Index of content:
Volume 33, Issue 6, June 2006
- Imaging Continuing Education Course: Room 330 A
- CE: Breast Imaging Physics and Technology ‐ I
33(2006); http://dx.doi.org/10.1118/1.2241387View Description Hide Description
Digital mammography was developed to address several technical limitations of screen film mammography with the goal of improving the accuracy of detecting breast cancer. The recent publication of the results of the ACRIN DMIST study has demonstrated such an improvement in a subset of women, notably, younger women and those with dense breasts. Nevertheless, the study also indicated that a significant fraction of cancers were not detected by either film or digital mammography. This is likely due to a number of reasons including the biology of the cancers, inadequate conspicuity of the lesions and variability of the skills of the radiologists. While it probably is not possible to detect all these cancers with mammography there are promising new techniques that can be developed on the platform of digital mammography to improve detection. One of these is computer‐aided detection, the use of computer artificial intelligence algorithms to identify patterns in the digital images that are suspicious for the presence of cancer. These provide some of the advantages of double reading of the mammograms (interpretation by two different radiologists), a process known to improve the sensitivity of cancer detection. Another new technique is contrast‐enhanced digital mammography (CEDM), which images leakage of an iodine contrast agent from microscopic vessels formed in the vicinity of a growing tumour. By imaging this tumour angiogenesis, cancers that are invisible on mammography might be seen. In addition, better information about the extent of the disease will be helpful in planning therapy. In mammography all of the anatomy in the 3‐dimensional breast is superimposed in two dimensions to form the image.Tomosynthesis and breast CT provide three‐dimensional images to separate the structures within the breast, possibly allowing tumors to be seen more easily and eliminating the overlap of structures from different parts of the breast that can falsely resemble a cancer. Telemammography can help improve the accessibility of high quality mammography in sparsely‐populated communities. In this presentation, the current status and the potential of these exciting new techniques will be considered.
Martin Yaffe's laboratory carries out research on topics related to digital mammography in collaboration with GE Healthcare. Martin Yaffe is a member of the Scientific Advisory Board of XCounter.
1. Become familiar with current challenges in breast cancerimaging.
2. Learn about new techniques that are available or under development to address these challenges.
- CE: Breast Imaging Physics and Technology ‐ II
33(2006); http://dx.doi.org/10.1118/1.2241479View Description Hide Description
Since 2003, the number of full‐field digital mammography (FFDM) units in the United States has been increasing by about 4% per month. As of May 1, 2006, there were 1379 full‐field digital mammography units at 977 MQSA‐certified facilities in the United States. With the fall 2005 announcement that FFDM increased the effectiveness of detecting breast cancer in women with dense breasts (as well as premenopausal women and women under the age of 50), the rate of increase for digital units is expected to increase even further. FFDM systems are subject to the Food and Drug Administration's mammography regulations, as are analog systems). This presentation will discuss the steps medical physicists must take to ensure their facilities may expeditiously accredit their FFDM units. In addition, the presentation will cover preliminary QC recommendations made by the ACR's Subcommittee on Digital Mammography in preparation for their upcoming Digital Mammography FFDM Quality Control Manual.
- CE: Breast Imaging Physics and Technology ‐ III
33(2006); http://dx.doi.org/10.1118/1.2241662View Description Hide Description
Use of output from a computerized analysis of a breast image by radiologists may help them in the tasks of detection or diagnostic, and potentially improve the overall interpretation of breast images and the subsequent patient care. Many factors motivate the attempts to aid or automate radiological diagnosis. Inadequacies in interpretation performance may be due to the presence of imagenoise or normal anatomical structure as well as to known limitations in the human search and perception process. Developments in breast CAD have led to clinically‐used detection systems in screening mammography and preclinical classification systems for diagnostic breast imaging.Diagnostic breast CADsystems provide output for the characterization of lesions on special‐view mammography, breast sonography, and breast MRI in order to aid in patient management decisions, such as biopsy decisions. As imaging continues to expand in the digital era, computer‐aided diagnosis(CAD) may become an integrated tool in the online diagnostic workup of suspect breast lesions using multi‐modality images and advanced PACS. This presentation reviews research in computerized analysis of mammographic, sonographic, and magnetic resonance breast images for detection and diagnosis. It will include the characterization of lesions and the estimation of the probability of malignancy for use in the diagnostic workup of suspect lesions. CADsystems in diagnostic workup usually involve having the computer extract the margin of the lesion from the surrounding parenchyma, extract characteristics (features) of the lesions, merge these computer‐extracted features into an estimate of the probability of malignancy, and as an option, retrieve automatically similar lesions from an online reference library. The aim of CAD in diagnostic workup is to increase classification sensitivity and specificity as well as to reduce intra‐and inter‐observer variability. While the breadth and depth of CAD is increasing, continued and expanded efforts are needed for collecting and confirming databases, establishing methods for evaluation, integrating effectively and efficiently with PACS and RIS systems, and providing means for clinical evaluation.
1. To appreciate the development of CAD in multi‐modality imaging for detection and diagnosis of breast cancer.
2. To understand the benefits and challenges as CAD moves into the digital era and is integrated with PACS and HIS.
3. To recognize the necessary steps for advancing and integrating CAD clinically.
COI: Maryellen Giger is a shareholder and consultant, and receives research funding from R2 Technology, Inc.
- CE: Breast Imaging Physics and Technology ‐ IV
33(2006); http://dx.doi.org/10.1118/1.2241821View Description Hide Description
Digital mammography is quickly becoming the technology of choice for breast imaging with several FDA‐approved systems already available and more on the way. Digital detectors in mammography have different characteristics than the traditional screen‐film systems and care should be taken when implementing these systems into a clinical environment. This lecture is going to discuss the practical issues for the medical physicist who wants to learn how to optimize dose and image quality in mammography primarily focusing on full‐field digital mammographysystems (FFDM). The lecture will be broken into several parts. The first will review currently available FFDM equipment including an overview of automatic exposure modes, quality control pertaining to image quality and dose, and system technique selection. The second part will discuss techniques for measuring dose and image quality in FFDM. The third part will discuss factors affecting image quality and dose and ways to optimize FFDM systems in a clinical environment.
- CE: Radiation Safety and Risk Management ‐ I
33(2006); http://dx.doi.org/10.1118/1.2241394View Description Hide Description
The main goal of this presentation is to discuss factors which affect patient radiationdose delivered during various diagnostic radiology imaging examinations and to relate these radiationdoses to potential biological risks. Measurement methods to estimate patient radiationdoses and some examples of dose reduction for radiography,mammography,fluoroscopy,angiography and CT will be reviewed. Applications of these measurements to patient dose estimation will be shown. Procedures to obtain quick computational estimates of patient doses for IRB submissions, patient inquiries and fetal dose estimations will be provided. Approaches to convert entrance skindoses,dose area products and dose length products to effective doses and risks will be discussed. Typical patient radiationdose values for common diagnosticimaging procedures will be given. Limitations, uncertainties and ranges for patient radiationdose estimates will be examined. The utilization of “reference values” for patient radiationdoses will be reviewed. Some guidelines to aid physicists with relating radiationdose issues to the public and informational media will also be included. The material is intended to provide a brief overview of one crucial aspect of the responsibilities with which diagnosticmedical physicists and medical health physicists must routinely handle in their jobs. Our expectation is to stimulate introspective assessments and to expand the manner in which patient radiationdose determinations are viewed and performed.
1. To review fundamental X‐ray dosimetry quantities.
2. To identify important factors that affect patient dose delivered by various X‐ray imaging modalities.
3. To describe common methods to measure patient dose and review strategies in developing patient dose charts for routine diagnosticimaging procedures.
4. To examine the limitations of some current dosimetry methodologies.
5. To present a practical guidance to physicists in providing day‐to‐day clinical support service such as IRB submissions, patient inquiries and fetal dose estimations.
- CE: Radiation Safety and Risk Management ‐ II
33(2006); http://dx.doi.org/10.1118/1.2241486View Description Hide Description
The application of the structural shielding design techniques and goals as outlined in NCRP Report 147: Structural Shielding Design for Medical X‐ray Imaging Facilities (2004) will be the basis for this practical course. The wide variety of facilities installing medical imaging equipment requires the medical physicist to consider an array of radiation protection concerns for the installation of radiographic/fluoroscopic equipment. To meet the challenge of maintaining construction costs to a minimum while providing adequate radiation shielding protection requires the physicist to utilize all available materials to reduce radiation exposure to surrounding personnel and the public. Estimating future workloads as well as considering current workloads for radiographic/fluoroscopic equipment as the medical imaging community transitions from a film/screen based world to a digital world can present challenges. Practical examples of these methods of structural shielding designs will be explored in this course.
1. Understand the radiation exposure protection limits for surrounding areas of radiographic/fluoroscopic installations.
2. Understand the effectiveness of various shielding materials found in facilities to provide required structural shielding necessary to reduce anticipated radiation exposure levels to acceptable limits.
3. Understand the calculation of anticipated workloads for radiographic/fluoroscopic equipment and the effect of these workloads on structural shielding evaluations.
- CE: Radiation Safety and Risk Management ‐ III
33(2006); http://dx.doi.org/10.1118/1.2241670View Description Hide Description
The application of the structural shielding design techniques and goals as outlined in AAPM Task Group Report 108: PET and PET/CT Shielding RequirementsMedical Physics (Vol. 33., Issue 1 (2006)) will be the basis for this practical course. As the use of PET and PET/CT units expands rapidly in the medical arena, the requirements for providing adequate radiation protection for both occupational personnel in these facilities and the public in uncontrolled areas around them necessitate the involvement of a qualified medical physicist. The many areas involved in implementing a PET/CT program including the Hot Lab, Patient Uptake Rooms, Patient Restrooms, Scan Rooms, and Disposal areas will be used as practical examples of typical structural shielding designs and evaluation methods. The testing of PET shielding insures that the shielding is properly installed and that individuals do not exceed the radiation exposure levels required by applicable regulations and ALARA policies. Testing of PET and PET/CT shielding is a complex multidimensional problem since there are multiple sources and the radiation is emitted isotropically from the patients. Thus efficient testing can both save time and reduce radiation exposure to the physicists doing the testing. This course will discuss efficient methods for shielding testing. It will also review the instrumentation available to physicists for making the measurements. Practical methods of testing of a PET/CT facility will be presented.
1. Understand the exposure factors to be used for currently used PETisotopes to determine required structural shielding to meet exposure limits for occupational personnel and the public.
2. Understand the effectiveness of existing and additional structural shielding materials that provide radiation protection and methods to calculate the required amounts of these materials.
3. Understand the methods to be used to evaluate the adequacy of PET and PET/CT installations to insure adequate shielding has been provided to meet applicable state and ALARA requirements.
- CE: Radiation Safety and Risk Management ‐ IV
33(2006); http://dx.doi.org/10.1118/1.2241829View Description Hide Description
The application of the structural shielding design techniques and goals as outlined in NCRP Report 147: Structural Shielding Design for Medical X‐ray Imaging Facilities (2004) will be the basis for this practical course. The wide variety of facilities installing CTimaging equipment requires the medical physicist to consider an array of radiation protection concerns for the installation of these units. To meet the challenge of maintaining construction costs to a minimum while providing adequate radiation shielding protection requires the physicist to utilize all available materials to reduce radiation exposure to surrounding personnel and the public. Estimating future workloads as well as considering current workloads for uses of CTscanners as the ability to perform many more scans more quickly can present challenges. Practical examples of implementing multi‐slice scanners with a variety of imaging purposes into facilities with a wide variety of existing shielding materials will be explored in this course.
1. Understand the methods of structural shielding design to use for sing and multi‐scan CTscanners.
2. Understand the radiation exposure limits for surrounding areas occupied by the public and occupational personnel.
3. Understand methods to predict applicable workloads for various types of facilities and CTscanners.