Image Technology News - November 2008 - (Page 17)

Computed Tomography COMPARISON CHART ultislice technology is one of the latest developments in CT technology that greatly improves the amount of diagnostic information that can be acquired in a timely manner. With single-slice technology, users are constrained by patient movement, patient’s limited breath-hold, useful contrast media duration and the X-ray tube overheating. The additional speed of multislice (also referred to as multidetector) CT (MDCT) allows radiologists to develop scanning protocols without these limitations. This means that narrower slices, more slices and greater volume coverage are now possible simultaneously. High-resolution scans with fewer artifacts are now routinely produced and CT can now be used for angiography, cardiology and trauma exams. The finer resolution makes it possible for radiologists to routinely view 3D representations of the data. M advantage of the second workstation is that users can analyze images, organize patient lists, etc., without interfering with the scanner. As far as ease of use is concerned, users should try each system out before purchasing. One test that may be done is to discern how many button pushes are required for a specific type of scan. 4. Rotation time: Rotation time not only affects the total scan time but also the impact of patient movement on image quality. Rotating the X-ray tube faster means that exposure rates must be increased and the data must be transferred from the detector faster. Manufacturers have significantly improved the life span of tubes in today’s scanners; however, the 0.5 second rotation times are usually only available on high-end scanners. 5. Image reconstruction time: Waiting to reconstruct images can have a significant bearing on the overall exam time. Because the main advantage of multislice is its ability to produce more images, this could be a serious problem. Two developments help ameliorate this problem: reconstruction “on-the-fly” and much improved image reconstruction times. Being able to view the images on-the-fly can save time. Improved computer architectures and faster processors mean that images can now be reconstructed at 0.5 second intervals. Buyers are strongly recommended to invest in the fastest reconstruction possible. 6. Radiation dose: Multislice CT scanners will give the same radiation dose as a single slice if they are used in exactly the same way. Unfortunately, using thin slices can dramatically increase the X-ray dose. Therefore, controlling the Xray dose is more important when using multislice. It is unrealistic to think that technologists will be able to control the dose manually as they already have many other considerations during a scan. Instead, manufacturers have developed dose control mechanisms that can automatically optimize the dose for each slice of a scan. Published results indicate that significant dose savings can be made. 7. Clinical applications: Each manufacturer has developed special software for specific clinical applications. Examples include CT fluoroscopy, cardiac scanning and 3D analysis. 8. Obsolescence: Multislice technology has developed rapidly and more development is expected. All manufacturers offer some form of guaranteed priced upgrade route; the difference lies in how the upgrades are accomplished. It is important to note that buying a new (and upgraded) system later is less expensive than buying a new system now and upgrading. The decision about when to buy should be based more on the viability of existing equipment. PARTICIPANTS GE Healthcare www.gehealthcare.com It is interesting to note that most improvements in speed have been at the expense of the quality of the data acquired by the scanner. For example, moving from the axial scanning to helical scanning means more data interpolation is necessary and leads to reduced image quality. However, the overall quality of the diagnostic information available has increased. So, axial scanning is only used for a few exams today. Multislice technology is another such evolution. Multislice scanners are able to collect multiple slices simultaneously by using a wider Xray beam. Although the wider beam compromises the quality of the data, the benefits more than compensate for the compromises made by designers. Hitachi Medical Systems www.hitachimed.com NeuroLogica Corp. www.neurologica.com Philips Healthcare www.medical.philips.com Siemens Medical Solutions www.usa.siemens.com/medical Key Considerations for MDCT 1. Number of slices: It is important to realize that the total slice width is limited by the “cone-beam effect.” Therefore, as the number of slices increases, the width of each slice decreases, not the overall width. Therefore, only studies involving thin slices will benefit from more slices. 2. Slice width: Each manufacturer has a different design of multislice detector, leading to a different range of slice widths available. Most clinical exams will be made with 3mm to 5-mm slices. Clinically there is little difference between a 4-mm and a 3.75-mm slice. Every detector can accommodate that. The difference comes in the narrowest slice width available, usually less than 1 mm. The effective slice width can be significantly larger than the nominal slice width. Users should ask manufacturers for the effective slice widths and compare those. 3. User interface: Perhaps the most obvious difference among systems is that some systems have one user workstation as standard, while other systems have two. The Toshiba America Medical Systems www.medical.toshiba.com Editor’s Note: All submitted information appears on our Web site at ITNonline.net. Comparison Chart Conducted by Reilly Communications Group Reilly Communications Group assumes no responsibility or liability for any errors or omissions in this chart. Reilly Communications Group obtained the model specifications from the manufacturers. The chart outline and introduction are from the Healthcare Product Comparison System (HPCS) published by ECRI Institute, a non-profit health services research agency. HPCS is a comprehensive database of brand-name model specifications for more than 450 types of devices available in three ways: online, CD-ROM, or print editions. For more information, contact ECRI Institute at (610) 825-6000, Ext. 5265; eMail: hpcs@ecri.org; or visit www.ecri.org. Please direct all chart inquiries to: charts@rcgpubs.com Open and fold out or remove for wall display ITNonline.net | Nov/Dec 2008 | ITN | 17 http://www.gehealthcare.com http://www.hitachimed.com http://www.neurologica.com http://www.medical.philips.com http://www.usa.siemens.com/medical http://www.medical.toshiba.com http://www.ITNonline.net http://www.ecri.org http://www.ITNonline.net

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Image Technology News - November 2008 Contents RSNA CT Systems Imaging An Image is Worth a Thousand Words Ultrasound Systems MBI Takes on FFDM Trouble in Multi-PACS Paradise When is Appropriateness Criteria Appropriate? RIS/PACS in a Web 2.0 World Digital Mammography Helps Center Continue its Commitment to the Best in Patient-Focused Breast Cancer Cardiovascular Imaging Systems PARCA Extends Expertise to World PACS Market

Image Technology News - November 2008

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