First implementation of photon-counting dector computed tomography for optimizing segmentation in head-and-neck...

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Oncology

Background:

• Photon-counting detector computed tomography (PCD-CT) represents an advancement over traditional energy-integrating detector CT (EID-CT).
• PCD-CT's utility for radiotherapy delineation has not been previously explored.

Purpose of the Study:

• To investigate the feasibility and performance of PCD-CT for clinical target volume (CTV) and organs at risk (OARs) delineation in head-and-neck cancer patients.
• To compare delineation accuracy and confidence between PCD-CT and EID-CT.

Main Methods:

• Prospective study of 12 head-and-neck cancer patients.
• Delineation of CTV and OARs by three physicians using EID-CT (120 kVp) and PCD-CT (140 keV and 50 keV virtual monoenergetic levels).
• Assessment of segmentation accuracy and physician confidence ratings.

Main Results:

• PCD-CT achieved a dose reduction ratio (CTDI EID-CT/PCD-CT) of 2.72.
• High inter-observer agreement (DSC > 0.8) for structures like mandible, oral cavity, and parotid glands on both EID-CT and PCD-CT.
• Significant improvements in delineation agreement for lips and oral cavity using combined PCD-CT energy levels (p<0.01).
• PCD-CT demonstrated superior contouring confidence compared to EID-CT.

Conclusions:

• PCD-CT is a feasible imaging technique for radiotherapy planning.
• PCD-CT-based delineation is comparable to EID-CT, with added benefits of lower radiation dose, enhanced image quality, and increased confidence.
• Combining multiple energy levels in PCD-CT significantly improves delineation of specific anatomical structures.