基于C型臂的Tomosynthesis快速重建方法

传统的层析X射线摄影合成(Tomosynthesis)算法不适合对C型臂X射线投影进行切片重建.提出了一种改进的Tomosynthesis算法CTS(C-arm based Tomosynthesis),依据C型臂成像原理,将不同角度的X射线投影按其映射关系在三维空间内旋转-叠加来重建切片.该算法可以对等中心C型臂连续采集的一组有限角度X射线投影进行切片重建.通过计算机模拟空心球和空心圆柱模型的C型臂X射线投影,用该算法对其二维投影进行切片重建,并利用重建结果分析了CTS算法的重建精度以及抗噪声干扰能力.最后给出了将CTS算法推广到可以对非等中心C型臂进行切片重建的步骤.CTS为基于C型臂的术中三维成像提供了一种参考方法.

基于tomosynthesis的图像重建方法

首先对tomosynthesis方法及其原理进行了分析 ,通过对tomosynthesis中各断层像和投影像间的关系方程组的变形 ,证明tomosynthesis与直接重建法 (ART)在本质上是相同的。tomosynthesis的重建过程的实质就是反投影重建法 ,是在有限角的情况下的不完全数据重建。在全方位投影信息情况下 ,我们可以把全方位投影信息视为两个有限角投影信息的组合。最后利用tomosynthesis中按行重建的概念 ,以行为单位进行重建。计算机仿真结果证明结论正确。

多源Tomosynthesis迭代算法在动态模型中的应用

提出了一种新的tomosynthesis扫描方法,并将该方法应用到动态重建场合,用于抑制运动在成像中产生的伪迹。新的方法采用多源(双源与四源)环形扫描方式和迭代重建算法对两种动态数字模型进行仿真重建。通过比较单源重建和多源重建的结果,评价多源tomosynthesis在动态重建方面的性能。结果表明多源tomosynthesis的扫描方式能够有效抑制动态重建中的伪迹,改善重建质量。本文的结果证实了多源tomosynthesis在动态重建中的有效性,对于进一步改善心脏和呼吸运动成像质量具有积极的实际意义。

Follow-up of endovascular aortic aneurysm repair:Preliminary validation of digital tomosynthesis and contrast enhanced ultrasound in detection of medium- to long-term complications

AIM: To validate the feasibility of digital tomosynthesis of the abdomen(DTA) combined with contrast enhanced ultrasound(CEUS) in assessing complications after endovascular aortic aneurysm repair(EVAR) by using computed tomography angiography(CTA) as the gold standard.METHODS: For this prospective study we enrolled 163 patients(123 men; mean age, 65.7 years) referred for CTA for EVAR follow-up. CTA, DTA and CEUS were performed at 1 and 12 mo in all patients, with a maximum time interval of 2 d.RESULTS: Among 163 patients 33 presented complications at CTA. DTA and CTA correlated for the presence of complications in 32/33(96.96%) patients and for the absence of complications in 127/130(97.69%) patients; the sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) and accuracy of DTA were 97%, 98%, 91%, 99%, and 98%, respectively. CEUS and CTA correlated for the presence of complications in 19/33(57.57%) patients and for the absence of complications in 129/130(99.23%) patients; the sensitivity, specificity, PPV, NPV and accuracy of CEUS were 58%, 99%, 95%, 90%, and 91%, respectively. Sensitivity, specificity and accuracy of combining DTA and CEUS together in detecting EVAR complications were 77%, 98% and 95%, respectively.CONCLUSION: Combining DTA and CEUS in EVAR follow-up has the potential to limit the use of CTA only in doubtful cases.

Efficacy of digital breast tomosynthesis combined with magnetic resonance imaging in the diagnosis of early breast cancer

BACKGROUND The incidence and mortality rate of breast cancer in China rank 120th and 163rd,worldwide,respectively.The incidence of breast cancer is on the rise;the risk increases with age but is slightly reduced after menopause.Early screening,diagnosis,and timely determination of the best treatment plan can ensure clinical efficacy and prognosis.AIM To evaluate the clinical value of magnetic resonance imaging(MRI) combined with digital breast tomosynthesis(DBT) in diagnosing early breast cancer and the effect of breast-conserving surgery by arc incision.METHODS This study was divided into two parts.Firstly,110 patients with early breast cancer confirmed by pathological examination and 110 with benign breast diseases diagnosed simultaneously in Changzhi People’s Hospital of Shanxi Province and Shanxi Dayi Hospital from May 2019 to September 2020 were included in the breast cancer group and the benign group,respectively.Both groups underwent DBT and MRI examination,and the pathological results were used as the gold standard to evaluate the effectiveness of the combined application of DBT and MRI in the diagnosis of early breast cancer.Secondly,according to the operation method,110 patients with breast cancer were divided into either a breast-conserving group(69 patients) or a modified radical mastectomy group(41 patients).The surgical effect,cosmetic effect,and quality of life of the two groups were compared.RESULTS Among the 110 cases of breast cancer,66 were of invasive ductal carcinoma(60.00%),and 22 were of ductal carcinoma in situ(20.00%).Among the 110 cases of benign breast tumors,55 were of breast fibromas(50.00%),and 27 were of breast adenosis(24.55%).The sensitivity,specificity,and area under the curve(AUC) of DBT in the differential diagnosis of benign and malignant breast tumors were 73.64%,84.55%,and 0.791,respectively.The sensitivity,specificity,and AUC of MRI in the differential diagnosis of benign and malignant breast tumors were 84.55%,85.45%,and 0.850,respectively.The sensitivity,specificity,and AUC of DBT combined with MRI in the differential diagnosis of benign and malignant breast tumors were 97.27%,93.64%,and 0.955,respectively.The blood loss,operation time and hospitalization time of the breast-conserving group were significantly lower than those of the modified radical treatment group,and the difference was statistically significant(P < 0.05).After 3 mo of observation,the breast cosmetic effect of the breast-conserving group was better than that of the modified radical group,and the difference was statistically significant(P < 0.05).Before surgery,the quality-of-life scores of the breast-conserving and modified radical mastectomy groups did not differ(P > 0.05).Three months after surgery,the quality-of-life scores in both groups were higher than those before surgery(P < 0.05),and the quality-of-life score of the breast-conserving group was higher than that of the modified radical group(P < 0.05).In the observation of tumor recurrence rate two years after the operation,four patients in the breast-conserving group and one in the modified radical treatment group had a postoperative recurrence.There was no significant difference in the recurrence rate between the two groups(χ2 = 0.668,P = 0.414 > 0.05).CONCLUSION MRI combined with DBT in diagnosing early breast cancer can significantly improve the diagnostic efficacy compared with the two alone.Breast-conserving surgery leads to better cosmetic breast effects and reduces the impact of surgery on postoperative quality of life.

Comparison of metal artifact in digital tomosynthesis and computed tomography for evaluation of phantoms

We compared metal artifact in X-ray digital tomosynthesis (DT) and modern computed tomography (CT) reconstruction to improve the image quality. We compared the images of a prosthetic phantom (titanium) and a contrast-detail phantom obtained by DT using conventional filtered backprojection (FBP), metal artifact reduction (MAR) processing, and simultaneous iterative reconstruction technique (SIRT) methods and those obtained by CT using conventional FBP and adaptive statistical iterative reconstruction methods. The effectiveness of each method for enhancing the visibility of a prosthetic phantom was quantified in terms of the intensity profile and root mean square error, and the removal of ghosting artifacts was quantified in terms of the artifact spread function (ASF). In addition, low contrast resolution was evaluated in terms of the contrast-to- noise ratio. Image error was smaller in the MAR DT images in the near in-focus-plane, and the intensity profiles revealed the beam hardening effect. Streak artifacts were reduced in the SIRT DT and adaptive statistical iterative reconstruction CT images. The ASF performances of the algorithms were ranked in descending order: 1) MAR DT;2) CT (adaptive statistical iterative reconstruction, and conventional FBP);3) SIRT DT;and 4) conventional FBP DT. The low contrast resolution was higher in the CT images than in the DT images. In conclusion, a review of the results revealed that the metal artifact reduction was highest for tomosynthesis with MAR processing, and the low contrast resolution performance was highest for CT.

Comparison between Visualization of Microcalcifications by Digital Breast Tomosynthesis and Full-Field Digital Mammography

Objective: To date, few studies have compared the diagnostic performance and visibility of microcalcifications obtained using digital breast tomosynthesis (DBT) with those obtained from full-field digital mammography (FFDM). The visualization and characterization of microcalcifications with DBT remain controversial. The purpose of this study was to compare the visibility of microcalcifications and determine whether DBT exhibits a diagnostic advantage for visualizing microcalcifications over FFDM. Methods: We retrospectively reviewed 120 cases including DBT and FFDM imaging (60 histologically verified as breast cancers and 60 as benign microcalcifications or normal). DBT images with a wide scan-angle of 50° and FFDM images were obtained using a flat-panel system (MAMMOMAT Inspiration, Siemens). Images were independently reviewed by four board-certified radiologists and evaluated for the presence of microcalcifications, probability of malignancy (BI-RADS classification), and visibility. Results: In predicting the malignancy of detected microcalcifications, no significant difference was found between readers’ areas under the receiver operating characteristic curve for DBT and FFDM (p = 0.068). The visibility scores of detected microcalcifications were 3.74 ± 1.06 for DBT and 3.46 ± 0.93 for FFDM, respectively. The visibility of microcalcifications when using DBT was found to be significantly superior to that of FFDM (p < 0.05). Conclusion: Our results suggest that the image quality of DBT with a wide scan-angle is comparable or superior to that obtained with FFDM in terms of both visibility and assessment of microcalcifications.

X-ray digital linear tomosynthesis imaging

Aims: The purpose of this review includes the fol-lowing: 1) to identify indications for volumetric X-ray digital linear tomosynthesis by using a filtered back projection (FBP) algorithm and 2) to compare X-ray digital linear tomosynthesis, X-ray digital ra-diography, conventional tomography, and computed tomography. Review: The methods include the fol-lowing: 1) an overview of the tomosynthesis system in comparison with conventional X-ray imaging tech-nology;2) an overview of the properties of diagnostic imaging for the chest, hip joint, and temporomandibular joint when imaging overlying structures and their effect of various artificial images;and 3) a review of each system. Summary: Tomosynthesis is worthy of further evaluation because of its flexibility and ability to suppress streak artifacts through an appropriate choice of an FBP algorithm. Tomosynthesis may be considered the imaging technique of choice for investigation of bone changes and detection of pulmonary nodules. Understanding the potential of tomosynthesis imaging will improve diagnostic accuracy in clinical applications.

Comparison of Different Reconstruction Algorithms for Decreasing the Exposure Dose during Digital Breast Tomosynthesis: A Phantom Study

We compared reconstruction algorithms [filtered back projection (FBP), maximum likelihood expectation maximization (MLEM), and the simultaneous iterative reconstruction technique (SIRT)] in terms of the radiation dose and image quality, for exploring the possibility of decreasing the radiation dose during digital breast tomosynthesis (DBT). The three algorithms were implemented using a DBT system and experimentally evaluated using measurements, such as signal difference-to-noise ratio (SDNR) and intensity profile, on a BR3D phantom (infocus plane image). The possible radiation dose reduction, contrast improvement, and artifact reduction in DBT were evaluated using different exposure levels and the three reconstruction techniques. We performed statistical analysis (one-way analysis of variance) of the SDNR data. The effectiveness of each technique for enhancing the visibility of the BR3D phantom was quantified with regard to SDNR (FBP versus MLEM, P < 0.05;FBP vs. SIRT, P < 0.05;MLEM vs. SIRT, P = 0.945);the artifact reduction was quantified with regard to the intensity profile. MLEM and SIRT produced reconstructed images with SDNR values indicative of low-contrast visibility. The SDNR value for the half-radiation dose MLEM and SIRT images was close to that of the FBP reference radiation dose image. Artifacts were decreased in the MLEM and SIRT images (in the infocus plane) according to the intensity profiles that we obtained. With MLEM and SIRT, the radiation dose may be decreased to half comparison with FBP.

A Comparison of Reconstruction Algorithms Regarding Exposure Dose Reductions during Digital Breast Tomosynthesis

This study compared reconstruction algorithms [filtered back projection (FBP) and simultaneous iterative reconstruction technique (SIRT)] with respect to radiation doses and image quality and suggested the possibility of decreasing the exposure dose in digital breast tomosynthesis (DBT). These two existing algorithms were implemented using a DBT system and experimentally evaluated using contrast-detail (CD) phantom measurements, such as contrast-to-noise ratio (CNR), root mean square error (RMSE), intensity profile, and artifact spread function (ASF), and the results obtained with FBP and SIRT were compared. The potential dose reduction, contrast improvement, quantum noise reduction, and artifact reduction in DBT were evaluated using different exposures and the two reconstruction techniques. The effectiveness of each technique for enhancing the visibility of a CD phantom was quantified with respect to CNR and RMSE, and artifact reduction was quantified with respect to the intensity profile and ASF. SIRT produced reconstructed images with CNR values indicative of high-contrast detection. Image error was smaller in the in-focus plane SIRT images, and artifacts were decreased in these images according to the determined intensity profiles and ASF. These results suggest that when using SIRT, the exposure dose could possibly be decreased to half.

Application of X-ray digital tomosynthesis in knee joint trauma examination

Objective: To explore the clinical value of X-ray digital tomosynthesis(DTS)in the diagnosis of knee joint fractures. Methods: A total of 28 cases of thoracic trauma, X-ray film cannot be clearly diagnosed or can confirm the diagnosis but the need for further identification of forensic diagnosis of cases of DTS scan and three-dimensional reconstruction in order to control the study. Results: 1. The reconstructed images after DTS scanning showed that the knee joint fractures were clearly diagnosed, and the detection rate of 28 knee joint fractures was 92.86%. 2. DTS scanning could clearly detect the fresh knee joint fracture's fracture line, corresponding line and broken bones. For the old fracture, DTS scanning could clearly show the condition of the fracture end's healing. Conclusions: The technique is of great value in the diagnosis of knee joint fracture, especially in the examination of complex structure, thick body and review of internal fixation after fracture.

Dual-Energy Subtraction X-Ray Digital Tomosynthesis: Basic Physical Evaluation

The present study was performed to determine the potential of applying dual-energy subtraction (DES) digital tomo-synthesis to basic physical evaluations. Volumetric X-ray DES digital tomosysnthesis was used to obtain an image of a detectability phantom (an artificial lesion). The image quality of DES digital tomosynthesis was compared to that of DES radiography. The purpose of this study was to determine enhanced visibility quantified in terms of the contrast- to-noise ratio, figure-of-merit, and root-mean-square error. In the in-focus plane, the image quality is better by DES digital tomosynthesis than by DES radiography. The potential usefulness of DES digital tomosynthesis for evaluating a detectability phantom was demonstrated. Further studies are required to determine the ability of DES digital tomosyn-thesis to quantify the spatial relationships between the artificial lesion components of these devices, as well as to iden- tify lesions with diagnostic consequences.

Preliminary attempt on maximum likelihood tomosynthesis reconstruction of DEI data

Tomosynthesis is a three-dimension reconstruction method that can remove the effect of superim- position with limited angle projections. It is especially promising in mammography where radiation dose is concerned. In this paper, we propose a maximum likelihood tomosynthesis reconstruction algorithm （ML-TS） on the apparent absorption data of diffraction enhanced imaging （DEI）. The motivation of this contribution is to develop a tomosynthesis algorithm in low-dose or noisy circumstances and make DEI get closer to clinic application. The theoretical statistical models of DEI data in physics are analyzed and the proposed algorithm is validated with the experimental data at the Beijing Synchrotron Radiation Facility （BSRF）. The results of ML-TS have better contrast compared with the well known ＇shift-and-add＇ algorithm and FBP algorithm.

岛津大平板多功能透视摄影系统技术规范及应用探讨

目的:探讨岛津大平板数字X线多功能透视摄影系统技术操作规范,评价数字化大平板X线多功能透视摄影系统的断层融合技术和全景摄影技术在普放特殊位置检查中的重要作用。颈椎寰枢关节胸骨、颞下颌关节、茎突骶尾骨等特殊位置和全脊柱摄影在常规DR摄影位置中不易清晰显示,应用大平板X线多功能透视摄影系统的断层融合和全景摄影技术能解决上述问题。

比较数字断层融合与数字X线摄影检出模拟肺结节的能力

目的利用仿真体模对比分析数字断层融合(DTS)与数字X线摄影(DR)检出模拟肺结节的能力。方法采用五种规格(直径3、5、8、10、12mm)、三种密度(CT值100、-630及-800HU)的模拟肺结节共15个,先后分别置于体模两肺的上、中、下肺野,形成模拟肺结节共计90个(15个×6)。以常规曝光参数分别进行DTS和DR,由2名放射科医师独立评价DTS及DR对肺结节的检出率;测量DTS的辐射剂量,转换为有效剂量,与文献报道的DR有效剂量进行对比。结果 DTS对模拟肺结节的检出率为78.89%(71/90),DR的检出率为28.89%(26/90),DTS检出率高于DR(P<0.01);对于三种不同密度(CT值100、-630和-800HU)的模拟结节,DTS与DR的检出率差异均有统计学意义(P<0.01)。DTS的有效剂量高于文献报道的DR剂量。结论对于肺结节,DTS较DR具有更高的检出率。

基于GPU实现的数字合成X射线体层成像投影数据的模拟方法

数字合成X射线体层成像技术能利用有限角度下的投影数据重建物体任意断层的图像。在数字合成X射线体层成像重建算法研究中,模拟投影数据是重要的步骤,本文提出了一种基于GPU光线投射算法的数字合成X射线体层成像投影数据模拟方法。比较传统CPU模拟手段,GPU模拟方法计算速率快,且基于硬件支持的三线性插值能够得到更加接近实际的投影结果。本文采用传统CPU模拟方法和GPU模拟方法分别计算投影数据,对两种方法获得投影使用ART算法和小波-伽辽金方法进行重建,得到较好的重建效果。

Imaging of the treated breast post breast conservation surgery/oncoplasty: Pictorial review

Mammographic appearance of the normal breast is altered in the post-operative setting. It is essential to be aware of the normal findings as well as to identify features of recurrent disease with particular emphasis on radiologicalpathological concordance. Digital breast tomosynthesis and volumetric breast density add incremental value in this clinical setting. We present a pictorial review of various cases to illustrate normal post-operative findings as well as mammographic features suspicious for recurrent disease.

A Study of Quasi-Monochromatic X-Ray Sources for Breast Cancer Early Detection

Objectives: Early detection and treatment provide the opportunity to decrease the mortality rate from breast cancer. Quasi-monochromatic technique can enhance low contrast lesion detection by eliminating beam-hardening artifacts. We hypothesized that this technique would be feasible and can be used to assist in breast cancer early detection. Methods: The performance of stationary Digital Breast Tomosynthesis with quasi-monochromatic X-ray sources was evaluated using both simulated and physical phantoms. Normalized spectra in the fraction of total photons vs. photon energy were generated. Results: As expected, the peaked energies from sources, from smallest to largest, are Mo/Mo, W/Ag-1000, and W/Ce-10, W/Ce-100. For contrast vs. noise standard deviation on the simulated CIRS phantom, W/Ce-100 and W/Ce-10 have similar performance on both low and high contrast objects. For low contrast object, W/Ce-100 is barely noticeably better than W/Ce-10, and they are better than both W/Ag-1000 and Mo/Mo. For high contrast objects W/Ce-10 is slightly better than W/Ce-100. The spectra of the implemented W/Ce-10 X-ray source were measured, which matched the simulation well. The contrast noise ratios of reconstructed objects in American College of Radiology mammographic phantom with and without using W/Ce-10 combination are 7.1 and 5.4, respectively. Conclusions: The combination of stationary digital breast tomosynthesis and quasi-monochromatic technique can compensate the loss of X-ray flux due to heavy K-edge filtering. This technique can enable the stationary DBT scanners to operate at acceptable scanning times with better low contrast lesion detectability. Advances in Knowledge: The stationary digital breast tomosynthesis can provide high quality images within short scanning time by using X-ray source array, which makes quasi-monochromatic technique feasible.