Digital Mammography Units Research Articles

Evaluation of testicular tumour calcification with digital orchiography

To analyse the calcification of testicular tumours in the orchiectomy specimens detected by digital orchiography obtained in a full-field digital mammography (FFDM) unit. Orchiectomy specimens of 37 consecutive patients were imaged by FFDM. Detected foci of calcification were stratified as: type 1, dense microcalcification; type 2, faint microcalcification; type 3, macrocalcification. Histopathology identified the tumour types, the presence of intratubular germ cell neoplasia (IGCN) and associated calcifications. Orchiography results correlated with the histopathology. On orchiography, 32/37of the specimens (86 %) had co-existing foci of calcification. Histopathology results revealed foci of calcification in 23/37 (62 %) of orchiectomy specimens. Of the 20 IGCN cases, 80 % presented with calcifications on orchiography. Fifty-six percent (14/25) of type 1, 70 % (12/17) of type 2, and 30 % (2/6) of type 3 foci of calcification were observed in IGCN-positive cases. This study classifies the morphology of testicular tumour calcification in three main groups by digital orchiography. In half of the testicular cancers, histopathologically proven IGCN is also found in addition to the index tumour. Type 2 foci of microcalcification detected by orchiography may be related to IGCN and may prompt further clinical assessment. • Orchiography can detect and classify calcification in 86 % of testicular cancers. • Intratubular germ cell neoplasia (IGCN) co-exists in 54 % of testicular cancers. • Type 2 foci of microcalcification detected by orchiography may be related to IGCN. • Orchiography may play a possible future role in the diagnosis of testicular IGCN.

SU-E-P-20: Evaluation of Mean Glandular Dose From Digital Mammography Exams at Hamad Medical Corporation Qatar and Compared with International Guidance Levels

Purpose: The primary objective of this study was to measure the mean glandular dose (MGD) from craniocaudal (CC) and mediolateral oblique (MLO) views from mammography patients in Hamad Medical Corporation (HMC) and to compare them with the international guidance levels. Methods: All patients data was taken from two Selenia digital mammography units for 18 months period. Quality control was implemented for two the mammography machines and the correction actions have been done for the image quality evaluation with rejected film analysis. The total number of collected patient data was 4085 mammography exams which considered around 93% of the overall mammography procedures done in Qatar during that period. Results: Based on the IAEA selection criteria of breast thickness between 2–7 cm and kV machine value from 26 to 33 kV, only 3280 mammography procedures satisfies the above criteria and are analysed accordingly (National Centre for Cancer Care & Research (NCCCR) 949 and Hamad General Hospital‐HGH‐2331 exposures). Conclusion: Referring to the limiting dose values in the European guidelines, the results from the two mammography units showed that 94.5% and 99.7% of the mean glandular doses are acceptable from NCCCR and HGH respectively.

Scatter radiation intensities around full-field digital mammography units.

The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding.

Validation of a digital mammographic unit model for an objective and highly automated clinical image quality assessment

In mammography, image quality assessment has to be directly related to breast cancer indicator (e.g. microcalcifications) detectability. Recently, we proposed an X-ray source/digital detector (XRS/DD) model leading to such an assessment. This model simulates very realistic contrast-detail phantom (CDMAM) images leading to gold disc (representing microcalcifications) detectability thresholds that are very close to those of real images taken under the simulated acquisition conditions. The detection step was performed with a mathematical observer. The aim of this contribution is to include human observers into the disc detection process in real and virtual images to validate the simulation framework based on the XRS/DD model. Mathematical criteria (contrast-detail curves, image quality factor, etc.) are used to assess and to compare, from the statistical point of view, the cancer indicator detectability in real and virtual images. The quantitative results given in this paper show that the images simulated by the XRS/DD model are useful for image quality assessment in the case of all studied exposure conditions using either human or automated scoring. Also, this paper confirms that with the XRS/DD model the image quality assessment can be automated and the whole time of the procedure can be drastically reduced. Compared to standard quality assessment methods, the number of images to be acquired is divided by a factor of eight.

Asymmetries: Comparison Between Full Field Digital Mammography and Digital Breast Tomosyntesis

INTRODUCTION: Breast Tomosynthesis (DBT) is a procedure developed from digital mammography unit to enable the acquisition of a three-dimensional (3D) volume of thinsection data. The slice examination of breasts can reduce or even eliminate tissue overlap. The purpose of this study was to evaluate if breast tomosynthesis can help to differentiate the assymetries from the overlapping tissues. MATERIALS AND METHODS: A total of 48 cases of asymmetries were referred to perform stereotactic guided core needle biopsy or vacuum assisted biopsy. Each case was analyzed with full field digital mammography(FFDM) and with digital breast tomosynthesis (DBT) previously to the procedure. The study included 47 women (age range 34-78 years, mean age 44, 3 years;) and all the lesions were sampled. The histopathologic results were compared with those obtained with FFDM and DBT. RESULTS: of the 48 cases of asymmetries, 19 (39, 58%) did not change with DBT and 27 (60, 41%) attenuated or disappeared. Among the 19 lesions, the stereotactic guided biopsy diagnosed 8 cases of breast cancer (4 invasive ductal carcinoma, 3 invasive lobular carcinoma, 1 ductal carcinoma in situ), 1 of lobular neoplasia, 1 atypical ductal hyperplasia, 6 of fibroadenoma and 3 cases of normal breast tissue. There were no cases of breast cancer or atypical hyperplasia in those images that attenuated or disappeared with DBT. In this study the biopsy could be avoided in 60, 41% of the cases of asymmetries with the performance of the DBT. DISCUSSION: These results indicate that DBT can be useful in the differentiation between the asymmetries and the overlapping tissues, allowing a decrease in the number of unnecessary biopsies in these cases.

A study to determine the differences between the displayed dose values for two full-field digitalmammography units and values calculated using a range of Monte-Carlo-based techniques:a phantom study

Modern full-field digital mammography (FFDM) units display the mean glandular dose (MGD) and the entrance or incident air kerma (K) to the breast following each exposure. Information on how these values are calculated is limited and knowing how displayed MGD values compare and correlate to conventional Monte-Carlo-based methods is useful. From measurements done on polymethyl methacrylate (PMMA) phantoms, it has been shown that displayed and calculated MGD values are similar for thin to medium thicknesses and appear to differ with larger PMMA thicknesses. As a result, a multiple linear regression analysis on the data was performed to generate models by which displayed MGD values on the two FFDM units included in the study may be converted to the Monte-Carlo values calculated by conventional methods. These models should be a useful tool for medical physicists requiring MGD data from FFDM units included in this paper and should reduce the survey time spent on dose calculations.

Scatter Radiation Intensities about Full Field Digital Mammography (FFDM) Units

Scatter Radiation Intensities about Full Field Digital Mammography (FFDM) Units

A comparison of mean glandular dose diagnostic reference levels within the all-digital Irish nationalbreast screening programme and the Irish symptomatic breast services

Data on image quality, compression and radiation dose were collected from symptomatic breast units within the Republic of Ireland. Quantitative and qualitative data were analysed using SPSS. Recommendations of mean glandular dose (MGD) diagnostic reference levels were made at various levels for film-screen and full field digital mammography units to match levels published worldwide. MGDs received by symptomatic breast patients within Ireland are higher than those received in the all-digital Irish Breast Screening service; 55-65 mm breast: 1.75 mGy (screening) vs. 2.4 mGy (symptomatic) at the 95th percentile; various reasons are proposed for the differences. MGDs achieved in the screening service may be lower because of the exacting requirements for radiographer training, characteristics of the patients and equipment quality assurance levels. More precise imaging guidelines, standards and training of symptomatic radiographers performing mammography are suggested to remediate MGDs delivered to the breasts of Irish women attending the symptomatic breast services.

The readout thickness versus the measured thickness for a range of screen film mammography and full-field digital mammography units

To establish a simple method to determine breast readout accuracy on mammography units. A thickness measuring device (TMD) was used in conjunction with a breast phantom. This phantom had compression characteristics similar to human female breast tissue. The phantom was compressed, and the thickness was measured using TMD and mammography unit readout. Measurements were performed on a range of screen film mammography (SFM) and full-field digital mammography (FFDM) units (8 units in total; 6 different models/manufacturers) for two different sized paddles and two different compression forces (60 and 100 N). The difference between machine readout and TMD for the breast area, when applying 100 N compression force, for nonflexible paddles was largest for GE Senographe DMR+ (24 cm × 30 cm paddle: +14.3%). For flexible paddles the largest difference occurred for Hologic Lorad Selenia (18 cm × 24 cm paddle: +26.0%). None of the units assessed were found to have perfect correlation between measured and readout thickness. TMD measures and thickness readouts were different for the duplicate units from two different models/manufacturers.

OT2-05-04: ACRIN PA 4006: Comparison of Full-Field Digital Mammography with Digital Breast Tomosynthesis Image Acquisition in Relation to Screening Call-Back Rate.

Abstract Background With competing parameters of specificity and sensitivity, breast cancer screening must limit both missed cancers and false-positive call-backs (with potential to biopsy) to reduce cost and unnecessary anxiety to patients. Full-field digital mammography (FFDM) has been shown to provide improved sensitivity over analog mammography in the detection of breast cancers, particularly in women with dense breasts. Unfortunately, call-back rates for both digital and analog screening mammography have similar, elevated rates of approximately 10% (E. Pisano et al, NEJM, 2005). Incorporation of digital breast tomosynthesis (DBT), a novel 3-D reconstruction of multiple low-dose digital mammographic images, may reduce the number of call-back visits needed by providing many of the benefits of diagnostic imaging at screening. This study will assess variations in DBT image acquisition while limiting radiation dose to women with varying breast sizes and densities, to define parameters to be used in a larger national screening tomosynthesis trial. Eligibility: Asymptomatic women 25 years and older with no breast cancer history are eligible for Group A or B (see below). Pregnant women, women unable to tolerate compression of the breast associated with mammography, women with implants, and women with breasts too large for DBT are excluded from participation. Trial design/target accrual: This multicenter trial uses Hologic digital mammography units at two institutions in Philadelphia, Pennsylvania. The timing of the study-related imaging visits are segregated into two cohorts, screening (Group A) and diagnostic (Group B). Group A comprises 500 women who will undergo both FFDM and DBT at screening. Initial independent interpretations of the FFDM and DBT from local readers will determine call back. Enriched Group B comprises 50 women who have been informed of abnormal findings from a FFDM screening within 30 days of enrollment. They will be recruited prior to their diagnostic imaging and consent to DBT of both breasts as part of their diagnostic imaging. Participants from both Groups will be followed or biopsied as recommended by their treating physician. Follow up includes medical record review and images collection at approximately 1-year. Follow-up data may be collected up to 18 months. Specific aims and statistical methods: ACRIN PA 4006 will evaluate the specificity of 2-D FFDM versus a combination of 2-D and 3-D tomosynthesis imaging in breast cancer screening. Specificity will be measured by the participant call-back rate by each modality. Sensitivity and specificity by lesion-type characteristics, especially focused on DBT assessment of calcifications, will be compared. Current accrual: Currently, the trial accrual has reached 259 of 550. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT2-05-04.

Comparison of dedicated digital specimen radiography with direct digital specimen mammography images

The objective was to compare the image quality obtained from a dedicated specimen modality with the image quality from a standard direct digital mammography unit.

SU‐E‐I‐93: Comparison of the AEC Thickness Tracking Using the Signal‐ Difference‐To‐Noise Ratio in 113 Flat‐Panel Digital Mammography Units

Purpose: Signal‐difference‐to‐noise ratio (SDNR) can be served as an indicator representing the sensitivity of an x‐ray system. This study aimed to evaluate the automatic exposure control (AEC) performance using the SDNR based on the national survey data in Taiwan. Methods: Measurements were made on all the 113 flat‐panel digital mammography units in Taiwan during our 2010 national survey. They included GE Senographe 2000D (38), DS (15) and Essential (3), Hologic Selenia with Mo (20) and W (24) targets, Siemens Mammomat NovationDR(8) and Inspiration (4), and IMS Giotto Image3D (1). A disk was placed on top of the 2, 4 and 6‐cm thick acrylic blocks to simulate the contrast. Clinical AEC modes were selected to acquire images and SDNR were then measured as the mean pixel value differences between the disk and the background divided by the noise using the equation defined in ACRIN DMIST recommendations. Results: AEC systems of different manufacturers/models, or even different units with the same models resulted in different target/filter combinations and techniques when performing the thickness tracking. For example, 6‐cm thickness led to 40% Mo/Mo and 60% Mo/Rh in Hologic Selenia systems with Mo target and 4‐cm thickness led to 26% for Mo/Mo and 74% for Mo/Rh in GE 2000D systems. Decreasing SDNRs were observed when thickness increased in all the eight digital models. When normalized the mean SDNR of each model to their 4‐cm‐thickness data, large deviations between 2 cm and 6 cm were observed in the GE systems (94.7%, 87.1% and 63.0% for DS, Essential and 2000D, respectively). Deviations of the other five models ranged from 36.9% to 59.6%. Conclusions: Evaluating AEC performance using SDNR showed the decreasing trend with increasing thickness in all the eight digital models. Considering the average glandular dose together, Figure of Merit will be further investigated in the future.

SU‐E‐I‐87: Pilot Testing of Software for Automated Remote Quality Control of Digital Mammography Equipment for Use in the Ontario Breast Screening Program

Purpose: We have evaluated the feasibility of using a software package to monitor the results of quality control (QC) testing on digital mammography units in the Ontario Breast Screening Program. The intent is to make the quality control process more efficient for the technologist and physicist, and improve the consistency of test performance and results interpretation. Methods: A DICOM service class provider, “GLADYS” (originally developed at University Hospitals Leuven) was installed at pilot screening sites. All images acquired on the sitesˈ mammography systems are automatically sent to GLADYS over the PACS networks. GLADYS recognizes QC images by predetermined patient names and performs an automated analysis, measuring various parameters and generating summary thumbnail images. Clinical images are de‐identified and the technique factors and dose are extracted for tracking. The QC and dose reports are sent by email to the central monitoring site. At the central site QC image measures are plotted and thumbnail images displayed for artefact evaluation. The patient header information is stored such that dose reports can be generated. Results: GLADYS has been installed at two remote screening sites, and locally for a total of six machines. QC and dose data have been collected for the past 5.5 months. 285 QC images have been analyzed. Artefacts and changes in automatic exposure control or detector behaviour are easily perceived. Dosimetry information from 18282 patient images has been collected, with an average mean glandular dose of 1.3 mGy. Conclusions: The automated analysis works well, and reduces the technologistˈs QC workload. The addition of features to allow for automated immediate feedback to the remote sites of test results to ensure rapid response to detected problems is under development. Incorporation of centralized automatic quality control has the potential to improve the consistency and reliability of the tests and results, while streamlining QC procedures.

SU‐E‐I‐142: A Review of Digital Mammography Detector Failure Modes Encountered in Clinical Practice

Purpose: Flat panel detector failure in digital mammography systems can result in significant added operating expense, clinical down‐time and added personnel time for trouble‐shooting and acceptance testing prior to clinical use. The purpose of this study is to review modes of full‐field digital mammography detector failure and detector lifetime encountered in a clinical setting.Methods: Mammography detector history was maintained over 6 years for 3 facilities. When detector failure occurred, the reason for detector rejection and duration of detector lifetime were determined.Results: Out of the 11 digital mammography units followed during the review period, a total of 15 detector failures occurred. All rejected detectors and failure modes were verified by the manufacturer. Detector failure modes included dead pixel clusters (10), excessive ghosting (3), gate failure (1), detector crystallization (1) and charge build‐up defect (1) (One detector exhibited 2 different failure modes). Detector lifetime ranged from a minimum of 1 month (gate failure) to a maximum of 36 months (detector still in clinical use). The mean detector lifetime was 15 months Conclusions: Data from multiple digital mammography units and facilities collected over 6 years show that relatively short detector lifetime is common. Compiled detector failure data is useful for comparing ownership expense expected for different digital mammography models and to assist in determination if service contract coverage of detector replacement is advisable.

TH-B-301-01: FFDM Quality Control Testing in Canada - a Vendor-Neutral Approach

Lack of national and international standards for quality control for digital mammography dictates that users have to follow manufacturerˈs recommendations. This leads to significant additional work for facilities with digital mammography systems from multiple vendors. Therefore, a comprehensive and unified quality control test for medical physicists and mammography technologists was developed for the Screening Mammography Program of British Columbia (SMPBC), in collaboration with Ontario Breast Screening Program with the intent of using them as a national standard in Canada. The quality control tests developed for the ACRIN DMIST study were used as the starting point for the new tests; however, due to the recent implementation of AEC algorithms by some manufacturers, it has become difficult to use the uniform phantom suggested by DMIST work. To address this, a simple 19 cm diameter semicircle uniform phantom was designed. Furthermore, it was found that the technologist weekly image quality test should be performed on “FOR PRESENTATION” images so that changes in image processing algorithms (similar to changes in film processing conditions) can be identified. IHE Mammography Integration Profile compliance was also included as part of the Medical Physicists tests. The new unified quality control procedures have been adopted as the standard in the province of BC for more than two years. This unified approach has made it possible to streamline and manage the quality control of screening mammography facilities within the province. The technologist weekly image quality test done with “FOR PRESENTATION” images instead of “FOR PROCESSING” images (as suggested by ACRIN DMIST study findings) have uncovered changes in image processing algorithms that were implemented by manufacturers without the knowledge of the users. The new semicircle uniform phantom is found to be suitable for testing the AEC performance of every digital mammography unit used in the province of BC. Due to the success in the use of the new unified QC tests in the province of BC, we are in the process of promoting this as a national standard for digital mammography quality control in Canada. This presentation will provide an overview of the development and implementation of these vendor neutral unified quality control procedures and its advantages. Learning Objectives: 1. Understand the type of testing required for Digital mammography systems. 2. Understand the advantages of a unified QA procedure. 3. Understand some of the technical and logistical issues involved in implementing vendor neutral QA procedures. 4. Understand the importance of using IHE Mammography Integration Profile as part of the Medical Physicist testing.

Radiation protection of patients in diagnostic radiology: Status of practice in five Eastern-European countries, based on IAEA project

The purpose of this work was to investigate status of imaging technology and practice in five countries in Eastern-European region and evaluate the impact of IAEA projects on radiation protection of patients. Information collected using standardized IAEA protocol included status of technology, practices and patient dose levels in interventional procedure, radiography, mammography and computed tomography (CT). In spite of increased number of digital units, single phase generators or units older than 30 year are still in use. Examples of obsolete practice such as using fluoroscopy for positioning, photofluorography, chest fluoroscopy and soft-beam technique for chest radiography are also in use. Modern multi-slice CT or digital mammography units are available; however, there is lack of adequate radiation protection and medical physics support in hospitals. Information on patient doses in interventional procedures, conventional radiography, mammography and CT was collected to have baseline data and corrective measures were proposed with appropriate follow up actions taken.

Dosimetric and image quality comparison of two digital mammography units with different target/filter combinations: Mo/Mo, Mo/Rh, W/Rh, W/Ag

Our aim was to allocate a digital mammography unit to the screening programme on the basis of the ALARA (as low as reasonably achievable) radiation protection principle. Two Hologic Selenia mammography units were studied: one with a molybdenum anode and the other with a tungsten anode. After optimisation of the image production chain, we evaluated doses in a phantom under standard conditions. In this phase, we exposed a polymethyl-methacrylate (PMMA) phantom to the two mammography units and recorded the exposure parameters used by them. The phantom was subsequently replaced by a dedicated Radcal ionisation chamber on which preliminary dose assessments were conducted. Image quality of the two systems was compared by exposing a phantom containing geometrical inserts and setting the exposure parameters used for the dose assessments on each mammography unit. Dosimetric assessments of exposure data were recorded from the mammographic examinations of approximately 400 women (1,600 exposures). The unit with the tungsten anode achieved a lower patient dose. As a result, the Selenia-W device was allocated to the breast screening programme.

A novel approach to digital breast tomosynthesis for simultaneous acquisition of 2D and 3D images

The complexity of anatomical structure within the breast represents the ultimate limit to signal detection on a mammogram. To increase lesion conspicuity Digital Breast Tomosynthesis (DBT) has been recently proposed and several manufacturers are currently performing clinical trials. In this study we investigate the potential of DBT with variable dose distribution by using a phantom in which details of interest are within a heterogeneous background. To compare the performance of a commercial digital mammography unit and a DBT prototype, 2D and 3D images of the breast phantom were obtained at similar dose levels. As expected, DBT showed superior performance over digital mammography. Although certain details of interest are not detectable with digital mammography, DBT can reveal their signal by reducing the complexity of tissue structures. Additionally, the potential of the central projection in variable dose DBT is similar to the standard projection obtained with digital mammography. Finally, the uniform and variable dose approaches provided almost identical reconstructed slices. This preliminary investigation demonstrates that breast tomosynthesis acquired with variable dose distribution exhibits inherent 3D reconstruction advantages for structure noise removal and provides a 2D projection with a physical image quality close to that of standard mammography.

Evaluation of mean glandular dose in a full-field digital mammography unit in Tabriz, Iran

This study was aimed at evaluating the mean glandular dose (MGD) and affecting factors during mammography examinations by a full-field digital mammography unit. An extensive quality control program was performed to assure that the unit is properly working. Required information including compressed breast thickness (CBT), breast parenchymal pattern and technical factors used for imaging were recorded. An entrance skin exposure measurement was also performed using slabs of polymethylmethacrylate with 2-8 cm thickness. On the basis of recorded information and measured data, the MGD was estimated for 1145 mammography examinations obtained from 298 patients. Mean CBTs of 4.9 and 5.8 cm and MGDs of 2 and 2.4 mGy were observed for craniocaudal and mediolateral oblique views, respectively. Significant correlation was seen between MGD and CBT, breast parenchymal pattern and applied kVp and mAs.

Influence of Using Manual or Automatic Breast Density Information in a Mass Detection CAD System

The goal of this article is to analyze and compare the performance of a developed mass computer-aided detection (CAD) system that takes breast density information into account when using manual or automatic breast density annotations in the training step. The advantages of considering this breast density information will be highlighted. The image database used in this article is 92 mediolateral oblique (MLO) and 92 craniocaudal (CC) mammograms obtained by a full-field digital mammographic unit. All mammograms contain at least one mass. The evaluation of the experiments is performed using free receiver operating characteristic analysis for evaluating the detection performance and pixel-based receiver operating characteristic analysis for evaluating the segmentation accuracy. In addition, the performance of the automatic breast density classifier is shown using confusion matrices. When the breast density information is not considered and at a specificity of two false positives per image, the sensitivity obtained by the CAD system is 0.747 for the CC views and 0.853 for the MLO views. Considering the breast density information, the sensitivity for CC and MLO mammograms increases to 0.800 and 0.893, respectively, using manual classification, and 0.827 and 0.907, respectively, using automatic estimation. The same trend is observed when evaluating the CAD segmentation accuracy for detected masses in terms of area under the curve values: without considering breast density, these are 0.920 +/- 0.057 and 0.917 +/- 0.072; using manual classification, 0.934 +/- 0.039 and 0.932 +/- 0.046; and using automatic estimation, 0.947 +/- 0.038 and 0.946 +/- 0.045 for CC and MLO views, respectively. The experiments showed improved results when breast density information was taken into account. Moreover, the results obtained when using automatic breast density estimation outperformed those based on the manual annotations provided by expert radiologists. In this sense, the experiments showed that breast density information can be beneficial for CAD systems, and this information can be estimated robustly by an automatic procedure, which reduces the inter- and intra-class variability of the radiologists.