Volume 36, Issue 6, June 2009
Index of content:
- SAM Imaging Symposium: Room 304A
- CE ‐ Imaging: Computed Tomography I: Optimizing CT Dose and Image Quality
36(2009); http://dx.doi.org/10.1118/1.3182190View Description Hide Description
CT technology has improved dramatically over the past decade and its clinical utilization has increased significantly as well. While CT can yield exquisite descriptions of anatomy that were not previously possible (at least not with noninvasive techniques), its increased utilization has led concerns over radiationdose;CT has now been identified as the single largest contributor to medical radiationdose to the population and accounts for approximately 50% of medical exposure. Methods to reduce radiationdose have been the focus of all stakeholders (medical physicists, technologists, radiologists, manufacturers and regulators). Reducing dose while maintaining acceptable image quality can be complex and this is made even more complex when considering patients of different sizes. This talk will first describe methods currently used, and some being developed, to estimate radiationdose in patients. This will include a discussion of measurement techniques as well as Monte Carlo simulation‐based techniques. Specific attention will be paid to the differences in dose to patients of different sizes ranging from pediatric patients to obese adult patients. Tradeoffs in image quality and radiationdose will also be described in this context as well. Radiationdose reduction techniques, including a review of various tube current modulation schemes currently being employed will also be described. The effect of these dose reduction methods on both radiationdose and image quality will be discussed, again with attention to how they can be deployed with patients of different size.
1. Understand how radiationdose for CT studies is currently estimated
2. Understand the trade‐offs of dose and image quality, especially for large (obese) patients and in pediatric patients
3. Review of the manufacturers' dose modulation methods and how these affect dose in different patients
- CE ‐ Imaging: MRI II: ACR MRI Accreditation Program Update
36(2009); http://dx.doi.org/10.1118/1.3182304View Description Hide Description
In October 2008 the American College of Radiology (ACR) expanded the MRI accreditation program to six modules (body, head, MR angiography (MRA), spine, muskuloskeletal and cardiac). The new program enables accreditation of dedicated MR systems, such as those used only for neuro or cardiac imaging, as well as accreditation of special‐purpose MR scanners, such as orthopedic systems. The program introduces a second, smaller ACR phantom, to be used for accreditation and quality control of these small bore orthopedic MR systems.
ACR MRI accreditation is now available for a wide range of MRI system configurations and clinical uses. The expansion of the program presents a challenge to the medical physicist, who needs to be aware of which ACR phantom and coil to use for phantom image acquisition, as well as how to address specific image quality issues.
1. Present the requirements of the new six‐module ACR MRI accreditation program.
2. Discuss the medical physicist/MRI scientist qualifications and CME requirements.
3. Describe small and large phantom image acquisition and analysis.
4. Discuss considerations for low field, 3T, dedicated and special purpose MRI systems in the accreditation and phantom image evaluation process.
36(2009); http://dx.doi.org/10.1118/1.3182305View Description Hide Description
In October, 2008, the ACR MRI Accreditation Program was updated to a more flexible, modular process. The ACR MR Accreditation process includes the initial application, and the submission of clinical and phantom images and forms.
The medial physicist plays a critical role in the accreditation process, along with the lead technologist and the supervising radiologist. A team approach is necessary to ensure that all information is accurate and appropriate for the examinations (both clinical and phantom) submitted for accreditation. The medical physicist should assist the facility in assessing the condition of the scanner as well as optimizing the clinical protocols.
This lecture will provide a brief overview of the application steps, and some of the most common problems encountered during clinical portion of the accreditation submission.
1. Understand the basics of the ACR MR Accreditation process.
2. Understand the relationship of the medical physicist in this process as it relates to clinical protocols.
3. Understand some of the most common pitfalls and misconceptions in the accreditation process.
- CE ‐ Imaging: Radionuclide Imaging II: PET/CT: Technology Updates, Quality Assurance and Applications
36(2009); http://dx.doi.org/10.1118/1.3182440View Description Hide Description
In the past few years, positron emission tomography/computed tomography (PET/CT) imaging has increasingly been used for the diagnosis, staging, and restaging of malignant diseases. The success of this emerging modality has primarily been due to its ability to combine the advantages of both PET and CTimaging while minimizing their separate weaknesses. One of the main advantages of PET/CT imaging is its ability to generate functional images depicting the biodistribution of radioactive compounds that are correlated with anatomical landmarks thereby increasing the physicians' confidence in image interpretation and improving patient management.
The aim of this lecture is to provide an overview of the basic physics principles of PET/CT imaging as well as the advantages and drawbacks of using CT for attenuation correction of PET data. In addition, the lecture will cover the latest in design specifics of commercially available PET/CT scanners from different manufacturers as well as review PET/CT quality control and assurance techniques.
1. To learn the basic physics principles of PET/CT imaging
2. To understand the advantages and drawbacks of using CT for attenuation correction of PETimages.
3. Become familiar with design specifics of commercially available PET/CT scanners.
4. Learn quality control and assurance techniques for PET/CT imaging
36(2009); http://dx.doi.org/10.1118/1.3182441View Description Hide Description
Hybrid SPECT/CT is rapidly becoming a mainstream imaging modality and creating a new paradigm for SPECTimaging. The ability to contemporaneously acquire electromechanically registered dual‐modality SPECT and CT scans improves the SPECTimage quality due to CT‐based attenuation correction, and enhances the diagnostic confidence of SPECT by providing an anatomical overlay. The first generation SPECT/CT systems used single‐slice CTscanners and produced CTimages of limited quality for anatomical overlay. The CTsystems integrated into the latest generation of SPECT/CT systems are fully‐functional diagnostic scanner (scan parameters includes tube current, tube voltage, rotation speed, collimation, pitch, slice thickness, FOV, etc.). In addition to generating high‐quality attenuation maps these CTsystems can produce CT scans with diagnostic image quality, capable of greatly improving both the localization and specificity of abnormalities detected on the corresponding SPECT scan. In some cases, these systems are also capable of performing diagnostic CT scans with contrast enhancement. The widest use of SPECT/CT is currently in oncology, with applications including: tumor localization, staging and response to treatment; pre‐surgical mapping (e.g., parathyroid adenomas, sentinel lymph nodes); differentiation of skeletal metastases from other disease processes; functional image‐based radiation therapy treatment planning (e.g., lung perfusion); and quantitative SPECT/CT‐based internal radionuclide therapy dosimetry/treatment planning. Cardiac SPECT/CT is currently focused primarily on improved attenuation correction of SPECT myocardial perfusion images. SPECT/CT is also being utilized for imaging bone and other non‐malignant diseases.
This lecture will review the physics principles underlying SPECT/CT imaging, present several examples of the clinical application of SPECT/CT, and provide an overview of the currently available SPECT/CT scanner types and models.
1. To understand the physical principles underlying SPECT/CT image acquisition, processing, and reconstruction.
2. To understand current and future clinical applications of SPECT/CT imaging.
3. To become familiar with the various commercially‐available SPECT/CT product offerings.
- CE ‐ Imaging: Breast Imaging IV: FFDM in the Field: Physicist's Role in the QC of Third‐Party Review Work Stations
36(2009); http://dx.doi.org/10.1118/1.3182586View Description Hide Description
The FDA requires that new mammography modalities follow a QC program which is similar to the MQSA final rules for film‐screen mammography. Early full‐field digital mammography (FFDM) manufacturers fulfilled this requirement by publishing QC manuals which covered all the required medical physicist and technologist QC tests for their FFDM unit and soft‐copy review work station.
In recent years, the FDA has allowed FFDM users to interpret digital mammograms on monitors other than the those provided by the FFDM manufacturer. There are several 5MP monitor manufacturers each with their own mammography QC requirements, documentation, software, and photometers. These monitors may also be rebranded and installed by PACS vendors with their own QC manuals. A physicist surveying a FFDM unit may find many combinations of FFDM manufacturer, monitor manufacture and PACS vendor QC requirements for the review workstation. Further complicating this, a single FFDM unit may use multiple, work stations from different manufacturers or a single work station may be used by multiple FFDM units perhaps from different manufacturers. A consulting medical physicist visiting multiple sites is especially likely to find a changing variety of combinations. Because these are all covered under MQSA regulations, it is important the physicist perform and document the correct QC tests.
This lecture will review the various monitor QC tests suggested or required by TG‐18, the major FFDM manufacturers, current 5MP monitor manufacturers, and PACS vendors. Suggestions will be offered on sets of tests which can be performed on a large number of monitors regardless of their manufacturers. Suggestions will also be made on surveys which will fulfill the requirements of nearly all manufacturers. Such a surveys may include may tests which are not required for the monitor tested but are simple to perform.
1. Understand the review workstation tests required by FFDM manufacturers and the requirements those manufacturers have for third‐party monitors.
2. Understand the TQ18 monitor tests which are applicable to current 5MP monitors.
3. Learn the QC tests required by various 5MP monitor manufacturers and PACS vendors.
36(2009); http://dx.doi.org/10.1118/1.3182587View Description Hide Description
Digital mammography has become 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 compared to the traditional screen‐film systems and require different quality control tests by the FDA approval process. This lecture is going to discuss the practical issues for the medical physicist who wants to learn the differences in these Quality Control tests and how they impact the mammography facility and ACR accreditation. The lecture will be broken into several parts. The first will review currently available FFDM equipment and their respective Quality Control tests. The second part will compare similar QC tests and discuss the key differences. The third part will look ahead to the new FFDM QC program being developed by the ACR.
1. To describe current quality control procedures for FFDM systems.
2. To review the impact of QC on ACR accreditation for FFDM systems.
3. To preview the forthcoming ACR FFDM QC program.