The Applied Research Of ASIR Technique In Bladder Tumor Model With The Low-dose CT Scans

ObjectiveTo compare the quality and lesion conspicuity of images of bladder tumor model which acquired on computed tomography(CT) with standard-dose and low-dose with adaptive statistical iterative reconstruction(ASIR) and CT virtual cystoscopy(CTVC) imaging, evaluate the application of adaptive statistical iterative reconstruction technique for low dose CT of bladder tumors.Materials and methodsChoose a fresh porcine bladder, ligated 20 golds(1~10mm, ≤ 5mm13 golds, >5mm7 golds) to simulate bladder tumor, using high resolution CT(GE optima CT660) with different doses(120k Vp,20, 40, 60, 80, 100, 120, 140, 160, 180, 200 m As canning), and with 11 different levels of ASIR(0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%,90% and 100%) for data reconstruction, get the CTVC images. Get the objective and subjective evaluation of image collected in different conditions of different ASIR levels, measure and compare the average noise, the average signal-to-noise ratio(SNR) and the average contrast to noise ratio(CNR)and tumor detection rate.Results1.Image noise and CT value: in the tube current under certain circumstances, each image with the 80% level ASIR, the noise is decreased obviously. The noise of 100 m A-90%ASIR image with 200 m A-FBP image noise is similar, and the scanning dose reduction is about 50%. In addition, the technology of ASIR has no significant influencein the CT value of different tissues2.Image of SNR: in the same tube current, with the increase of ASIR levels, image SNR value increased gradually. Using 200 m A as aroutine dose of standard SNR, 60 m A-100%ASIR image and 200 m A-FBPimage are similar on the SNR, and the scanning dose reduction is about 67.4%.3.Image of CNR: in the same tube current, with the increase of ASIR level, image CNR value increased gradually. 100 m A-90%ASIR image CNR and 200 m A-FBP image are similar on the CNR, and the scanning dose reduction of about 50%.4.CTVC image of subjective score: more than 80 m A group along with the increase of ASIR level, the subjective image quality appeared slightly elevated, but when ASIR level increased more than 60%, there has been a slight decline in subjective image quality. 80 m A group of 20%-60%ASIRimage subjective score reached conventional dose FBP image reconstruction; when the tube current is 20 m A-60 m A,the subjective image quality score were lower than conventional dose image.5.Detection rate of the CTVC image on bladder tumor: in case the tube current is constant, the lesion detection rate dose not increase obviously with the increase of ASIR level.Conclusion1.In the scanning of the bladder tumor model, ASIR technology can reduce noise caused by m A reduction, while improving the signal to noise ratio of the image. ASIR technology can reduce half of the dose, while keeping the image quality same with the conventional dose levels, so ASIR technology can reduce the radiation dose that received by the patients.2.ASIR technique has no effect on the CT value of bladder tumor model images, and therefore does not affect the determination of the lesions.3. ASIR technique can improve the subjective image quality of bladder tumor model CTVC images, be more delicate, but a high level of ASIR will play the opposite effect.4. ASIR technique can improve the lesion detection rate of bladder tumor model CTVC images slightly, but has no significant meaning, and a further study is needed.