“Committed to ALARA“ VS. “Admitting to guesswork” – Second best is not an option.
Enable the Right Dose with Best-in-Class Technology
In order to reduce radiation to the right dose, of course, the first prerequisite is still the appropriate hardware: healthcare institutions need the right technology. Siemens has a long tradition of being an innovation leader in CT technology: whether it was the introduction of CARE (Combined Applications to Reduce Exposure) in the 1990s, Dual Source CT in the 2000s, or the Stellar Detector in the 2010s, Siemens has continuously been one step ahead. Therefore, it was a logical consequence that Siemens was named “the low dose leader to catch” when its SOMATOM Definition Flash won the 2011 Best in KLAS award.1 Overall, this was due to the fact that Siemens offers a comprehensive and innovative portfolio of unique dose reduction features:
Focus on the Individual Patient and Examination
In order to achieve the right dose for a patient, there are three important factors to consider: the size and stature of the patient, the type of examination, and the applied radiation dose. With Siemens’ technology, all of these aspects can be addressed:
ADMIRE (Advanced Modeled Iterative Reconstruction) our latest right dose technology and the next generation in iterative reconstruction from Siemens. ADMIRE sets a new benchmark in iterative reconstruction instead of limiting its potential for clinical routine.
SAFIRE (Sinogram Affirmed Iterative Reconstruction) finally made it possible to benefit from iterative reconstruction with a dose reduction potential of up to 60%2 in clinical routine, even in environments where time is crucial, such as acute care.
CARE Dose4D, for example, offers real-time anatomic exposure control. This allows adjusting the dose modulation according to the patient’s anatomy and position during the scan.
One of the main parameters of a scan protocol is the tube voltage, kV. The SOMATOM scanners offers different kV values from 70 to 150 kV depending on the scanner type. The tube voltage is an important parameter that has an impact on radiation dose and image impression.
For quite some time, iterative reconstruction has been heavily discussed in the CT community as a highly promising method to achieve significant dose reduction without compromising image quality. And once again Siemens has set the benchmark on low dose imaging with the introduction of the first raw-data based iterative reconstruction – SAFIRE. For the first time, raw data (or sinogram data) are actually being utilized in the iterative image improvement process. With this, SAFIRE can achieve a radiation dose reduction of up to 60%2. Or instead improve image quality (contrast, sharpness and noise), even surpassing the already impressive image quality realized with IRIS.
SAFIRE in 3 steps:
1. Multiple iterative loops performed in the raw-data domain correct geometrical imperfections and other artifacts
2. Image reconstruction from the “corrected” raw-data
3. Multiple iterative loops performed in the image domain remove image noise for a final and excellent image quality
SAFIRE Clinical benefits:
1. SAFIRE allows dose reduction in a wide protocol spectrum
2. Provides a excellent image quality
3. Fast and customizable workflow with up to 20 images per second
Because at Siemens dose reduction has continued to be give top priority for both patients and medical staff. We can now introduce another low dose solution – once again Siemens has set the benchmark on low dose imaging with the introduction of iterative reconstruction. IRIS delivers excellent image quality with lower dose levels. With IRIS, Siemens’ smart approach to iterative reconstruction, dose reduction can be achieved in a wide range of daily routine CT applications.3
Dose reduction with CT has been limited by the currently used filtered back projection reconstruction algorithm as displayed on the left. When using this conventional reconstruction of acquired raw data into image data, a trade-off between spatial resolution and image noise has to be considered. Higher spatial resolution increases the ability to see the smallest detail; however, it is directly correlated with increased image noise.
In an iterative reconstruction, a correction loop is introduced into the image generation process as shown on the right. To avoid long reconstruction times the new Iterative Reconstruction in Image Space first applies a raw data reconstruction only once. During this initial raw data reconstruction, a so-called and newly developed master volume is generated that contains the full amount of raw data information, but at the expense of significant image noise. During the following iterative corrections the image noise is removed without degrading image sharpness. The new technique results in increased image quality or dose savings for a wide range of clinical applications.
The Adaptive Dose Shield - available on the SOMATOM Definition Edge and SOMATOM Definition Flash - eliminates over-radiation pre- and post-spiral to the patient (marked in red). It is unique to the CT industry and part of the innovative new STRATON X-ray tube design. By dynamically moving shields into place on the X-ray tube it blocks clinical irrelevant dose. The Adaptive Dose Shield dynamically opens at the beginning of a spiral range and then dynamically closes at the end. Now all clinically irrelevant dose is eliminated. Not only for dedicated applications, but for every single spiral acquisition.3
KLAS “CT 2011: Focused On Dose” report, 11/2011
Best in KLAS and Leader in the CT 64-slice and above category
“Best in KLAS Awards Medical Equipment and Infrastructure” report, June 2012
www.KLASresearch.com | © 2011 KLAS Enterprises, LLC. All rights reserved.
In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The following test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogenity, low-contast resolution, and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file.
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