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Clinical Investigation of Sequential Dual-Energy CT Imaging for Radiotherapy Target Delineation

L Chen

L Chen1*, Y Dong1 , Y Zhang2 , J Liu1 , T Lin1 , J Fan1 , R Price1 , C Ma1 , (1) Fox Chase Cancer Center, Philadelphia, PA, (2) Tongdu Hospital, Xian, China


SU-K-201-16 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: 201

Purpose: Dual-energy CT allows for imaging patient’s anatomy with selective soft tissue contrast and noise suppression. The purpose of this study is to investigate the clinical application of sequential dual-energy CT imaging in radiotherapy target delineation for head and neck patients.

Methods: Six patients were included in this study. Each patient was scanned on a GE 1.5T MR scanner and a Siemens SOMATOM Definition AS (Open 20RT) 5 minutes after an intravenous injection of 100 ml 37% organically bound iodine ISOVUE-370. The CT scanner allowed for sequential acquisition of two image datasets at 80kVp and 140kVp with the same acquisition time and radiation dose as a single energy scan. Images were reconstructed for nominal monoenergies between 40keV and 190keV, and a mixed energy of 120kVp, which is equivalent to that currently used in routine clinical practice. The reconstructed images were compared using the Varian VelocityAI software. During the comparison of those images, attention was focused on any differences in the bone and soft tissues.

Results: Our data showed that there were meaningful clinical differences in CT images at different nominal energies. On the 190keV image, the iodine induced artifacts for the soft palate was significantly reduced compared with the 120kVp image. The dental filling artifacts showed similar behavior. Comparing the contrast-enhanced brain metastases at different energies, the 40keV image delineated the tumor much clearer than images for other energies. The brain tumor volume at 40keV was comparable to that on T1-wighted MR images. In contrast, the brain metastases were not seen on the 190keV image.

Conclusion: Our results demonstrated that dual-energy CT imaging was advantageous for target delineation for head and neck patients. The tumor contrast in brain metastases at 40keV appeared to be comparable to that with T1 weighted MR imaging.

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