ABSTRACT
Purpose To compare radiation dose and image quality of different scan modes for CT pulmonary angiography (CTPA) including high-pitch flash mode, dual energy CT (DECT) mode, 128-slice mode of dual source CT and 64-slice CT mode. Materials and Methods One hundred and sixty-seven patients with suspected pulmonary embolism were retrospectively studied. All the patients underwent CTPA. Twenty patients were selected randomly from the patients scanned by high-pitch flash mode. Patients who were scanned by the other three modes were selected with body mass index and age matched those in high-pitch flash mode, with 20 patients in each group. Two radiologists assessed signal-to-noise ratio (SNR) and image quality with 5-piont scale. Dose parameters of volume CT dose index (CTDIvol), dose length product (DLP), and effective dose (ED) were compared among the four groups. Results Mean CTDIvol, DLP and ED were (3.72±0.74) mGy, (137.5±28.7) mGy · cm, and (2.34±0.41) mSv for Flash mode;(5.31±1.21) mGy, (181.6±34.5) mGy· cm and (3.24±0.57) mSv for DECT mode;(5.66±1.47) mGy, (198.7±42.1) mGy·cm and (3.58±0.63) mSv for 128-CT mode;and (6.75±1.68) mGy, (231.5±54.2) mGy·cm and (4.21±0.89) mSv for 64-CT mode. There was no significant difference of SNR and image quality among the four modes (P>0.05). Conclusion There are no significant difference of image quality among the four groups. Flash mode allows for minimum radiation dose compared to other modes. DECT mode and 128-CT mode get higher radiation dose with no difference between them. 64-CT mode gets the highest radiation dose.