This paper presents the optimized image quality and average glandular dose in digital mammography, and provides
recommendations concerning anode-filter combinations in digital mammography, which is based on amorphous
selenium (a-Se) detector technology.
The full field digital mammography (FFDM) system based on a-Se technology, which is also a platform of
tomosynthesis prototype, was used in this study. X-ray tube anode-filter combinations, which we studied, were
tungsten (W) - rhodium (Rh) and tungsten (W) - silver (Ag). Anatomically adaptable fully automatic exposure control
(AAEC) was used. The average glandular doses (AGD) were calculated using a specific program developed by
Planmed, which automates the method described by Dance et al. Image quality was evaluated in two different ways: a
subjective image quality evaluation, and contrast and noise analysis.
By using W-Rh and W-Ag anode-filter combinations can be achieved a significantly lower average glandular dose
compared with molybdenum (Mo) - molybdenum (Mo) or Mo-Rh. The average glandular dose reduction was achieved
from 25 % to 60 %.
In the future, the evaluation will concentrate to study more filter combinations and the effect of higher kV (>35 kV)
values, which seems be useful while optimizing the dose in digital mammography.
This paper will present a new breast positioning system for amorphous selenium (a-Se) based full field digital mammography (FFDM) system, which is also a platform of tomosynthesis prototype. Clinical images demonstrate that this method is capable extending the breast away from the chest wall, and maximizing the breast volume.
Breast positioning system consists of two transparent moving sheets that apply traction of the breast controlled by motor. Sheets are under and above the compressed breast. Breast positioning sheets pull the breast into the imaging area during the compression. Digital mammography system is based on amorphous selenium flat panel detector (FPD) technology where the overall thickness of the selenium structure is 200 μm, and the pixel size on this detector is 85 μm.
Preliminary results will be presented. Clinical study showed increment of the breast volume imaged, and it brought up to 1.0 cm - 2.0 cm more breast tissue. New breast position system also holds a promise of slight decrement of compression force used in the examination.
Maximizing the exposured breast tissue is complicated, but important aspect in the breast cancer detection and diagnosis. Increasing the field of view with an additional volume of breast tissue imaged is a key point in digital mammography and
digital breast tomosynthesis (DBT).
This paper will present new anatomically adaptable automatic exposure control (AEC), called Flex-AEC+, for amorphous selenium (a-Se) full field digital mammography (FFDM) system.
The AEC operation is based on a principle where the imaging chain components are all modelled into the system software. Once the imaging parameters are all known it enables the system to exactly define the tissue composition imaged and utilize exposure parameters optimal for it. Based on the detected object composition together with the other imaging parameters the amount of signal produced by the amorphous selenium flat panel is exactly calculated and the desired dose of the exposure on the detector is thereby reached accurately. The AEC consists of 48 individual detection areas that cover a selenium flat panel area of 100 cm2. It is therefore able to measure a well representative sample of the tissue to be exposed and adjust the exposure parameters optimal for the breast tissue composition.
Clinical benefits of AEC are found because of fully understanding the behaviour of the x-ray beam together with the calculation models of the AEC. This gives better understanding of breast anatomy in all mammography screening and diagnostic cases, and responses to various tissue compositions by optimizing the image quality and dose.
The spectrum of the x-ray radiation changes remarkably when passing through the various materials on its path. Optimal image quality and dose requires anatomically adjusted imaging parameters, which will represent the true breast tissue composition taking account in all different glandular tissue in the breast. Based on the detected object composition together with the other imaging parameters the amount of signal produced by the selenium flat panel is exactly calculated, and the desired image quality and dose is reached accurately.
Our goal is to evaluate diagnostic digital breast tomosynthesis and ultrasound imaging clinical value in detecting and diagnosing early stage breast cancers. Determine if fusion imaging would decrease the number of biopsies and reduce further patient workup otherwise required to establish a definitive diagnosis. This paper presents the clinical results based on the study conducted at Helsinki University Central Hospital. Presentation demonstrates clinical dual modality images and results. Tomosynthesis of amorphous selenium based full field digital mammography system will be also presented.
Forty asymptomatic women enrolled in the study based on prior identification of suspicious findings on screening mammograms where the possibility of breast cancer could not be excluded. Abnormal screening mammogram findings included tumor-like densities, parenchymal asymmetries and architectural distortions. Eight women were operated and 32 were not referred for surgery. Those cases, which were operated, three lesions represented ductal carcinoma in situ, two ductal carcinomas, one atypical ductal hyperplasia, one fibroadenoma and one radial scar. The 32 not operated cases revealed to be benign or superimposition of normal parenchymal breast tissue. The cases were returned to biennial screening. Ultrasound did not show clearly any lesions, but using tomosynthesis and ultrasound together we were able to analyze and locate the lesions exactly. Special tomosynthesis improves overall lesion detection and analysis. The value of tomosynthesis and ultrasound fusion imaging will be to provide additional clinical information in order to improve decision making accuracy to either confirm or exclude a suspected abnormality and in particular detect small breast cancers.
Our goal in this paper is to evaluate the capability of real-time selenium-technology-based full-field digital mammography (FFDM) system in breast tomosynthesis. The objective of this study is to find out the present status of amorphous selenium technology in the sense of advanced applications in clinical use. We were using tuned aperture computed tomography (TACT+) 3-dimensional (3D) technology for reconstruction. Under evaluation were amorphous selenium signal-to-noise-ratio, flat panel image artefacts and acquisition time to perform full-field digital mammography 3D examination. To be able to validate the system we used a special breast phantom. We found out that 3D imaging technology provides diagnostic value and benefits over 2-dimensional (2D) imaging. 3D TACT advantages are to define if mammography finding is caused by a real abnormal lesion or by superposition of normal parenchymal structures, to be able to diagnose and analyze the findings properly, to detect changes in breast tissue which would otherwise be missed, to verify the possible multifocality of the breast cancers, to verify the correct target for biopsies and to reduce number of biopsies performed. Slice visualization and 3D volume model provide greater diagnostic information compared to 2D projection screening and diagnostic imaging.
The advent of digital detectors will enable several advanced imaging applications to be used in the fight against breast cancer. For example, dynamic imaging applications such as tomosynthesis, contrast enhanced and dual energy mammography have demonstrated promising results. In this paper, we will assess the suitability of this detector for these advanced applications. MTF and DQE measurements were performed on a selenium FFDM detector to assess image quality. Ghosting properties of a digital detector are also an important factor, since it can strongly degrade image quality. In this paper, we will also report on the ghosting characteristics of the selenium detector, using typical exposures envisioned to be used in tomosynthesis exams. The physical mechanisms that create ghost images will be discussed and will be quantified.
KEYWORDS: Digital mammography, 3D image processing, 3D modeling, Mammography, Diagnostics, Atomic force microscopy, 3D displays, Breast, Digital imaging, Stereoscopy
The purpose of this study is to find out the impact of 3-dimensional digital mammography and digital spot imaging following analysis of the abnormal findings of screening mammograms. Over a period of eight months, digital 3-D mammography imaging TACT Tuned Aperture Computed Tomography+, digital spot imaging (DSI), screen-film mammography imaging (SFM) and diagnostic film imaging (DFM) examinations were performed on 60 symptomatic cases. All patients were recalled because it was not possible to exclude the presence of breast cancer on screening films. Abnormal findings on the screening films were non-specific tumor-like parenchymal densities, parenchymal asymmetries or distortions with or without microcalcifications or just microcalcifications. Mammography work-up (film imaging) included spot compression and microfocus magnification views. The 3-D softcopy reading in all cases was done with Delta 32 TACT mammography workstation, while the film images were read using a mammography-specific light box. During the softcopy reading only windowing tools were allowed. The result of this study indicates that the clinical diagnostic image quality of digital 3-D and digital spot images are better than in film images, even in comparison with diagnostic work-up films. Potential advantages are to define if the mammography finding is caused by a real abnormal lesion or by superimposition of normal parenchymal structures, to detect changes in breast tissue which would otherwise be missed, to verify the correct target for biopsies and to reduce the number of biopsies performed.
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