Respiratory-gated Segment Reconstruction for Radiation Treatment Planning using 256-slice CT-scanner during Free Breathing

摘要

The conventional respiratory-gated CT scan technique includes anatomic motion induced artifacts due to thelow temporal resolution. They are a signifi cant source of error in radiotherapy treatment planning for the thoraxand upper abdomen. Temporal resolution and image quality are important factors to minimize planning targetvolume margin due to the respiratory motion. To achieve high temporal resolution and high signal-to-noise ratio,we developed a respiratory gated segment reconstruction algorithm and adapted it to Feldkamp-Davis-Kressalgorithm (FDK) with a 256-detector row CT.The 256-detector row CT could scan approximately 100 mm in the cranio-caudal direction with 0.5mm slice thickness in one rotation. Data acquisition for the RS-FDK relies on the assistance of the respiratorysensing system by a cine scan mode (table remains stationary). We evaluated RS-FDK in phantom study withthe 256-detector row CT and compared it with full scan (FS-FDK) and HS-FDK results with regard to volumeaccuracy and image noise, and fi nally adapted the RS-FDK to an animal study. The RS-FDK gave a more accuratevolume than the others and it had the same signal-to-noise ratio as the FS-FDK. In the animal study, theRS-FDK visualized the clearest edges of the liver and pulmonary vessels of all the algorithms.