Absorbed Dose (D)
The absorbed dose is the amount of energy deposited in matter after being exposed to a certain amount of radiation measured in gray (Gy) units. One gray is defined as the amount of radiation required to deposit 1 joule (J) of energy in 1 kilogram of any kind of matter.
Adaptive Cardio Sequence
A mode in which the CT scanner registers the ECG in real time; it analyzes if the heartbeats are normal and triggers the scan during a predefined phase of the ECG
Adaptive ECG-Pulsing
A CT scan mode in which the current intensity is modulated such that the
radiation is maximal during the prescribed phase of the ECG and the radia-
tion is reduced to a minimum during the rest of the ECG.
ADMIRE
Advanced Modeled Iterative Reconstruction
AEF
Arterial enhancement fraction
ALARA
As Low As Reasonably Achievable
Alpha particles
Alpha (α) particles are fast-moving Helium-4 (4He) nuclei.
Angiography
Radiographic visualization of the blood vessels after injection of a radiopaque substance (contrast agent). In CT, iodine is frequently used as a contrast agent.
Anode
The electron-collecting electrode of the X-ray tube.
API
Automatic Patient Instruction
Apoptosis
A genetically determined process of cell self-destruction marked by fragmentation of nuclear DNA. It can be activated by radiation.
ASA
Advanced Smoothing Algorithm, a type of image filter used in image processing.
AWP
Acquisition workplace
bi-segment reconstruction
Taking data from up to two heartbeats to improve temporal resolution.
CARE
Combined Applications to Reduce Exposure
CARE technologies in our scanner portfolio provide dose and contrast efficiency, as well as image quality, with every scan.
CARE Dose
Dose-modulated acquisition that adapts tube current during the exam to provide optimum image quality at the lowest radiation dose.
CARE Dose4D
A system that modulates radiation intensity according to patient size and anatomical region as the CT scan progresses.
CARE keV
CARE keV is an adaptation of CARE kV specifically developed for photon-counting technology. In combination with CARE Dose 4D, both dose relevant parameters, tube current and tube voltage, are tailored to the individual patient, the system capabilities, and the clinical task.
- CARE keV takes the dose efficiency of monoenergetic reconstructions into account by automatically adjusting the appropriate kV and effective mAs settings. This optimizes the applied dose while maintaining the image quality, that is, the CNR (Contrast-to-Noise Ratio) at specific keV levels.
- CARE keV provides consistent CNR levels across all scan modes, offering a holistic solution for photon-counting scanners.
- CARE keV and CARE Dose 4D modulate the applied kV, mAs, and reconstruction keV to provide optimal dose efficiency and image quality with every scan.
CAT
Computed Axial Tomography
cCTA
Coronary CT angiography
CNR
Contrast-to-noise ratio
Convolution Kernel
The convolution algorithm "Kernel" affects image sharpness, noise, and resolution. It applies a specific mathematical algorithm and digitally filters raw data during image reconstruction.
CTA
CT Angiography
CTDI
Computed Tomography Dose Index or CT Dose Index is the sum of absorbed dose inside and outside the slice (the latter from scattered radiation).
CTDIvol
A measure of dose absorbed during a CT examination. It describes the average dose in the scan volume for the selected scan parameters.
CTDIw is calculated by weighting measured CTDI100 values from different positions in plastic phantoms: one third in the center and two thirds in the periphery.
CTDI100 is the integral of the dose profile in a single axial scan from -50 mm to +50 mm, divided by the scan length.
CTDIvol is CTDIw corrected by the pitch factor: CTDIvol = CTDIw / pitch.
DAS
Data Acquisition System
DECT
Dual Energy CT
Deterministic damage
Radiation poisoning that definitely occurs and whose severity depends on the amount of radiation received. Organic tissue damage is certain when exposed to high ionizing radiation.
DICOM
Digital Imaging and Communication in Medicine
Dose-Length Product (DLP)
DLP is the product of CTDIvol and the examination length.
DSA
Digital Subtraction Angiography
DSCT
Dual Source CT. Dual Source indicates a scan with both X-ray tubes. This mode is used in Flash scans and for cardiac scanning. Using Dual Source scanning, a temporal resolution of 66 ms can be achieved for fast cardiac scanning.Now that Dual Source scanning can be combined with Quantumplus (see page 7), full spectral information and reconstructions can be utilized in Flash and cardiac scans.
Effective mAs
Actual mAs value divided by pitch; effective mAs = mAs / pitch.
Electromagnetic radiation
Radiation exhibiting properties of both particles and waves and consisting of electric and magnetic fields.
Equivalent Dose (H)
Absorbed dose (D) multiplied by a radiation weighting factor (wr). For X-rays used in CT, wr = 1, so H = D.
Measured in sievert (Sv).
Examination range
Portion of the body to be scanned along the longitudinal (z) axis.
Examination Task Card
Interface for editing and saving individual scan protocols in an intuitive way. Includes patient registration, scan range setup, parameter settings, and protocol saving. Notes:
• Only numbers 0–9, letters A–Z, and underscores are allowed
• No spaces or country-specific characters
• Modified protocols show a dot in front
• Unused protocols should be deleted
• Siemens default protocols can be restored
FAST
Fully Assisting Scanner Technologies
FBP
Filtered Back-Projection
FDA
Food and Drug Administration
Flash Spiral
ECG-triggered technique based on dual-source spiral scanning at very high pitch, enabling heart imaging in one heartbeat
FoV
Field of View
HCE
High Contrast Enhancement image filter.
HD FoV
High Definition Field of View
ICRP
International Commission on Radiological Protection
iMAR
Iterative Metal Artifact Reduction
Integrated IR
Integrated Iterative Reconstruction
IR
Iterative Reconstruction
IRIS
Iterative Reconstruction in Image Space
IRS
Image Reconstruction System
Iterative Reconstruction
Correction loop in image generation comparing synthesized and measured projection data. Reduces noise and enhances resolution while preserving edges, improving over FBP.
iTRIM
Iterative temporal resolution improvement method
IVR
Interleaved Volume Reconstruction
Kernel
Reconstruction parameter impacting image sharpness, noise, and resolution through digital mathematical filtering.
keV
Kiloelectron vol
kV
Kilovolt; italicized (kV) indicates tube voltage.
LCE
Low Contrast Enhancement image filter.
LCS
Lung cancer screening
mAs
Product of X-ray tube current (mA) and exposure time (s). Determines photon quantity.
MinDose
Retrospective ECG-gated spiral scan with pulsing plateaus and 4 percent tube current.
MinIP
Minimum Intensity Projection
MIP
Maximum Intensity Projection
Modulation
Adjustment of a parameter to keep it within a desired range.
MPR
Multiplanar Reformatting
MSCT
Multislice CT
PACS
Picture Archiving & Communication System
PBV
Perfused Blood Volume
PET
Positron Emission Tomography
PEV
Polyp Enhanced Viewing
Pitch
Applicable only to spiral CT; table feed per rotation divided by slice width of one detector row.
Plexiglas phantoms
Plexiglas dummies used to measure radiation doses at different body locations.
PWM
Perfusion-weighted map
Quantum
The scan mode for low tube voltages (e.g., 90 kV). Quantum standard scans allow for monoenergetic spectral reconstructions and are optimized for scans with very low dose. Quantum scan modes are also found in all pediatric protocols.
Quantumplus
The main and signature scan mode of the NAEOTOM Alpha for standard scans. Quantumplus offers:• Full spectral capabilities – always• Full advanced Dual Energy reconstructions with the ability for standardized reading and quantifications• Consistent results for processing algorithm
Quantum HD / Highresultra
The Ultra High Resolution (Highresultra) scan mode gives access to high spatial resolution and allows for reconstructions with kernels up to Br98. Since the high resolution is achieved by the ultra fine pixels of the QuantaMax photon-counting detector, no dose is lost to a UHR comb.
QuantumSn
Our QuantumSn scans with tin filter allow for monoenergetic spectral reconstructions and are optimized for non-contrast scans.
Radiation
Emission of radiant energy as waves or particles.
Right Dose Management
Siemens programs supporting dose reporting and documentation. Includes Optimize CARE CT consultancy.
RRT
Rapid Results Technology
RTP
Radiation Therapy Planning
SAFIRE
Sinogram Affirmed Iterative Reconstruction
SFoV
Scan Field of View
SNR
Signal-to-noise ratio
SPECT
Single-photon emission computed tomography
Spiral CT
CT scan performed with continuous table movement and spiral X-ray tube trajectory.
SRS
Siemens Remote Service
SSD
Shaded Surface Display
TAVI
Transcatheter Aortic Valve Implantation (EU term)
TAVR
Transcatheter Aortic Valve Replacement (US term)
TBDE
TwinBeam Dual Energy
Topogram
Overview scan with fixed tube position and continuous table movement.
Tube current
Current applied to the cathode of the X-ray tube.
Tube voltage
Voltage between anode and cathode.
UFC
Ultra Fast Ceramic Detector enabling up to 30 percent dose reduction and very short afterglow.
UHR
Ultra High Resolution collimator with comb design improving high-contrast resolution.
VOI
Volume of Interest
cVRT
cinematic Volume Rendering Technique
X-CARE
Organ-based dose modulation reducing radiation intensity when irradiating from the front.
XRS
X-ray Rotating System