Zhiguo Zhou, Presenter: Nothing to Disclose

Qingguo Wang, Abstract Co-Author: Nothing to Disclose

Yan Feng, Abstract Co-Author: Nothing to Disclose

To evaluate the image quality by low kVp from kV assist in combination with ASiR in CTU.

We retrospectively analyzed 45 patients which underwent CTU with kV assist switched on, on a multi-detector CT scanner ( Discovery CT750 HD, GE healthcare). Before confirming CT scan, kV assist software allowed optimal kVp being selected automatically according to the scout view. The patients were divided into 2 groups for analysis retrospectively. Group A took 80 or 100kVp (n=32,BMI<28) and images were reconstructed with 50%ASiR. Group B (n=13，BMI>=28) took 120kVp and images were reconstructed with FBP respectively. The main parameters of protocol were setup with a baseline of noise index at 12, auto mA range at 100-700mA and rotation time at 0.5s. Measure CT values and SD values of bilateral renal pelvis and subcutaneous fat tissue on abdomen, and calculate mean CNR and mean SNR of bilateral renal pelvis. Record CTDIvol and DLP of each patient. Use Student T test to analyze all data.

The mean CT value of bilateral renal pelvis in group A was significantly higher than in group B (271.35±57.60HU vs 221.80±35.28HU), (p＜0.05).  The SD value of of abdominal subcutaneous fat in group A was significantly lower than group B(7.94±2.11HU vs 10.52±2.27HU),(p＜0.05).  The mean value of CNR in group A was significantly higher than in group B(53.61±24.74 vs 32.30±6.52),( p＜0.05).  The mean value of SNR in group A was significantly higher than in group B (38.13±19.86 vs 21.76±4.85),( p＜0.05).  The value of CTDIvol in group A was significantly lower than in group B (9.26±2.77mSv vs 16.19 ± 5.60mSv), (p＜0.05).

kV assist software allowed low kVp(80 or 100 kVp) apply for small patients. In combination with 50%ASiR , low kVp got better image quality and 44% radiation dose reduction than 120kVp with FBP in CTU.

For small shape patients in CTU, low kVp token by kV assist combination with 50%ASiR , better image quality and lower radiation dose were accomplished than patients with 120 kVp and FBP. They simplified examination and improved quality.

Zhou, Z, Wang, Q, Feng, Y, Clinical Application of Low kVp from kV Assist in Combination with Adaptive Statistical Iterative Reconstruction (ASiR) in Computed Tomography Urography (CTU).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015872.html