CAJ | 학술논문

目的分析自适应统计迭代重建算法(ASIR)在腹部CT扫描中对图像质量的影响,探讨其降低辐射剂量的程度.方法利用Discovery CT 750 HD机型,分别在噪声指数(NI)和ASIR值为10和0(A组)、12和30％(B组)、13和40％(C组)、14和50％(D组)、15和60％(E组)、16和70％(F组)条件下对带有腹环的模体Catphan 500进行扫描,每组扫描3次,每次扫描选取6套图像,每组共18套图像.分析图像的空间分辨率、密度分辨率、CT值的准确性、噪声及辐射剂量.空间分辨率和辐射剂量直接进行比较,密度分辨率、噪声、CT值的准确性用单因素方差分析进行比较.结果对于空间分辨率,在标准算法下A～F组可分辨的线对数分别为6、6、6、6、6、5 lp/cm,刀锋算法下A～F组可分辨线对数分别为7、7、7、7、7、6 lp/cm.A～F组的噪声分别为(15.23 ±0.18)、(14.58±0.19)、(14.55 ±0.20)、(14.39±0.20)、(14.11±0.24)和(13.60±0.25) HU,组间差异具有统计学意义(F=118.330,P=0.001),密度分辨率的主观评分分别为(3.12±0.64)、(2.89 ±0.60)、(2.78±0.44)、(3.22±0.44)、(2.56±0.53)、(2.44±0.73)分,组间差异具有统计学意义(F=2.548,P=0.040).A～F组的CT容积剂量指数(CTDIvol)值分别为20.99、14.54、12.37、10.67、9.30、8.16 mGy.结论当NI≤15、ASIR≤60％时,腹部条件下扫描的图像质量没有明显变化,辐射剂量最多可降低约55.7％.当NI值、ASIR值进一步增高时,图像的空间分辨率下降,NI值等于15、ASIR等于60％组图像质量高于其余各组.
목적 분석자괄응통계질대중건산법(ASIR)재복부CT소묘중대도상질량적영향,탐토기강저복사제량적정도.방법 이용Discovery CT 750 HD궤형,분별재조성지수(NI)화ASIR치위10화0(A조)、12화30％(B조)、13화40％(C조)、14화50％(D조)、15화60％(E조)、16화70％(F조)조건하대대유복배적모체Catphan 500진행소묘,매조소묘3차,매차소묘선취6투도상,매조공18투도상.분석도상적공간분변솔、밀도분변솔、CT치적준학성、조성급복사제량.공간분변솔화복사제량직접진행비교,밀도분변솔、조성、CT치적준학성용단인소방차분석진행비교.결과 대우공간분변솔,재표준산법하A～F조가분변적선대수분별위6、6、6、6、6、5 lp/cm,도봉산법하A～F조가분변선대수분별위7、7、7、7、7、6 lp/cm.A～F조적조성분별위(15.23 ±0.18)、(14.58±0.19)、(14.55 ±0.20)、(14.39±0.20)、(14.11±0.24)화(13.60±0.25) HU,조간차이구유통계학의의(F=118.330,P=0.001),밀도분변솔적주관평분분별위(3.12±0.64)、(2.89 ±0.60)、(2.78±0.44)、(3.22±0.44)、(2.56±0.53)、(2.44±0.73)분,조간차이구유통계학의의(F=2.548,P=0.040).A～F조적CT용적제량지수(CTDIvol)치분별위20.99、14.54、12.37、10.67、9.30、8.16 mGy.결론 당NI≤15、ASIR≤60％시,복부조건하소묘적도상질량몰유명현변화,복사제량최다가강저약55.7％.당NI치、ASIR치진일보증고시,도상적공간분변솔하강,NI치등우15、ASIR등우60％조도상질량고우기여각조.
Objective To investigate the effect of adaptive statistical iterative reconstruction (ASIR) on the image quality and radiation dose reduction for abdominal computed tomography (CT) at different noise index (NI) values and ASIR values.Methods The phantom Catphan 500 matched with abdominal ring was scanned by the abdominal CT protocol when NI and ASIR values were 10 and 0 (group A),12 and 30％ (group B),13 and 40％ (group C),14 and 50％ (group D),15 and 60％ (group E),16and 70％ (group F)respectively on the Discovery CT750 HD.The phantom was scanned 3 times repeatedly and 6 set of images were obtained each time,so each group contained 18 set of images.Image spatial resolution and radiation dose were compared directly,and image density resolution,image noise,accuracy of CT values were compared with ANOVA.Results For image spatial resolution,the line pair per centimeter that can be distinguished from group A to group F were 6,6,6,6,6 and 5 lp/cm for images reconstructed with " standard" kernel,which were 7,7,7,7,7 and 6 lp/cm for images reconstructed with " edge"kernel.The difference of objective noise and their deviations [(15.23 ± 0.18),(14.58 ± 0.19),(14.55 ±0.20),(14.39 ± 0.20),(14.11 ± 0.24),(13.60 ± 0.25) HU] and the subjective quality scores (SQS)[(3.12±0.64),(2.89±0.60),(2.78 ±0.44),(3.22±0.44),(2.56±0.53),(2.44±0.73)] for image density resolution from group A to group F were statistically significant (Fnoise =118.330,FSQS =2.548,P ＜ 0.05).The CTDIvol from group A to group F were 20.99,14.54,12.37,10.67,9.30 and 8.16 mGy.Conclusion When NI≤ 15 and ASIR≤ 60％,the image quality can be maintained with 55.7％of radiation dose reduction at most,but the image spatial resolution becomes lower as the values of NI and ASIR become greater.The image quality at NI equal to 15 and the ASIR equal to 60％ is better than any other groups.