DBT Systems Research Articles

Spiral breast computed tomography with a photon-counting detector (SBCT): The future of breast imaging?

Dedicated breast computed tomography (BCT) is an emerging breast imaging modality. The latest development has been the introduction of a spiral breast computed tomography scanner equipped with a photon-counting detector (SBCT).SBCT promises multiple advantages: Unlike conventional mammography, contrast enhanced spectral mammography (CESM: both 2D), and digital breast tomosynthesis (DBT: pseudo 3D), SBCT enables 3D breast imaging without tissue overlap. SBCT achieves high isotropic spatial resolution of breast tissue enabling the assessment of both soft tissue and microcalcifications. Similar to CESM and MRI, SBCT supports contrast-enhanced imaging, enabling the assessment of breast neovascularization. Unlike mammography and its derived methods (CESM, DBT), SBCT does not require compression of the breast. Accordingly, women consistently report significantly increased patient comfort compared to mammography in a previous investigation.Radiation safety is crucial in breast imaging. Studies showed different results in terms of dose, with some staying within the limits of two-view FFDM defined by the ACR and others exceeding the limit by up to 21%. Therefore, a higher radiation dose compared to state-of-the-art mammography and DBT systems has to be acknowledged.SBCT is currently under scientific investigation in multiple trials. Three major indications are currently explored: Whereas our colleagues in Zurich/Switzerland investigate the role of SBCT for opportunistic screening, in our department SBCT is mainly indicated for the work-up of equivocal lesions, and for preoperative staging.In this narrative review, we summarize the concepts of SBCT and potential implications for patient care. We report on our initial clinical experience with the technology and outline future developments of SBCT.

A phantom study comparing technical image quality of five breast tomosynthesis systems

BackgroundDigital breast tomosynthesis (DBT) is a three-dimensional breast imaging method. DBT vendors employ various approaches in both image acquisition and data processing, which may affect image quality and radiation exposure to patients. ObjectiveThis study aimed to evaluate the performance of five DBT systems: Fujifilm Amulet Innovality (using both a standard mode and high-resolution mode), GE Senographe Essential, Hologic Selenia Dimensions, Planmed Clarity 3D, and Siemens Mammomat Inspiration. Materials and methodsThe performance of each device and imaging technique was evaluated and compared by phantom measurements performed with four quality assurance phantoms. Technical image quality assessments consisted of measuring artefact extent, in-plane resolution, relative noise power spectrum, and geometric accuracy. ResultsArtefact spreading varied remarkably between the devices, and the full width at half maximum values of artefact spread functions varied from 3.5 mm to 10.7 mm. Noticeable in-plane resolution anisotropy, determined using modulation transfer function (MTF) analysis, was typically observed between tube travel direction and chest wall-nipple direction. The MTF50 varied from 1.1 mm−1 to 1.6 mm−1 and from 1.5 mm−1 to 4.1 mm−1 in the tube travel and chest wall-nipple directions, respectively. Moreover, distinctly different noise power spectra were observed between the systems. The geometric accuracy in every system was within 0.5%. ConclusionTechnical image quality assessments with image quality phantoms revealed remarkable differences in artefact spread, in-plane resolution, and noise properties between the DBT systems and imaging methods.

75. Image quality and dose measurements in digital breast tomosynthesis

Purpose DBT is a three-dimensional reconstruction technique of mammographic images that potentially offers the possibility to overcame the breast tissue-superposition reducing false-positive recalls and increasing cancer detection-rate compared to 2D mammography [1] . The aim of this study is to compare different commercial DBT units in terms of image quality and dose using a set of new phantoms. Methods The CDMAM phantom was used to compare the Contrast-Details curves in 2D and DBT mode principally for stability assessment. The TomophanTM phantom was used to perform measurements of Slice Sensitive Profile, slice-to-slice incrementation, chest-wall offset, z-axis geometry, Artefact Spread Function, low contrast detectability. An aluminium edge was employed to determine in plane MTF. The Pixmam phantom was used to estimate the AGD and to calculate SDNR. All measurements were performed on reconstructed images. Results The contrast-details curves are represented in Fig. 1 for all systems. The AGD and SDNR at 45 mm PMMA, the MTF 0.5 in tube-travel and chest wall-nipple directions, the ASF, the SSP and CNRLC are shown in Table 1 . Conclusions Our results are in good agreement with recent literature reported [2] , [3] . It is not simple to compare DBT systems because there are many differences in terms of detection process (direct/indirect), scan angular range, reconstruction algorithms and the presence or not of the grid. The analysis of all collected data can be useful in a contest of a quality assurance program to define a set of values that could be used as benchmarks.

Geometric calibration of a stationary digital breast tomosynthesis system based on distributed carbon nanotube X-ray source arrays.

Stationary digital breast tomosynthesis (sDBT) with distributed X-ray sources based on carbon nanotube (CNT) field emission cathodes has been recently proposed as an approach that can prevent motion blur produced by traditional DBT systems. In this paper, we simulate a geometric calibration method based on a proposed multi-source CNT X-ray sDBT system. This method is a projection matrix-based approach with seven geometric parameters, all of which can be obtained from only one projection datum of the phantom. To our knowledge, this study reports the first application of this approach in a CNT-based multi-beam X-ray sDBT system. The simulation results showed that the extracted geometric parameters from the calculated projection matrix are extremely close to the input values and that the proposed method is effective and reliable for a square sDBT system. In addition, a traditional cone-beam computed tomography (CT) system was also simulated, and the uncalibrated and calibrated geometric parameters were used in image reconstruction based on the filtered back-projection (FBP) method. The results indicated that the images reconstructed with calibrated geometric parameters have fewer artifacts and are closer to the reference image. All the simulation tests showed that this geometric calibration method is optimized for sDBT systems but can also be applied to other application-specific CT imaging systems.

Second generation stationary digital breast tomosynthesis system with faster scan time and wider angular span.

The aim of this study was to characterize a new generation stationary digital breast tomosynthesis system with higher tube flux and increased angular span over a first generation system. The linear CNT x-ray source was designed, built, and evaluated to determine its performance parameters. The second generation system was then constructed using the CNT x-ray source and a Hologic gantry. Upon construction, test objects and phantoms were used to characterize system resolution as measured by the modulation transfer function (MTF), and artifact spread function (ASF). The results indicated that the linear CNT x-ray source was capable of stable operation at a tube potential of 49kVp, and measured focal spot sizes showed source-to-source consistency with a nominal focal spot size of 1.1mm. After construction, the second generation (Gen 2) system exhibited entrance surface air kerma rates two times greater the previous s-DBT system. System in-plane resolution as measured by the MTF is 7.7cycles/mm, compared to 6.7cycles/mm for the Gen 1 system. As expected, an increase in the z-axis depth resolution was observed, with a decrease in the ASF from 4.30mm to 2.35mm moving from the Gen 1 system to the Gen 2 system as result of an increased angular span. The results indicate that the Gen 2 stationary digital breast tomosynthesis system, which has a larger angular span, increased entrance surface air kerma, and faster image acquisition time over the Gen 1s-DBT system, results in higher resolution images. With the detector operating at full resolution, the Gen 2s-DBT system can achieve an in-plane resolution of 7.7cycles per mm, which is better than the current commercial DBT systems today, and may potentially result in better patient diagnosis.

MO‐B‐209‐00: Certificate Extension Process for DBT and the Medical Physicist's Role

This presentation will describe the role of medical physicists during FDA's certificate extension process (CE). The presentation will outline FDA's CE process, with detailed discussions on training, MEE, and requirements for continued QA for the facility, vis‐a‐vis medical physicist's responsibilities. A few important tests will be discussed that need special emphasis for each of the DBT systems currently approved by FDA. What can be accepted as additional didactic and hands on training in fulfilling modality related training will be explained. Learning Objectives: Understand the certificate extension process Understand medical physicist's responsibility in performing QC tests following the QC manual Learn about proper presentation of data in reporting and generating soft copy phantom image Understand on‐going responsibilities in monitoring QC technologists’ tests

MO‐B‐209‐01: Certificate Extension Process for DBT and the Medical Physicist's Role

This presentation will describe the role of medical physicists during FDA's certificate extension process (CE). The presentation will outline FDA's CE process, with detailed discussions on training, MEE, and requirements for continued QA for the facility, vis‐a‐vis medical physicist's responsibilities. A few important tests will be discussed that need special emphasis for each of the DBT systems currently approved by FDA. What can be accepted as additional didactic and hands on training in fulfilling modality related training will be explained. Learning Objectives: Understand the certificate extension process Understand medical physicist's responsibility in performing QC tests following the QC manual Learn about proper presentation of data in reporting and generating soft copy phantom image Understand on‐going responsibilities in monitoring QC technologists’ tests

Study on growth characteristic and microbial desulfurization activity of the bacterial stain MP12

The growth characteristic and interrelated microbial desulfurization activity of stain MP12 on both DBT and crude oil systems were investigated in order to desulfurize crude oil. The results showed that DMSO was the most suitable sulfur source for stain MP12 growth and expression of desulfurization activity, while initial 2-HBP had very significant influences on the growth and desulfurization activity. Moreover, a novel method using the production rate of sulfate was developed for rapid determination of desulfurization activity in crude oil system. Analysis of total 2-HBP and total sulfate molar balance suggested that the total 2-HBP buildup had a very good match with the total sulfate buildup during microbial desulfurization of crude oil. The desulfurization activity of high density cells could be increased sharply with an increase of agitation speed. In conclusion, the strain MP12 was able to effectively desulfurize recalcitrant organic sulfur compounds in both DBT and crude oil systems.

Dependency of image quality on system configuration parameters in a stationary digital breast tomosynthesis system

In principle, a stationary digital breast tomosynthesis (s-DBT) system has better image quality when compared to continuous motion DBT systems due to zero motion blur of the source. The authors have developed a s-DBT system by using a linear carbon nanotube x-ray source array. The purpose of the current study was to quantitatively evaluate the performance of the s-DBT system; and investigate the dependence of imaging quality on the system configuration parameters. Physical phantoms were used to assess the image quality of each configuration including inplane resolution as measured by the modulation transfer function (MTF), inplane contrast as measured by the signal difference to noise ratio (SdNR), and depth resolution as measured by the z-axis artifact spread function. Five parameters were varied to create five groups of configurations: (1) total angular span; (2) total number of projection images; (3) distribution of exposure (mAs) across the projection images; (4) entrance dose; (5) detector pixel size. It was found that the z-axis depth resolution increased with the total angular span but was insensitive to the number of projection images, mAs distribution, entrance dose, and detector pixel size. The SdNR was not affected by the angular span or the number of projection images. A decrease in SdNR was observed when the mAs was not evenly distributed across the projection images. As expected, the SdNR increased with entrance dose and when larger pixel sizes were used. For a given detector pixel size, the inplane resolution was found to be insensitive to the total angular span, number of projection images, mAs distribution, and entrance dose. A 25% increase in the MTF was observed when the detector was operating in full resolution mode (70 μm pixel size) compared to 2 × 2 binned mode (140 μm pixel size). The results suggest that the optimal imaging configuration for a s-DBT system is a large angular span, an intermittent number of projection views, and a uniform mAs distribution over all views. With the detector operating at full resolution, a stationary DBT system can achieve an inplane resolution of 5.1 cycles per mm, which is significantly better than continuous motion DBT systems.

TH‐C‐332‐09: The Effect of Variable Exposure Distribution On Microcalcification Detectability in Tomosynthesis

Purpose: To investigate the fundamental limitation of tomosynthesis acquisition on the detectability of microcalcifications (MCs) and to investigate the effects of employing unequal dose distribution (variable exposure) across the tomosynthesis projections. Method and Materials: Ray tracing was used through a 5‐cm thick homogeneous slab phantom, which contained 150‐, 280‐, and 400‐micron diameter spheres embedded at the center. In this study we accounted for acquisition geometry and x‐ray quantum noise. Detectability was calculated using a nonprewhitening observer. In the sinogram data, detectability was computed by integrating observer response over all projection views. In the reconstructed image, observer response was computed using a 2D matched template at the in‐focus slice of the sphere. To test variable distribution of exposure, 50% of the exposure was concentrated in the center three projection views, and the rest was divided equally among the remaining projection views. Results: We determined that the detectability of MCs is reduced for larger projection angles because of the increased pathlength through the phantom and larger source‐to‐detector distance. The spheres are projected on the detector as ellipses at larger angles, which blurs the MCs and decreases detectability. Detectability of MCs using the variable exposure method is approximately 10–20% higher than detectability in the equal exposure distribution method. Conclusion: The detectability of MC is reduced in a tomosynthesis acquisition because of the acquisition geometry if all projections are made with the same exposure. A variable exposure method can improve MC detectability in DBT systems. In future work we will examine the effect of breast structure noise on the variable exposure method. Conflict of Interest: Research sponsored by Hologic, Inc. and Dexela Ltd.

Oxidative technology proven to process ULSD

The growth characteristic and interrelated microbial desulfurization activity of stain MP12 on both DBT and crude oil systems were investigated in order to desulfurize crude oil. The results showed that DMSO was the most suitable sulfur source for stain MP12 growth and expression of desulfurization activity, while initial 2-HBP had very significant influences on the growth and desulfurization activity. Moreover, a novel method using the production rate of sulfate was developed for rapid determination of desulfurization activity in crude oil system. Analysis of total 2-HBP and total sulfate molar balance suggested that the total 2-HBP buildup had a very good match with the total sulfate buildup during microbial desulfurization of crude oil. The desulfurization activity of high density cells could be increased sharply with an increase of agitation speed. In conclusion, the strain MP12 was able to effectively desulfurize recalcitrant organic sulfur compounds in both DBT and crude oil systems.