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Digital Breast tomosynthesis

NHSBSP Publication No 69 September 2010

Authors

Members of the Digital Breast Tomosynthesis Working Party

Professor Fiona J gilbert Aberdeen Biomedical Imaging Centre, University of Aberdeen (Chair)

Professor Kenneth C young National Coordinating Centre for the Physics of Mammography, Guildford

Dr susan m astley Imaging Sciences, University of Manchester

ms Patsy Whelehan Centre for Oncology and Molecular Medicine, University of Dundee

Dr maureen g C gillan Aberdeen Biomedical Imaging Centre, University of Aberdeen

Published byNHS Cancer Screening Programmes Fulwood House Old Fulwood Road Sheffield S10 3TH

Tel: 0114 271 1060 Fax: 0114 271 1089

Email: [email protected] Website: www.cancerscreening.nhs.uk

© NHS Cancer Screening Programmes 2010

The contents of this document may be copied for use by staff working in the public sector but may not be copied for any other purpose without prior permission from NHS Cancer Screening Programmes.

The document is available in PDF format on the NHS Cancer Screening Programmes website.

ISBN 978-1-84463-071-4

Typeset by Prepress Projects Ltd, Perth (www.prepress-projects.co.uk) Printed by Bell & Bain, Glasgow

NHSBSP September 2010

Digital Breast Tomosynthesis | iii

CONTENTS

ACKNOWLEDGEMENTS iv

1. INTRODUCTION 1

1.1 Overview of tomosynthesis 11.2 Digital Breast Tomosynthesis Working Party 21.3 Methodology 3

2. TECHNICAL ASPECTS OF TOMOSYNTHESIS 4

2.1 General principles 42.2 Technical features of current digital breast tomosynthesis systems 42.3 Reconstruction of DBT images 72.4 Tomosynthesis image display 82.5 Workstation requirements for DBT 8

3. ISSUES FOR THE NHS BREAST SCREENING PROGRAMME 9

3.1 Context 93.2 Equipment 93.3 PACS 93.4 Resource and practical issues 103.5 Technical and clinical evaluation of DBT equipment for use in the NHSBSP 113.6 Technical quality control and radiation dose monitoring 113.7 Training 113.8 Research required 123.9 Summary of recommendations 12

APPENDIX 1: Digital breast tomosynthesis system questionnaire 13

APPENDIX 2: Responses to questionnaire: comparison of DBT systems 16

APPENDIX 3: Bibliography of publications from manufacturers of digital breast tomosynthesis systems 29

APPENDIX 4: Manufacturers’ contact details 33

REFERENCES 34


iv | Digital Breast Tomosynthesis

ACKNOWLEDGEMENTSThe authors would like to acknowledge the support of Sarah Sellars, Assistant Director, NHS Breast Screening Programme, and of the following companies who sent and presented information on the development of their tomosynthesis systems: Dexela, GE, Hologic, Sectra, Siemens and XCounter.

Figures 1 and 2 are based on data first published in 2003 in Digital x-ray tomosynthesis: current state of the art and clinical potential by James T Dobbins III and Devon J Godfrey.1 They appear with the kind permission of Professor Dobbins and IOP Publishing Limited.


Digital Breast Tomosynthesis | 1

1. INTRODUCTION

1.1 Overview of tomosynthesis

In standard two dimensional (2D) film or full field digital mammography (FFDM), overlapping dense fibroglandular tissue within the breast can reduce the visibility of malignant abnormalities or simulate the appearance of an abnormality. This can lead to unnecessary recalls, biopsies and psychological stress for the women concerned. In addition mammography is known to be less sensitive in women with dense breasts, who are at higher risk of developing breast cancer.2 This is of particular concern for the NHS as it extends the screening programme to women aged 47–49, as these pre- or perimenopausal women have a higher proportion of dense breast tissue.3,4 It is also potentially problematic for women aged 40–49 whose family history places them at moderate or high risk of the disease and for whom annual mammography is therefore recommended.5

Digital breast tomosynthesis (DBT) is a newly developed form of three dimensional (3D) imaging with the potential to improve the accuracy of mammography by reducing tissue overlap. This overlap, which is sometimes known as anatomical noise, degrades image quality in standard 2D projection imaging. The fundamental principles of tomographic imaging were established in the 1930s. However it was several decades before any practical clinical applications were reported, with the development of flat panel digital display detectors, rapid computer processing and advances in reconstruction and post-processing algorithms.1 In DBT, multiple projection images of the breast are acquired from different angulations of the x-ray tube.6 The images are then processed using algebraic reconstruction algorithms to produce tomographic sections through the breast. These sections can be viewed on a soft copy workstation, either as slices or sequentially in a dynamic video mode. By minimising the superimposition of overlying breast tissue, DBT has the potential to differentiate malignant features more definitively from non-malignant ones.

The superiority of DBT to standard 2D projection mammography was first demonstrated using phantoms and mastectomy specimens.7–10 Later studies with prototype systems indicate that the image quality of DBT is highly dependent on system geometry and the selection of optimal image acquisition, reconstruction and display parameters.6,11–13

1.1.1 Lesion visibility

It has been noted that masses and architectural distortions are more clearly visible with DBT than with film–screen mammography and that lesions can be more accurately classified.14–20 One study reported equal or better visualisation of microcalcifications using DBT,21 although other studies suggest that resolution is less sharp than with conventional mammography.17,18,22 This lower resolution may result partly from system geometry, the reconstruction of images after processing22,23 and the need to combine image slices into thicker slabs for optimal visualisation of microcalcification clusters. It has been suggested that a standard-view digital mammogram should be acquired along with two-view DBT for optimal assessment of microcalcifications.6,24,25 The development of computer aided detection (CAD) algorithms for DBT may also facilitate lesion detection and image interpretation.6,26–28


2 | Digital Breast Tomosynthesis

1.1.2 Cancer detection and recall rate

A blinded reader study of 60 mixed cases reported no significant change in cancer detection rate when using DBT but noted that the false positive recall rate was 83% lower than when using FFDM.29 A blinded assessment of 100 cases reported a 40% improvement in sensitivity and 20% reduction in recall rate with DBT when compared with mammography.30 A 43% reduction in recall rate (from 7.5% to 4.3%) was observed by an American screening population study involving 1957 women.31 A retrospective multireader performance study with 125 cases, including 35 cancer cases, reported a 30% reduction in false positive recall rate using a combination of DBT and FFDM when compared with FFDM alone.32 Using DBT alone or in combination with FFDM produced no significant improvement in sensitivity, however.32 Teertstra et al33 reached a similar conclusion regarding sensitivity in their blinded assessment of images from 513 women with abnormal screening mammography or clinical symptoms.

1.1.3 Number of DBT views

It was initially suggested that DBT image acquisition be restricted to the mediolateral oblique (MLO) view.34 However a later study by the same research group reported that 65% of lesions were judged equally visible on both MLO and craniocaudal (CC) views while 35% were more visible, or only visible, on one or the other.35 Using a different DBT system a retrospective, non-blinded consensus study of 36 patients with subtle lesions reported better visibility with one-view DBT than with either one- or two-view FFDM.18 One of the largest screening studies to date reported a 42% reduction in recall rate when using one-view DBT rather than conventional mammography, although the study had insufficient cancer cases to establish any differences in sensitivity.36 In a study of 200 suspicious breast lesions, Gennaro et al37 demonstrated that the sensitivity, specificity and lesion conspicuity of one-view DBT were comparable with those of two-view FFDM.

1.1.4 Reader performance

Multireader studies have reported improved receiver operating characteristic (ROC) performance using the combination of DBT and FFDM rather than FFDM alone; inter-reader variability has also been found to decrease, even among radiologists with differing levels of experience.38–42 The need for substantial reader training has nevertheless been highlighted.32,43,44

1.2 Digital Breast Tomosynthesis Working Party

1.2.1 Remit

The Digital Breast Tomosynthesis Working Party was set up to examine the current status of DBT technology, to advise on whether this technology should be considered for use in the NHS Breast Screening Programme (NHSBSP) and, if so, to identify areas where more detailed research is needed to assess DBT’s clinical utility.



1.2.2 Composition

The multidisciplinary working party included

• a radiologist from the NHSBSP with extensive experience in breast imaging research and health technology evaluation

• an experienced breast screening radiographer with particular expertise in digital mammography and DBT

• the NHSBSP’s lead medical physicist with expertise in the evaluation and quality assurance of equipment, including digital mammography and DBT systems

• an imaging scientist with special interests in breast image analysis• a research fellow with experience in health technology evaluation.

1.3 Methodology

The working party met on two occasions. At the first meeting the aims of the group were established and companies involved in the production of DBT equipment were identified. It was agreed that representatives of these companies would be invited to give presentations and be interviewed using a structured questionnaire (Appendix 1). DBT equipment companies were identified through personal contact and through international radiology meetings (among them the European Congress of Radiology, Symposium Mammographicum, the International Workshops on Digital Mammography and the Radiological Society of North America). The structured questionnaire was drafted, circulated and agreed by members of the working party before distribution to the companies’ representatives.These were then invited to attend the second meeting of the working party in London, allowing its members where necessary to clarify information supplied in the questionnaire. Companies unable to send a representative to the meeting participated by teleconference. Information derived from the questionnaires and interviews is summarised in Appendix 2. The companies which participated are listed in Appendix 3. A table summarising the technical data for their equipment was sent out in March 2010, allowing each company to check and, where necessary, update the information to reflect new developments.



2. TECHNICAL ASPECTS OF TOMOSYNTHESIS

2.1 General principles

In conventional geometric tomography, a plane of interest is established by moving the detector (originally a film–screen cassette) and the x-ray tube in opposite directions. This establishes a plane of interest (or a plane of focus). The contribution of structures in all other planes is blurred in the resulting tomographic image. Features within the plane of focus appear relatively sharp. The great disadvantage of this approach is that there is only a single plane of focus for each exposure and geometric configuration. In tomosynthesis an arbitrary number of planes may be retrospectively reconstructed from a single sequence of projection images. Typically a series of projection images is obtained while the x-ray tube moves in a circular or linear motion. However the motion of the x-ray tube could be more complex and the imaging detector could be stationary or moving. After the acquisition sequence is complete the projection images are combined by shifting and adding these together to bring a specific plane into focus. Different planes can be brought into focus by varying the amount of shifting. The advantages of tomosynthesis over conventional projection imaging are

• depth localisation• improved conspicuity, owing to the removal of the clutter caused by overlying tissue structures• improved contrast of local structure by limiting the dynamic range to a single plane.

Practical tomosynthesis differs from computed tomography (CT) in that projections are obtained over only a limited range of angles; it is thus often described as ‘limited angle tomography’. In CT, projections are obtained through either 180° or 360° rotations of x-ray tubes and detectors. This allows a complete sampling of the tissues to be imaged and the reconstitution of a complete 3D dataset; by this means slices can be reconstructed in any direction. The main disadvantage of CT imaging of the breast is the higher radiation dose involved in conventional system designs. At the moment, dedicated breast CT systems remain a subject of research and none is yet commercially available.

2.2 Technical features of current digital breast tomosynthesis systems

This section discusses in more detail the current features of digital breast tomosynthesis systems. It examines how these systems differ from conventional projection breast imaging and, in particular, how designs differ between the various manufacturers.

A number of key design features distinguish the different DBT systems. The most important of these are the mechanism for collecting data, the detector, the way in which images are acquired, and the software used to reconstruct and display the images. These are all interrelated and each is currently the subject of active research.

2.2.1 Detector and tube technology

The development of DBT was held back for many years by the lack of suitable x-ray imaging detectors. The main requirements for a suitable detector are



• a large imaging area• rapid readout• high detective quantum efficiency (DQE).

The introduction of flat panel detectors into breast imaging systems meets all of these requirements. Digital mammography systems are now available with an imaging field of up to 24 × 30 cm. The whole projection image can be read out in a fraction of a second, enabling a series of projection images to be taken in a few seconds. Current detectors can achieve a DQE of 50% at low spatial frequencies (< 1 cycle per mm) at the doses normally used in projection mammography. However it has been a particular challenge for digital mammography to maintain a high DQE at the dose levels used for DBT projections, which are 10–15 times lower than those used in conventional projection imaging. This challenge has been met by minimising the presence of electronic noise in the images.

One way to lower the relative noise in the projection images used in DBT is to employ higher energy x-ray spectra, a development also seen in conventional digital mammography systems. Manufacturers have thus introduced x-ray tubes with either a rhodium (Rh) or a tungsten (W) target, rather than the molybdenum (Mo) targets normally used in film–screen imaging. Accompanying this change in target materials has been the introduction of filter materials other than the conventional molybdenum. Rhodium filters are in widespread use, with thicknesses ranging from 25 to 50 µm. The advantage of using a higher energy spectrum is that the x-rays are more penetrating; this leads to a lower breast dose while a greater photon flux reaches the imaging detector, thereby reducing the relative amount of quantum noise in the image. The disadvantage is that a lower radiographic contrast is generated by the structures of interest in the breast. On balance, however, adopting these spectra leads to an improvement in the ratio of contrast to noise. This trend has continued with the development of DBT systems with even higher energy spectra that use a tungsten/aluminium (W/Al) or tungsten/silver (W/Ag) target–filter combination.

2.2.2 Image acquisition parameters

GeometryThe geometrical configuration used in DBT varies considerably between manufacturers. A distinction can be made between systems that use a completely isocentric motion and those that use a partial isocentric motion. In the first (Figure 1) the x-ray tube and detector rotate about the same axis. In the second (Figure 2) the detector remains stationary.

Tomography angleThe range of angles over which projection images are acquired is called the tomography angle. On most systems the tomography angle can be varied. The approach adopted by the different manufacturers can be classed as a narrow or wide angle. The Hologic and Sectra systems use narrow tomography angles of 15º and 11º respectively. The Hologic system is capable of being operated at a tomography angle of up to 30º. The GE and XCounter systems operate at slightly wider angles of 25º and 26º respectively, while Siemens favours a very wide tomography angle of 50º. The advantages and disadvantages of using narrow or wide tomography angles remain a matter for research and debate. However it is claimed that a wide angle provides better depth resolution while a narrow one enhances in-plane resolution.



Figure 1 Complete isocentric motion, in which both the x-ray tube and image receptor rotate about a common axis.

Figure 2 Partial isocentric motion, in which the detector is stationary.

R76 Topical Review

(a)

(c)

(b)

Figure 5. Tomosynthesis geometries using isocentric motion. (a) Complete isocentric motion, inwhich both the x-ray tube and image receptor rotate about a common axis. (b) Partial isocentricmotion, in which the detector stays in one plane (or is stationary) and the x-ray tube rotates aboutsome point of rotation. (c) Partial isocentric motion of Niklason et al, in which the detector isstationary. (Figure adapted from figure A1 in Niklason et al (1997).)

and shifted data to account for magnification differences as the tube and detector rotate. Theselatter two steps may be summarized in the following equation from Kolitsi et al:

r =(

h − ad sin α

b cos α − a

)(1 − a

b cos α

)(15)

where r is the location in a fictitious plane containing QrPr of an object projected at location hin the horizontal plane. This fictitious plane containing QrPr has the property that the lengthof the line segment QrPr does not change length as a function of α. Therefore, a series of

R76 Topical Review

(a)

(c)

(b)

Figure 5. Tomosynthesis geometries using isocentric motion. (a) Complete isocentric motion, inwhich both the x-ray tube and image receptor rotate about a common axis. (b) Partial isocentricmotion, in which the detector stays in one plane (or is stationary) and the x-ray tube rotates aboutsome point of rotation. (c) Partial isocentric motion of Niklason et al, in which the detector isstationary. (Figure adapted from figure A1 in Niklason et al (1997).)

and shifted data to account for magnification differences as the tube and detector rotate. Theselatter two steps may be summarized in the following equation from Kolitsi et al:

r =(

h − ad sin α

b cos α − a

)(1 − a

b cos α

)(15)

where r is the location in a fictitious plane containing QrPr of an object projected at location hin the horizontal plane. This fictitious plane containing QrPr has the property that the lengthof the line segment QrPr does not change length as a function of α. Therefore, a series of

DoseManufacturers typically aim to perform a tomographic acquisition that results in a radiation dose comparable with the dose used in projection breast imaging. A detailed procedure is being prepared for publication that will extend the current UK, EU and International Atomic Energy Authority breast dosimetry protocols to include DBT systems.45 An earlier paper by the same authors extends the existing protocols to include the type of spectra used in modern 2D and 3D systems.46

Number of projectionsThe number of DBT projections is influenced by various factors, including the scan time, electronic noise and the tomography angle. In the clinical trials for the Hologic system, for example, 15 projections were used with a 15º tomography angle. The Siemens system uses 25 projections with a 50º tomography angle. Each projection will typically contribute approximately the same dose.



In general, sufficient projections are needed to ensure adequate angular sampling. A number of simulation studies have been conducted to compute the optimal numbers of projections for specific systems.12,13

2.3 Reconstruction of DBT images

Reconstruction algorithms aim to produce images in which the low contrast objects are conspicuous, fine detail is visible and there are few artefacts. Clearly a balance has to be struck between dose, number of views and image quality.

The imaged volume is constructed from a sequence of between 9 and 48 projection mammograms acquired over a limited range of angles (between –25º and +25º, depending on the manufacturer). From the reconstructed volume a series of images can be displayed to show tissue at different depths in the breast. This overcomes the limitation of overlapping breast tissue in standard 2D projection mammograms. It also improves the conspicuity of lesions, as they can be displayed in images that include less background clutter than in a standard mammogram, which in turn allows for improved contrast.

The mathematical basis for the reconstruction of projection images was provided in 1917 by Radon,47 who showed how to reconstruct a single 2D slice from a set of one-dimensional projections. This enabled the development of computed tomography, which would become an important clinical tool from the late 1970s. In 1932 Ziedses des Plantes,48 working on a new technique that he called planigraphy, developed a method for reconstructing an arbitrary number of planes from a set of projection images. The first practical application of this came much later49 but early systems were hampered by the use of film (one per projection) and by the crude optical mechanisms for viewing the data. It was not until high quality projection images could be recorded digitally that tomosynthesis became a viable clinical technique.7

Once projection data have been obtained they must be pre-processed prior to reconstruction, for example with a logarithmic transformation.1 This allows pixel values to be related to tissue attenuation.

Many reconstruction algorithms are based on filtered backprojection, in which the signal at a detector is smeared back into the image space along a line in the direction of the attenuating tissue that gave rise to the signal.50 Projections are filtered in advance of this to reduce artefacts and the blurring inherent in the method. Owing to the limited number of angles at which images are acquired in DBT, the frequency space corresponding to the object being imaged is filled unevenly. A number of adaptations have been developed to compensate for the resulting artefacts in the reconstructed images.51–53 Filtered backprojection is more rapid than iterative methods and variants of it are used in both the Hologic and the Siemens systems.

Iterative methods have also been applied in the reconstruction of DBT images, however.8,54,55 In these, estimates of error are used successively to improve the reconstruction. The XCounter, Sectra and Dexela systems apply iterative methods. Simultaneous algebraic reconstruction has also been applied to DBT.56 This method conceives the image being reconstructed as an array of unknown values that can be found by solving a set of algebraic equations in terms of the projection data and by iterating this process until a solution is identified. A variant of this method is used in the GE system.



2.4 Tomosynthesis image display

The reconstructed slices produced by commercial DBT systems are 0.5–3 mm thick. Images are viewed as a stack and the reader scrolls through them as if moving through the breast, with features moving in and out of focus.

The optimal thickness of tissue in which to identify breast abnormalities may occasionally be thicker than typical slice thickness; to address this overlapping slabs can be formed, each comprising several slices. These slabs are typically a few millimetres thick and, again, are viewed as if scrolling through the breast with features moving in and out of focus. A single slab encompassing the thickness of the breast thus resembles a conventional projection mammogram. If the slab thickness selected is insufficient and a single cluster of microcalcifications appears in several slabs the relationship between the particles will not be apparent when these slabs are viewed individually. The contrast of individual particles may nevertheless be greater than in a conventional mammogram and individual particles will move in and out of focus as the viewer scrolls through the slabs. The use of CAD for microcalcifications may overcome this limitation, although it is not yet clear how best to display prompts when viewing images in this way.

2.5 Workstation requirements for DBT

A supplement to the Digital Imaging and Communications in Medicine (DICOM) standard (Supplement 125) on how DBT images should be stored and displayed has only recently been published.57 As a result it may not be possible to display images produced by one manufacturer’s system on another’s workstation, although this should change in time. Workstations used for DBT also place additional demands on computer memory and power. This is particularly true if the workstation is used to perform the reconstruction as well as to display the images.



3. ISSUES FOR THE NHS BREAST SCREENING PROGRAMME

3.1 Context

The new DBT technology is advancing even as the NHSBSP continues to work through the challenges of implementing 2D FFDM. It is expected that FFDM and Picture Archiving and Communications System (PACS) will be embedded by the time evidence-based conclusions are possible on the clinical utility of DBT in the NHSBSP. As a result the transition to DBT, if it happens, will not represent a great technological leap. The resource implications are nevertheless likely to be considerable.

3.2 Equipment

In April 2010 approximately one-third of NHSBSP centres had at least one FFDM unit. However most of the units are unable to undertake DBT. Were DBT to become a standard modality within the NHSBSP, these units would thus have to be replaced before end of life; alternatively the change in practice would have to be deferred until they reached end of life. FFDM units are expensive but DBT units are still more expensive and likely to remain so. Even for FFDM units amenable to a simple upgrade (eg software only) such upgrades involve considerable costs. Any evidence-based conclusion that DBT has a place in the NHSBSP on clinical grounds would need to include a rigorous assessment of cost-effectiveness.

3.3 PACS

DBT has significant implications for PACS, a system encompassing image viewing, image transfer, and short- and long-term archiving solutions. Reporting workstations that are suitable for 2D FFDM are not necessarily suitable for reporting DBT. Current DBT images do not comply with the new supplement 125 to the DICOM standard; however it is hoped that compliance will be achieved by existing and future manufacturers as new DBT equipment enters the market. In the meantime non-compliance with the DICOM supplement does not preclude image storage in PACS, although this would have to be explored with individual manufacturers.

In addition to the DICOM conformance issues, there are significant costs to upgrading existing workstations for DBT and centres currently choosing reporting workstations for FFDM will want to select the most futureproof versions available within their cost constraints.

DBT is a modality that generates large files for each examination and this makes particular demands on the imaging IT network infrastructure. Sufficient bandwidth is needed in both cabling and switching to ensure that image transfer speeds do not fall to unacceptable levels as a result of the increased traffic. Expert IT advice would be required in Trusts to address this.

Image transfer management hardware and software (such as shuttles and servers) are part of PACS solutions and the specification for these, too, must be robust enough to cope with the image volumes and traffic involved in the NHSBSP. The detailed requirements will depend on whether DBT is adopted as a screening tool or exclusively for diagnostic assessment.



Although image storage is probably the simplest element of PACS it can be managed in various ways. Most local PACS will have short-term storage provision. If this provision is not expanded, however, the length of time for which images are stored will diminish as image volumes increase. Several options for long-term storage are under consideration: some Trusts have made their own on-site long-term storage arrangements; there are also various regional initiatives being developed in and outside of the Connecting for Health framework; and there is the potential for national long-term storage arrangements. In each case the image volumes associated with any additional work would need to be calculated, costed and catered for. The question also arises of when, or whether, raw data should be stored and NHSBSP centres might find national guidance on this helpful. Storing raw data is probably of greatest benefit for research and for the development and evaluation of new software products. These include CAD algorithms and quantitative breast density estimation software.

3.4 Resource and practical issues

3.4.1 Variables afecting examination times

Examination times for the first DBT system to become commercially available in the UK* do not appear to be significantly different from 2D FFDM, although independent quantitative data to support this impression are as yet unavailable. One key factor governing examination times comes into play if both 2D and 3D images are needed; it is the ability of the equipment to perform both examinations in a single compression episode. As the comparison table at Appendix 2 shows, this is not a universal design feature in DBT. The speed with which the system allows the grid between 2D and 3D imaging to be removed and replaced is another factor affecting the examination time as is the number of projection images acquired. It may take radiographers longer to check 3D image quality than to check 2D images as all projection images must be scrolled or cined through in order to detect motion blur. Movement perpendicular to the chest wall between projection images indicates movement of the subject during the exposure sequence. Movement parallel to the chest wall is caused by the projection variation. Acquisition workstation and gantry designs for DBT are not expected to differ significantly from FFDM, and nor is their installation. Here too, however, information is limited.

3.4.2 Variables affecting reporting times

Reporting times are significantly longer for DBT than 2D examinations because the quantity of information to be processed by the observer is much greater. The number of reconstructed slices to be viewed will depend on the slice thickness and the breast thickness. Even with efficient scrolling and cine options, however, the time taken to view all the reconstructed images is likely to be considerably greater than in a 2D examination. There is presently insufficient evidence to quantify reporting times for either diagnostic or screening use of DBT.

CAD is not currently available for DBT but is in development. It is expected to be particularly useful for microcalcifications and may limit reporting time increases if it enables observers to concentrate their searches on soft-tissue abnormalities.

*A second DBT system has now become commercially available in the UK, although it has not yet undergone formal clinical evaluation.



3.5 Technical and clinical evaluation of DBT equipment for use in the NHSBSP

New designs for FFDM systems currently undergo technical evaluation by the National Coordinating Centre for Physics in Mammography (NCCPM). Once methodologies are developed for testing DBT systems, the tests will need to be applied to each such system as it comes on the market. Ideally, technical evaluations should be published soon after the release of equipment new to the UK.

Clinical user evaluation methodologies should be devised that minimise as far as is practicable the workload for evaluation centres and the time taken to produce reports. More efficient than the current user evaluation system would be a detailed NHSBSP specification that sets out the necessary clinical and practical features and performance criteria. Each manufacturer would be expected to match their product against this specification and provide evidence that the performance criteria are met. This might require some UK clinical user evidence, for which installations in approved centres would continue to be needed. It is particularly important to assess the ergonomic implications of new equipment designs. All of these findings could be collated into a single web-based document which would be updated when a new system came on the market.

3.6 Technical quality control and radiation dose monitoring

Suitable test protocols for commissioning, routine testing by physicists, and routine testing by radiographers would all need to be developed for DBT. Radiographer testing has been particularly challenging in the case of standard FFDM because manufacturers’ recommendations and methodologies vary and UK physicists’ preferences add a further dimension. Ideally manufacturers should liaise with UK mammography physicists at an early stage to agree suitable test protocols for DBT; NCCPM is currently working with most of the major manufacturers on the testing of their DBT systems as part of the OPTIMAM research project.

A robust but practical methodology for calculating radiation dose to the breast is urgently needed for DBT, and one is currently in development (see section 2.2).

3.7 Training

The process of training radiographers to use DBT is not expected to be radically different from applications training on any new equipment. DBT is more complex than standard FFDM, however, and the time needed to complete the training is thus likely to be longer. The training provided by equipment suppliers tends to increase with the number of systems purchased; centres installing DBT should therefore satisfy themselves in advance that sufficient training is available and that any linguistic and other difficulties associated with a lack of UK-based trainers can be kept to a minimum.

One supplier has worked with field experts to devise a sophisticated two-day DBT reporting training course, although the conditions for evaluating its effectiveness (or that of any other user training) are not yet in place. A two-day training course represents a significant time investment for a busy radiologist or film reader; options for shorter courses and online training should therefore be explored that support the achievement of competence in DBT interpretation. System suppliers and UK Breast Screening Training Centres could work together on developing and evaluating these training courses.



3.8 Research required

Further clinical research is needed as studies published to date have yielded conflicting results. DBT needs to be compared with current standard imaging practice across key performance indicators such as sensitivity and specificity in screening and accuracy in diagnostic assessment.58 If it is found that DBT performance is at least as effective as FFDM then one of the primary aims of the research should be to be establish whether DBT could or should be used as a standalone imaging modality and whether one- or two-view DBT would be needed. This would help to determine if DBT should be used as a screening tool or if it should be restricted to the diagnostic setting. It is possible that DBT would prove more useful in women with dense breasts or in younger women; this too needs to be established. Effective comparison between DBT and standard FFDM is aided by systems that can undertake both acquisitions in a single compression, thus avoiding the confounding effects of small differences in positioning. Further work is needed to determine the optimal configuration and to develop specific phantoms and performance standards for DBT. This would form the basis for a formal comparison of commercially available systems that differ in key design features such as projection angle range, number of projections and reconstruction algorithms. Preliminary work towards these objectives has been reported as part of an EU-funded initiative (www.highrex.eu) and forms part of the OPTIMAM research project.59

Only when a robust body of clinical research data is available will it be possible to conclude whether and where DBT fits in UK clinical practice. Many questions of a more detailed nature also remain. Some practical issues require investigation, such as the method for displaying and reviewing DBT images and its impact on reporting times. Acceptability to women should also be investigated in light of compression and examination times which are longer than with standard FFDM.

A UK DBT research strategy is needed, developed by the NHSBSP in consultation with the Royal College of Radiologists Breast Group and other key stakeholders, to ensure that these key questions are answered as soon as possible.

3.9 Summary of recommendations

1. Manufacturers should be encouraged to make images produced compliant with the new DICOM standard for DBT (Supplement 125).

2. Manufacturers should be encouraged to develop systems able to perform DBT projection image acquisitions in the same compression episode as 2D acquisition.

3. Technical and clinical evaluation of new systems, technical quality control and dose calculation methodology development should be completed as soon as possible.

4. When making FFDM purchasing decisions, breast imaging centres might want to consider futureproofing in readiness for possible DBT implementation.

5. Robust cost-effectiveness evaluation should be undertaken, either after or (preferably) in parallel with clinical research demonstrating the utility of DBT.

6. UK Breast Screening Training Centres and DBT suppliers should collaborate in the production and rigorous evaluation of training courses for DBT reporting.

7. A comprehensive UK research strategy needs to be developed.



APPENDIX 1: DIGITAL BREAST TOMOSYNTHESIS SYSTEM QUESTIONNAIRE

The purpose of this questionnaire is to obtain information on the technical and clinical performance of commercial DBT systems to enable us to determine whether any system(s) are appropriate or likely to be appropriate in the near future for a clinical trial in the UK NHSBSP.

Please answer the questions and include any comments in the spaces provided. Indicate which information (if any) that you want to be kept confidential. Any additional information you wish to be considered by the committee should be included as an Appendix.

Company name

Company representative

1. Has the system been submitted for FDA (or equivalent) approval?

If so, estimated target date for approval?

2. Is the system commercially available?

If not, estimated target date?

3. If commercially available, number and location of systems installed worldwide

4. Is the system CE marked?


5. Is NCCPM evaluation completed?


6. Can existing 2D systems be upgraded to incorporate the DBT package?

If so, please state which 2D model(s) can be upgraded.

7. Anode/filter material

8. Detector type

9. Detector element size

10. DBT projection exposure mode



11. Plate size

12. (a) Actual pixel size

(b) Pixel size in reconstructed image

13. Minimum reconstruction slice thickness

14. Optimal slice thickness

15. Slab thickness

16. Recommended viewing protocol

17. Time from beginning of first projection exposure to end of last exposure

18. Rotation angle of system (degrees)

19. Range of gantry angles over which DBT can be acquired (degrees)

20. Projection exposure angles (give each angle)

21. Number of exposures

22. Exposure (mAs) at each angle

23. How are exposures controlled?

24. Phantom studies: radiation dose and phantom thickness

25. Breast studies: radiation dose and breast thickness for a single MLO view

26. Mean glandular breast radiation dose

27. Image processing time (reconstruction and display)

28. Breast compression (compared with standard 2D)

29. How is compression controlled?

30. Maximum compressed breast thickness for DBT imaging

31. Reconstruction algorithms

32. Is the DBT system able to acquire a 2D mammogram in the same compression?

33. Recommended DBT views

34. Image size (MB) per 2D view (raw and processed data)



35. Image size (MB)

(a) Raw projection images total

(b) Processed projection images total

(c) Full reconstructed dataset

(d) Overall total

36. Can the same workstation be used for DBT and 2D?

37. Workstation storage capacity (GB and number of cases)

38. Format used for image storage

39. Can images be displayed on a PACS workstation?

40. Is CAD available for masses, calcifications or both?

41. Are CAD marks displayed in DBT slices or in 2D image?

42. What is the DBT system sensitivity/specificity for detection of soft tissue masses? (Give reference)

43. What is the DBT system sensitivity/specificity for detection of microcalcifications? (Give reference)

44. What would be your predicted reduction in recall rate compared with 2D? (Give reference)

45. Estimated reading time per case for DBT? (Give reference)



APPENDIX 2: RESPONSES TO QUESTIONNAIRE: COMPARISON OF DBT SYSTEMS



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

1. H

as th

e sy

stem

be

en s

ubm

itted

for

FDA

(or

equi

vale

nt)

appr

oval

?If

so, e

stim

ated

targ

et

date

for

appr

oval

?

Con

fiden

tial

Sel

enia

Dim

ensi

ons

2D is

so

ftw

are

upgr

adea

ble

to

3D o

pera

tion

and

has

FDA

ap

prov

al.

Sel

enia

Dim

ensi

ons

3D s

yste

m h

as b

een

subm

itted

to F

DA

Con

fiden

tial

Cur

rent

ly n

o pl

ans

to s

ubm

it fo

r FD

A

appr

oval

Est

imat

ed 2

011

No

2. Is

the

syst

em

com

mer

cial

ly

avai

labl

e?If

not,

estim

ated

ta

rget

dat

e?

Con

fiden

tial

Yes,

out

side

US

AN

ot c

omm

erci

ally

av

aila

ble

No.

Aw

aitin

g re

sults

of o

ngoi

ng

clin

ical

tria

ls

befo

re d

ecid

ing

on c

omm

erci

al

avai

labi

lity

Yes,

out

side

US

A.

Ava

ilabl

e fo

r ne

w

syst

ems

and

as a

n up

grad

e to

Mam

mom

at

Insp

iratio

n FF

DM

sy

stem

No.

Uni

t is

only

a

prot

otyp

e sy

stem

3. If

com

mer

cial

ly

avai

labl

e, n

umbe

r an

d lo

catio

n of

sys

tem

s in

stal

led

wor

ldw

ide?

Con

fiden

tial

A s

igni

fican

t num

ber

of

com

mer

cial

sys

tem

s co

verin

g al

l maj

or

Eur

opea

n co

untr

ies,

Sou

th

Am

eric

a, M

iddl

e E

ast,

Afr

ica

and

Asi

a-P

acifi

c.

Larg

e nu

mbe

r of

rese

arch

un

its in

stal

led

in U

SA

Not

com

mer

cial

ly

avai

labl

eN

/AFi

rst c

omm

erci

al

syst

ems

curr

ently

be

ing

inst

alle

d.

Thre

e te

st s

ites

with

rese

arch

pr

otot

ype

(Mal

mö,

N

ew Y

ork

and

Nor

th C

arol

ina)

.M

ore

than

20

inst

alla

tions

w

orld

wid

e

N/A

4. Is

the

syst

em C

E

mar

ked?

If no

t, es

timat

ed

targ

et d

ate?

Con

fiden

tial

Yes

Con

fiden

tial

No.

Aw

aitin

g re

sults

of

clin

ical

tria

ls b

efor

e se

ttin

g a

targ

et

date

Yes

N/A



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

5. Is

NC

CP

M

eval

uatio

n co

mpl

eted

?If

not,

estim

ated

ta

rget

dat

e?

Con

fiden

tial

Dim

ensi

ons

2D te

chni

cal

eval

uatio

n co

mpl

eted

, re

port

aw

aite

d.U

ser

eval

uatio

n on

D

imen

sion

s 2D

for

scre

enin

g un

der

way

, sh

ould

repo

rt e

arly

201

0

Con

fiden

tial

No

plan

s fo

r ev

alua

tion

until

de

cisi

on m

ade

on

com

mer

cial

isat

ion.

Test

ing

by E

UR

EF

grou

p ha

s be

en

perf

orm

ed a

s pa

rt

of H

ighR

eX E

U

proj

ect

Mam

mom

at

Insp

iratio

n 2D

te

chni

cal a

nd

clin

ical

eva

luat

ion

repo

rts

in p

ress

No

6. C

an e

xist

ing

2D

syst

ems

be u

pgra

ded

to in

corp

orat

e th

e D

BT

pack

age?

If so

, ple

ase

stat

e w

hich

2D

mod

el(s

) ca

n be

upg

rade

d

Con

fiden

tial

Sel

enia

Dim

ensi

ons

2D

can

be u

pgra

ded

to D

BT

capa

bilit

y by

lice

nce

key.

Sel

enia

Dig

ital S

yste

ms

can

be fo

rklif

t upg

rade

d to

S

elen

ia D

imen

sion

s w

hen

appr

opria

te

Sen

ogra

phe

Ess

entia

l will

be

the

plat

form

fo

r D

BT

whe

n co

mm

erci

ally

av

aila

ble

2D S

ectr

a M

icro

Dos

e L3

0 w

ill

be u

pgra

deab

le

Yes,

Mam

mom

at

Insp

iratio

nN

o, th

is is

a

dedi

cate

d D

BT

devi

ce

7. A

node

/filte

r m

ater

ials

W a

node

/Rh

filte

rW

ano

de. T

hree

filte

rs

avai

labl

e: R

h an

d A

g fo

r 2D

, Al f

or 3

D

Ano

des:

Mo

and

Rh

Filte

rs: M

o an

d R

h

W/A

lM

o/M

o, M

o/R

h, W

/R

h (2

D)

W/R

h (3

D)

W/A

l

8. D

etec

tor

type

CM

OS

act

ive

pixe

l sen

sor

dete

ctor

a-S

e de

tect

or m

ater

ial o

n a-

Si T

FT a

rray

CsI

Spe

ctra

l pho

ton

coun

ting,

cr

ysta

lline

Si

Sol

id-s

tate

de

tect

or o

f a-S

eP

hoto

n co

untin

g ga

seou

s lin

e de

tect

or

9. D

etec

tor

elem

ent

size

74.8

µm

70 µ

m ×

70

µm10

0 µm

× 1

00 µ

mLi

ne d

etec

tors

50

µm

85 µ

m60

µm

10. D

BT

proj

ectio

n ex

posu

re m

ode

Pul

sed

acqu

isiti

ons

in

cont

inuo

us s

wee

p at

va

riabl

e ve

loci

ty

Pul

sed

acqu

isiti

ons

in

cont

inuo

us s

wee

pS

tep

and

shoo

tC

ontin

uous

Con

tinuo

usC

ontin

uous

11. P

late

siz

e29

× 2

3 cm

24 c

m ×

29

cm24

cm

× 3

1 cm

24 c

m ×

26

cm24

cm

× 3

0 cm

Mul

tislit

det

ecto

r, sp

read

ove

r 24

cm

× 3

0 cm



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

12. (

a) A

ctua

l pix

el

size

(b) P

ixel

siz

e in

re

cons

truc

ted

imag

e

(a) 7

4.8

µm(b

) 74.

8 µm

× 7

4.8

µm

× 1

mm

(a) 7

0 µm

in 2

D, 1

40 µ

m in

3D

(pro

ject

ions

)(b

) 88

µm a

ppro

x. fo

r 18

× 2

4 cm

fiel

d of

vie

w.

108

µm a

ppro

x. fo

r 24

× 2

9 cm

fiel

d of

vie

w.

Mat

ched

to d

ispl

ayed

pix

el

size

for

the

2D im

age

whe

n it

is d

ispl

ayed

to fi

t to

scre

en o

n a

5 M

P m

onito

r

(a) 1

00 µ

m ×

100

µm

(b) 1

00 µ

m ×

100

µm

(a) 5

0 µm

(b) T

o be

de

term

ined

(a) 8

5 µm

(b) 8

5–10

0 µm

(v

aria

ble)

(a) 6

0 µm

(b) 6

0 µm

13. M

inim

um

reco

nstr

uctio

n sl

ice

thic

knes

s

0.5

mm

1 m

mC

onfid

entia

l1

mm

1 m

m1

mm

14. O

ptim

al s

lice

thic

knes

s1

mm

1 m

mC

onfid

entia

lC

urre

nt d

efau

lt is

sam

e as

slic

e th

ickn

ess

(3 m

m)

1 m

mN

ot c

linic

ally

ev

alua

ted

15. S

lab

thic

knes

sU

ser

confi

gura

ble

1–99

mm

sel

ecta

ble

on th

e S

ecur

View

DX

Wor

ksta

tion

Con

fiden

tial

Def

ault

is s

ame

as s

lice

thic

knes

s (3

mm

)

3, 5

, 7 m

mU

ser

confi

gura

ble

from

2 m

m to

full

brea

st th

ickn

ess

16. R

ecom

men

ded

view

ing

prot

ocol

Dep

ends

whe

ther

DB

T pr

iors

and

/or

FFD

M p

riors

ar

e av

aila

ble.

Han

ging

pr

otoc

ol c

an in

tegr

ate

FFD

M, t

omo,

MR

I and

US

View

ing

prot

ocol

defi

ned

by u

ser.

Use

r ca

n re

ad, i

n an

y or

der,

3D im

ages

from

an

y vi

ew, c

orre

spon

ding

2D

imag

es if

ava

ilabl

e an

d pr

iors

. 3D

imag

es

can

be s

crol

led

man

ually

or

aut

omat

ical

ly p

laye

d in

cin

e m

ode.

2D

and

3D

im

ages

acq

uire

d un

der

one

com

pres

sion

are

co

-reg

iste

red

for

view

ing

Con

fiden

tial

Rec

onst

ruct

ed 2

D

imag

e pu

t in

first

la

yer

follo

wed

by

full

stac

k.R

econ

stru

cted

2D

imag

e m

ay

also

be

used

fo

r co

mpa

rison

w

ith a

ny p

riors

. O

ther

wis

e pr

otoc

ols

follo

w

2D a

nd c

an b

e ad

just

ed b

ased

on

pref

eren

ce

Con

figur

able

at

syn

go

Mam

moR

epor

t w

ith T

omoV

iew

er

Not

inve

stig

ated



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

17. T

ime

from

be

ginn

ing

of fi

rst

proj

ectio

n ex

posu

re

to e

nd o

f las

t ex

posu

re

2–4

s<

4 s

Con

fiden

tial

3–10

s (e

xpos

ure

time

typi

cally

< 2

s)

< 2

5 s

18 s

18. R

otat

ion

angl

e of

sy

stem

(deg

rees

)30

0 (+

150/

–150

)+

195

to –

155

+16

5 to

–18

5–1

00/+

180

± 1

80±

100

19. R

ange

of g

antr

y an

gles

ove

r w

hich

D

BT

can

be a

cqui

red

(deg

rees

)

Full

rang

e, a

s ab

ove

Full

rang

e, a

s ab

ove

25 Det

ecto

r an

gle

for

tom

o: +

20 to

+90

(R

MLO

) or

–20

to

–90

(LM

LO)

Full

rang

e, a

s ab

ove

± 9

0±

100

20. P

roje

ctio

n ex

posu

re a

ngle

s (g

ive

each

ang

le, d

egre

es)

–20,

–15

, –11

, –7,

–4,

–2,

–1

, 0.5

, 0, 0

.5, 1

, 2, 4

, 7,

11, 1

5, 2

0

Cur

rent

com

mer

cial

co

nfigu

ratio

n ha

s 15

eq

ually

spa

ced

proj

ectio

ns(–

7.50

, –6.

43, –

5.36

, –4.

29,

–3.2

1, –

2.14

, –1.

07, 0

.00,

1.

07, 2

.14,

3.2

1, 4

.29,

5.

36, 6

.43,

7.5

0)

Con

fiden

tial

21 p

roje

ctio

ns0,

0.5

5, 1

.1, 1

.65,

2.

2, 2

.75,

3.3

, 3.8

5,

4.4,

4.9

5, 5

.5,

6.05

, 6.6

, 7.1

5, 7

.7,

8.25

, 8.8

, 9.3

5, 9

.9,

10.4

5, 1

1

± 2

5, e

very

sec

ond

degr

ee48

ang

les

spre

ad

equa

lly o

ver

±13

21. N

umbe

r of

ex

posu

res

1715

exp

osur

es o

ver

a 15

° an

gula

r ra

nge.

The

se

wer

e de

term

ined

thro

ugh

a st

udy

to b

e op

timal

pa

ram

eter

s fo

r sc

reen

ing

use.

Diff

eren

t num

ber

of

expo

sure

s an

d an

gula

r ra

nges

are

pos

sibl

e fo

r cl

inic

al s

tudi

es

950

000

exp

osur

es

for

a fu

ll im

age

owin

g to

co

ntin

uous

read

out

of 2

1 de

tect

or li

nes

25C

ontin

uous

line

ar

scan

ning

. Ang

les

defin

ed b

y po

sitio

n of

line

det

ecto

rs

22. E

xpos

ure

(mA

s) a

t ea

ch a

ngle

Varia

ble

5.88

mA

s fo

r 48

mm

co

mpr

esse

d br

east

at

28 k

V

Varia

ble.

Tot

al e

xpos

ure

is s

ubdi

vide

d in

to e

qual

ex

posu

res

at e

ach

angl

e

Varia

ble

0.03

mA

s pe

r pr

ojec

tion

Uni

form

: tot

al

mA

s/25

App

rox.

1 m

As/

angl

e



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

23. H

ow a

re

expo

sure

s co

ntro

lled?

Aut

omat

ic e

xpos

ure

cont

rol

Use

r se

lect

able

. AE

C

mod

es: A

uto

Filte

r, A

uto

kV, A

uto

Tim

e.A

lso

poss

ible

to u

se

Man

ual m

ode.

The

AE

C

mod

e al

low

s fo

r au

to-

sens

or s

elec

tion

or m

anua

l se

lect

ion

of s

enso

r re

gion

(a

nd p

ossi

bilit

ies)

Aut

omat

ic

expo

sure

con

trol

. M

anua

l kV

and

m

As

sele

ctio

n w

ill

also

be

poss

ible

Aut

omat

ic.

Adj

usts

out

put

dyna

mic

ally

bas

ed

on m

easu

red

CN

R

in th

e im

age

Aut

omat

ickV

sel

ecte

d ba

sed

on th

ickn

ess,

mA

s ba

sed

on p

re-p

ulse

Pre

sele

ctio

n ba

sed

on b

reas

t thi

ckne

ss

and

com

posi

tion

24. P

hant

om s

tudi

es:

radi

atio

n do

se a

nd

phan

tom

thic

knes

s

A s

tudy

of r

adia

tion

dose

ha

s be

en u

nder

take

n in

col

labo

ratio

n w

ith

the

Med

ical

Phy

sics

D

epar

tmen

t at R

oyal

M

arsd

en u

sing

Mon

te

Car

lo m

odel

ling.

Thi

s ha

s be

en v

alid

ated

usi

ng

phan

tom

s.Fo

r st

udy

at U

VA M

ark

Will

iam

s (A

ssoc

iate

P

rofe

ssor

of R

adio

logy

, B

iom

edic

al E

ngin

eerin

g,

and

Phy

sics

, UVA

) ch

oose

s th

e m

As

so th

at,

give

n th

e be

am s

pect

rum

ap

prop

riate

for

that

bre

ast

type

, the

MG

D is

equ

al to

or

less

than

the

aggr

egat

e M

GD

of a

n ac

tual

two-

view

FFD

M. T

his

is d

one

usin

g lo

ok-u

p ta

bles

Rad

iatio

n do

se le

vel i

n bo

th 2

D a

nd 3

D im

agin

g ca

n be

set

by

serv

ice

engi

neer

via

sel

ectio

n of

dos

e ta

bles

, allo

win

g im

agin

g w

ith a

ran

ge

of d

ose/

imag

e qu

ality

op

timiz

atio

ns d

epen

ding

on

use

r pr

efer

ence

.D

efau

lt 2D

imag

ing

dose

is

1.2

mG

y w

hen

imag

ing

the

AC

R p

hant

om (e

quiv

alen

t to

4.2

cm

50/

50 b

reas

t).

Def

ault

3D im

agin

g do

se

is 1

.45

mG

y fo

r sa

me

phan

tom

Con

fiden

tial

0.68

mG

y fo

r C

DM

AM

pha

ntom

, 6

cm P

MM

A

equi

vale

nt

1–2

mG

y fo

r 5

cm

brea

st e

quiv

alen

t P

MM

A p

hant

om,

acco

rdin

g to

cus

tom

er

pref

eren

ce

Typi

cal 1

.4 m

Gy

AG

D fo

r 45

mm



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

25. B

reas

t stu

dies

: ra

diat

ion

dose

and

br

east

thic

knes

s fo

r a

sing

le M

LO v

iew

1.26

mG

y fo

r 4.

8 cm

bre

ast

1.41

mG

y fo

r 4–

4.5

cm

brea

stS

ame

dose

as

FFD

M s

cree

ning

.E

xact

val

ues

vers

us b

reas

t th

ickn

ess

are

confi

dent

ial

0.68

mG

y fo

r st

anda

rd b

reas

t. D

ose

leve

ls w

ill b

e ad

just

ed, b

ased

on

resu

lts fr

om c

linic

al

stud

ies

1–2

mG

y fo

r a

5 cm

br

east

, acc

ordi

ng

to c

usto

mer

pr

efer

ence

1.2

mG

y fo

r 4.

0 cm

, 2

mG

y fo

r 7.

0 cm

26. M

ean

glan

dula

r br

east

rad

iatio

n do

se1.

26 m

Gy

Ave

rage

for

1900

im

ages

was

2.3

mG

y fo

r co

mpr

esse

d br

east

th

ickn

ess

of 6

.1 c

m

± 1

.4 c

m.

Con

fiden

tial

From

firs

t 100

pa

tient

s: 0

.68

mG

y pe

r vi

ew, d

ose

leve

ls n

ot fi

nalis

ed

See

abo

veTy

pica

l 1.2

mG

y fo

r 4.

0 cm

, 2 m

Gy

for

7.0

cm

27. I

mag

e pr

oces

sing

tim

e (re

cons

truc

tion

and

disp

lay)

2 m

in3–

4 s

Con

fiden

tial

< 1

5 s

in

com

mer

cial

pr

oduc

t

< 1

min

15 m

in in

pro

toty

pe

28. B

reas

t co

mpr

essi

on

(com

pare

d w

ith

stan

dard

2D

)

Sam

e as

2D

Con

figur

able

. Clin

ical

tria

l us

ed s

ame

com

pres

sion

as

2D

Sam

e as

2D

Sam

e as

2D

Pilo

t stu

dy

plan

ned

to a

sses

s ho

w re

duct

ion

in c

ompr

essi

on

affe

cts

dose

and

im

age

qual

ity

Sam

e as

2D

, co

nfigu

rabl

eLe

ss th

an 2

D,

typi

cally

bel

ow

100

N

29. H

ow is

co

mpr

essi

on

cont

rolle

d?

Mot

oris

edM

anua

lly u

sing

foot

sw

itch,

gan

try

butt

ons

or

man

ual k

nob

Mot

oris

edM

otor

ised

Opt

imis

ed

com

pres

sion

fe

atur

e (O

pcom

p)

Mot

oris

ed u

sing

fo

ot p

edal

30. M

axim

um

com

pres

sed

brea

st

thic

knes

s fo

r D

BT

imag

ing

8 cm

15.5

cm

Con

fiden

tial

10 c

m fo

r pr

otot

ype

8 cm

9 cm

31. R

econ

stru

ctio

n al

gorit

hms

Itera

tive

reco

nstr

uctio

nFi

ltere

d ba

ckpr

ojec

tion

Sim

ulta

neou

s al

gebr

aic

reco

nstr

uctio

n te

chni

ques

Itera

tive

reco

nstr

uctio

n ba

sed

on th

e La

nge–

Fess

ler

algo

rithm

Ana

lytic

, filte

red

back

proj

ectio

nIte

rativ

e re

cons

truc

tion



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

32. I

s th

e D

BT

syst

em

able

to a

cqui

re a

2D

m

amm

ogra

m in

the

sam

e co

mpr

essi

on?

Yes

Yes.

In c

ombi

ned

3D/2

D

prot

ocol

, sys

tem

acq

uire

s 3D

imag

e, re

turn

s to

0

degr

ees,

repl

aces

ant

i-sc

atte

r gr

id, a

cqui

res

a 2D

im

age.

Use

of t

he c

ombo

mod

e (2

D +

3D

) can

be

part

of

the

acqu

isiti

on w

orkfl

ow

prot

ocol

Con

fiden

tial

A re

cons

truc

ted

2D

proj

ectio

n im

age

can

be g

ener

ated

fr

om th

e sa

me

data

set a

s 3D

sl

ices

. Qua

lity

of

reco

nstr

ucte

d 2D

im

age

has

to b

e ve

rified

in c

linic

al

tria

l

Yes

No

33. R

ecom

men

ded

DB

T vi

ews

MLO

(MLO

and

CC

als

o su

ppor

ted)

MLO

and

CC

for

scre

enin

g us

e.A

dditi

onal

imag

es fo

r di

agno

stic

use

can

be

acqu

ired

in a

ny a

ngle

or

with

any

pad

dle

norm

ally

us

ed fo

r di

agno

stic

pu

rpos

es. M

agni

ficat

ion

is

not u

sed

for

DB

T

MLO

, no

need

id

entifi

ed fo

r ot

her

view

s

Aw

aitin

g re

sults

fr

om c

linic

al tr

ials

co

mpa

ring

two-

view

pro

ject

ion

mam

mog

raph

y w

ith C

C a

nd M

LO

view

DB

T as

wel

l as

MLO

onl

y D

BT

Cus

tom

er

pref

eren

ceM

LO

34. I

mag

e si

ze (M

B)

per

2D v

iew

(raw

and

pr

oces

sed

data

)

Raw

23

MB

Pro

cess

ed 2

3 M

BC

ombi

ned

46 M

B23

MB

per

imag

e us

ing

CM

OS

det

ecto

r

16 M

B (1

8 ×

24

cm)

26 M

B (2

4 ×

30

cm)

Unc

ompr

esse

d si

ze is

sa

me

raw

or

proc

esse

d.

How

ever

thes

e co

mpr

ess

diffe

rent

ly in

PA

CS

. P

roce

ssed

file

s co

mpr

ess

abou

t 3.5

:1, r

aw fi

les

abou

t 2:1

8 M

B (1

9 ×

23

cm)

14 M

B (2

4 ×

30

cm)

50 M

B r

aw a

nd

proc

esse

d20

MB

/vie

w40

MB

for

24 ×

30

cm r

aw a

nd

proc

esse

d



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

35. I

mag

e si

ze (M

B)

per

view

1. R

aw p

roje

ctio

n im

ages

tota

l2.

Pro

cess

ed

proj

ectio

n im

ages

to

tal

3. F

ull r

econ

stru

cted

da

tase

t4.

Ove

rall

tota

l

For

23 ×

29

cm:

1. 4

142.

414

3. 1

265

for

55 m

m b

reas

t4.

209

3

For

18 ×

24

cm:

1. 3

02.

8 (N

B: p

roce

ssed

pr

ojec

tion

imag

es a

re n

ot

stor

ed in

divi

dual

ly b

ut a

re

com

pres

sed

as a

DIC

OM

se

cond

ary

capt

ure

obje

ct

and

cann

ot b

e fu

rthe

r co

mpr

esse

d by

the

PAC

S.)

3. 4

0 fo

r 55

mm

bre

ast

4. 3

12 (c

anno

t be

furt

her

com

pres

sed

by th

e PA

CS

)Fo

r 24

× 3

0 cm

:1.

39

2. 1

23.

46

for

55 m

m b

reas

t4.

388

For

19 ×

23

cm1.

72

2. 7

23.

app

rox.

500

for

45 m

m b

reas

t4.

Ove

rall

tota

l is

not t

he s

um o

f all

prev

ious

item

s as

no

t all

the

data

m

ay b

e sa

ved

or s

tore

d. G

E

prod

uct s

olut

ion

is

confi

dent

ial.

For

24 ×

31

cm1.

126

2. 1

263.

app

rox

800

for

45 m

m b

reas

t with

1

mm

slic

e sp

acin

g4.

Ove

rall

tota

l is

not t

he s

um o

f all

prev

ious

item

s as

no

t all

the

data

m

ay b

e sa

ved

or s

tore

d. G

E

prod

uct s

olut

ion

is

confi

dent

ial.

For

24 ×

26

cm1.

Up

to 8

00,

depe

ndin

g on

th

ickn

ess

2. U

p to

400

3. A

ppro

x. 1

50 M

B

typi

cal

4. 1

350

for

appr

ox.

60 m

m b

reas

t

For

24 ×

30

cm:

1. 5

002.

500

3. 5

00 (d

epen

ding

on

bre

ast s

ize:

1

slic

e =

max

. 10

MB

)4.

150

0 fo

r 50

mm

br

east

For

24 ×

30

cm:

1. 4

02.

< 4

03.

< 9

80 fo

r 45

mm

ob

ject

4. <

480

0



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

36. C

an th

e sa

me

wor

ksta

tion

be u

sed

for

DB

T an

d 2D

?

Yes

Yes.

Wor

ksta

tion

is a

n ex

tens

ion

of H

olog

ic

Sec

urVi

ew w

orks

tatio

n.2D

imag

es c

an b

e re

view

ed a

s w

ith th

e S

elen

ia s

yste

m. 3

D im

age,

or

co-

regi

ster

ed 2

D/3

D

imag

es c

an b

e di

spla

yed.

S

yste

m s

uppo

rts

stan

dard

w

orks

tatio

n to

ols

for

both

2D

and

3D

. Spe

cific

3D

to

ols

incl

ude

met

hods

to

scr

oll t

hrou

gh th

e 3D

da

tase

t, ci

ne m

ode

for

auto

mat

ic s

crol

ling,

hei

ght

mea

surin

g to

ols,

2D

/3D

ov

erla

p, c

ine

scro

lling

in

mul

tiple

win

dow

s

Yes

Yes.

The

m

ulti-

mod

ality

w

orks

tatio

n al

low

s th

e ra

diol

ogis

t to

wor

k w

ith a

nd

com

pare

any

cas

e fr

om o

ne s

ingl

e w

orks

tatio

n

Yes

Yes

37. W

orks

tatio

n st

orag

e ca

paci

ty (G

B

and

num

ber

of c

ases

)

2 TB

. Upg

rade

able

as

requ

ired

1 TB

. Sto

res

appr

oxim

atel

y 45

00 c

ombi

ned

2D/3

D

imag

es

Con

fiden

tial

Con

figur

able

1 TB

New

PC

for

DB

T(In

tel Q

uad

Cor

e W

3520

, 2.6

6 G

Hz,

6

GB

RA

M,

1000

GB

)

3000

GB

, ap

prox

imat

ely

2000

cas

es

38. F

orm

at u

sed

for

imag

e st

orag

eD

ICO

M2D

: MG

3D: M

G S

econ

dary

C

aptu

re (S

C) a

nd in

201

0 w

ill s

uppo

rt D

ICO

M T

omo

IOD

(see

bel

ow)

DIC

OM

MG

en

hanc

ed

(3D

obj

ect f

or

Mam

mog

raph

y –

supp

lem

ent 1

25)

DIC

OM

DIC

OM

MG

for

proj

ectio

nsD

ICO

M C

T fo

r sl

ices

DIC

OM



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

39. C

an im

ages

be

disp

laye

d on

a P

AC

S

wor

ksta

tion?

Yes

Cur

rent

ly, H

olog

ic

supp

orts

MG

sec

onda

ry

capt

ure

form

at w

hich

ca

n be

dis

play

ed o

nly

on

a H

olog

ic w

orks

tatio

n.

Exp

ect t

o re

leas

e su

ppor

t fo

r th

e D

ICO

M S

OP

cla

ss

for

mul

tifra

me

DB

T ‘B

reas

t To

mos

ynth

esis

Imag

e S

tora

ge’ f

or m

odal

ity M

G

by s

umm

er 2

010.

Whe

n th

e PA

CS

wor

ksta

tion

also

sup

port

s th

is, i

t will

be

pos

sibl

e to

dis

play

im

ages

on

PAC

S. U

ntil

then

, ind

ivid

ual s

lices

and

an

nota

tions

can

be

save

d as

sec

onda

ry c

aptu

re

and

disp

laye

d on

PA

CS

w

orks

tatio

ns. S

tand

ard

2D

MG

imag

es c

an c

urre

ntly

be

dis

play

ed o

n PA

CS

w

orks

tatio

ns

Yes

Yes

Yes

Dep

ends

on

PAC

S

wor

ksta

tion.

Im

ages

> 2

GB

are

a

prob

lem

for

som

e w

orks

tatio

ns

40. I

s C

AD

ava

ilabl

e fo

r m

asse

s,

calc

ifica

tions

or

both

?

Not

for

DB

TIf

a 2D

imag

e is

take

n as

pa

rt o

f DB

T ac

quis

ition

, C

AD

can

be

calc

ulat

ed

from

the

2D im

ages

. 3D

C

AD

exp

ecte

d to

be

rele

ased

in 2

010

Yes

No.

Wor

k on

goin

g fo

r m

icro

calc

ifica

tions

Not

yet

for

DB

TN

o

41. A

re C

AD

mar

ks

disp

laye

d in

DB

T sl

ices

or

in 2

D im

age?

2D im

ages

onl

yC

AD

mar

ks, c

alcu

late

d fr

om th

e 2D

imag

es, c

an

be p

lace

d on

eith

er o

r bo

th o

f the

2D

and

3D

im

age

sets

. Whe

n 3D

CA

D

is re

leas

ed m

arks

will

be

disp

laya

ble

on th

e D

BT

slic

es

2D im

ages

N/A

Will

be

in s

lices

an

d on

2D

imag

esN

/A



Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

39. C

an im

ages

be

disp

laye

d on

a P

AC

S

wor

ksta

tion?

Yes

Cur

rent

ly, H

olog

ic

supp

orts

MG

sec

onda

ry

capt

ure

form

at w

hich

ca

n be

dis

play

ed o

nly

on

a H

olog

ic w

orks

tatio

n.

Exp

ect t

o re

leas

e su

ppor

t fo

r th

e D

ICO

M S

OP

cla

ss

for

mul

tifra

me

DB

T ‘B

reas

t To

mos

ynth

esis

Imag

e S

tora

ge’ f

or m

odal

ity M

G

by s

umm

er 2

010.

Whe

n th

e PA

CS

wor

ksta

tion

also

sup

port

s th

is, i

t will

be

pos

sibl

e to

dis

play

im

ages

on

PAC

S. U

ntil

then

, ind

ivid

ual s

lices

and

an

nota

tions

can

be

save

d as

sec

onda

ry c

aptu

re

and

disp

laye

d on

PA

CS

w

orks

tatio

ns. S

tand

ard

2D

MG

imag

es c

an c

urre

ntly

be

dis

play

ed o

n PA

CS

w

orks

tatio

ns

Yes

Yes

Yes

Dep

ends

on

PAC

S

wor

ksta

tion.

Im

ages

> 2

GB

are

a

prob

lem

for

som

e w

orks

tatio

ns

40. I

s C

AD

ava

ilabl

e fo

r m

asse

s,

calc

ifica

tions

or

both

?

Not

for

DB

TIf

a 2D

imag

e is

take

n as

pa

rt o

f DB

T ac

quis

ition

, C

AD

can

be

calc

ulat

ed

from

the

2D im

ages

. 3D

C

AD

exp

ecte

d to

be

rele

ased

in 2

010

Yes

No.

Wor

k on

goin

g fo

r m

icro

calc

ifica

tions

Not

yet

for

DB

TN

o

41. A

re C

AD

mar

ks

disp

laye

d in

DB

T sl

ices

or

in 2

D im

age?

2D im

ages

onl

yC

AD

mar

ks, c

alcu

late

d fr

om th

e 2D

imag

es, c

an

be p

lace

d on

eith

er o

r bo

th o

f the

2D

and

3D

im

age

sets

. Whe

n 3D

CA

D

is re

leas

ed m

arks

will

be

disp

laya

ble

on th

e D

BT

slic

es

2D im

ages

N/A

Will

be

in s

lices

an

d on

2D

imag

esN

/A

Dex

ela

ho

log

icg

es

ectr

as

iem

ens

XC

oun

ter

42. W

hat i

s th

e D

BT

syst

em s

ensi

tivity

/sp

ecifi

city

for

dete

ctio

n of

sof

t tis

sue

mas

ses?

Unk

now

nS

ensi

tivity

and

spe

cific

ity

can

be c

alcu

late

d an

d as

sum

es th

at a

forc

ed

BIR

AD

S s

core

of 4

or

5 is

con

side

red

posi

tive

and

a sc

ore

of 1

, 2 o

r 3

is c

onsi

dere

d ne

gativ

e.

(In a

forc

ed B

IRA

DS

sc

ore

0 is

not

allo

wed

.) S

ensi

tivity

and

spe

cific

ity

have

not

bee

n re

port

ed

sepa

rate

ly fo

r m

asse

s an

d m

icro

calc

ifica

tions

. Fo

r th

e co

mbi

ned

coho

rt,

com

pris

ing

appr

oxim

atel

y 50

% o

f eac

h, u

sing

2D

pl

us D

BT

vers

us 2

D a

lone

, se

nsiti

vity

impr

oved

by

10.7

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APPENDIX 3: BIBLIOGRAPHY OF PUBLICATIONS FROM MANUFACTURERS OF DIGITAL BREAST TOMOSYNTHESIS SYSTEMS

Dexela

Williams MB, Judy PG, Mitali J et al. Tomographic dual modality breast scanner. In: Krupinski EA ed. Proceedings of the 9th International Workshop on Digital Mammography, 2008. Berlin: Springer-Verlag, 2008, 5116: 99–107.

Wu T, Stewart A, Stanton M et al. Tomographic mammography using a limited number of low-dose cone-beam projection images. Med Phys, 2003, 30(3): 365–380.

GE

Buls N, Mommaerts L, Wathion I et al. Development of multi-spectrum and multi-geometry computational model for x-ray breast imaging. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Chan HP, Wei J, Zhang Y et al. Digital breast tomosynthesis (DBT) mammography: effect of number of projection views on computerized mass detection using 2D and 3D approaches. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Gennaro G. Inter-reader variability: tomosynthesis versus digital mammography. Oral presentation to RSNA, 2008, Chicago, Illinois, USA.

Gennaro G, Baldan E, Bezzon E. Clinical performance of digital breast tomosynthesis versus full-field digital mammography: preliminary results. In: Krupinski EA ed. Proceedings of the 9th International Workshop on Digital Mammography, 2008. Berlin: Springer-Verlag, 2008, 5116: 477–482.

Gennaro G, Toledano A, Baldan E et al. Clinical performance of digital breast tomosynthesis compared to digital mammography: blinded multireader study. Oral presentation to European Congress of Radiology, 2009, Vienna, Austria.

Gennaro G, Toledano A, di Maggio C et al. Digital breast tomosynthesis versus digital mammography: a clinical performance study. Eur Radiol, 2010, 20(7): 1545–1553.

Gennaro G, Dromain C, Balleyguier CS et al. Digital breast tomosynthesis vs digital mammography: analysis of discordant cancer cases. Oral presentation to ECR, 2010, Vienna, Austria.

Helvie M. Characterization of benign and malignant breast masses by digital breast tomosynthesis mammography. Oral presentation to RSNA, 2008, Chicago, Illinois, USA.



Helvie M. Research digital tomosynthesis mammography: detection of T1 invasive breast carcinomas not diagnosed by conventional breast imaging or physical exam. Oral presentation to RSNA, 2008, Chicago, Illinois, USA.

Helvie M, Hadjiiski L, Zhang Y et al. Digital breast tomosynthesis mammography: initial assessment of non-palpable microcalcifications. Oral presentation to RSNA, 2008, Chicago, Illinois, USA.

Helvie M, Chan H-P, Hadjiiski L et al. Digital breast tomosynthesis mammography: successful assessment of benign and malignant microcalcifications. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Klausz R, Souchay H. Digital tomosynthesis: finite thickness slices or tomographic planes? Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Kontos D, Ikejimba L, Bakic PR et al. Digital breast tomosynthesis parenchymal texture analysis for breast cancer estimation: results from a screening trial. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Kopans D. Calcification in digital breast tomosynthesis (DBT). Oral presentation to RSNA, 2008, Chicago, Illinois, USA.

Kopans D, Moore R. Digital breast tomosynthesis (DBT): NCI 3000 Women Trial. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Malhaire C, Thibault F, Dromain C et al. Digital breast tomosynthesis: approaching mammographic challenges. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Moore R, Kopans D. Initial callback rates for conventional and digital breast tomosynthesis mammography: comparison in the screening setting. Oral presentation to RSNA, 2007, Chicago, Illinois, USA.

Raeymaeckers S, Buls N, Souchay H et al. Image quality phantom for digital breast tomosynthesis. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Rouault S, Muller S, Iordache R et al. Designing an anthropomorphic breast phantom for breast tomosynthesis. Eur Radiol, 2009, 19: 533–586.

Roubidoux M, Rahnama-Moghadam S, Hadjiiski L et al. Digital tomosynthesis mammography compared to clinical mammogram spot views. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Souchay H, Klausz R. Out-of-plane propagation of texture as a function of acquisition parameters in digital breast tomosynthesis. Oral presentation to Tomosynthesis Imaging Symposium, 2009, Duke University, Durham, North Carolina, USA.

Souchay H, Hersemeule G, Hendrick ER. Image quality performance evaluation of digital breast tomosynthesis on GE Senographe Essential system. Oral presentation to ECR, 2010, Vienna, Austria.

Thibault F, Dromain C, Breucq C et al. Digital breast tomosynthesis (DBT): a multi-reader clinical performance study. Oral presentation to ECR, 2010, Vienna, Austria.



Williams MB, Judy PG, More MJ et al. The impact of anisotropic sampling on the MTF of reconstruction in limited aperture tomosynthesis. In: Samei E, Hsieh J eds. Physics of Medical Imaging 2009, Proceedings of SPIE, Lake Buena Vista, Florida, USA, 2009, 7258: 72581P–72581P-7.

Hologic

Good WF, Abrams GS, Catullo VJ et al. Digital breast tomosynthesis: a pilot observer study. AJR, 2008, 190: 865–869.

Gur D, Abrams GS, Chough DM et al. Digital breast tomosynthesis: observer performance study. AJR, 2009, 193(2): 586–591.

Michell M, Wasan RK, Whelehan P et al. Digital breast tomosynthesis: a comparison of the accuracy of digital breast tomosynthesis, two-dimensional digital mammography and two-dimensional screening mammography (film–screen). Breast Cancer Res 2009, 11(Suppl 2): O1.

Niklason L. Comparison of FFDM with breast tomosynthesis to FFDM alone: performance in fatty and dense breasts. Oral presentation to Tomosynthesis Imaging Symposium, 2009, Duke University, Durham, North Carolina, USA.

Niklason L. Inter-reader variability for the decision to recall and BIRADS characterization: comparing breast tomosynthesis plus FFDM to FFDM alone. Oral presentation to Tomosynthesis Imaging Symposium, 2009, Duke University, Durham, North Carolina, USA.

Poplack SP, Tosteson TD, Kogel CA, Nagy HM. Digital breast tomosynthesis: initial experience in 98 women with abnormal digital screening mammography. AJR, 2007, 189(3): 616–623.

Rafferty EA. Inter-reader variability: comparing breast tomosynthesis combined with FFDM to FFDM alone. Oral presentation to ECR Satellite Symposium, 2009, Vienna, Austria.

Rafferty EA. Multicenter, retrospective study: comparing breast tomosynthesis combined with FFDM to FFDM alone. Oral presentation to ECR Satellite Symposium, 2009, Vienna, Austria.

Rafferty EA, Niklason L, Jameson LA. Breast tomosynthesis: one view or two? Oral presentation to RSNA, 2006, Chicago, Illinois, USA.

Rafferty EA, Niklason L, Halpern E et al. Assessing radiologist performance using combined full-field digital mammography and breast tomosynthesis versus full-field digital mammography alone: results of a multi-center, multi-reader trial. Oral presentation to RSNA, 2007, Chicago, Illinois, USA.

Rafferty E, Smith A, Niklason L. Assessing radiologist performance in dense versus fatty breasts using combined full-field digital mammography and breast tomosynthesis compared to full-field digital mammography alone. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

Smith AP, Rafferty EA, Niklason L. Clinical performance of breast tomosynthesis as a function of radiologist experience level. In: Krupinski EA ed. Proceedings of the 9th International Workshop on Digital Mammography, 2008. Berlin: Springer-Verlag, 2008, 61–66.

Smith AP, Rafferty EA, Niklason L. Breast tomosynthesis reduces radiologist performance variability compared to digital mammography. Oral presentation to ECR 2009, Vienna, Austria.



Teertstra HJ, Loo CE, van den Bosch MA et al. Breast tomosynthesis in clinical practice: initial results. Eur Radiol, 2010, 20(1): 16–24.

Sectra

None.

Siemens

Andersson I, Ikeda DM, Zackrisson S et al. Breast tomosynthesis and digital mammography: a comparison of breast cancer visibility and BIRADS classification in a population of cancers with subtle mammographic findings. Eur Radiol, 2008, 18: 2817–2825.

Lo JY, Baker JA, Orman J et al. Breast tomosynthesis initial clinical experience with 100 human subjects. Oral presentation to RSNA, 2006, Chicago, Illinois, USA.

Svahn T, Andersson I, Chakraborty D et al. The diagnostic accuracy of breast tomosynthesis vs digital mammography: a free-response observer performance study. Oral presentation to RSNA, 2009, Chicago, Illinois, USA.

XCounter

Carton AK, Ullberg C. Optimization of a dual-energy contrast-enhanced technique for a photon counting digital breast tomosynthesis system. In: Krupinski EA ed. Proceedings of the 9th International Workshop on Digital Mammography, 2008. Berlin: Springer-Verlag, 2008: 116–123.

Maidment ADA, Ullberg C. Clinical evaluation of a photon-counting tomosynthesis mammography system. In: Astley SM, Brady M, Rose C, Zwiggelaar R eds. Proceedings of the 8th International Workshop on Digital Mammography, 2006. Berlin: Springer-Verlag, 2006, 4046: 144–151.

Maidment ADA, Albert M, Thunberg S et al. Evaluation of a photon-counting breast tomosynthesis imaging system. In: Flynn MJ ed. SPIE International Symposium on Medical Imaging, 2005. San Diego: SPIE, 5745: 572–582.

Maidment ADA, Ullberg C, Lindman K et al. Evaluation of a photon-counting breast tomosynthesis imaging system. In: Flynn MJ ed. SPIE International Symposium on Medical Imaging, 2006. San Diego: SPIE, 6142: 61420B.



APPENDIX 4

Manufacturers’ contact details

Dexela

Dexela Ltd Wenlock Business Centre 50–52 Wharf Road London N1 7EU

Tel: +44 (0)207 148 3107 Fax: +44 (0)207 148 3107 Web: www.dexela.com

Hologic

Hologic UK Ltd Unit 2, Link 10 Napier Way Crawley, West Sussex, RH10 9RA

Tel: +44 (0)129 352 2080 Fax: +44 (0)129 352 8010 Web: www.hologic.com

GE

GE Healthcare (UK) Pollards Wood Nightingales Lane Chalfont St Giles Bucks HP8 4SP

Tel: +44 (0)1494 545200 Web: www.gehealthcare.com

Sectra

Sectra Ltd Baird House Seebeck Place Knowlhill Milton Keynes MK5 8FR

Tel: +44 (0)1908 673107 Fax: +44 (0)1908 242904 Web: www.sectra.com

Siemens

Siemens Healthcare (UK) Newton House Sir William Siemens Square Frimley Camberley Surrey GU16 8QD

Tel: 0845 600 1966 Web: www.medical.siemens.com

XCounter

XCounter AB Svärdvägen 11 S-182 33 Danderyd Sweden

Tel: +46 8 622 23 00 Fax: +46 8 622 23 12 Web: www.xcounter.se



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