Digital X-ray Tomosynthesis Research Articles

Functional hemodynamic imaging markers for the prediction of pathological outcomes in breast cancer patients treated with neoadjuvant chemotherapy.

Achieving pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) is a significant predictor of increased likelihood of survival in breast cancer patients. Early prediction of pCR is of high clinical value as it could allow personalized adjustment of treatment regimens in non-responding patients for improved outcomes. We aim to assess the association between hemoglobin-based functional imaging biomarkers derived from diffuse optical tomography (DOT) and the pathological outcome represented by pCR at different timepoints along the course of NACT. Twenty-two breast cancer patients undergoing NACT were enrolled in a multimodal DOT and X-ray digital breast tomosynthesis (DBT) imaging study in which their breasts were imaged at different compression levels. Logistic regressions were used to study the associations between DOT-derived imaging markers evaluated after the first and second cycles of chemotherapy, respectively, with pCR status determined after the conclusion of NACT at the time of surgery. Receiver operating characteristic curve analysis was also used to explore the predictive performance of selected DOT-derived markers. Normalized tumor HbT under half compression was significantly lower in the pCR group compared to the non-pCR group after two chemotherapy cycles (). In addition, the change in normalized tumor upon reducing compression from full to half mammographic force was identified as another potential indicator of pCR at an earlier time point, i.e., after the first chemo cycle (). Exploratory predictive assessments showed that AUCs using DOT-derived functional imaging markers as predictors reach as high as 0.75 and 0.71, respectively, after the first and second chemo cycle, compared to AUCs of 0.50 and 0.53 using changes in tumor size measured on DBT and MRI. These findings suggest that breast DOT could be used to assist response assessment in women undergoing NACT, a critical but unmet clinical need, and potentially enable personalized adjustments of treatment regimens.

Economic evaluation of supplemental breast cancer screening modalities to mammography or digital breast tomosynthesis in women with heterogeneously and extremely dense breasts and average or intermediate breast cancer risk in US healthcare

ObjectiveTo evaluate the cost-effectiveness of supplemental breast imaging modalities for women with heterogeneously and extremely dense breasts and average or intermediate risk of breast cancer (BC) in the USA, and analyze capacity requirements for supplemental magnetic resonance imaging (MRI) and contrast-enhanced mammography (CEM).MethodsClinical and economic outcomes for supplemental imaging modalities including full- and abbreviated-protocol MRI (Fp-MRI, Ab-MRI), CEM, and ultrasound (U/S) as add-on to x-ray mammography (XM) or digital breast tomosynthesis (DBT), were compared to XM or DBT alone, in a decision tree linked to a Markov chain validated by comparison with a microsimulation analysis. A Delphi panel supplemented model input parameters from the literature. A capacity model evaluated the number of additional daily scans and scanners required for Fp-MRI and CEM.ResultsCompared to XM or DBT alone, all supplemental imaging protocols were cost-effective. Both Fp- and Ab-MRI, and to a lesser extent CEM and U/S, yielded superior clinical outcomes to XM or DBT. Compared to XM alone, U/S and Ab-MRI had the lowest incremental cost-effectiveness ratios (ICER). For U/S, the ICER was $23,394 for the average-risk population and $13,241 for the intermediate-risk population. For CEM, the ICER was $38,423 and $23,772, respectively. For the extremely dense subpopulation with intermediate risk, supplemental screening requirements could be accommodated by conducting one Fp-MRI scan per day per existing general scanner.ConclusionsWhile ultrasound had the lowest ICER, MRI and CEM demonstrated the best clinical outcomes, compared to XM or DBT alone for women with dense breasts and intermediate and high risk. Existing MRI scanner capacity has the potential to meet most of the supplemental screening needs of this population.

Clinical value of digital tomographic fusion imaging in the diagnosis of avascular necrosis of the femoral head in adults

BackgroundTo explore the clinical significance of digital tomographic fusion imaging in the diagnosis of avascular disease of the femoral head in adults.MethodsEighty-two adult patients with avascular necrosis of the femoral head confirmed by MRI in the department of orthopedics of our hospital were studied retrospectively. The related signs of adult avascular necrosis of the femoral head were diagnosed by digital tomographic fusion imaging, and the detection rates of digital X-ray (DR) and digital tomosynthesis (DTS) were compared to clarify the clinical value of digital tomographic fusion imaging in the diagnosis of adult avascular necrosis of the femoral head.ResultsDTS detected DR and 78 cases identified 55 cases. Taking the results of CT/MRI as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value of DR and DTS in the diagnosis of ANFH were calculated. There was a significant difference in the detection rate between the two methods (P < 0.05).ConclusionThe digital tomographic fusion imaging technique has the advantages of high detection rate and excellent image quality, is economical, and is worth popularizing. For those with negative X-rays, DTS diagnosis and CT or/and MRI can avoid unnecessary CT and MRI examinations, which is helpful to reduce the waste of medical resources.

Диагностика заболеваний молочной железы в программе вспомогательных репродуктивных технологий

Objective. To study the state of the breasts in women who undergo assisted reproductive technologies treatment, using modern methods of radiation imaging. Patients and methods. Pre- and prospective examination and analysis of the data of radiation imaging of the breasts of 220 women, having tubal factor infertility in combination with benign mammary dysplasia, who have successful or unsuccessful experience of participation in assisted reproductive technology programmes. The average age of patients was 42.5 years. Assessment points were: breast tissue density according to the findings of ultrasound, mammography and tomosynthesis, presence of clustered microcalcifications, presence of benign dysplastic processes and fibroadenomas of the breasts. Results. In the group of 35–39-year old patients, the most common pathological processes were fibrocystic mastopathy and fibroadenomas. The main diagnostic methods were ultrasound visualization and US-controlled core-needle vacuum-assisted biopsy. In the group of 40–44-year old women, the predominant pathological process was microcalcification clusters alongside high mammographic density. The main diagnostic methods were digital x-ray tomosynthesis and X-ray-guided core-needle vacuum-assisted biopsy. In the group of 45–49-year old women, cases of breast cancer were diagnosed. 12 women in this group had breast implants. Conclusion. Hormonal medication used in assisted reproductive technologies under the protocols of in-vitro fertilization and intracytoplasmatic sperm injection influence the state of the breasts, increasing a risk of developing diffuse benign mammary dysplasias and, quite possible, a risk of developing breast cancer later in life. Key words: breast diseases, assisted reproductive technologies, tomosynthesis, mammotome, clustered microcalcifications

P117] Dose estimation of eye lens for pediatric inner ear X-ray diagnosis

Purpose Recently, digital X-ray tomosynthesis using flat panel detectors (FPD) has been used to diagnose the inner ears of pediatric patients. This imaging provides intermediate functionality between X-ray photographs and X-ray computer tomography (CT) scans. However, during inner ear diagnosis, digital X-ray tomosynthesis includes the eye lens in its field of view; an organ sensitive to X-ray doses. The purpose of this research is to evaluate the X-ray dosage upon the eye lens during inner ear diagnosis using digital tomosynthesis and to compare this dosage with X-ray CT exposure. Methods Small optically stimulated luminescence (OSL) dosimeters (nanodot: Nagase Landauer, Ltd.) were positioned on the eye lens of a phantom and on the bed of an X-ray TV device to measure the kinetic energy released per unit mass of air (air kerma). We performed tomosynthesis, assuming the conditions for an inner ear examination of an infant. The irradiant conditions were a tube voltage of 60–110 kV, an added filter of 0.1 mmCu, a swing angle θ of ± 20 °, and 76 photographs of a flame. The absorbed dose for the eye lens was calculated using the mass energy absorption coefficient ratio of the eye lens and air. In addition, the eye lens absorbed dose was compared with an X-ray CT scan. Results As the tube voltage increased, the absorbed dose increased. Moreover, when placed in a posterior-anterior (PA) position, as the phantom thickness increased, the absorbed dose decreased. On the contrary, when in an anterior-posterior (AP) position, as phantom thickness increased, the absorbed dose increased. Conclusions The eye lens absorbed dose in the PA position decreased by 90% compared to AP-positioning when using digital tomosynthesis for inner ear diagnosis of pediatric patients. Additionally, the eye lens absorbed dose in PA-positioned digital tomosynthesis decreased 93% compared to X-ray CT scans. Therefore, it is useful to reduce the exposure dose of the eye lens during inner ear diagnosis of pediatric patients via the use of digital tomosynthesis imaging.

Spatial Resolution and Blurring Artifacts in Digital X-ray Tomosynthesis

Digital tomosynthesis (DTS) is an X-ray imaging technique that produces cross-sectional images with a scanning motion in narrow angular ranges. This method is promising for the inspection of internal defects in thin slab objects, such as printed circuit boards. However, this limited angular scan approach can have limited resolution in the depth direction. In addition, it can cause ghosting artifacts that originate from other planes in the reconstructed plane. In this paper, we characterized the imaging performance of a DTS method that uses the filtered backprojection for reconstruction. Various imaging parameters were examined, such as the total scan angle and the number of projections used for the reconstruction. We analyzed the signal and noise characteristics of the reconstructed images obtained for a thin tungsten wire and a thin aluminum disc. We obtained in-plane and in-depth modulation transfer functions (MTFs) from the reconstructed wire response images. From the reconstructed disc response images, we calculated the signal difference between the disc region and the adjacent background region along the depth direction, which is called the artifact spread function (ASF). A narrow angular scan enhances the in-plane MTF performance compared to that obtained from the conventional computed tomography, but it degrades the in-depth MTF performance (i.e., it decreases the depth resolution). In addition, the narrow angular scan degrades the ASF performance and causes severe out-of-plane blur artifacts. The optimal scanning angular range is, therefore, required to obtain tomographic images with high spatial resolution and less blur artifacts. The analysis method performed in this paper could be useful for this optimization.

Digital x-ray tomosynthesis with interpolated projection data for thin slab objects

In relation with a thin slab-object inspection, we propose a digital tomosynthesis reconstruction with fewer numbers of measured projections in combinations with additional virtual projections, which are produced by interpolating the measured projections. Hence we can reconstruct tomographic images with less few-view artifacts. The projection interpolation assumes that variations in cone-beam ray path-lengths through an object are negligible and the object is rigid. The interpolation is performed in the projection-space domain. Pixel values in the interpolated projection are the weighted sum of pixel values of the measured projections considering their projection angles. The experimental simulation shows that the proposed method can enhance the contrast-to-noise performance in reconstructed images while sacrificing the spatial resolving power.

Comparison of analytic and iterative digital tomosynthesis reconstructions for thin slab objects

For digital x-ray tomosynthesis of thin slab objects, we compare the tomographic imaging performances obtained from the filtered backprojection (FBP) and simultaneous algebraic reconstruction (SART) algorithms. The imaging performance includes the in-plane molulation-transfer function (MTF), the signal difference-to-noise ratio (SDNR), and the out-of-plane blur artifact or artifact-spread function (ASF). The MTF is measured using a thin tungsten-wire phantom, and the SDNR and the ASF are measured using a thin aluminum-disc phantom embedded in a plastic cylinder. The FBP shows a better MTF performance than the SART. On the contrary, the SART outperforms the FBP with regard to the SDNR and ASF performances. Detailed experimental results and their analysis results are described in this paper. For a more proper use of digital tomosynthesis technique, this study suggests to use a reconstuction algorithm suitable for application-specific purposes.

Detective quantum efficiency of a phosphor-coupled photodiode array detector for use in digital X-ray tomosynthesis systems

The X-ray imaging performance of a phosphor-coupled photodiode array detector was assessed for use in a cone-beam computed tomography (CBCT) system for printed-circuit board inspection. The radiographic image quality of a detector is mainly responsible for the tomographic image quality. The radiographic image quality can be improved by increasing the X-ray exposure level, but CT scans at higher exposure can impose an enormous heat load on the X-ray tube. In this study, the detective quantum efficiency (DQE) was used to describe the image quality per air kerma as a metric to assess the detector performance. Measurement results were obtained for 40-kVp and 50-kVp tungsten-target X-ray beams, which show that the DQE of the detector is tolerant of air kerma levels as low as 0.8 μGy. Below this level, the electronic noise of the detector system could degrade the DQE performance. The concept of DQE and the measurement procedure are described, including the modulation-transfer function and the noise-power spectrum.

Multimodal breast cancer imaging using coregistered dynamic diffuse optical tomography and digital breast tomosynthesis.

Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detector cover, respectively. We demonstrate system performance using static and dynamic tissue-like phantoms as well as in vivo images acquired from the pool of patients recalled for breast biopsies at the Massachusetts General Hospital Breast Imaging Division.

Dose from tomosynthesis of the bony anatomy: Comparison with digital radiography and CT

Introduction Digital x-ray tomosynthesis can be employed to evaluate MSK/orthopedic conditions, such as revelation of subtle fractures, avoiding CT scan when standard exam is not sufficient. Purpose The purpose of this study is to evaluate effective doses from tomosynthesis of bony anatomy and compare them with doses from CT and digital radiography. Materials and methods We simulated tomosynthesis acquisitions of the hip, lumbar spine and shoulder using PCXMC20Rotation. Tomosynthesis projections were simulated using parameters from FujiFilm FDR AcSelerate with fixed mAs/projection, FID = 130 cm, 0.2 mm Cu filtration. For the same anatomical district, we also simulated radiographs with PCXMC2.0 and CT scans, performed on a Siemens Somatom Definition CT scanner, with CT-Expo (120 kVp, Z-current modulation). Effective doses were computed for all techniques. Results Hip tomosynthesis [60 projections (60° total angle), 5 mAs/projection, 80 kVp] delivers an effective dose of 0.8 mSv, 15 times the dose of an AP radiograph of the same anatomy and 20% of the dose delivered by CT [CTDI vol, mean = 9.5Gy]. Shoulder tomosynthesis [60 projections (60° total angle), 4mAs/projection, 65 kVp] delivers an effective dose of 0.4 mSv, 3 times the dose delivered by an AP radiograph of the same anatomy and 20% of the dose delivered by CT [CTDI vol, mean = 12Gy]. Finally, lumbar spine tomosynthesis [45 projections (40° total angle), 12.5 mAs/projection, 100kVp] delivers an effective dose of 1.8 mSv, 8 times the dose of a LL+AP radiograph and 22% of the dose delivered by CT [CTDI vol, mean = 17Gy]. Conclusion Dosimetric evaluation of radiographic tomosynthesis for bony anatomy shows that it spares 80% of the dose of a CT scan.

Geometric estimation method for x-ray digital intraoral tomosynthesis

It is essential for accurate image reconstruction to obtain a set of parameters that describes the x-ray scanning geometry. A geometric estimation method is presented for x-ray digital intraoral tomosynthesis (DIT) in which the detector remains stationary while the x-ray source rotates. The main idea is to estimate the three-dimensional (3-D) coordinates of each shot position using at least two small opaque balls adhering to the detector surface as the positioning markers. From the radiographs containing these balls, the position of each x-ray focal spot can be calculated independently relative to the detector center no matter what kind of scanning trajectory is used. A 3-D phantom which roughly simulates DIT was designed to evaluate the performance of this method both quantitatively and qualitatively in the sense of mean square error and structural similarity. Results are also presented for real data acquired with a DIT experimental system. These results prove the validity of this geometric estimation method.

A review of geometric calibration for different 3-D X-ray imaging systems

A precise knowledge of geometry is always pivotal to a 3-D X-ray imaging system, such as computed tomography (CT), digital X-ray tomosynthesis, and computed laminography. To get an accurate and reliable reconstruction image, exact knowledge of geometry is indispensable. Nowadays, geometric calibration has become a necessary step after completing CT system installation. Various geometric calibration methods have been reported with the fast development of 3-D X-ray imaging techniques. In these methods, different measuring methods, calibration phantoms or markers, and calculation algorithms were involved with their respective advantages and disadvantages. This paper reviews the history and current state of geometric calibration methods for different 3-D X-ray imaging systems. Various calibration algorithms are presented and summarized, followed by our discussion and outlook.

Acoustic Performance of Mesh Compression Paddles for a Multimodality Breast Imaging System

A system incorporating automated 3-D ultrasound and digital X-ray tomosynthesis is being developed for improved breast lesion detection and characterization. The goal of this work is to develop and test candidates for a dual-modality mesh compression paddle. A Computerized Imaging Reference Systems (Norfork, VA, USA) ultrasound phantom with tilted low-contrast cylindrical objects was used. Polyester mesh fabrics (1- and 2-mm spacing), a high-density polyethylene filament grid (Dyneema, DSM Dyneema, Stanley, NC, USA) and a solid polymethylpentene (TPX; Mitsui Plastics, Inc., White Plains, NY) paddle were compared with no overlying structures using a GE Logic 9 with M12L transducer. A viscous gel provided coupling. The phantom was scanned 10 times over 9 cm for each configuration. Image volumes were analyzed for signal strength, contrast and contrast-to-noise ratio. X-ray tests confirmed X-ray transparency for all materials. By all measures, both mesh fabrics outperformed TPX and Dyneema, and there were essentially no differences between 2-mm mesh and unobstructed configurations.

Calibration-Free Coronary Artery Measurements for Interventional Device Sizing using Inverse Geometry X-ray Fluoroscopy: In Vivo Validation.

Proper sizing of interventional devices to match coronary vessel dimensions improves procedural efficiency and therapeutic outcomes. We have developed a novel method using inverse geometry x-ray fluoroscopy to automatically determine vessel dimensions without the need for magnification calibration or optimal views. To validate this method in vivo, we compared results to intravascular ultrasound (IVUS) and coronary computed tomography angiography (CCTA) in a healthy porcine model. Coronary angiography was performed using Scanning-Beam Digital X-ray (SBDX), an inverse geometry fluoroscopy system that performs multiplane digital x-ray tomosynthesis in real time. From a single frame, 3D reconstruction of the arteries was performed by localizing the depth of vessel lumen edges. The 3D model was used to directly calculate length and to determine the best imaging plane to use for diameter measurements, where out-of-plane blur was minimized and the known pixel spacing was used to obtain absolute vessel diameter. End-diastolic length and diameter measurements were compared to measurements from CCTA and IVUS, respectively. For vessel segment lengths measuring 6 mm to 73 mm by CCTA, the SBDX length error was -0.49 ± 1.76 mm (SBDX - CCTA, mean ± 1 SD). For vessel diameters measuring 2.1 mm to 3.6 mm by IVUS, the SBDX diameter error was 0.07 ± 0.27 mm (SBDX - minimum IVUS diameter, mean ± 1 SD). The in vivo agreement between SBDX-based vessel sizing and gold standard techniques supports the feasibility of calibration-free coronary vessel sizing using inverse geometry x-ray fluoroscopy.

Is Lung Cancer Screening Possible with Digital Chest Tomosynthesis?

Lung Cancer ManagementVol. 2, No. 5 EditorialIs lung cancer screening possible with digital chest tomosynthesis?Alberto Terzi & Luca BertolacciniAlberto TerziThoracic Surgery Unit, S. Croce City Hospital, Via Michele Coppino, 26-12100 Cuneo, ItalySearch for more papers by this author & Luca Bertolaccini* Author for correspondenceThoracic Surgery Unit, S. Croce City Hospital, Via Michele Coppino, 26-12100 Cuneo, Italy. Search for more papers by this authorEmail the corresponding author at luca.bertolaccini@gmail.comPublished Online:3 Oct 2013https://doi.org/10.2217/lmt.13.36AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInReddit View articleReferences1 Vallebona A. Axial transverse laminagraphy. Radiology55(2),271–273 (1950).Crossref, Medline, CAS, Google Scholar2 Dobbins JT III, Godfrey DJ. Digital x-ray tomosynthesis: current state of the art and clinical potentials. Phys. Med. Biol.48(19),R65–R106 (2003).Crossref, Medline, Google Scholar3 Vikgren J, Zachrisson S, Svalkvist A et al. Comparison of chest tomosynthesis and chest radiography for detection of pulmonary nodules: human observer study of clinical cases. Radiology249(1),1034–1041 (2008).Crossref, Medline, Google Scholar4 Gomi T, Nakajima M, Fujiwara H et al. Comparison between chest digital tomosynthesis and CT as a screening method to detect artificial pulmonary nodules: a phantom study. Br. J. Radiol.85(1017),e622–e629 (2012).Crossref, Medline, CAS, Google Scholar5 Zhao F, Zeng Y, Peng G et al. Experimental study of detection of nodules showing ground-glass opacity and radiation dose by using anthropomorphic chest phantom: digital tomosynthesis and multi detector CT. J. Comput. Assist. Tomogr.36(5),523–527 (2012).Crossref, Medline, Google Scholar6 The National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N. Engl. J. Med.365(5),395–409 (2011).Crossref, Medline, Google Scholar7 Terzi A, Bertolaccini L, Viti A et al. Lung cancer detection with digital chest tomosynthesis: baseline results from the observational study SOS. J. Thorac. Oncol.8(6),685–692 (2013).Crossref, Medline, Google Scholar8 Wang J, Dobbin JT III, Li Q. Automated lung segmentation in digital chest tomosynthesis. Med. Phys.39(2),732–740 (2012).Crossref, Medline, Google ScholarFiguresReferencesRelatedDetails Vol. 2, No. 5 Follow us on social media for the latest updates Metrics Downloaded 36 times History Published online 3 October 2013 Published in print October 2013 Information© Future Medicine LtdFinancial & competing interests disclosureStudy grant aided by Cassa di Risparmio di Cuneo Foundation. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.No writing assistance was utilized in the production of this manuscript.PDF download

X-ray digital intra-oral tomosynthesis for quasi-three-dimensional imaging: system, reconstruction algorithm, and experiments

At present, there are mainly three x-ray imaging modalities for dental clinical diagnosis: radiography, panorama and computed tomo- graphy (CT). We develop a new x-ray digital intra-oral tomosynthesis (IDT) system for quasi-three-dimensional dental imaging which can be seen as an intermediate modality between traditional radiography and CT. In addition to normal x-ray tube and digital sensor used in intra- oral radiography, IDT has a specially designed mechanical device to complete the tomosynthesis data acquisition. During the scanning, the measurement geometry is such that the sensor is stationary inside the patient's mouth and the x-ray tube moves along an arc trajectory with respect to the intra-oral sensor. Therefore, the projection geometry can be obtained without any other reference objects, which makes it be easily accepted in clinical applications. We also present a compressed sensing- based iterative reconstruction algorithm for this kind of intra-oral tomo- synthesis. Finally, simulation and experiment were both carried out to evaluate this intra-oral imaging modality and algorithm. The results show that IDT has its potentiality to become a new tool for dental clinical diagnosis. © 2013 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10

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.

A digital x-ray tomosynthesis coupled near infrared spectral tomography system for dual-modality breast imaging

A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as anatomical priors in optical image reconstruction. Currently, the total scan time for a combined NIRST-DBT exam is ~50s with data collection from 8 wavelengths in the optical scan requiring ~42s to complete. The system was tested in breast simulating phantoms constructed using intralipid and blood in an agarose matrix with a 3 cm x 2 cm cylindrical inclusion at 1 cm depth from the surface. Diffuse image reconstruction of total hemoglobin (HbT) concentration resulted in accurate recovery of the lateral size and position of the inclusion to within 6% and 8%, respectively. Use of DBT structural priors in the NIRST reconstruction process improved the quantitative accuracy of the HbT recovery, and led to linear changes in imaged versus actual contrast, underscoring the advantages of dual-modality optical imaging approaches. The quantitative accuracy of the system can be further improved with independent measurements of scattering properties through integration of frequency or time domain data.

A phantom-based calibration method for digital x-ray tomosynthesis.

The purpose of this study was to develop a phantom-based experimental calibration method to minimize the reconstruction artifacts for the geometric misalignments of the digital tomosynthesis prototype. A calibration phantom with ten fiducial markers was designed. Using this calibration phantom, the projection matrices of an experimental digital tomosynthesis prototype were acquired from each projection view under a series of misalignment conditions. The American College of Radiology mammography phantom was imaged and reconstructed with and without using the correction of the corresponding calibration projection matrices. The effectiveness of the calibration technique was then quantitatively analyzed through comparison of the calibrated and uncalibrated images. As the isocenter horizontal-shift increases, the reconstruction artifacts become clearly distinguishable. Using the calibration technique, the reconstruction artifacts resulting from the isocenter horizontal-shift were effectively minimized for the prototype. For the specific experimental conditions utilized in this study, the phantom-based calibration method effectively reduced reconstruction artifacts for the prototype investigated in this study. The calibration method holds potential to benefit other tomosynthesis applications.