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R E Hendrick

Publications and source records attributed to R E Hendrick.

At least 19 recordsLinked to original sources
PubMed2001

Relationship between phantom failure rates and radiation dose in mammography accreditation.

The American College of Radiology Mammography Accreditation Program (ACR MAP) reviews both clinical mammograms and a phantom image to assess clinical and technical quality from each mammography unit. The phantom contains details representing fibers (speculations), speck groups (microcalcifications), and masses. The depiction of these structures by the mammographic system is scored by medical physicists. The phantom image is taken using the facility's exposure technique for a 4.2-cm thick breast of average composition. The mean glandular dose (MGD) is determined from a set of thermoluminescent dosimeters placed on top of the chest wall edge of the phantom. Phantom scores and MGD data collected from 1993 to 1999 based on 31 535 unit evaluations are presented in this paper. The relationship between the failure rate for phantom image quality and MGD has been analyzed. While over all doses the phantom failure rate was 11%, for doses of 0.26 to 0.50 mGy the failure rate was 43%. The phantom failure rate fell continuously to about 6% for MGDs in the range of 1.51-2.0 mGy. With further increases in dose, failure rates began to rise. Factors that may account for these results are presented and discussed.

Dose-Response Relationship, Radiation↗
PubMed2001

Comparison of full-field digital mammography with screen-film mammography for cancer detection: results of 4,945 paired examinations.

PURPOSE: To prospectively compare full-field digital mammography (FFDM) with screen-film mammography (SFM) for cancer detection in a screening population. MATERIALS AND METHODS: At two institutions, 4,945 FFDM examinations were performed in women aged 40 years and older presenting for SFM. Two views of each breast were acquired with each modality. SFM and FFDM images were interpreted independently. Findings detected with either SFM or FFDM were evaluated with additional imaging and, if warranted, biopsy. RESULTS: Patients in the study underwent 152 biopsies, which resulted in the diagnosis of 35 breast cancers. Twenty-two cancers were detected with SFM and 21 with FFDM. Four were interval cancers that became palpable within 1 year of screening and were considered false-negative findings with both modalities. The difference in cancer detection rate was not significant. FFDM had a significantly lower recall rate (11.5%; 568 of 4,945) than SFM (13.8%; 685 of 4,945) (P <.001, McNemar chi(2) model; P <.03, generalized estimating equations model). The positive biopsy rate for findings detected with FFDM (30%; 21 of 69) was higher than that for findings detected with SFM (19%; 22 of 114), but this difference was not significant. CONCLUSION: No difference in cancer detection rate has yet been observed between FFDM and SFM. FFDM has so far led to fewer recalls than SFM.

Biopsy↗
PubMed2001

Rates and causes of disagreement in interpretation of full-field digital mammography and film-screen mammography in a diagnostic setting.

OBJECTIVE: This study was performed to determine the rates and causes of disagreements in interpretation between full-field digital mammography and film-screen mammography in a diagnostic setting. SUBJECTS AND METHODS: Patients undergoing diagnostic mammography were invited to participate in the digital mammography study. Three views, selected by the radiologist interpreting the film-screen mammography, were obtained in both film-screen mammography and digital mammography. Radiologists independently assigned a Breast Imaging Reporting and Data System (BI-RADS) category to the film-screen mammography and the digital mammography images. The BI-RADS categories were grouped into the general categories of agreement, partial agreement, or disagreement. A third and different radiologist reviewed all cases of disagreement, reached a decision as to management, and determined the primary cause of disagreement. RESULTS: Six radiologists reviewed digital mammography and film-screen mammography diagnostic images in a total of 1147 breasts in 692 patients. Agreement between digital mammography and final film-screen mammography assessment was present in 937 breasts (82%), partial agreement in 159 (14%), and disagreement in 51 (4%), for a kappa value of 0.29. The primary causes of disagreement were differences in management approach of the radiologists (52%), information derived from sonography or additional film-screen mammograms (34%), and technical differences between the two mammographic techniques (10%). CONCLUSION: Significant disagreement between film-screen mammography and digital mammography affecting follow-up management was present in only 4% of breasts. The most frequent cause of disagreement in interpretation was a difference in management approach between radiologists (interobserver variability). This source of variability was larger than that due to differences in lesion visibility between film-screen mammography and digital mammography.

Adult↗
PubMed2000

Correlation of high-resolution breast MR imaging with histopathology; validation of a technique.

A high-resolution three-dimensional surface gradient coil set was used to obtain magnetic resonance (MR) images of breast specimens, using a gradient-echo pulse sequence (TR/TE 1000/8 msec, flip angle 75 degrees), with 117 micrometer in-plane resolution and 1 mm slice thickness. Breast tissues were obtained from one autopsy and three surgical specimens. High-resolution breast MR images and histopathology sections (7 micrometer thickness) were acquired in the same anatomical plane. Radiographs were acquired of the sliced specimens (approximately 5 mm thick) so that images from all three methods could be correlated. It was found that in vitro high-resolution breast MRI correlated well with low-resolution microscopic histology, demonstrating normal anatomy (lobules, ducts, connective tissue strands, blood vessels) and pathology (tumor content, margins, and presence of microcalcifications) of the breast more clearly than conventional pre-gadolinium breast MRI. High-resolution breast MRI may improve specificity, when added to a conventional breast MRI protocol.

Biopsy↗
PubMed2000

Breast imaging using an amorphous silicon-based full-field digital mammographic system: stability of a clinical prototype.

An amorphous silicon-based full-breast imager for digital mammography was evaluated for detector stability over a period of 1 year. This imager uses a structured CsI:TI scintillator coupled to an amorphous silicon layer with a 100-micron pixel pitch and read out by special purpose electronics. The stability of the system was characterized using the following quantifiable metrics: conversion factor (mean number of electrons generated per incident x-ray), presampling modulation transfer function (MTF), detector linearity and sensitivity, detector signal-to-noise ratio (SNR), and American College of Radiology (ACR) accreditation phantom scores. Qualitative metrics such as flat field uniformity, geometric distortion, and Society of Motion Picture and Television Engineers (SMPTE) test pattern image quality were also used to study the stability of the system. Observations made over this 1-year period indicated that the maximum variation from the average of the measurements were less than 0.5% for conversion factor, 3% for presampling MTF over all spatial frequencies, 5% for signal response, linearity and sensitivity, 12% for SNR over seven locations for all 3 target-filter combinations, and 0% for ACR accreditation phantom scores. ACR mammographic accreditation phantom images indicated the ability to resolve 5 fibers, 4 speck groups, and 5 masses at a mean glandular dose of 1.23 mGy. The SMPTE pattern image quality test for the display monitors used for image viewing indicated ability to discern all contrast steps and ability to distinguish line-pair images at the center and corners of the image. No bleeding effects were observed in the image. Flat field uniformity for all 3 target-filter combinations displayed no artifacts such as gridlines, bad detector rows or columns, horizontal or vertical streaks, or bad pixels. Wire mesh screen images indicated uniform resolution and no geometric distortion.

Female↗
PubMed2000

Optimizing techniques in screen-film mammography.

This article provides a practical approach to the steps needed to optimize mammography techniques. Those steps consist of a series of activities that begin with the choice of mammography film, then choosing the optimum film processing for that film type, selecting the appropriate technique factors for exposure, and the proper viewing of processed mammography films. In each area, the basic physics underlying film and film processing, mammography equipment performance, image contrast, and image display, are used to determine optimized mammography techniques.

Data Display↗
PubMed2000

Full breast digital mammography with an amorphous silicon-based flat panel detector: physical characteristics of a clinical prototype.

The physical characteristics of a clinical prototype amorphous silicon-based flat panel imager for full-breast digital mammography have been investigated. The imager employs a thin thallium doped CsI scintillator on an amorphous silicon matrix of detector elements with a pixel pitch of 100 microm. Objective criteria such as modulation transfer function (MTF), noise power spectrum, detective quantum efficiency (DQE), and noise equivalent quanta were employed for this evaluation. The presampling MTF was found to be 0.73, 0.42, and 0.28 at 2, 4, and 5 cycles/mm, respectively. The measured DQE of the current prototype utilizing a 28 kVp, Mo-Mo spectrum beam hardened with 4.5 cm Lucite is approximately 55% at close to zero spatial frequency at an exposure of 32.8 mR, and decreases to approximately 40% at a low exposure of 1.3 mR. Detector element nonuniformity and electronic gain variations were not significant after appropriate calibration and software corrections. The response of the imager was linear and did not exhibit signal saturation under tested exposure conditions.

Algorithms↗
PubMed1998

Improvement in mammography quality control: 1987-1995.

PURPOSE: To assess possible changes in quality control (QC) practices at mammography sites in the United States. MATERIALS AND METHODS: Mammography site surveys were conducted in 1990, 1992, and 1995 through the Colorado Mammography Advocacy Project (CMAP). Data from mammography sites applying for American College of Radiology (ACR) accreditation were collected between August 1987 and August 1993 through the ACR Mammography Accreditation Program. Data from both of these surveys were analyzed to assess temporal changes in mammography QC practices in the United States between 1987 and 1995. RESULTS: CMAP results indicated statistically significant improvement in medical physicist QC practices between 1990 and 1992 and in technologist QC practices between 1990 and 1995. Improvements in radiologic technologist QC practices coincided with increases in radiologic technologist continuing education in mammography. ACR results indicated statistically significant improvement in technologist QC practices between 1988 and 1992. CONCLUSION: There have been substantial improvements in QC practices at mammography sites in the United States during the past decade.

Chi-Square Distribution↗
PubMed1997

Radiation risk from screening mammography of women aged 40-49 years.

Although direct evidence of carcinogenic risk from mammography is lacking, there is a hypothetical risk from screening because excess breast cancers have been demonstrated in women receiving doses of 0.25-20 Gy. These high-level exposures to the breast occurred from the 1930s to the 1950s due to atomic bomb radiation, multiple chest fluoroscopies, and radiation therapy treatments for benign disease. Using a risk estimate provided by the Biological Effects of Ionizing Radiation (BEIR) V Report of the National Academy of Sciences and a mean breast glandular dose of 4 mGy from a two-view per breast bilateral mammogram, one can estimate that annual mammography of 100,000 women for 10 consecutive years beginning at age 40 will result in at most eight breast cancer deaths during their lifetime. On the other hand, researchers have shown a 24% mortality reduction from biennial screening of women in this age group; this will result in a benefit-to-risk ratio of 48.5 lives saved per life lost and 121.3 years of life saved per year of life lost. An assumed mortality reduction of 36% from annual screening would result in 36.5 lives saved per life lost and 91.3 years of life saved per year of life lost. Thus, the theoretical radiation risk from screening mammography is extremely small compared with the established benefit from this life-saving procedure and should not unduly distract women under age 50 who are considering screening.

Adult↗
PubMed1997

Benefit of screening mammography in women aged 40-49: a new meta-analysis of randomized controlled trials.

Eight randomized controlled trials (RCTs) of screening mammography have been conducted involving women aged 40-49 at entry. Current data are now available from these trials at 10.5 to 18 years of follow-up (average follow-up time: 12.7 years). Meta-analysis has been performed using a Mantel-Haenszel estimator method to combine current follow-up data from the eight RCTs of mammography that included women aged 40-49 at entry, including new follow-up data presented at the NIH Consensus Development Conference held January 21-23, 1997. Combining the most recent follow-up data on women aged 40-49 at entry into all eight RCTs yields a statistically significant 18% mortality reduction among women invited to screening mammography (relative risk: 0.82; 95% confidence interval: 0.71-0.95). Combining all current follow-up data on women aged 40-49 at entry into the five Swedish RCTs yields a statistically significantly 29% mortality reduction among women invited to screening (relative risk: 0.71; 95% confidence interval: 0.57-0.89). Meta-analysis including the most recent follow-up data from all eight RCTs involving women aged 40-49 at entry demonstrates for the first time a statistically significant mortality reduction due to regular screening mammography in women of this age group.

Adult↗
PubMed1995

Benefit of mammography screening in women ages 40 to 49 years. Current evidence from randomized controlled trials.

BACKGROUND: Eight randomized controlled trials (RCTs) of screening mammography were conducted involving women ages 40 to 49 years at entry. Current data gathered for periods ranging from 7 to 18 years of follow-up are available from these trials. METHODS: Meta-analyses were performed using a Mantel-Haenszel estimator method to combine current follow-up data from the eight RCTs of mammography that included women ages 40 to 49 years. RESULTS: Combining all current data on women ages 40 to 49 years at entry into the trials yielded a 16% [corrected] benefit from screening mammography, without statistical significance at the 95% confidence level. Combining all data on women ages 40 to 49 years at entry, excluding results from the Canadian National Breast Screening Study, yielded a 24% [corrected] benefit to women invited for screening, with statistical significance at the 95% confidence level. CONCLUSIONS: These results suggest that screening mammography in women ages 40 to 49 years at entry can reduce mortality from breast cancer when combined with adequate follow-up.

Adult↗
PubMed1995

Recommended specifications for new mammography equipment: report of the ACR-CDC Focus Group on mammography equipment.

The American College of Radiology has published a report that describes desirable features for new mammography x-ray units that will contribute to high-quality imaging. It encompasses all aspects of x-ray equipment performance including mechanical considerations, the x-ray tube focal spot and spectrum, generator performance, collimation, scatter rejection, and the automatic exposure control. The report is intended to provide guidance to equipment manufacturers and to purchasers of mammography systems with regard to basic performance levels that should be expected.

Female↗
PubMed1995

A proposal for a national mammography database: content, purpose, and value.

A national mammography database is a centralized, computerized method of data collection consisting of two possible parts: a national mammography audit and a system for monitoring and tracking patients. A national mammography audit refers to collecting and analyzing medical audit data of individual mammography practices at a national level and is a critical step in improving the interpretive component of mammography. The monitoring and tracking component refers to a centralized system that provides women and physicians with a recruitment and follow-up mechanism to optimize participation in mammography services. Both parts of a national mammography database represent important components in the improvement of mammography quality. However, unique scientific, legal, and fiscal concerns are important to consider before establishing a national mammography database.

Female↗