tumor and surrounding healthy tissue is low. This work investigates the benefits of a novel split-filter DECT system to improve tumor segmentation in patients with pancreatic and liver cancer for radiation therapy applications.

Methods: DECT images were acquired with iodine contrast for pancreatic and liver cancer patients. Analysis was performed on the pancreatic and portal venous phase for pancreatic cancer patients and the portal venous and arterial phase for liver cancer patients. ROIs within the GTV and the surrounding healthy pancreas or liver tissue were used to quantify the tumor's contrast and CNR. An energy of 57 keV was chosen as the optimal energy for monoenergetic images in the pancreas and liver based on physician preference. Mixed images were reconstructed using the DECT data to mimic single-energy 120 kVp images. Multiple image reconstruction techniques and reconstruction kernels were investigated.

Results: Preliminary results show that portal venous phase and pancreatic phase DECT monoenergetic 57 keV images demonstrate greater tumor contrast compared to SECT mixed images (p=0.01). Though, the contrast was improved with monoenergetic images, the noise was also higher. The CNR from the DECT images was not significantly greater than the SECT images (p=0.11). However, the CNR in the DECT monoenergetic images was improved by about 70% with the addition of iterative reconstruction (SAFIRE).

Conclusion: DECT images demonstrated improved contrast in comparison to SECT images and thus may offer more accurate tumor delineation. The ability to generate additional data from a DECT exam may further improve the delineation accuracy. Noise may be a limiting factor for lower energy monoenergetic images. The use of SAFIRE was shown to greatly improve CNR.

Funding Support, Disclosures, and Conflict of Interest: Supported in part by a collaboration agreement with Siemens Medical Solutions

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