ABSTRACT
Objective To investigate the methods of reducing radiation dose in CT coronary angiography through optimizing individualized scan dosage protocol.Methods Two hundred patients (group A)underwent coronary CTA examination which was performed with fixed 120 kV and variable mA according to their BMI.The mA was set as 150-300 mA(BMI ＜ 18.5 kg/m2),300-500 mA (18.5 kg/m2 ≤ BMI ＜ 25.0 kg/m2),and 500-800 mA(BMI ≥ 25.0 kg/m2).When all examinations were finished,a linear regression was employed to analyze the correlation between mA and BMI,body surface(Suf),image noise(SD)respectively.The results of the analysis were used to formulate a regression equation,which was further used to establish a table list for quick search on how much mA that individualized coronary CTA scan would need.Another 200 patients(group B)enrolled for the individualized scan were scanned under new protocol that previous study established.The tube voltage was 100 and 120 kV.The tube current was variable according to the data in the table list.One-way ANOVA and Kruskal-wallis H test were used for statistics.Results Regression equation between mA and BMI,Suf,SD was:mA =17.984 × BMI + 169.149 × Suf-2.282 × SD-361.039.The SD(group A:32.08 ± 5.80,group B:28.60±4.47),dose index volume(CTDIvol)[group A:(41.97 ± 11.37)mGy,group B:(33.18±10.07)mGy],effective dose(ED)[group A:(10.91 ±3.07)mSy,group B:(8.83 ±2.72)mSv]had significant differences between the two groups(F =43.45,63.71,49.07 respectively,P ＜0.01 for all).The SD and ED results obtained in group B were better than those in group A.Conclusion Better performances were obtained when BMI combined Suf was used as a new individualized protocol than when BMI was used only,which means good image quality and lower radiation dosage in coronary CTA examination.
ABSTRACT
Objective To evaluate the therapeutic effects and pathologic changes of VX2 liver tumor in rabbits treated with CT-guided percutaneous ethanol injection (PEI) with different concentration. Methods Thirty-two New Zealand rabbits with VX2 liver tumor were randomly divided into 4 groups (each n=8), i.e. anhydrous ethanol, 75% ethanol, 50% ethanol and control group (administrated physiological saline). Tumor size, imaging and pothologic changes were observed 7 d, 14 d, 21 d and 60 d after PEI. Results The volume was (4.68±5.05) cm~3 in anhydrous ethanol group, (6.33±6.59) cm~3 in 75% ethanol group, (17.54±5.06) cm~3 in 50% ethanol group and (16.87±5.27) cm~3 in control group 21 d after PEI. Tumor size in control group was larger than that in 75% ethanol group (t=6.32, P＜0.05) and anhydrous ethanol group (t=6.74, P＜0.05), in 50% ethanol group was larger than that in 75% ethanol group (t=4.99, P＜0.05) and anhydrous ethanol group (t=12.77, P＜0.05). No difference of tumor size was found between 50% ethanol group and control group, nor between 75% ethanol group and anhydrous ethanol group. ALT and AST both increased in all groups 1 d after PEI and returned to normal 7 d later except anhydrous ethanol group. ALT and AST in anhydrous ethanol group were higher than those in other groups (t=4.10, 4.49, 3.06, 5.79, 5.91, 4.11, all P＜0.05), and no difference of ALT and AST was detected between other groups. Area of coagulation necrosis enlarged with the increase of ethanol concentration. Conclusion Anhydrous ethanol and 75% ethanol both have obvious inhibition function to the rabbit VX2 tumor, while 75% ethanol has little damage to the liver function and is suitable for PEI.