The Problem of X-Ray Attenuation Estimation Accuracy in Multislice Computed Tomography
Purpose. Revealing the trends of the inappropriate X-Ray attenuation estimations on MSCT. Data and Methods. There have been analyzed abdominal CT results of 100 patients, archived in the Radiological Information System of Moscow. The standard water phantom has been scannedalsowith different parameters. Scans were made on 64-row detectors CT scanners.All devices were calibrated on water and air. Results. There have been discovered inappropriate estimations of X-Ray attenuation, mainlays understating by 4-20 HU, more apparent in peripheral areas of the FOV These distortions had resulted in the overdiagnosis of diffused diseases of liver, pancreasand kidney. Phantom scans have confirmed that the estimations of X-Ray attenuation coefficient are really inhomogeneous. The trend is the rising understatement from FOV center to periphery. This doesn't depend on the tube current change in range of 100-550 mA. More appropriate estimations were noted using the narrowed FOV. Conclusions. There is a problem of the inappropriate X-Ray attenuation estimations on MDCT, mainly as thefalse hypoattenuation, more in the FOV periphery,which does not depend on the tube current. FOV decrease and use of 5-mm slices for measurements may enhance the estimation accuracy.