Room: Exhibit Hall
Purpose: Our previous study had demonstrated that dual energy CT (DECT) provided advantageous features in cranial target delineation. The purpose of this study is to investigate the clinical application of DECT for treatment planning of head & neck cancer.
Methods: A Siemens SOMATOM Definition AS (Open 20RT) was used in this study for treatment planning CT simulation of all head and neck patients since January 2018. The DECT scanner allowed for sequential acquisition of two image datasets at 80 kVp and 140 kVp with the same acquisition time and radiation dose as a conventional single-energy scan. Images were reconstructed for nominal monoenergies of 40 keV, 100 keV and 190 keV, and a mixed energy of 120 kVp, which is equivalent to that currently used in routine simulation scanning. The reconstructed images were compared using the Varian VelocityAI software with a focus on the anatomical appearance of the lymph nodes and primary tumor sites.
Results: Our data showed that there were clinically significant differences in DECT images at different nominal energies. At 40 keV, enhancement of the tumor was more clearly seen compared with CT images at 120 kVp, 100 keV and 190 keV. More significant differences were also found at the border and necrotic area of nodes using different energies. For most patients the 40 keV CT images showed more enhanced tumor areas surrounding the vessels compared with images at 120 kVp, 100 keV and 190 keV, respectively.
Conclusion: It was demonstrated that the appearance of the head & neck primary tumor and nodes was significantly different among CT images reconstructed at different monoenergies. Quantification of such differences is in progress with corresponding MR images to evaluate clinical significance. In order to contour the gross tumor volume and nodes accurately, MR imaging is recommended.