Estimate of Radiation Doses in MDCT Using Patient Weight / 의학물리

The purpose of this study provides measurements of radiation dose from MDCT of head, chest, abdomen and pelvic examinations. A series of dose quantities that are measured of patient weight to compare the dose received during MDCT examinations. Data collected included: weight together with CT dose descriptors, volume CT dose index (CTDIvol) and dose length product (DLP). The effective dose was also estimated and served as collective dose estimation data. Data from 1,774 adult patients attending for a CT examination of the head (n=520) or chest (n=531) or abdomen (n=724) was obtained from spiral CT units using a same CT protocol. Mean values of CTDIvol was a range of 48.6 mGy for head and 6.9, 10.5 mGy for chest, abdomen examinations, respectively. And mean values of DLP was range of 1,604 mGy.cm for head, 250 mGy.cm for chest, 575 mGy.cm for abdomen examinations, respectively. Mean effective dose values for head, chest, abdominal CT were 3.6, 4.2, and 8.6 mSv, respectively. The degree of CTDIvol and DLP was a positive correlation with weight. And there was a positive correlation for weight versus CTDIvol (r2=0.62), DLP (r2=0.694) in chest. And head was also positive correlation with weight versus CTDIvol (r2=0.691), DLP (r2=0.741). We conclude that CTDIvol and DLP is an important determinant of weight within the CT examinations. The results for this study suggest that CT protocol should be tailored according to patient weight.

A Study on Usefulness of Specific Agents with Liver Disease at MRI Imaging: Comparison with Ferucarbotran and Gd-EOB-DTPA Contrast Agents / 의학물리

The purpose of this experiment is to know the relation of the detection and characterization of liver's diseases as comparison of finding at MR imaging using a Ferucarbotran (SPIO) and Gd-EOB-DTPA (Primovist) agents in diffuse liver disease. A total of 50 patients (25 men and 25 women, mean age: 50 years) with liver diseases were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) "with 8 Ch body coil for comparison of diseases and contrast's uptake relation, which used the LAVA, MGRE." All images were performed on the same location with before and after Ferucarbotran and Gd-EOB-DTPA administrations (p<0.05). Contrast to noise ratio of Ferucarbotran and Gd-EOB-DTPA in the HCC were 3.08+/-0.12 and 7.00+/-0.27 with MGRE and LAVA pulse sequence, 3.62+/-0.13 and 2.60+/-0.23 in the hyper-plastic nodule, 1.70+/-0.09 and 2.60+/-0.23 in the meta, 2.12+/-0.28 and 5.86+/-0.28 in the FNH, 4.45+/-0.28 and 1.73+/-0.02 in the abscess and ANOVA test was used to evaluate the diagnostic performance of each disease (p<0.05). In conclusions, two techniques were well demonstrated with the relation of the detection and characterization of liver's diseases.

A Study on Compensation for Imaging Qualities Having Artifact with the Change of the Center Frequency Adjustment and Transmission Gain Values at 1.5 Tesla MRI / 의학물리

The purpose of this study is to compensate for susceptibility and a ferromagnetic body artifact using CFA and TGV on MR Imaging. A total of 30 patients (15 men and 15 women, mean age: 45 years) were performed on head and neck diseases. MR Unit used a 1.5T superconducting magnet (GE medical system, High Density). This study have investigated by changing with CFA and TGV (70, 90, 110, 130, 150) searching for compensation values about susceptibility and a ferromagnetic body artifact in 60 kg standards of body weight (p<0.05). As a quality results, Image qualities were obtained at different score from CFA and TGV (70, 90, 110, 130, 150=3.23+/-0.35, 4.31+/-0.02 4.23+/-0.21, 5.12+/-0.25, 7.13+/-0.72, 8.31+/-0.01, 5.21+/-0.15, 6.14+/-0.08, 5.23+/-0.72, 5.91+/-0.06, p<0.05). Absolute CNRs (TG, CNRpre, CNRpost) were acquired with (70:-1.44+/-0.11, -2.7+/-0.04, 90:-2.18+/-0.42, -4.41+/-0.43, 110:-2.89+/-0.43, -5.23+/-0.02, 130:-2.34+/-0.05, -5.26+/-0.01, 150: -2.09+/-0.08, -3.87+/-0.12, p<0.05). In conclusions, this study could be compensated for metal and flow artifacts surrounding the tissues having artifact by changing CFA and TGV.