Patient size compensated automatic tube current modulation in multi-detector row CT of the abdomen and pelvis

Abstract

Rationale and purpose: To evaluate the performance of a patient size-compensated automatic tube current modulation (PSC-AutomA) technique from the perspectives of image quality and radiation dose in multi-detector-row computed tomography (MDCT) scan of the abdomen and pelvis.

Materials and methods: Institutional review board approval was obtained and the study was Health Insurance Portability and Accountability Act-compliant. One hundred and seventeen patients (mean age: 48.8 years; range: 17-89 years; male/female: 57/60) underwent abdominal-pelvic CT scan on a 64-slice MDCT using the noise indexes (NI) recommended by the PSC-AutomA technique. Two radiologists independently evaluated all examinations for noise, streak artifacts, and diagnostic acceptability at the dome of liver, porta hepatis, and the upper margin of acetabulum. The CT dose index (CTDI) volume and effective dose of the CT performed using a recommended NI were compared to the CT performed using a fixed NI of 12. Statistical analysis of the data was performed with nonparametric tests.

Results: The NI recommended by the PSC-AutomA technique was strongly correlated with patient size (r = 0.98, P < .001) with a mean NI of 14.2 HU. The recommended NI of 98.2% (115/117) patients was different from the fixed NI of 12. Approximately 71.8% (84/117) subjects were scanned with a NI higher than 12, whereas 26.5% (31/117) subjects were scanned with a NI lower than 12. All examinations (100%; 117/117) were graded as possessing diagnostic image quality. Compared with the CT performed by using a fixed NI 12, the overall CTDI and effective dose reduction by the PSC-AutomA technique were 11.1% and 11.8%, respectively.

Conclusion: The PSC-AutomA technique can recommend an appropriate NI in MDCT scan of the abdomen and pelvis according to patient size, allowing a balanced optimization of both radiation dose and image quality, simultaneously.