SOMATOM Definition AS
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SOMATOM Definition AS
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Stellar ready

“Stellar ready” means that the SOMATOM® Definition AS now offers you the option to upgrade to a Stellar detector. As the first fully integrated CT detector, it measures smaller signals over a wider range and enhances image quality.

The new SOMATOM Definition AS Stellar ready now offers you the option to upgrade the system with a Stellar detector. The system is also designed to be able to rotate with 0.28 s and makes possible a scan speed coverage of up to 23 cm/s.

  • The Stellar detector is the first fully integrated CT detector. It enables processing of the digitized signal without any losses while reducing the electronic noise of the detector (TrueSignal technology).
  • In combination with Edge technology, the system therefore delivers a much sharper slice profile and makes possible the reconstruction of true 0.5 mm slices and offers unmatched spatial resolution in routine clinical protocols with excellent dose efficiency.
  • In addition, HiDynamics extends the dynamic range up to 102dB, which eliminates the need to modify amplification and avoids detector saturation. 

Systems with the Stellar detector can therefore measure smaller signals over a wider dynamic range – which directly reduces the noise and enhances the CT image quality.


  • Full flexibility to upgrade to a Stellar detector
  • Processing of the signal without losses
  • Reduction of electronic noise
  • Enhanced image quality
  • Dynamic range up to 102 dB
  • Scan speed of up to 23 cm/s and rotation of 0.28 s

For more information about the Stellar detector, please click here.

The Entry into Dual Energy

Dual Energy takes your diagnostic possibilities to a new level. It adds quantitative information to the morphology of a conventional CT scan. Receive crisp image quality and sharper contrast with the possibility to significantly reduce metal artifacts.

Dual Energy on the SOMATOM® Definition AS now offers you ongoing technological advances from the original pioneer in Dual Energy canning. Expect crisp images with no compromise on dose for Dual Energy scans, and a broad use in different clinical applications.
Two examples:

  • In the diagnosis of gout, syngo.CT DE Gout can potentially save your patients from painful and stressful invasive examinations and assists you in the assessment of uric acid crystals in joints non-invasively.
  • In cases where metal implants hinder radiation therapy planning for patients with prostate cancer and hip implants, monoenergetic Dual Energy images deliver a crisp and reduced artifact view of the anatomy – even in complex cases.


  • Material characterization added to morphology
  • No compromise on image quality
  • All dose-saving features available, such as SAFIRE¹ and CARE Dose4D
  • As easy as a spiral scan
  • Evaluation software applications for a variety of clinical challenges
  • Motion artifact reduction with robust image registration
  • Dedicated scan protocol for contrast media enhanced scans

Single-Click Readiness

Every CT examination poses individual and specific requirements to achieve the optimum clinical outcome.

Every CT examination poses individual and specific requirements to achieve the optimum clinical outcome. These vary from institution to institution, from user to user, and from patient to patient. The challenge is to find and apply the ideal settings for every individual examination, but at the same time achieve a high degree of reproducibility for the same type of examination when done by different operators.

Siemens’ unique FAST (Fully Assisting Scanner Technologies) research and development philosophy solves this. By automatically suggesting the best set of parameters for every individual examination based on the selected body region, FAST Planning enables the scan and reconstruction planning to become as fast as just a single click.


  • Immediate, organ-based scan and recon range setting with FAST Planning
  • Precise spine recon preparation with just a single click with FAST Spine
  • FAST Adjust allows intuitive scan parameter adjustment with the push of a button
  • Higher reliability and reproducibility in cardiac CT with the FAST Cardio Wizard
  • Image evaluation with a single click with syngo.via²

Your Single Source for Low Dose CT

Applying the lowest radiation dose possible is of utmost importance for both you and, of course, your patients.

Applying the lowest radiation dose possible is of utmost importance for both you and, of course, your patients. Therefore you always want to be assured that you have taken every means available to you to protect your patient from unnecessary radiation.

This desire for as little radiation exposure as possible lies at the heart of our CARE (Combined Applications to Reduce Exposure) research and development philosophy. 

Consequently, with Siemens’ continuing effort, investment and dedication to achieve highest dose protection, the SOMATOM® Definition AS uniquely combines all features available for single source CT to reduce radiation: next to its already outstanding dose protection portfolio from previous product generations, it is also inherited features from the highly renowned SOMATOM Definition Flash (i.e. X-CARE) and provides innovative dose saving features with FAST CARE (i.e. CARE kV), making even pediatric scans routine.


  • CNR and dose optimized kV settings with CARE kV
  • The Adaptive Dose Shield prevents unnecessary dose in every spiral scan
  • X-CARE protects the most radiation-sensitive organs
  • Low dose cardiac exams with Adaptive ECG Pulsing and the Adaptive Cardio Sequence
  • Superior raw-data-based image quality improvement or up to 60% dose reduction with SAFIRE1,3

Open CT for all Patients

Every patient is different. So is every clinical question.

Every patient is different. So is every clinical question. Our goal was to create a new kind of CT that is actually open for every patient and addresses the versatile needs of your institution. The result is a system with an exclusive composition of features and functionalities that make it the perfect fit for your dedicated clinical imaging needs: Whether you want to master the toughest battles in cardiac or acute care, want to excel in neurology or oncology or just want to be sure not to exclude any patient from pediatric to bariatric imaging, the SOMATOM® Definition AS is the ideal single source CT for your needs.

With its full on-site upgradability from 20 to 128 slices, it can grow with your demands and can be fully customized to your requirements. And, it supports you in overcoming limitations posed by conventional CT systems with a bore diameter of up to 804 cm and a table load capacity of up to 307 kg. 

The SOMATOM Definition AS will deliver clinical excellence independent from the given conditions and opens CT for all patients. 



  • Highest spatial resolution to visualize even small details
  • Enough power reserves, large bore, and high-capacity table for bariatric imaging
  • 70 kV scan mode for pediatric imaging
  • Dynamic CT imaging with up to 42 cm coverage using the Adaptive 4D Spiral
  • 3D image guidance in minimally invasive procedures designed to help simplify complex interventions
  • Full on-site upgradability from 20 to 128 slices

Sliding Gantry

The SOMATOM® Definition AS with Sliding Gantry meets the demands for a reliable as well as flexible CT system for applications as diverse as trauma imaging, surgery, and intervention even with a small footprint.

This configuration features a CT gantry that is decoupled from the conventional CT table and installed on rails. The Sliding Gantry is available for all SOMATOM Definition AS configurations (20-, 40-, 64-, 128-slices).
No matter if the challenge is CT-guided angiography, CT-guided surgery, or trauma, the Sliding Gantry is the perfect solution serving all these needs.

CT-Guided Angiography
The SOMATOM Definition AS with Sliding Gantry in conjunction with an AXIOM Artis angiographic system opens new horizons for image-guided angiographic interventions. Both the Sliding Gantry CT and the angiographic system operate with a common patient table, which accommodates the floating features required for DSA and fluoroscopy applications and the fixed table required for Sliding Gantry CT.

CT-Guided Surgery
The SOMATOM Definition AS with Sliding Gantry enables high-resolution CT imaging to be utilized during surgical procedures without the need to move the anaesthetized patient. The SOMATOM Definition AS is installed in a Sliding Gantry configuration within the operating room. When used in conjunction with a radiolucent operating table, the SOMATOM Definition AS with Sliding Gantry enables real-time scanning to correct operative techniques for any shift in organ position since imaging planning was undertaken.

Double-Room Solution
With the the SOMATOM Definition AS with Sliding Gantry it is possible to install a double-room option (i.e. room 1 – acute care; room 2 – routine) that enables the use of the CT system in two adjacent examination rooms. In this configuration a separate examination table is present in each room and the SOMATOM Definition AS with Sliding Gantry moves between the two rooms as required. The double-room Sliding Gantry configuration can be installed with a parking position either within one of the rooms or in a space between the two rooms.


  • The Sliding Gantry is available for all SOMATOM Definition AS configurations from 20-slices to 128-slices (AS+) and the SOMATOM Definition AS Open
  • Open for different tables
  • Two room solution with one acquisition workplace possible
  • Small footprint for optimized room usage


Related Products, Services & Resources

1In 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.

2syngo.via can be used as a standalone device or together with a variety of syngo.via-based software options, which are medical devices in their own right.

3The following test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogeneity, low-contrast 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.

4Available with the SOMATOM Definition AS Open configuration.