XVI锥形束CT辐射剂量与扫描参数相关性建模

目的 定量研究不同扫描参数组合导致的医科达XVI锥形束CT辐射剂量变化,为评估影像引导放疗中成像剂量的参数依赖性提供数学模型。方法 基于Versa HD加速器XVI,利用PTW 30 009千伏电离室和UNIDOS webline静电计,在PTW标准CT剂量指数（CTDI）体部模体中,测量标准扫描参数及多种扫描电压（kVp）、管电流（mA）组合下的模体内各点比释动能,并计算加权CTDI_w。利用SigmaPlot 10.0软件将测量结果拟合为以管电流和/或扫描电压为变量的模型。结果 标准扫描参数下,瓦里安OBI锥形束CT的CTDI_w值仅为医科达XVI的11.23%（胸部参数）和9.15%（盆腔参数）。在标准及其余4个扫描电压条件下,模体中心和外周各点比释动能与管电流均呈现线性正比关系,但斜率a值差异较大（0.479~6.679）,主要受扫描电压值、模体测量位置、剂量描述方法等因素影响。模体内各点剂量和CTDI_w值均可拟合为以扫描电压为变量的非线性经验公式（R²>0.997）,各系数差异有统计学意义（P<0.05）。同时改变管电流和扫描电压对模体中心点剂量的影响可以表述为mGy=（5.917-0.197×kVp+0.002×kVp²-5.063×10^-6×kVp³）×mA。结论 医科达XVI锥形束CT剂量显著依赖于扫描参数,数学模型可用于快速准确描述其变化特征。     

5岁儿童仿真模体千伏锥束CT模拟剂量测量

目的 利用热释光探测器（TLD）在CIRS 5岁仿真儿童模体内测量瓦里安千伏锥束CT（kV-CBCT）标准扫描参数下各重要器官剂量,并以此计算有效剂量。方法 挑选一致性在2%以内的TLD并退火。首先基于相同骨盆扫描模式分别用CT电离室和TLD测量CIRS骨盆仿真模体相同体积内的剂量和读数,二者比值即为TLD转换系数;将夹在组织等效插件中的TLD放入儿童模体器官内预留的插孔,在头部、胸部和骨盆3种标准扫描条件模式下,测量器官剂量,并计算有效剂量。结果 TLD转换系数是3.91 mGy/每读数;在头部、胸部和骨盆3种标准扫描条件下,得出全身有效剂量分别是0.63、6.85和19.3 mSv。结论 用CT电离室刻度过的TLD测量kV-CBCT给儿童仿真模体带来的辐射剂量的方法具有可行性。本研究中骨盆扫描条件的有效剂量高于胸部和头部,即该条件预期产生的辐射危害较大,诱发继发性癌症风险较高。     

千伏锥形束CT引导放疗系统最小误差与剩余误差分析

目的 分析千伏锥形束CT(kVCBCT)引导放疗系统可以发现的最小摆位误差和校正后剩余摆位误差。方法 采用小球(ball-bearing,BB)体模,比较经kVCBCT引导放疗系统得到的位移值与设定的位移值。设定的位移值分别为0.5、1.0、1.5和2.0 mm。侧向、纵向和垂直3个方向上的位移值均每日分析1次,共分析5次。校正后剩余摆位误差分析,采用CIRS Model 002LFC胸部体模,在侧向、纵向和垂直3个方向上均设置摆位误差,设置的数值为0、±5、±10和±15 mm。采用点标记法,共同配准体模的定位CT影像与kVCBCT影像,得出侧向、纵向和垂直3个方向上的摆位误差。根据配准结果移动治疗床,至侧向、纵向和垂直3个方向上摆位误差减少到最小。对校正位置后的体模再次行kVCBCT扫描,将再次获得的kVCBCT影像与定位CT采用点标记法配准,得到的侧向、纵向和垂直3个方向上的数值为经kVCBCT系统引导后剩余摆位误差。每日分析1次,共分析7次。结果 kVCBCT引导放疗系统可以发现的误差至少为0.5 mm。侧向、纵向和垂直3个方向上引导后剩余误差分别为(0.2±0.4)、(0.1±0.4)和(-0.4±0.3)mm,对3组数值行方差分析进行两两比较:侧向和纵向剩余误差无差别(P=0.63),垂直向和侧向剩余摆位误差的差异具有统计学意义(P=0.01),垂直向和纵向剩余摆位误差差异具有统计学意义(P=0.02)。结论 建立了kVCBCT引导放疗系统可以发现最小摆位误差和校正后剩余摆位误差的分析方法,kVCBCT引导放疗系统可以发现的误差至少为0.5 mm,侧向、纵向和垂直3个方向上引导后剩余误差约为1 mm。     

双能锥形束CT的分解算法和成像物体尺寸依赖性研究

目的:分析"直接分解"和"迭代分解"两种双能锥束CT(DECBCT)分解算法对于不同尺寸模体图像质量和物质分解精度的影响。方法:利用CatPhan604模体和定制套环组合,模拟不同尺寸的患者成像部位,在Edge加速器锥形束CT(CBCT)系统上分别获取高能140 kVp和低能100 kVp的CBCT,并分别利用两种算法...     

锥形束CT和多层螺旋CT对寰枢椎成像的辐射剂量和图像质量差异研究

目的比较锥形束CT(CBCT)和多层螺旋CT(MSCT)应用于寰枢椎成像的检查剂量和成像质量的差异。方法使用普兰梅卡CBCT扫描仪的30种曝光条件和东芝320排MSCT的15种曝光条件对头颈部体模进行扫描。基于蒙特卡罗算法剂量评价软件PCXMC计算CBCT的有效剂量(E);以剂量长度乘积(DLP)乘以成人颈部特异性转换系数得到MSCT的E值。两独立样本的t检验或Wilcoxon秩和检验用于比较两种成像方式的辐射剂量和主、客观图像质量。采用双盲法对图像的边缘清晰度、对比度、软组织层次、伪影进行5分制主观评分,测量感兴趣区(ROI)的信号与噪声,计算对比信噪比(CNR)。结果 CBCT容积剂量指数、E值分别为2.9 mGy、27.61 μSv,均低于MSCT的8.8 mGy、433.16 μSv,差异有统计学意义(z=-3.05、-5.25,P<0.05);CBCT组的噪声和CNR分别为27.74 HU和3.69,MSCT组为7.84 HU和27.1,差异有统计学意义(z=-5.39、-5.42,P<0.05);CBCT组的总体图像质量、对比度、伪影评分分别为3.5、3.0、5分,均高于MSCT组2.0、2.0、4.0分,差异有统计学意义(z=-2.32、-2.46、-3.31,P<0.05)。结论寰枢椎CBCT和MSCT扫描均可获得满足诊断要求的图像质量,与MSCT相比,CBCT寰枢椎扫描有效地降低了辐射剂量,符合辐射防护最优化原则。     

Implagraphy牙颌面锥形束CT不同扫描体位的辐射剂量对比研究

目的 测算Implagraphy牙颌面锥形束CT(CBCT)体模不同扫描体位的组织器官吸收剂量、当量剂量及有效剂量,为相应的防护措施提供客观依据。方法 使用仿真成年男性头颈部体模及热释光剂量计,分别测量Implagraphy CBCT下颌、上颌及颞下颌关节(TMJ)扫描时脑垂体、眼晶状体、腮腺、颌下腺、舌下腺、颅骨板障、下颌松质骨、颈椎松质骨、颊部皮肤、颈部皮肤、甲状腺、食管及口腔黏膜等组织器官的吸收剂量,计算眼晶状体、皮肤的当量剂量,及Implagraphy CBCT不同扫描体位的有效剂量E₁₉₉₀及E₂₀₀₇。结果 Implagraphy CBCT各扫描体位的吸收剂量分别为:下颌扫描(0.99±0.09)~(12.85±0.09)mGy,上颌扫描(0.93±0.01)~(13.07±0.02)mGy,TMJ扫描(0.68±0.01)~(10.18±0.04)mGy,相同组织器官在不同扫描体位的吸收剂量的差异具有统计学意义(F=19.61~30992.27,P<0.05)。在不同扫描体位,眼晶状体及皮肤的当量剂量分别为(1.11±0.07)~(5.76±0.06)mSv和(6.96±0.06)~(10.64±0.07)mSv,差异具有统计学意义(F=4473.02、9385.50,P<0.05)。有效剂量E₁₉₉₀及E₂₀₀₇分别为:下颌扫描(191.35±1.53)和(325.17±2.58)μSv,上颌扫描(106.62±2.17)和(226.28±2.81)μSv,TMJ扫描(104.21±1.02)和(142.36±1.90)μSv。结论 在牙颌面CBCT检查过程中,采用尽可能小的扫描视野、准确地扫描体位,正确使用铅胶帽、围领及防护镜等屏蔽措施,使X射线辐射照射保持在可以合理达到的尽可能低的水平。     

锥形束CT在放疗中的应用

锥形束CT是图像引导放疗的重要工具,在放疗过程中可测量和修正摆位误差、计算肿瘤靶区外扩范围,在通过校正后还可进行剂量计算验证。但锥形束CT在使用过程中需要提高图像质量,并在图像采集过程中控制辐射剂量,采用最佳的配准方式以达到图像引导和剂量引导双重功能。本文重点介绍了锥形束CT的成像系统、临床应用和目前存在的问题。     

加速器机载kV锥形束CT有效剂量的分析

目的 分析医用直线加速器机载kV锥形束CT扫描过程中患者的有效剂量随扫描条件的变化。方法 用PTW TM30009电离室分别在T40017头模和T40016躯干模体中,改变XVI锥形束CT的管电压、毫安秒、准直器以及机架旋转范围等参数测量加权CT剂量指数,计算相应的剂量长度乘积和有效剂量。结果 kV锥形束CT的加权剂量指数和有效剂量随管电压呈二次方变化,随毫安秒线性变化,与准直器以及机架旋转范围密切相关。临床常用条件下,kV锥形束CT单次扫描的剂量长度乘积和有效剂量低于参考剂量水平。结论 锥形束CT扫描过程中患者接受的有效剂量与扫描条件密切相关。锥形束CT扫描时,应该根据患者的解剖部位合理选择成像参数,最大限度减少患者接受剂量。     

基于U-Net模型从低能锥形束CT图像实现高能成像的研究

目的基于U-Net网络深度学习的方法, 实现在放疗临床中低能锥形束CT(CBCT)图像转换成高能CBCT图像, 以期提供双能CBCT成像图像基础且降低辐射剂量。方法利用放疗机载CBCT设备采集CIRS电子密度模体和CIRS头部体模在80和140 kV能量下的CBCT图像数据, 数据集按10∶1分为训练集和测试集。利用U-Net网络从低能量(80 kV)CBCT图像预测高能量(140 kV)下CBCT图像。采用平均绝对误差(MAE)、结构相似度指数(SSIM)、信噪比(SNR)和峰值信号噪声比(PSNR)4种度量指标, 定量评价预测高能CBCT图像。结果预测高能图像与真实高能图像之间总体结构差异较小(SSIM:0.993 ±0.003)。预测高能图像噪声较低(SNR:15.33±4.06), 但组织间分辨力有损失。预测高能图像比真实高能图像平均CT值偏低, 在低密度组织中差异较小(<10 HU, P > 0.05), 而在高密度组织中差异大(< 21 HU, t = -7.92, P < 0.05)。结论利用深度学习方法可以从低能CBCT图像获得结构相似度高的高能...     

基于锥形束CT的头颈部肿瘤在线与离线结合图像引导放疗的研究

目的 分析锥形束CT(CBCT)在线摆位校正与离线自适应校正在减小头颈部肿瘤临床靶区(CTV)外放,从而减轻正常组织并发症中的作用。方法 16例行三维适形放疗的头颈部癌症患者入组。分次放疗前后均行在线CBCT扫描1次,并与计划CT图像配准,记录各个方向的配准差值。放疗前后的配准差值分别作为放疗分次间误差和分次内误差,用于计算每例患者的系统误差和随机误差。利用CTV外放计算公式,计算在线校正前后CTV外放;以0.5 mm为允许的最大残余系统误差,计算离线校正系统摆位误差后CTV外放。结果 未经在线校正,左右、头脚和前后方向上群体化CTV外放分别为5.7 mm、5.6 mm和7.3 mm;每分次放疗均行在线校正,3个方向上群体化CTV外放分别为1.7 mm、1.7 mm和2.3 mm;对系统摆位误差进行离线自适应校正,3个方向上群体化CTV外放分别为2.7 mm、2.5 mm和3.6 mm。结论 基于CBCT图像分析的在线校正和离线自适应校正均能明显减小摆位误差,有助于缩小CTV外放,并有望减轻正常组织并发症。     

胸部能谱成像模式与常规CT扫描的辐射剂量及图像质量的仿真体模研究

目的 通过仿真胸部体模研究胸部能谱CT不同方案成像模式与常规胸部CT扫描的辐射剂量、图像质量、对比噪声比及主观评分对比,获得最佳能谱扫描参数。方法 对仿真胸部体模分别进行常规胸部CT扫描以及3种不同扫描方式的能谱CT成像。3种能谱模式为宝石能谱CT （GSI）Assist模式（方案A）、管电流平均值时的GSI模式（方案B）及管电流最大值时的GSI模式（方案C）。所有扫描方式分别在噪声指数（NI）=9和11时,螺距0.984∶1,依次扫描。记录辐射剂量,同时测量感兴趣区（ROIs）5个不同层面水平的脂肪和肌肉组织的图像噪声值（SD）以评价图像质量。所有扫描序列由两位资深放射医师对肺窗肺纹理及分支5分制主观评分。结果 NI=9和11时,常规CT平扫与方案A、B、C的有效剂量（E）值分别为（8.0、8.5、6.2、10.4）和（5.3、5.1、4.3、6.2）mSv。NI=9时,常规胸部CT平扫与方案A、C的SD值差异有统计学意义（F=4.496,P<0.05）;NI=11时,方案A、B、C与常规胸部CT平扫SD值差异有统计学意义（F=8.425,P<0.05）;常规胸部CT扫描中,NI分别为9和11时SD值差异有统计学意义（t=－2.570,P<0.05）;在相同能谱扫描模式中,NI不同,SD值差异均无统计学意义（P>0.05）。NI相同扫描模式不同及扫描模式相同NI不同时,CNR及主观评分差异均无统计学意义（P>0.05）。结论 合理的能谱扫描模式与常规扫描的辐射剂量没有明显差异,但能谱扫描模式可以获得较高的图像质量。此外,选择合适的噪声指数在图像质量相仿的同时可以明显降低辐射剂量。综合辐射剂量及图像质量,能谱CT智能模式可以达到辐射剂量及图像质量的双向平衡。     

双源双能量CT肺动脉成像辐射剂量与图像质量的比较研究

_目的：比较第一代双源双能量 CT（DECT）与第二代双源双能量 CT 肺动脉成像（CTPA）的辐射剂量和图像质量。方法：120例疑似肺栓塞患者行 DE-CTPA 检查,其中40例患者行第二代双源 DECT 80/Sn140 kV 检查（第一组）,40例患者行第二代双源 DECT 100/Sn140 kV 检查（第二组）,40例患者行第一代双源 DECT 140/80 kV 检查（第三组）。测量每例患者肺动脉主干、肺动脉段、空气及背部脂肪的 CT 值及标准差,对肺动脉图像进行主观评分,计算图像信噪比（SNR）、对比噪声比（CNR）及每例患者的有效剂量（ED）。结果：第一组肺动脉平均 CT 值[（354．1±73．4）HU]明显高于第二组[（290．1±73．1）HU,P＜0．001]和第三组[（303．9±73．3）HU,P＜0．001],但第二组与第三组差异无统计学意义（P＝0．399）;第三组平均 SNR（24．8±8．4）低于第一组（40．4±12．9,P＜0．001）和第二组（44．6±12．9,P＜0．001）,但第一组与第二组差异无统计学意义（P＝0．115）。第一组平均 CNR（435．3±77．7）明显高于第二组（355．8±77．8,P＜0．001）和第三组（384．8±79．0,P＝0．005）,但第二组与第三组差异无统计学意义（P＝0．100）。三组图像主观质量评分差异无统计学意义（P＞0．05）。第一组的 ED[（1．2±0．3）mSv]明显低于第二组[（2．4±0．7）mSv]和第三组[（3．0±0．7）mSv],差异均有统计学意义（P＜0．05）。结论：第二代双源 DECT 80/Sn140 kV 扫描方案可在大幅度降低辐射剂量的同时获得满足诊断需求的图像。     

A pragmatic approach to determine the optimal kVp in cone beam CT: balancing contrast-to-noise ratio and radiation dose

Objectives:

To determine the optimal kVp setting for a particular cone beam CT (CBCT) device by maximizing technical image quality at a fixed radiation dose.

Methods:

The 3D Accuitomo 170 (J. Morita Mfg. Corp., Kyoto, Japan) CBCT was used. The radiation dose as a function of kVp was measured in a cylindrical polymethyl methacrylate (PMMA) phantom using a small-volume ion chamber. Contrast-to-noise ratio (CNR) was measured using a PMMA phantom containing four materials (air, aluminium, polytetrafluoroethylene and low-density polyethylene), which was scanned using 180 combinations of kVp/mA, ranging from 60/1 to 90/8. The CNR was measured for each material using PMMA as background material. The pure effect of kVp and mAs on the CNR values was analysed. Using a polynomial fit for CNR as a function of mA for each kVp value, the optimal kVp was determined at five dose levels.

Results:

Absorbed doses ranged between 0.034 mGy mAs⁻¹ (14 × 10 cm, 60 kVp) and 0.108 mGy mAs⁻¹ (14 × 10 cm, 90 kVp). The relation between kVp and dose was quasilinear (R² > 0.99). The effect of mA and kVp on CNR could be modelled using a second-degree polynomial. At a fixed dose, there was a tendency for higher CNR values at increasing kVp values, especially at low dose levels. A dose reduction through mA was more efficient than an equivalent reduction through kVp in terms of image quality deterioration.

Conclusions:

For the investigated CBCT model, the most optimal contrast at a fixed dose was found at the highest available kVp setting. There is great potential for dose reduction through mA with a minimal loss in image quality.     

Image quality assessment of three cone beam CT machines using the SEDENTEXCT CT phantom

Objectives:

The SEDENTEXCT Project proposed quality assurance (QA) methods and introduced a QA image quality phantom. A new prototype was recently introduced that may be improved according to previous reports. The purpose of this study is to evaluate image quality in various protocols of three cone beam CT (CBCT) machines using the proposed QA phantom.

Methods:

Using three CBCT machines, nine image quality parameters, including image homogeneity (noise), uniformity, geometrical distortion, pixel intensity value, contrast resolution, spatial resolution [line pair (LP) chart, point spread function (PSF) and modulation transfer function (MTF)] and metal artefacts, were evaluated using a QA phantom proposed by SEDENTEXCT. Exposure parameters, slice thickness and field of view position changed variously, and the number of total protocols was 22.

Results:

Many protocols showed a uniform gray value distribution except in the minimum slice thickness image acquired using 3D Accuitomo 80 (Morita, Kyoto, Japan) and Veraviewepocs 3Df (Morita). Noise levels differed among the protocols. There was no geometric distortion, and the pixel intensity values were correlated with the CT value. Low contrast resolution differed among the protocols, but high contrast resolution performed well in all. Many protocols showed that the maximum line pair was larger than 1 LP mm⁻¹ but smaller than 3 LP mm⁻¹. PSF and MTF did not correlate well with the pixel size. The measured metal artefact areas varied for each device.

Conclusions:

We studied the image quality of three CBCT machines using the SEDENTEXCT phantom. Image quality varied with exposure protocols and machines.     

Effective doses from panoramic radiography and CBCT (cone beam CT) using dose area product (DAP) in dentistry

Objectives:

We compared the effective dose from panoramic radiography with that from cone beam CT (CBCT) using dose area product under adult and child exposure conditions.

Methods:

The effective doses of the cephalo, panorama, implant and dental modes of Alphard 3030 (Asahi Roentgen Ind., Co. Ltd, Kyoto, Japan) CBCT and the Jaw, Wide, Facial and temporomandibular joint modes of Rayscan Symphony (RAY Co., Ltd, Hwaseong, Republic of Korea) CBCT were compared with those of CRANEX^® 3+ CEPH (Soredex Orion Corporation, Helsinki, Finland) panoramic radiography equipment under adult and child exposure conditions. Each effective dose was calculated using a conversion formula from dose area product meter measured values (VacuTec Messtechnik GmbH, Dresden, Germany). The conversion formulae used were suggested by Helmrot and Alm Carlsson and Batista et al, and they were applied with the tube voltage taken into consideration.

Results:

The maximum effective doses from the Alphard 3030 and Rayscan Symphony were 67 and 21 times greater than that from panoramic radiography, respectively. The ratios of the effective dose under the child setting to that under the adult condition were 0.60–0.62 and 0.84–0.95, and the maximum differences in effective doses between the adult and child exposure settings were equivalent to 27 and 4 times greater than a panoramic examination in the Alphard 3030 and Rayscan Symphony, respectively.

Conclusions:

The effective CBCT doses were higher than those of panoramic radiography. The differences in effective doses between the adult and child CBCT settings were dependent on equipment type and exposure parameters. Therefore, adequate mode selection and control of exposure as well as further research are necessary to minimize the effective dose to patients, especially for radiosensitive children.     

An assessment of Sri Lankan radiographer's knowledge and awareness of radiation protection and imaging parameters related to patient dose and image quality in computed tomography (CT)

IntroductionAs computed tomography (CT) examinations have considerably risen, safe operation is essential to reduce the patients’ dose. The main objective of this study was to evaluate the level of knowledge and awareness regarding the CT exposure parameters and radiation protection in CT imaging among Sri Lankan radiographers.MethodsAn online survey-based study was devised and distributed among the Sri Lankan CT radiographers working in 63 CT units. Questions were divided into three subsections that collected data on the participants’ demographic features, knowledge of the radiation protection, and imaging parameters.ResultsEighty-eight radiographers from 32 CT units (out of 63 CT units) distributed across 11 districts (out of 27 districts) participated in this survey.The percentages of correct responses for the questions related to radiation protection, imaging parameters, noise, Diagnostic Reference Level (DRL), and CT dosimetric parameters were 71%, 79%, 87%, 50%, and 66%, respectively. Although the years of experience did not influence any of above aspects, the level of education significantly impacted the knowledge about radiation protection, exposure parameters, and noise.ConclusionThe radiographer's knowledge of radiation protection and most imaging parameters associated with patient safety and image quality is satisfactory. However, findings also show that participants should fill the knowledge gap in radiation-related risks, CT exposure parameters, dosimetric parameters, and DRL.Implications for practiceThe study suggests the necessity of initiating continuous education programs for radiographers in line with national radiation protection legislation requirements that can be linked with code of practice.     

Comparison of radiation dose,contrast enhancement and image quality of prospective ECG-Gated CT coronary angiography: Single versus dual source CT

IntroductionThe updated National Institute of Clinical Excellence (NICE) guidelines of 2017 state that new generation cardiac CT scanners (Aquilion ONE, Brilliance iCT, Discovery CT750 HD and Somatom Definition Flash) are recommended as an option for first-line imaging of the coronary arteries in people with suspected stable coronary artery disease (with an estimated likelihood of coronary artery disease of 10–29%) in whom imaging with earlier generation CT scanners is difficult. New generation cardiac CT scanners are also recommended as an option for first-line evaluation of disease progression, to establish need for revascularisation in people with known coronary artery disease in whom imaging with earlier generation CT scanners is difficult. CT scanning might not be necessary in situations in which immediate revascularisation is being considered. The European Society of Cardiology 2019 clinical practice guidelines recommend non-invasive functional imaging for myocardial ischaemia or coronary CT angiography (CTA) as the initial test to diagnose CAD in symptomatic patients in whom obstructive CAD cannot be excluded by clinical assessment alone. Given increased computed tomography coronary angiogram (CTCA) utilisation, radiation dose, contrast enhancement and image quality of prospective ECG-gated CTCA between 256-slice single-source and 192x2-slice dual-source CT scanners were retrospectively evaluated.MethodsProspectively gated CTCA data from 63 patients on a 256-slice CT (group A) and 71 patients on a 192x2-slice dual source CT (group B) from January to December 2016 were retrospectively evaluated respectively. Scanner-reported dose length product values were used with a conversion factor (k = 0.014 mSv/mGy x cm) to estimate effective dose. Contrast enhancement was assessed with mean CT attenuation at selected regions of interest on axial coronary images. Image quality of the coronary arteries was assessed by a 4-point grading score (1 = non-diagnostic, 4 = excellent image quality).ResultsThe radiation doses in group B were significantly lower than group A (3.68 + 2.13 mSv versus 4.81 + 1.56 mSv, p < 0.001). There were no significant differences in contrast enhancement in the left coronary artery, proximal right coronary artery and left ventricular wall for both groups. Vessel image quality scores for group B were higher than group A (right coronary artery (RCA): 3.2 + 0.7 versus 2.4 + 0.7, p < 0.001; left anterior descending (LAD) artery: 3.0 + 0.8 vs 2.5 + 0.6, p < 0.001; left circumflex (LCx) artery: 3.3 + 0.7 vs 2.6 + 0.6, p < 0.001). Coronary artery contour scores for group B were significantly higher than group A (RCA: 3.2 + 0.8 versus 2.3 + 0.7, p < 0.001; LAD: 3.0 + 0.7 versus 2.4 + 0.6, p < 0.001; LCx: 3.3 + 0.6 versus 2.5 + 0.6, p < 0.001).ConclusionProspective ECG-gated CTCA performed on 192x2-slice CT results in better image quality and lower radiation dose than 256-slice CT. There were no significant differences in contrast enhancement in left main coronary artery (LMCA), proximal RCA and left ventricular wall in both groups.Implications for practiceIn institutions with both 256-slice and 192x2-slice CT scanners, we recommend that CTCAs be preferentially performed using the 192x2-slice CT scanner.