Digital Mammography Equipment Research Articles

Abstract PO4-20-01: A PROSPECTIVE PILOT STUDY OF MAMMOGRAPHIC PREDICTION OF WOMEN’S RISK (M-POWER) IN NIGERIA

Abstract Background There have been no sustained efforts at stemming the rising incidence and mortality from breast cancer in sub-Saharan African countries like Nigeria. Mammography is the gold standard for breast cancer screening and is associated with improved survival particularly among women 50 to 69. Reports from various parts of Nigeria show very low mammography screening uptake. Causes include lack of geographical access, financial issues (less than 5% of the population is covered by the National Health Insurance Scheme), lack of awareness and the increasing expertise gap from the continued brain drain, despite the already low number of radiologists in the country. Given these obstacles, our long-term goal is to devise a rational basis for identifying mammographic risk categories so that this resource can be deployed cost-effectively. We propose to carry out a 5-year prospective mammographic study in Nigerian women and to use machine learning to develop a risk prediction algorithm, so that following a single screening mammogram, the appropriate frequency of subsequent mammograms can be determined. Our immediate goal is to examine the feasibility of performing such a study. To this end, we have initiated a cross-sectional pilot study that will recruit up to 2000 women in multiple urban centers in Nigeria. Objective: To explore feasibility of creating a digital mammography image database representative of the radiological features of the breast of Nigerian women. Objective: To explore feasibility of creating a database that can be used to inform a predictive mammographic risk model for breast cancer and identify the appropriate population that will benefit from breast cancer screening in Nigeria. Design This is a prospective, open-label, cross-sectional pilot study in 2000 eligible women in Nigeria and will include a single screening mammography examination. The mammography images will be read by the study radiologist. The Pilot phase will determine the feasibility and aid in the design of the of the Extension phase in which up to 20,000 participants will undergo yearly mammography examination for 5 years. Incident cases of breast cancer during the study period will permit the development of deep learning algorithms for predicting the risk of breast cancer in this population. Main Eligibility Criteria: Inclusion Criteria All consecutive women aged ≥40 years and < 65 years presenting for screening mammography at the participating institutions will be eligible. Signed study-specific written informed consent. Exclusion Criteria Complaint of a focal dominant lump or a bloody or clear nipple discharge. History of breast implants. Any woman who is pregnant or has reason to believe that she might be pregnant. Statistical Methods Analyses of continuous data will be summarized using descriptive statistics where the following parameters will be reported: Number of observations, Number of missing observations, Mean, Median, Standard deviation (SD), Minimum (Min), Maximum (Max) Categorical data will be presented with absolute and relative frequency (n and %). Present Accrual and Target accrual Two hundred ninety-six women have been enrolled and screening digital mammographic images using GE Digital mammography equipment have been obtained on all participants at 2 study sites in 2 cities in Southern Nigeria. The target accrual is 2000 participants over 12 months. Conclusion Our preliminary experience to date suggests the feasibility of proceeding with a larger prospective study to define mammographic risk groups in Nigerian women which will permit the rational allocation of resources for breast cancer prevention activities in this underserved population. Contact Information: Dr Toyin Shonukan at tshonukan@yemanjacancercare.org Citation Format: Oluwatoyin Shonukan, Hyelakumi Ibrahim, Esther Udoh, Wahab Egbeolu, Kanyinsola Oyeyinka, Jonas Haggstrom. A PROSPECTIVE PILOT STUDY OF MAMMOGRAPHIC PREDICTION OF WOMEN’S RISK (M-POWER) IN NIGERIA [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-20-01.

Study of the performance change in digital mammography systems depending on the total number of examinations

Digital mammography equipment should operate at a high-performance level for detecting breast cancer over the lifetime of the systems. This study investigates the performance of the Fujifilm Amulet Innovality full-field digital mammography system in relation to the number of exposures. The performance of twelve systems, from new and up to 17 000 examinations, was compared. The x-ray output, half-value layer (HVL), contrast-detail (C-D) detectability, contrast-to-noise ratio (CNR), mean glandular dose (MGD), signal transfer property (STP), pre-sampled modulation transfer function (MTF), normalized noise power spectra (NNPS), detective quantum efficiency (DQE) tests were performed to determine the performance change. The noise sources were also analyzed in the spatial domain. The x-ray output and HVL values at 28 kV with tungsten anode and rhodium filter were 15 μGy/mAs ± 1.0 (coefficient of variation (cov) = 7.0%) and 0.54 mmAl ± 0.008 (cov = 1.5%), respectively. The average MGDs for 60 mm equivalent breast to reach the achievable image quality level for 0.1 mm and 0.25 mm detail diameters of circular discs on the CDMAM 3.4 phantom image were 1.17 mGy ± 0.13 (cov = 11%) and 1.40 mGy ± 0.09 (cov = 6%), respectively. The average MGD for 53 mm equivalent breast was 1.08 mGy ± 0.14 (cov = 13%) at dose setting Normal in automatic exposure control (AEC) mode. All tested devices demonstrated good linearity with R2 ≥ 0.999 in the STP curves. The average MTF at 5.0 mm−1 spatial frequency was 0.66 ± 0.007 (cov = 1.0%). The average NNPS was 2.38 × 10−6 mm2 ± 2.13 × 10−7 (cov = 9.0%) at 5.0 mm−1. The average DQE value at 5.0 mm−1 was 0.33 ± 0.02 (cov = 5.0%), and the mean peak DQE was 0.66 ± 0.03 (cov = 5.0%). The mean power coefficient (b), determined from the power relationship between linearised standard deviation and detector dose while analyzing noise sources, was 0.49 ± 0.007 (cov = 1.4%). There was no gradual change in the x-ray tube and detector performance by the number of exposures, and taking up to 68 000 images did not decrease the quality of the systems.

Construction and Analysis of a Digital Mammography Database: Analysis of Breast Compression Pressures at Four Facilities

We analyzed the compression pressures in 2772 mammography images of 807 patients acquired by digital mammography equipment at four facilities. The analysis included the average compression pressure at all facilities, difference in compression pressure at each facility, differences between the pressures used by radiological technologists in the same facility, and difference attributed to the breast structure. We also analyzed the effects of the compression pressure on the breast thickness and mean glandular dose (MGD) at each facility. The median values of the compression pressure and breast thickness for the 2772 images at all facilities were 86.5 N and 43 mm, respectively. The compression pressures differed among the institutions. The maximum difference in the median pressures among the four facilities was 38.6 N, while the difference in the breast thickness was 6 mm. The radiological technologists working at the same facility used almost the same compression pressure. However, differences between the compression pressures used by different radiological technologists were observed. The compression pressure in a dense breast was smaller than that in a non-dense breast. The difference in the compression pressure affected the breast thickness and MGD. The results of this analysis could be utilized for an optimal imaging in future digital mammography.

Determination of dose delivery accuracy and image quality in full - Field digital mammography

Accuracy of dose delivered, image quality and some technical parameters of the Fujifilm – Amuletf full field digital mammography X-ray equipment has been undertaken. The study was conducted to review the overall condition of the first full – field digital mammography equipment in Ghana with the aim of optimizing mammography practice. Quality control assessment and Mean glandular dose estimation was performed using the International Atomic Energy Agency Human Health Series 2 and 17 protocol and the European guidelines for quality assurance in breast cancer screening and diagnosis. Quantitative image analysis was performed with ImageJ software using the “Rose Model”. The results from the quality control test performed indicates that the system is functioning well. Signal-to-noise and contrast-to-noise values determined from images shows that the images are of standard quality. With the exception of 9.00 mm breast thickness which recorded a displayed Mean Glandular Dose (MGD) of 7.17 mGy, all other MGD calculated or displayed were well within the acceptable level. The percentage difference between the calculated and console displayed MGD was within the acceptable difference level of 50%. The phantom dose values obtained can be used as baseline data for future studies which can assist in setting optimization activities. The mammography X-ray equipment at the Korle-Bu teaching Hospital, Accra – Ghana is functioning under optimized conditions. It is therefore recommended for further usage.

Comparison of contrast detail phantoms in mammography

Threshold contrast visibility measurements are used in mammography to assess image quality. The CDMAM contrast detail phantom version 3.4 was used to set the European standards for quality assurance in digital mammography. As such, the phantom has been widely used to assess the threshold contrast of clinical mammography equipment across Ireland. Recently an updated version of the phantom, version 4.0, was released. The CDMAM 4.0 consists of a new layout with more disc diameters and thicknesses than its predecessor. The new version was created with the aim to be more closely adopted to the image quality found in modern mammography systems and to reduce the variability across individual phantoms. This study compares the sensitivity of the two versions of the CDMAM phantom across a range of mammography systems at clinical settings. Contrast detail measurements were taken using the different phantoms on four different makes of digital mammography equipment and images were analysed using CDMAM Analysis v2.1.0 software package. Here we present resuts of a comparison in threshold contrast sensitivity between the two versions of the phantom.

Position paper: recommendations for a digital mammography quality assurance programV4.0.

In 2001 the ACPSEM published a position paper on quality assurance in screen film mammography which was subsequently adopted as a basis for the quality assurance programs of both the Royal Australian and New Zealand College of Radiologists (RANZCR) and of BreastScreen Australia. Since then the clinical implementation of digital mammography has been realised and it has become evident that existing screen-film protocols were not appropriate to assure the required image quality needed for reliable diagnosis or to address the new dose implications resulting from digital technology. In addition, the advantages and responsibilities inherent in teleradiology are most critical in mammography and also need to be addressed. The current document is the result of a review of current overseas practice and local experience in these areas. At this time the technology of digital imaging is undergoing significant development and there is still a lack of full international consensus about some of the detailed quality control (QC) tests that should be included in quality assurance (QA) programs. This document describes the current status in digital mammography QA and recommends test procedures that may be suitable in the Australasian environment. For completeness, this document also includes a review of the QA programs required for the various types of digital biopsy units used in mammography. In the future, international harmonisation of digital quality assurance in mammography and changes in the technology may require a review of this document. Version 2.0 represented the first of these updates and key changes related to image quality evaluation, ghost image evaluation and interpretation of signal to noise ratio measurements. In Version 3.0 some significant changes, made in light of further experience gained in testing digital mammography equipment were introduced. In Version 4.0, further changes have been made, most notably digital breast tomosynthesis (DBT) testing and QC have been addressed. Some additional testing for conventional projection imaging has been added in order that sites may have the capability to undertake dose surveys to confirm compliance with diagnostic reference levels (DRLs) that may be established at the National or State level. A key recommendation is that dosimetry calculations are now to be undertaken using the methodology of Dance et al. Some minor changes to existing facility QC tests have been made to ensure the suggested procedures align with those most recently adopted by the Royal Australian and New Zealand College of Radiologists and BreastScreen Australia. Future updates of this document may be provided as deemed necessary in electronic format on the ACPSEM's website ( https://www.acpsem.org.au/whatacpsemdoes/standards-position-papers and see also http://www.ranzcr.edu.au/quality-a-safety/radiology/practice-quality-activities/mqap ).

LATIN AMERICAN IMAGE QUALITY SURVEY IN DIGITAL MAMMOGRAPHY STUDIES.

Under International Atomic Energy Agency regional programme TSA3 Radiological Protection of Patients in Medical Exposures, Latin American countries evaluated the image quality and glandular doses for digital mammography equipment with the purpose of seeing the performance and compliance with international recommendations. Totally, 24 institutions participated from Brazil, Chile, Costa Rica, El Salvador, Mexico, Paraguay and Venezuela. Signal difference noise ratio results showed for CR poor compliance with tolerances; better results were obtained for full-field digital mammography equipment. Mean glandular dose results showed that the majority of units have values below the acceptable dose levels. This joint Latin American project identified common problems: difficulty in working with digital images and lack of specific training by medical physicists from the region. Image quality is a main issue not being satisfied in accordance with international recommendations; optimisation processes in which the doses are increased should be very carefully done in order to improve early detection of any cancer signs.

Objective measurements of image quality in synchrotron radiation phase-contrast imaging versus digital mammography.

Phase-contrast mammography with synchrotron radiation is an innovative X-ray imaging practice that improves the identification of breast lesions. Previous studies have proven the superiority of the mammography images taken in the phase-contrast modality using synchrotron radiation beams as compared with images taken in conventional mammography by subjective analyses. However, to our knowledge, no previous study has compared different acquisition systems in order to quantify this improvement by means of objective robust indicators. In this research, we intend to quantify the superiority of phase-contrast imaging by means of objective metrics of image quality. Images from the American College of Radiology Mammographic Accreditation Phantom were obtained at hospitals, in two digital mammography equipment and at the Elettra synchrotron radiation facility (Trieste, Italy), using free space propagation phase-contrast modality. Regions of interest were selected to analyze image quality at the fibers (phase object) and masses (area object) simulated on the phantom by means of the signal-to-noise ratio, the figure of merit, the contrast and the edge visibility. The image contrast and edge visibility were significantly higher at the phase-contrast modality as compared with digital mammography equipment. The figure of merit using phase-contrast modality was higher for the fibers and comparable for the masses. The results showed an improvement of the contrast and edge visibility in phase-contrast images. These improvements may be important in the detection of small lesions and details.

디지털 유방촬영장비에 관한 공간선량율 평가

유방촬영장비는 여성의 조기 유방의 병변을 진단하기 위하여 필수적으로 사용되는 장비이다. 계속적인 디지털 유방촬영장치가 보급되어짐에 따라 현재에는 대부분의 의료기관에서 디지털 유방촬영장치를 사용하고 있다. 하지만 이러한 디지털장비인 CR 또는 DR 유방촬영술의 무분별한 사용으로 여성 환자의 평균유효선량이 증가되고 있다. 이번 연구는 여성환자에게 사용되는 디지털 유방촬영장비의 공간선량율을 평가하여 방사선유효선량 과다 피폭으로 인하여 발생할 수 있는 방사선 2차 피해을 인식시키고자 하였으며, 더 나아가 디지털 유방촬영장치에서 발생되는 공간선량율 측정함으로써 환자에게 직접 촬영을 하는 방사선사 안전의식을 인식시키고자 한다. 결론적으로 디지털 유방촬영장비의 공간선량은 촬영장비를 기준으로 수평으로 높은 수치를 나타내었다. 이러한 결과를 고려한다면 디지털 유방촬영장비의 설치시에 수평 방향을 피하여 방사선사의 조작위치를 변경하거나 디지털 유방촬영 장비로부터 수평으로 되는 부위에 납유리차폐의 보완이 이루어져야 할 것이다. Mammography equipment is an essential detector for making an early diagnosis of female's breast lesion. Recently, in most hospitals, a digital mammography detector is used due to the wide and consistent supply of digital mammography equipment. However, the average effective radiation is increasing due to the indiscreet use of CR or DR mammography. The purpose of this study is to recognize the possible indirect radiation damage, which can be occurred due to an excessive effective exposure of radiation, by evaluating spacial radiation rate of the digital mammography detector used for female patient. Consequently, the high mount of spacial radiation showed digital mammography equipment on the horizontal direction. Considering the result, digital mammography equipment should be installed by avoiding along the horizontal direction.

A Pilot Study on the Development of Remote Quality Control of Digital Mammography Systems in the NHS Breast Screening Programme

In the UK, physicists and radiographers perform routine quality control (QC) of digital mammography equipment at daily, weekly and monthly intervals. The tests performed and tolerances are specified by standard protocols. The manual nature of many of the tests introduces variability due to the positioning of regions of interest (ROIs) and can be time consuming. The tools on workstations provided by manufacturers limit the range of analysis that radiographers can perform and do not allow for a standard set of tools and analysis because they are specific to a given manufacturer. Automated software provides a means of reducing the variability in the analysis and also provides the possibility of additional, more complex analysis than is currently performed on the daily, weekly and monthly checks by radiographers. To this end, a set of tools has been developed to analyse the routine images taken by radiographers. As well as automatically reproducing the usual measurements by radiographers more complex analysis is provided. A QC image collection system has been developed which automatically routes QC data from a clinical site to a centralised server for analysis. A Web-based interface has been created that allows the users to view the performance of the mammographic equipment. The pilot system obtained over 3000 QC images from seven X-ray units at a single screening centre over 2 years. The results show that these tools and methods of analysis can highlight changes in a detector over time that may otherwise go unnoticed with the conventional analysis.

Technical Means of Digital Mammography

This article reviews the current state of digital mammography equipment and assesses technical requirements for its functional units.

디지털 유방영상의 CAD 알고리즘 구현

건강에 대한 관심의 증대로 의료영상이 빠르게 증가하고 있으며, 컴퓨터 기술의 발전으로 의료영상의 디지털화가 빠르게 진전되어 PACS가 의료현장에 도입되었다. 이러한 현상에 의한 의료영상 생산의 증가는 의료영상을 판독하여야 하는 영상의학과 전문의의 업무량을 증가하게 하였다. 이러한 추세에 따라 컴퓨터를 이용한 보조 진단의 필요성이 대두되어 의료영상 판독 분야에 CAD라는 용어가 생겨나게 되었다. 본 연구에서는 디지털 X-선 유방촬영장치에 의하여 획득된 영상의 판독을 위한 CAD 알고리즘을 제안하였다. 제안된 알고리즘을 Visual C++로 프로그램하여 실험하였다. 본 연구에 사용한 일곱 샘플영상을 CAD 알고리즘으로 실행한 결과 다섯 샘플의 결과는 양성종양 및 유방암으로 확인되었고 두 샘플 영상은 error처리 되었다. 본 연구에서 제시한 알고리즘과 이를 구현한 프로그램을 이용한다면 판독업무에 많은 도움이 될 것이며, 유방암의 조기발견에 크게 기여할 것으로 사료된다. Medical imaging has increased rapidly in the increase of interest in health, with the development of computer technology, digitization of medical imaging is rapidly advancing, PACS has been introduced to the medical field. Increase in the production of medical images by these phenomena made increased the workload of radiologist who must read a medical image. in response to the need for secondary diagnosis using a computer, The term of CAD in medical radiology field was introduced. In this study, we have proposed a CAD algorithm for the interpretation of the image obtained by the digital X-ray mammography equipment. The experiments were performed by programmed in Visual C++ for the proposed algorithm. A result of the execution of the CAD algorithm seven sample images, the results of five samples was confirmed in breast cancer and benign tumors, both the images sample was error processing. If you use a program that implements this with the algorithm proposed in this study it is helpful to reading breast images, and it is considered to contribute significantly to the early detection of breast cancer.

Breast Positioning during Mammography: Mistakes to be Avoided.

AIMS AND OBJECTIVESBreast positioning is the key factor affecting a mammogram. If care is taken during positioning, it maximizes the amount of breast tissue being imaged, eliminates most of the artifacts, and increases sensitivity of the mammogram. This retrospective study was carried out in our department to assess correctness, and also the incorrectness of breast positioning, which need to be avoided to obtain an ideal mammogram.MATERIAL AND METHODSA total of 1369 female patients were included in this study. Mammography was performed on full field detector digital mammography equipment. Craniocaudal (CC) view and mediolateral oblique (MLO) view were carried out for each breast. Four views were done for 1322 patients. The remaining 47 patients had undergone a mastectomy and underwent two views for the other breast. Mistakes in improperly positioned mammogram were assessed with respect to proper visualization of nipple, position of pectoralis major, pectoral–nipple distance (PND), inframammary fold, and adequate coverage of all breast quadrants.RESULTSAs per prescribed guidelines, mistakes in positioning were recognized in 2.879% of total mammograms. Improper positioning of the nipple was the commonest problem, seen in 3.827% of mammograms, CC view. On MLO view, bilaterally, pectoralis shadow was not seen in 0.520% mammograms, its margin was not straight/convex in 0.706%, lower edge of pectoralis was above pectoralis–nipple line in 2.081%, and inframammary fold was not seen in 1.189%. There was inadequate coverage of lower quadrants in 2.787%, and mismatch in PND was seen in 3.864%. In few of the patients, the shortcomings as a result of improper positioning were noted on one view, the rest being normal.CONCLUSIONPositioning is the most important factor affecting the resultant mammography image. During mammography, many cases are improperly positioned and as a result the examination is inconclusive, which reduces the sensitivity of mammography.

First application of computed radiology to mammography with synchrotron radiation

The aim of this study was to evaluate the feasibility of phase-contrast mammography with synchrotron radiation using a high-resolution computed radiology (CR) system devoted to mammography. The study was performed at the Synchrotron Radiation for Medical Physics (SYRMEP) beamline of the Elettra synchrotron radiation (SR) facility in Trieste (Italy); X-ray beams were in the range 16-22 keV with a high degree of monochromaticity and spatial coherence. The CR system evaluated is the FCR Profect CS by Fujifilm Global. The first images were obtained from test objects and surgical breast specimens. Images obtained using SR and both screen-film and the CR system were compared with images of the same samples acquired with digital mammography equipment. In view of the good quality of the results obtained, the CR system was used in two mammographic examinations with SR. Images acquired using SR and both screen-film and CR were obtained with the same level of delivered dose. Image quality obtained with CR was similar or superior to that of screen-film images. Moreover, the digital images obtained with SR were always better than those acquired using the digital mammography system. Phase-contrast mammography with SR using the studied CR system is a feasible option.

SU-E-I-147: New Digital Mammography Equipment: Physical Characterization and Image Quality Evaluation

Purpose: Recently several new digital mammography equipments with different innovative features have been proposed on the market. This work compares 7 different systems with respect to physical characteristics, phantom image quality and dose. Methods: The studied units are: Fujifilm Amulet (innovative photoconductive switching read-out), GE Senographe DS, Hologic Selenia (old and new target/filter materials), Hologic Dimensions (new filter, new tomosynthesis modality), Sectra Microdose, Siemens Mammomat Inspiration (new active matrix flat panel imager). All system detectors have been characterized in terms of MTF, NNPS and DQE according to IEC 62220-1-2. Image quality has been assessed by means of contrast detail evaluation with the phantom CDMAM ver. 3.4 and the software CDMAM Analyser for automated image analysis using the Inverse Image Quality Figure IQFinv. Dose was expressed as average glandular dose (AGD). Performances have been evaluated in clinical setup using automatic exposure control modality (AEC) and in optimized setup. Optimization was based on contrast to noise ratio (CNR) measurements.Results: DQE of all systems ranked between 55% and 80%, being higher in systems applying direct conversion technology. Generally a higher DQE reflected in a higher IQFinv score. Target/filter combinations producing spectra of higher mean energy confirmed better performances than conventional Mo/Mo ones. Photoconductive switching readout exhibited a potential average 20% dose saving; also scanning acquisition showed improved image quality at equal dose compared to standard flat panel detectors. The tomosynthesis modality allowed acquisitions with less AGD than a standard 2-view screening examination for every breast thickness. Conclusions: Generally, technological innovations allow better image quality with lower AGD.

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.

Advances in mammographic imaging

Breast imaging in the UK is currently undergoing a major change, with the widespread implementation of full-field digital mammography (FFDM) equipment. This article looks at some of the advanced imaging techniques that have become possible following the development of FFDM units. These techniques may prove to be useful additions to standard mammography for some groups of women.

Specimen Radiographs Assist in Identifying and Assessing Resection Margins of Occult Breast Carcinomas

For carcinoma specimens with non-grossly identifiable lesions such as microcalcifications, difficulties may be encountered in locating these abnormalities and sampling the margins that are at risk. This is magnified in the case of skin-sparing procedures where the margin is a much greater surface area and is the operation of choice in patients with diffuse microcalcifications and/or multifocal in situ disease. The objective of this study was to determine the efficacy of specimen radiographs of mastectomy in identifying occult carcinoma associated with microcalcifications and assessing the resection margins. We reviewed the histology and corresponding specimen radiographs of 16 patients with diffuse and widespread microcalcifications and who underwent skin-sparing mastectomy. After the specimens were serially sectioned, specimen radiographs of each section of the specimens were obtained with digital mammography equipment. Findings in the specimen radiographs were used to direct the histologic sampling of the specimens. On gross examination, two (12.5%) mastectomy specimens had identifiable discreet masses; the lesions were 4 and 7 mm, respectively. Histologic examination revealed the presence of carcinoma in 13 (81%) cases; seven with both infiltrating and in situ carcinoma and six with in situ carcinoma alone. The remaining three patients demonstrated only changes of biopsy site without any residual carcinoma. Microcalcifications were associated with in situ carcinoma in all malignant cases. Among the 12 cases with microcalcifications present at or within 2 mm of the margins, in situ carcinoma was present at the margins in three cases and located within 2 mm of the margins in two cases. All margins were negative in all cases with microcalcifications that were at least 1 cm away from the resection margins. The average number of tissue blocks examined was 16.6 +/- 5.4. The average number of tissue blocks sampled among randomly selected mastectomy specimens was 15.2 +/- 5.4. There was no statistically significant difference in the number of blocks between mastectomy cases with specimen radiographs taken and those without (t-test). Our study suggests that specimen radiographs may assist in identifying occult breast carcinoma associated with microcalcifications and assessing the resection margins without increased sampling.

SU‐FF‐I‐118: Assessment of the Spatial Resolution of Digital Imaging Systems Using a Star Pattern

Purpose: To demonstrate a method of measuring the modulation transfer function (MTF) of digital imaging systems using the common star pattern test tool. The goal of this research is to develop a technique that brings precise and objective evaluation of spatial resolution to routine quality control in radiography and fluoroscopy. Method and Materials: Images of a 2‐degree star pattern were obtained on a variety of digital radiographic imaging systems, spanning a range of spatial resolution performance levels. One‐dimensional profiles from concentric circles around the center of the star were obtained from each star image. The circular profiles were unwrapped to produce a series of square waves, which were analyzed to produce the square wave response function (SWRF). Droege's method was used to compute the MTF from the SWRF. The MTF determined using the star pattern method was compared to published and quality control measurements of the MTF for several digital mammography and digital radiography systems. In implementing this method, important parameters that must be considered include the radial and angular sampling rates, the method for determining the zero‐frequency normalization and correction for beam nonuniformity. Results: The MTF computed from star pattern profile measurements closely matched the MTF obtained using other methods over the range of spatial frequencies between the Nyquist frequency and 1/3 of the Nyquist frequency. The star pattern MTF, which is a system measurement and includes the effects of detector and geometric unsharpness, was within 6–8% of reference values obtained from the scientific literature for two models digital mammography equipment. Conclusion: Images of a 2‐degree star pattern can produce estimates of the two‐dimensional system MTF. This method may offer a convenient means of assessing the spatial resolution of digital imaging systems for acceptance testing and quality control.

Quality assurance of full field digital mammography

Developments in digital mammography equipment have been very fast: the first digital mammography system was introduced in 1999, and new systems using different physical principles have since emerged and major improvements in equipment have occurred. These improvements have solved some important quality issues that were present in some early digital mammography systems. However, image quality problems still occur relatively frequent and technical quality control is important to recognize and quantify them. Both the acceptance/6-monthly quality control tests and (at least) weekly quality control as recommended in the European Guidelines are therefore essential for high-quality mammography. In the Dutch screening programme, technical quality control is performed against the Dutch Guidelines, which are very similar to the European Guidelines for Quality Assurance in Breast Cancer Screening and Diagnosis. However, some additional tests are performed: a more extensive noise evaluation and a more precise image quality evaluation. These might be included in an update of the European Guidelines. In this presentation, some major failures, which have occurred recently, will be shown: significant additional noise (electronic and structural noise), disturbing artefacts, insufficient image quality, major ghosting, and so on. Recently the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services (Euref) started a new project to update the European Guidelines, and is performing type testing in which it is determined whether a system is able to pass the Guidelines. When buying new mammography equipment, this type testing (by Euref) might be taken into account.