Protocol modifications for CT perfusion (CTp) examinations of abdomen-pelvic tumors: Impact on radiation dose and data processing time

Abstract

Limiting CTp cine-phase to 30 sec results in comparable BF&MTT values and increasing cine-phase sampling interval to 2 sec provides good correlation for all CTp parameters with substantial dose reduction and improved computational efficiency.

Reproducibility and variability of very low dose hepatic perfusion CT in metastatic liver disease

“…Several ways were described to reduce the total dose (1,21,(23)(24)(25)(26). Considering very high radiation doses measured in most of the previous studies (7-30.7 mSv) (4,8,(10)(11)(12)20), the effective dose of our pCTs remains very low at 2.9 mSv. In our study, a very short scan length (2 cm), very low tube current/voltage (as little as possible; 80 kVp, 80 mA), and decreased scan time (48 s) were the main reasons for diminished radiation without sacrificing satisfactory perfusion calculations as recommended by Miles et al (19).…”

“…Thus, as the ROI gets smaller, the reproducibility of perfusion parameters is declined. One of the most important limitations for routine clinical utilization of pCT is the high radiation dose (20). Radiation is becoming more of an issue, particularly for patients in need of repeated pCT examinations for monitoring therapy response (21).…”

“…In addition to pCT, routine chest and abdominal CTs also increase the total radiation burden. The effective doses of hepatic pCT are twice or triple the effective doses of conventional abdominal CTs (20). Total scan time, scan length, temporal interval between cine acquisitions and tube current/voltage are the main data affecting DLP of all pCT (22).…”

“…Wang et al (13) used 50 mA for hepatic pCT in nine healthy volunteers but the total effective dose was as high as 7 mSv. Mean blood volume Previous studies reported that lower scan times in hepatic pCT are not reliable and reproducible, particularly for permeability (20,23,28). Ng et al (28) proposed that at least 590 s were required for permeability with moderate confidence.…”

“…In this study we specifically used a lower scan time to decrease the radiation dose and we aimed to identify those parameters that are reproducible even at the lowest doses. Several authors have discussed that shortening of the scan time can alter the reproducibility of perfusion measurements although it reduces the radiation dose (20,29), motion artifacts, and provides more rapid postprocessing (20). Therefore, there must be a balance between the radiation burden and the reliability of measurements.…”