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PubMed2004

The value of postexcision preradiation mammography in patients with early-stage breast cancer.

The purpose of this study was to evaluate the benefit of postexcision preradiation mammography for patients with early-stage breast cancer. The records of 101 patients (103 breasts) with either ductal carcinoma in situ (DCIS) or early invasive breast cancer diagnosed based on microcalcifications on a mammogram between January 1999 and December 2001 at our institution were reviewed. Sixty-one patients had a postexcision preradiation mammogram, and 42 patients did not have a mammogram until the completion of radiation. Of the 61 patients who had a preradiation mammogram, 1 patient (2%) was found to have residual microcalcifications after the completion of chemotherapy. A core biopsy revealed DCIS, and a wide excision revealed no additional abnormalities. Of the 42 patients who underwent a postradiation mammogram, 1 patient had calcifications in the same quadrant as her original biopsy. A wide excision revealed only sclerosing adenosis. For women who receive chemotherapy before the initiation of radiation, a preradiation mammogram ought to be considered because there will frequently be a 6-month interval from the patient's lumpectomy to the initiation of radiation. However, for women scheduled to start radiation within an interval of 4 months or less, our data do not support the routine use of postexcision preradiation mammography. Although we recognize that our data may not be representative of the community at large, our observations do not support the routine use of postexcision preradiation mammography in women with small breast cancers.

Adult↗
PubMed2005

The first trial of phase contrast imaging for digital full-field mammography using a practical molybdenum x-ray tube.

RATIONALE AND OBJECTIVES: The image quality of a newly developed full-field digital phase contrast mammography (PCM) system and of a conventional screen-film (SF) mammography system were compared via images of a phantom and receiver operating characteristic (ROC) analysis of clinical images. METHODS: Magnified (1.75X) PCM images were scanned (sampling rate, 43.75 microm) and then reduced to original-sized, 25-micron pixel images printed on photothermographic film. Along with corresponding SF images, the phantom images were evaluated subjectively, and the clinical images of 38 patients were subjected to ROC analysis of mass and microcalcification. RESULTS: In the image quality of a phantom, the PCM exceeded the SF. In both mass and microcalcification, the ROC analysis Az values of the PCM clinical images surpassed those of the SF images. CONCLUSION: The PCM provides better images than the SF. Clinical trials suggest superior detection of both mass and microcalcification by full-field digital PCM over conventional SF mammography.

Breast Diseases↗
PubMed2004

Probability modeling applied to CAD systems for mammography.

A practical model based on basic probability theory is developed to evaluate the operational and financial performance of mammography systems. The model is intended to be used by decision makers to evaluate overall sensitivity, overall specificity, positive and negative predictive values, and expected cost. As an illustration, computer aided detection (CAD) systems that support a radiologist's diagnosis are compared with standard mammography to determine conditions that would support their use. The model's input parameters include the operational performance of mammography (with and without CAD), the age of the patient, the cost of administering the mammogram and the expected costs associated with false positive and false negative outcomes. Sensitivity analyses are presented that show the CAD system projecting financial benefit over ranges of uncertainty associated with each model parameter.

Breast Neoplasms↗
PubMedDate not supplied

Screening mammography controversies: resolved, partly resolved, and unresolved.

Since the 1960s, multiple randomized clinical trials have measured differences in breast cancer mortality between women 40 and 70 years of age who were offered screening mammography and control group women. This article describes briefly these trials, which nearly universally documented statistically significant reductions in breast cancer deaths. These trials also underestimated the benefit, regardless of age, due to screening parameters that were not optimized. In recent years, published articles analyzing studies of Swedish women have claimed that there is no reduction in overall mortality from breast cancer and other causes among women offered screening. Critical assessment of these articles noted that breast cancer deaths were less than 5% of all deaths and that no statistically significant reduction in overall mortality rates should be expected within the population that had been analyzed. The latest screening mammography controversies involve potential adverse consequences and risks, such as X-ray exposure, detection of ductal carcinoma in situ (DCIS), and "excessive" callback rates for additional imaging studies. Despite these controversies, the preponderance of scientific evidence continues to strongly support annual screening mammography for women 40 years of age and older.

Adult↗
PubMed1994

High detection rate of breast cancer by mass screening using mammography in Japan.

A trial of mass screening for breast cancer using both mammography and physical examination (independently) was carried out in women over 50 years of age in Tokushima Prefecture. Breast cancer was detected in eight of a total of 950 examinees by mammography alone, and no cases of breast cancer were detected by physical examination. The detection rate of breast cancer was 0.84%, which is very much higher than that obtained by conventional mass screening using physical examination alone. The detection rate increased especially in the sixth and seventh decades of life. All eight detected breast cancers were in the early stage. Based on these results, it is recommended to employ mammography in breast cancer screening for asymptomatic women aged over 50 years.

Adult↗
PubMed1999

Perceptions of screening mammography among women aged 40-49.

OBJECTIVE: The aim of this study was to survey women aged 40 to 49 to determine their perceptions of the benefits and the downsides of screening mammography for women in this age group, and the degree of support for targeting women aged 40 to 49 in the national BreastScreen program. METHOD: Telephone interviews were used in a two-stage survey of 200 women aged 40 to 49 from across Australia in 1997. Information that outlined some of the evidence for costs and effectiveness of screening in this age group was sent to the women after the first survey. RESULTS: Women saw both benefits and downsides of mammography screening in this age group. Although the proportion of women reporting downsides increased from (39%) to (69%), after reading the information most women (62%) still thought the benefits outweigh the downsides of offering a screening program to women aged 40-49 and the majority (66%) supported the notion of government funding for this. Most women agreed that women aged 40 to 49 have to be informed about all the advantages and disadvantages of screening before making a decision to attend. CONCLUSION: If women aged 40-49 were to be actively recruited to a government screening program, an information campaign should be undertaken that outlines the benefits and downsides of screening mammography to foster informed participation. IMPLICATIONS: Community views are a helpful contribution to debates about policy when existing data are ambiguous.

Adult↗
PubMed1999

A single issue program in an isolated area: mammography screening in Darwin, NT.

OBJECTIVE: A process evaluation of the Northern Territory (NT) mammography program, NT Breast Screen (NTBS), during its initial 18 months of operation. METHODS: The study was undertaken in Darwin, NT, from December 1994 to May 1996. Clinical outcomes were obtained by reviewing computerised and manual program records to determine waiting times for results, recall rates and cancer detection rates. Client satisfaction was assessed by a questionnaire sent to all women with normal results over a 12-week period. General practitioner satisfaction was assessed by a questionnaire sent to all general practitioners in the region who had one or more clients who had attended the service. RESULTS: During this time, 2,882 screening mammograms were performed; 98 women were recalled for assessment (3.4%). Breast cancer was detected in 10 women (3.5 per 1000 women screened). The program was well accepted by clients and general practitioners. Performance criteria were not met for waiting times for results. CONCLUSIONS: NTBS faced challenges because of its small and dispersed population, a lack of local radiologists with mammographic experience and the conflict with other pressing health issues, particularly in Aboriginal health. Despite these challenges, the program functioned effectively during its initial 18 months. IMPLICATIONS: Mammography screening programs in isolated areas can function effectively. The constraints encountered by NTBS are likely to apply to similar programs. Issues identified requiring further research are the psychological consequences of long waiting times for results, and the prioritisation of mammography for Aboriginal women.

Adult↗
PubMedDate not supplied

Cost-effectiveness analysis of interventions to enhance mammography compliance using computer modeling (CAN*TROL).

OBJECTIVE: Tailored telephone counseling and physician-based and clinic-based interventions have been shown to be cost-effective in enhancing utilization of mammography among nonadherent women. The objective of this study was to evaluate the costs and benefits of a broad implementation of these interventions from a health payer perspective. METHODS: CAN*TROL computer modeling was employed in the cost-effectiveness analysis of interventions in a 2000 Texas female population. The estimated effects of the various interventions and their related costs derived from the literature were applied to a hypothetical scenario of a broad implementation of these interventions. RESULTS: Seven studies were identified from the literature, six of them employed tailored telephone counseling (TC), whereas two used comprehensive physician-based (PB) or clinic-based (CB) interventions. The estimated intervention cost per women was 43 dollars for TC, 71 dollars for PB, and 151 dollars for CB. CAN*TROL model showed that after 15 years of implementation, TC, PB, and CB could reduce cancer mortality by 6.5, 2.2, and 10.7%, respectively. The cumulative net costs of interventions, mammography screening, and medical care costs were lower for TC (TC vs. PB vs. CB, 1.05 million vs. 1.06 million vs. 1.60 million). Nevertheless, CB resulted in more life-years saved (TC vs. PB vs. CB, 11,413 vs. 8515 vs. 14,559). The incremental cost-effectiveness ratio was more favorable for tailored telephone counseling interventions. One-way sensitivity analysis indicated that compliance rates and intervention costs had the most significant impact on the incremental cost-effectiveness ratio. CONCLUSION: Tailored telephone counseling interventions may be the preferred first-line intervention for getting nonadherent women aged 50 to 79 years on schedule for mammography screening.

Aged↗
PubMed1995

Physician-reported determinants of screening mammography in older women: the impact of physician and practice characteristics.

OBJECTIVE: Despite having markedly higher breast cancer risk, compliance of older women with screening mammography has been poor. This study was undertaken to determine which physician and patient practice characteristics were associated with high self-reported mammography referral rates for older women. METHODS: Primary care physicians (n = 129) from three socioeconomically diverse communities in Los Angeles were surveyed. Agreement with annual screening and self-reported referral rates were assessed for two groups of women, those 65 to 74 years of age and those 75 years and older. Screening outcomes were compared with physician and patient practice characteristics using bivariate and multivariate techniques. RESULTS: Although 73% of physicians agreed with annual screening of women aged 65 to 74 years, only 24% of physicians reported actually screening most women seen in this age group. Similarly, 57% of physicians agreed that women age 75 years and older should be screened annually, but only 21% reported recommending mammograms for most women seen in this age group. In multivariate analysis, white physicians (adjusted OR = 9.1), younger physicians (adjusted OR = 3.85), and those who used the American Cancer Society's low cost mammography projects (adjusted OR = 5.01) were more likely to report screening the majority of women seen. DISCUSSION: This study suggests that although physicians' intentions to screen older women may be relatively high, a gap exists between intentions and what is reported to be accomplished in practice. Race/ethnicity and physician specialty were the two strongest predictors of high self-reported referral rates, suggesting that targeted interventions may be useful.

Age Factors↗
PubMed1999

Pacemaker interference with screening mammography.

In female pacemaker recipients undergoing screening mammography, the impact of a pulse generator placed in the pectoral region has yet to be reviewed. We evaluated mammograms from 74 female pacemaker patients aged 40 years and older. The pulse generator obscured a portion of the mammogram in 7 patients (12%). During pacemaker implantation in women, the potential for the pulse generator to interfere with screening mammography should be considered. Baseline mammography should be obtained or reviewed; in high risk patients a nonconventional location for the pulse generator may be appropriate.

Adult↗
PubMed2003

Rural-urban differences in ductal carcinoma in situ as a proxy for mammography use over time.

CONTEXT: With emphasis on increasing use of mammography, the rate of ductal carcinoma in situ (DCIS) of the breast has increased dramatically in the United States starting in the early 1980s. It is unclear if rural and urban women have experienced similar increases. PURPOSE: To describe differences in incidence of DCIS between rural and urban women 50 to 69 years of age over time. This may be a proxy indicator of mammography use for the early detection of breast cancer. METHODS: The study population consisted of women 50 to 69 years of age who were diagnosed with DCIS during 1973-1997 and resided in Iowa, Utah, or New Mexico. Data from the Surveillance, Epidemiology, and End Results (SEER) programs in these states were used in the analysis. Location of the woman's residence was classified into urban when she lived in a county considered a Metropolitan Statistical Area, while she was considered rural if she resided elsewhere at the time of her diagnosis. FINDINGS: Increases in rates were different between rural (annual percentage change [APC]: 15.1) and urban women (APC: 34.4). During the 1990s among urban women, the rate of DCIS was still increasing (APC: 3.8), while there was no increase among rural women (APC: 0.2). Differences between rural and urban women within these 3 states were also identified. CONCLUSIONS: The data suggest differences in utilization of mammography between both populations; the increase was lower and started later for rural women. Possible reasons for such differences over time are discussed.

Aged↗
PubMed2000

Scatter/primary in mammography: comprehensive results.

Monte Carlo procedures using the SIERRA code (validated in a companion article) were used to investigate the scatter properties in mammography. The scatter to primary ratio (SPR) was used for quantifying scatter levels as a function of beam spectrum, position in the field, air gap, breast thickness, tissue composition, and the area of the field of view (FOV). The geometry of slot scan mammography was also simulated, and SPR values were calculated as a function of slot width. The influence of large air gaps (to 30 cm) was also studied in the context of magnification mammography. X-ray energy and tissue composition from 100% adipose to 100% glandular demonstrated little effect on the SPR. Air gaps over a range from 0 to 30 mm showed only slight effects. The SPR increased with increased breast thickness and with larger fields of view. Measurements from 82 mammograms provided estimates of the range of compressed breast thickness (median: 5.2 cm, 95% range: 2.4 cm to 7.9 cm) and projected breast area onto the film (left craniocaudal view, median: 146 cm2, 95% range: 58 cm2 to 298 cm2). SPR values for semicircular breast shapes, Mo/Mo spectra, and a 15 mm air gap were parametrized as a function of breast thickness and (semicircular) breast diameter. With the coefficients a = - 2.35452817439093, b = 22.3960980055927, and c = 8.85064260299289, the equation SPR= [a + b x (diameter in cm)--(-1.5) + c x (thickness in cm) --(-0.5)]-- -1 produces SPR data from 2 to 8 cm and from 3 to 30 cm breast diameters with an average error of about 1%.

Air↗
PubMed2001

A survey of clinical factors and patient dose in mammography.

A survey was conducted to estimate the mean glandular dose (MGD) for women undergoing mammography and to report the distribution of doses, compressed breast thickness, glandular tissue content, and mammographic technique factors used. From 24,471 mammograms, of 6,006 women, clinical data were collected. The survey data included mammograms from seven modern units using a molybdenum (Mo) anode and either Mo or rhodium (Rh) filter. Exposure factors for each mammogram were recorded automatically onto a floppy disk on each unit. All mammography units were calibrated individually using breast tissue equivalent attenuation slabs of varying glandular content, so the breast glandular content could be estimated on the basis of exposure factors and compressed breast thickness. The MGD was estimated for each mammogram based on the normalized glandular dose and calculated entrance exposure in air. The survey found a median MGD of 2.6 mGy. The median breast glandular tissue content was 28% and the median compressed breast thickness was 5.1 cm. Also, patient attenuation data were converted to equivalent BR-12 and acrylic thickness to help determine appropriate phantom thicknesses required for mammography unit automatic exposure control performance assessment.

Breast↗
PubMed2003

Evaluation of detector dynamic range in the x-ray exposure domain in mammography: a comparison between film-screen and flat panel detector systems.

Digital detectors in mammography have wide dynamic range in addition to the benefit of decoupled acquisition and display. How wide the dynamic range is and how it compares to film-screen systems in the clinical x-ray exposure domain are unclear. In this work, we compare the effective dynamic ranges of film-screen and flat panel mammography systems, along with the dynamic ranges of their component image receptors in the clinical x-ray exposure domain. An ACR mammography phantom was imaged using variable mAs (exposure) values for both systems. The dynamic range of the contrast-limited film-screen system was defined as that ratio of mAs (exposure) values for a 26 kVp Mo/Mo (HVL=0.34 mm Al) beam that yielded passing phantom scores. The same approach was done for the noise-limited digital system. Data from three independent observers delineated a useful phantom background optical density range of 1.27 to 2.63, which corresponded to a dynamic range of 2.3 +/- 0.53. The digital system had a dynamic range of 9.9 +/- 1.8, which was wider than the film-screen system (p<0.02). The dynamic range of the film-screen system was limited by the dynamic range of the film. The digital detector, on the other hand, had an estimated dynamic range of 42, which was wider than the dynamic range of the digital system in its entirety by a factor of 4. The generator/tube combination was the limiting factor in determining the digital system's dynamic range.

Breast Neoplasms↗
PubMed2004

On the noise variance of a digital mammography system.

A recent paper by Cooper et al. [Med. Phys. 30, 2614-2621 (2003)] contains some apparently anomalous results concerning the relationship between pixel variance and x-ray exposure for a digital mammography system. They found an unexpected peak in a display domain pixel variance plot as a function of 1/mAs (their Fig. 5) with a decrease in the range corresponding to high display data values, corresponding to low x-ray exposures. As they pointed out, if the detector response is linear in exposure and the transformation from raw to display data scales is logarithmic, then pixel variance should be a monotonically increasing function in the figure. They concluded that the total system transfer curve, between input exposure and display image data values, is not logarithmic over the full exposure range. They separated data analysis into two regions and plotted the logarithm of display image pixel variance as a function of the logarithm of the mAs used to produce the phantom images. They found a slope of minus one for high mAs values and concluded that the transfer function is logarithmic in this region. They found a slope of 0.6 for the low mAs region and concluded that the transfer curve was neither linear nor logarithmic for low exposure values. It is known that the digital mammography system investigated by Cooper et al. has a linear relationship between exposure and raw data values [Vedantham et al., Med. Phys. 27, 558-567 (2000)]. The purpose of this paper is to show that the variance effect found by Cooper et al. (their Fig. 5) arises because the transformation from the raw data scale (14 bits) to the display scale (12 bits), for the digital mammography system they investigated, is not logarithmic for raw data values less than about 300 (display data values greater than about 3300). At low raw data values the transformation is linear and prevents over-ranging of the display data scale. Parametric models for the two transformations will be presented. Results of pixel variance measurements made on raw data images will be presented. The experimental data are in good agreement with those of Cooper et al. It will be shown that the slope of 0.6 found by Cooper et al. for the log-log plot at low exposure is not due to transfer function nonlinearity, it occurs because of an additive variance term-possibly due to electronic noise. It will also be shown, using population statistics from clinical images, that raw data values below 300 are rare in tissue areas. Those tissue areas with very low raw data values are within about a millimeter of the chest wall or in very dense muscle at comers of images.

Breast Neoplasms↗
PubMed2005

A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography.

In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations and does not exceed 75% for the leakage radiation.

Algorithms↗
PubMed2005

Assessment of different computational models for generation of x-ray spectra in diagnostic radiology and mammography.

Different computational methods based on empirical or semi-empirical models and sophisticated Monte Carlo calculations have been proposed for prediction of x-ray spectra both in diagnostic radiology and mammography. In this work, the x-ray spectra predicted by various computational models used in the diagnostic radiology and mammography energy range have been assessed by comparison with measured spectra and their effect on the calculation of absorbed dose and effective dose (ED) imparted to the adult ORNL hermaphroditic phantom quantified. This includes empirical models (TASMIP and MASMIP), semi-empirical models (X-rayb&m, X-raytbc, XCOMP, IPEM, Tucker et al., and Blough et al.), and Monte Carlo modeling (EGS4, ITS3.0, and MCNP4C). As part of the comparative assessment, the K x-ray yield, transmission curves, and half value layers (HVLs) have been calculated for the spectra generated with all computational models at different tube voltages. The measured x-ray spectra agreed well with the generated spectra when using X-raytbc and IPEM in diagnostic radiology and mammography energy ranges, respectively. Despite the systematic differences between the simulated and reference spectra for some models, the student's t-test statistical analysis showed there is no statistically significant difference between measured and generated spectra for all computational models investigated in this study. The MCNP4C-based Monte Carlo calculations showed there is no discernable discrepancy in the calculation of absorbed dose and ED in the adult ORNL hermaphroditic phantom when using different computational models for generating the x-ray spectra. Nevertheless, given the limited flexibility of the empirical and semi-empirical models, the spectra obtained through Monte Carlo modeling offer several advantages by providing detailed information about the interactions in the target and filters, which is relevant for the design of new target and filter combinations and optimization of radiological imaging protocols.

Computer Simulation↗
PubMed2005

Validation of MTF measurement for digital mammography quality control.

The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography systems, and contained intrinsic system factors that could affect the MTF accuracy, such as noise, scatter, and flat-field nonuniformities. Our algorithm is not influenced by detector dose variations for MTF accuracy up to 1/2 the sampling frequency. We investigated several methods for noise reduction, including truncating the supersampled line spread function (LSF), windowing the LSF, applying a local exponential fit to the LSF, and applying a monotonic constraint to the supersampled edge spread function. Only the monotonic constraint did not introduce a systematic error; the other methods could result in MTF underestimation. Overall, our edge method consistently computed MTFs which were in good agreement with the true MTF. The edge method was then applied to images from a commercial storage-phosphor based digital mammography system. The calculated MTF was affected by the size (sides of 2.5, 5, or 10 cm) and the composition (lead or tungsten) of the edge device. However, the effects on the MTF were observed only with regard to the low frequency drop (LFD). Scatter nonuniformity was dependent on edge size, and could lead to slight underestimation of LFD. Nevertheless, this negative effect could be minimized by using an edge of 5 cm or larger. An edge composed of lead is susceptible to L-fluorescence, which causes overestimation of the LFD. The results of this work are intended to underline the need for clear guidelines if the MTF is to be given a more crucial role in acceptance tests and routine assessment of digital mammography systems: the MTF algorithm and edge object test tool need to be publicly validated.

Algorithms↗