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Objective To evaluate and compare the radiation dose and image quality of the new generation of whole body mobile CT (BodyTom CT) with commonly used fixed CT.Methods The image quality was evaluated with CATPHAN 500 performance test body model.The radiation dose was measured by conventional 100 mm pen ionization chamber and PMMA body phantom and head phantom (head diameter 160 mm,phantom diameter 320 rm and width 140 mm).Results The spatial and contrast resolution of BodyTom CT images were similar to two kinds of fixed CT(P ＞ 0.05).The CNR of image with BodyTom CT decreased by about 20％:In head scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-4.82,-6.98,P ＜ 0.05;with standard,t =-20.60,-20.09,P ＜0.05);in body scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-5.67,-12.82,P ＜ 0.05;with standard,t =-3.39,-9.18,P ＜ 0.05;with sharp,t =-3.88,-3.21,P ＜0.05).The radiation dose with BodyTom CT was significantly higher than that with fixed CT:in body model,22.97％ than that with Philps 64(t=9.48,P＜0.05),29.6％ than that with Toshiba 320 slice CT(t =11.66,P ＜0.05);in head model,29.76％ than that with Philps 64 slice CT(t=23.44,P＜0.05),33.22％ than that with Toshiba 320 slice CT(t=23.11,P＜0.05).Conclusions The radiation dose with mobile CT was over 20％ higher than that with routine multi-row CT while with the similar image quality.
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Objective:To explore optimized scheme of digital radiography (DR) image quality through applied image enhancement technique to process the low-dose radiographic images.Methods: The five informations of tissue structure with clinical significance in chest image were selected as reference points, and they were relatively measured with setting lesion information. Three enhanced techniques included of grey level transformation, smoothly denoising and sharpening were applied to process low dose photographic image. The objective and subjective evaluations were applied to compare the reference image and post-processed image, and the difference and relative analysis between them were applied to obtain statistical results.Results: All of the three enhancement processing techniques can effectively enhance the contrast noise ratio of images. Therefore, the low-dose photographic image that was comprehensive optimized could satisfy the requirement of clinical diagnosis, and the higher consistency between them and reference images was significant (r=0.943,P<0.05). On the aspect of difference, the difference between original image and reference image was significant (Z=-2.21359,P<0.05). While after comprehensive optimization, the difference between them was no significant. On the other hand, the difference of correlation between the two kinds of images was significant (r=0.871, P<0.05).Conclusion:The image enhancement processing technique can effectively improve the deficiency of low-dose photographic image, and enhance image quality, and reduce radiation dose of clinical patients. Therefore, it has higher value in clinical practice.
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Objective To explore the application value of optimal energy imaging technique of monoenergetic dual-energy computed tomography (DECT) in feeding arteries examination of rectal cancer.Methods The clinical data of 33 patients with rectal cancer who were admitted to the First Affiliated Hospital of Dalian Medical University from July 2012 to July 2014 were analyzed retrospectively.The polychromatic and monochromatic images of feeding arteries of tumors were reconstructed and evaluated using a subjective image quality score of 5-point scale by 2 observers.The consistency and scores of evaluation were analyzed by the κ test and MannWhitney U test.The CT value of feeding arteries of tumors and hip muscle,image noise and contrast to noise ratio (CNR) were measured and calculated by 2 observers,and were compared by the independent sample t test.The consistency of data between the 2 observers were measured by the intra-class correlation coefficients (ICC).Results Inferior mesenteric arteries were contributor of blood supply of tumors in all the 33 patients,including 4 cases with right inferior rectal artery as contributor of blood supply of tumors,2 cases with bilateral inferior rectal artery.Among patients with abnormal blood vessels,there were 8 patients with left colic artery and sigmoid artery having common trunk,4 patients with left colic artery originated from Inferior mesenteric artery,1 patient with absence of left colic artery.The 0-,1-,2-,3-,4-score polychromatic image quality of feeding arteries of tumors were detected in 0,13,13,5,2 patients and 0,11,14,6,2 patients by 2 observers,respectively.The 0-,1-,2-,3-,4-score monochromatic image quality of feeding arteries of tumors were detected in 0,0,7,7,19 patients and 0,0,6,9,18 patients by 2 observers,respectively.Good interobserver agreement was found for the evaluation of subjective scores (κ =0.864,0.897).The subjective scores of image quality of feeding arteries in the polychromatic images and in the monochromatic images were 1.9 ± 0.9 and 3.4 ± 0.8,with significant difference (Z =-5.21,P ＜ 0.05).The latter was superior to the former.The ICC values of the CT values of feeding arteries of tumor,hip muscle,image noise and CNR were 0.953,0.907,0.839,0.964 and 0.966,0.933,0.952,0.962 from the 2 observers,with a good consistency.The CT values of feeding arteries of tumor,gluteal muscles,image noise and CNR in the polychromatic images and in the monochromatic images were (234 ± 52)HU and (412±83)HU,(57±9)HU and (71 ±15)HU,(21 ±3)HU and (31 ±6)HU,9 ±3 and 11 ±4,respectively,with significant differences (t =-18.65,-4.44,-14.14,-6.55,P ＜ 0.05).The levels of monochromatic images of 33 patients were 51-61 keV,with a median of 55 keV.Conclusion The optimal energy imaging technique of monoenergetic DECT can improve the angiographic quality of feeding arteries in patients with rectal cancer.
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Objective To evaluate the difference of image quality and lesion detection between Gd+-EOB-DTPA with Gd+-DTPA-enhanced MRI in cases of hepatocellular carcinoma (HCC).Methods A total of 21 HCC patients underwent both Gd+-EOB-DTPA and Gd+-DTPA-enhanced MRI examination,comparing the difference between the two agents using the value of lesion display quality index,sensitivity,specificity,positive and negative predictive value,diagnosis accuracy and CNR.Results There were 25 lesions on the 21 HCC patients with 9 lesions ＜ 1.0 cm.24 lesions showed hypointensity and 1 lesion showed isointensity on hepatobiliary phase with Gd+-EOB-DTPA-enhanced MRI.15 lesions showed hypointensity,5 lesions showed isointensity and 5 lesions showed hyperintensity on portal venous phase with Gd+-DTPA-enhanced MRI.The value of lesion (in particular for the lesion ＜ 1.0 cm)display quality index,sensitivity,specificity,positive and negative predictive value,diagnosis accuracy on Gd+-EOB-DTPA-enhanced MRI and Gd+-DTPA-enhanced MRI were 17scors,89％,89％,89％,89％ and 12 scors,33％,33％,33％,67％ respectively.CNR on hepatobiliary phase with Gd+-EOB-DTPA-enhanced MRI was 639.35.CNR on arterial phase and portal venous phase with Gd+-DTPA-enhanced MRI were 225.25 and 93.25 respectively.The data showed that Gd+-EOB-DTPA-enhanced MRI was better than that of Gd+-DTPA-enhanced MRI.Conclusions Gd+-EOB-DTPA-enhanced MRI displays lesions (especially for lesions ＜ 1.0 cm) better compared with Gd+-DTPA-enhanced MRI increasing the diagnostic accuracy of small HCC.
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Objective To evaluate the feasibility of automatic tube current modulation(ATCM) in craniocervical artery CT angiography with 256-slice CT,while maintaining the image quality.Methods Sixty patients undergoing craniocervical artery CTA were enrolled into this study,and were divided into conventional tube current group(250 mAs,group A,n=30) and low tube current group(ATCM,group B,n=30).The signal-to-noise ratio(SNR),contrast-to noise ratio(CNR),volume CT dose index(CTDIvol) and effective dose(ED) were evaluated respectively.Results The mean image SNR was(37.47?9.39) and(36.85?7.96) for group A and group B respectively,and was not significantly different(P=0.79).The mean image CNR was(32.13?9.06) and(31.86?7.66) for group A and group B respectively,and was not significantly different(P=0.90).The CT volume dose index(CTDI) was 16.5 mGy and 410.55?0.94mGy for group A and group B respectively,and was significantly different(P