First implementation of photon-counting dector computed tomography for optimizing segmentation in head-and-neck
Niccolò Bertini1,2, Hubert S Gabryś1, Hatem Alkadhi3
1Department of Radiation Oncology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zurich, Switzerland.
Background And Purpose:
Photon-counting detector computed tomography (PCD-CT) offers advancements over conventional energy-integrating detector computed tomography (EID-CT). This study is the first to investigate the use of PCD-CT for delineation purposes.
Materials And Methods:
Twelve patients with head-and-neck cancer were prospectively included. Delineation of clinical target volume (CTV) and organs at risk (OARs) was performed by three physicians using EID-CT (120 kVp) and PCD-CT at virtual monoenergetic levels of 140 keV and 50 keV. Segmentation accuracy was assessed and contouring-confidence was rated.
Results:
The ratio of the mean computed tomography dose index (CTDI) for EID-CT/PCD-CT for all patients was 2.72. The study revealed high inter-observer agreement for the mandible, oral cavity, parotid glands, and submandibular glands, with DSCs exceeding 0.8 across both EID-CT and PCD-CT. No differences in delineation agreement were observed, while a significant improvement was found for the lips (p = 0.001) and oral cavity (p = 0.003) when combining 140 keV and 50 keV images in PCD-CT compared to EID-CT. PCD-CT outperformed EID-CT in terms of contouring confidence.
Conclusion:
The study established the feasibility of PCD-CT for radiotherapy planning. PCD-CT-based delineation provides results comparable to EID-CT, with the added advantages of reduced radiation dose, improved image quality and higher delineation confidence. Significant improvements in delineating specific structures, such as the lips and oral cavity, were observed when combining multiple energy levels in PCD-CT.
