Helical CT image acquisition
Helical ("spiral") CT image acquisition was a major advance on the earlier stepwise ("stop and shoot") method.
With helical CT, the patient is moved through a rotating x-ray beam and detector set. From the perspective of the patient, the x-ray beam from the CT traces a helical path. The helical path results in a three-dimensional data set, which can then be reconstructed into sequential images for a stack.
Helical CT allows a scan to be performed in a single breath-hold.
Most modern CT protocols use helical acquisition due to its speed and because it reduces misregistration from patient movement or breathing. Sequential scanning (step-and-shoot) acquisition is still used in some situations (e.g. helical acquisition can lead to artifacts on head CT).
The radiation dose administered during helical acquisition depends on the speed of the patient through the scanner, also known as the pitch.
Related Radiopaedia articles
Imaging technology
- imaging technology
- imaging physics
- imaging in practice
-
x-ray
- x-ray physics
- x-ray in practice
- x-ray production
- x-ray tubes
- tube rating
- filters
- automatic exposure control (AEC)
- beam collimators
- grids
- air gap technique
- cassette
- intensifying screen
- x-ray film
- image intensifier
- digital radiography
- digital image
- mammography
- x-ray artifacts
- radiation units
- radiation safety
- radiation detectors
- fluoroscopy
-
computed tomography (CT)
- CT physics
- CT in practice
- CT technology
- CT image reconstruction
- CT image quality
- CT dose
- CT contrast media
-
CT artifacts
- patient-based artifacts
- physics-based artifacts
- hardware-based artifacts
- ring artifact
- tube arcing
- out of field artifact
- air bubble artifact
- helical and multichannel artifacts
- CT safety
- history of CT
-
MRI
- MRI physics
- MRI in practice
- MRI hardware
- signal processing
-
MRI pulse sequences (basics | abbreviations | parameters)
- T1 weighted image
- T2 weighted image
- proton density weighted image
- chemical exchange saturation transfer
- CSF flow studies
- diffusion weighted imaging (DWI)
- echo-planar pulse sequences
- fat-suppressed imaging sequences
- gradient echo sequences
- inversion recovery sequences
- metal artifact reduction sequence (MARS)
-
perfusion-weighted imaging
- techniques
- derived values
- saturation recovery sequences
- spin echo sequences
- spiral pulse sequences
- susceptibility-weighted imaging (SWI)
- T1 rho
- MR angiography (and venography)
-
MR spectroscopy (MRS)
- 2-hydroxyglutarate peak: resonates at 2.25 ppm
- alanine peak: resonates at 1.48 ppm
- choline peak: resonates at 3.2 ppm
- citrate peak: resonates at 2.6 ppm
- creatine peak: resonates at 3.0 ppm
- functional MRI (fMRI)
- gamma-aminobutyric acid (GABA) peak: resonates at 2.2-2.4 ppm
- glutamine-glutamate peak: resonates at 2.2-2.4 ppm
- Hunter's angle
- lactate peak: resonates at 1.3 ppm
- lipids peak: resonates at 1.3 ppm
- myoinositol peak: resonates at 3.5 ppm
- MR fingerprinting
- N-acetylaspartate (NAA) peak: resonates at 2.0 ppm
- propylene glycol peak: resonates at 1.13 ppm
-
MRI artifacts
- MRI hardware and room shielding
- MRI software
- patient and physiologic motion
- tissue heterogeneity and foreign bodies
- Fourier transform and Nyquist sampling theorem
- MRI contrast agents
- MRI safety
-
ultrasound
- ultrasound physics
-
transducers
- linear array
- convex array
- phased array
- frame averaging (frame persistence)
- ultrasound image resolution
- imaging modes and display
- pulse-echo imaging
- real-time imaging
-
Doppler imaging
- Doppler effect
- color Doppler
- power Doppler
- B flow
- color box
- Doppler angle
- pulse repetition frequency and scale
- wall filter
- color write priority
- packet size (dwell time)
- peak systolic velocity
- end-diastolic velocity
- resistive index
- pulsatility index
- Reynolds number
- panoramic imaging
- compound imaging
- harmonic imaging
- elastography
- scanning modes
- 2D ultrasound
- 3D ultrasound
- 4D ultrasound
- M-mode
-
ultrasound artifacts
- acoustic shadowing
- acoustic enhancement
- beam width artifact
- reverberation artifact
- ring down artifact
- mirror image artifact
- side lobe artifact
- speckle artifact
- speed displacement artifact
- refraction artifact
- multipath artifact
- anisotropy
- electrical interference artifact
- hardware-related artifacts
- Doppler artifacts
- aliasing
- tissue vibration
- spectral broadening
- blooming
- motion (flash) artifact
- twinkling artifact
- acoustic streaming
- biological effects of ultrasound
- history of ultrasound
-
nuclear medicine
- nuclear medicine physics
- detectors
- tissue to background ratio
-
radiopharmaceuticals
- fundamentals of radiopharmaceuticals
- radiopharmaceutical labeling
- radiopharmaceutical production
- nuclear reactor produced radionuclides
- cyclotron produced radionuclides
- radiation detection
- dosimetry
- specific agents
- carbon-11
- chromium-51
- fluorine agents
- gallium agents
- Ga-67 citrate
- Ga-68
- iodine agents
-
I-123
- I-123 iodide
- I-123 ioflupane (DaTSCAN)
- I-123 ortho-iodohippurate
- I-131
-
MIBG scans
- I-123 MIBG
- I-131 MIBG
-
I-123
- indium agents
- In-111 Octreoscan
- In-111 OncoScint
- In-111 Prostascint
- In-111 oxine labeled WBC
- krypton-81m
- nitrogen-13
- oxygen-15
- phosphorus-32
- selenium-75
-
technetium agents
- Tc-99m DMSA
- Tc-99m DTPA
- Tc-99m DTPA aerosol
- Tc-99m HMPAO
- Tc-99m HMPAO labeled WBC
- Tc-99m MAA
- Tc-99m MAG3
- Tc-99m MDP
- Tc-99m mercaptoacetyltriglycine
- Tc-99m pertechnetate
- Tc-99m labeled RBC
- Tc-99m sestamibi
- Tc-99m sulfur colloid
- Tc-99m sulfur colloid (oral)
- thallium-201 chloride
- xenon agents
- in vivo therapeutic agents
- pharmaceuticals used in nuclear medicine
History of radiology
- key milestones
- 1880: Pierre Curie discovered piezoelectricity
- 1895: Wilhelm Roentgen detects x-rays
- 1896: Antoine Henri Becquerel discovered radioactivity
- 1896: Sydney Rowland founds the first radiology journal, Archives of Clinical Skiagraphy
- 1896: Thomas Edison invents the first commercially-available fluoroscope
- 1896: John Macintyre opens the world's first radiology department in Glasgow
- 1898: Marie Curie publishes her paper 'Rays emitted by uranium and thorium compounds'
- 1913: Albert Salomon commences research leading to mammography
- 1913: William Coolidge introduces his eponymous x-ray tube
- 1927: Egas Moniz develops cerebral angiography
- 1934: Frederic and Irene Joliot-Curie artificially produce radioisotopes
- 1936: John Lawrence uses phosphorus-32 to treat leukemia
- 1939: Kitty Clark publishes Clark’s Positioning in Radiography
- 1950s: David Kuhl invents Positron Emission Tomography (PET)
- 1953: Sven-Ivar Seldinger develops his famous technique
- 1957: Ian Donald invents fetal ultrasound
- 1964: Charles Dotter introduces image-guided intervention
- 1965: Benjamin Felson publishes his Principles of Chest Roentgenology
- 1971: Godfrey Hounsfield introduces the CT scanner (co-developed with Allan Cormack)
- 1977: Ray Damadian builds the first commercial MRI scanner
- 1989: Spiral CT introduced
- 2005: Frank Gaillard creates Radiopaedia.org :)
- 2012: inaugural International Day of Radiology
-
key figures in the history of radiology
- Antoine Henri Becquerel
- Gustav Bucky
- Kathleen "Kitty" Clark
- John Wesley Coltman
- William D Coolidge
- Allan M Cormack
- Marie Curie
- Pierre Curie
- Ray V Damadian
- Ian Donald
- Charles T Dotter
- Thomas A Edison
- Charles Thurstan Holland
- Godfrey N Hounsfield
- Frederick Joliot
- Irene Joliot-Curie
- David E Kuhl
- Paul C Lauterbur
- Peter Mansfield
- Egas Moniz
- Bernard Ziedses des Plantes
- Wilhelm C Roentgen
- Sven-Ivar Seldinger
- Albert Soiland
- Florence Stoney
-
important figures in the history of radiology
- Manoel de Abreu
- James Ambrose
- Antoine Béclère
- Eugene W Caldwell
- Ben Felson
- Felix Fleischner
- Ronald Grainger
- Peter Kerley
- Alban Köhler
- John Macintyre
- Philip ES Palmer
- Maurice M Reeder
- Sydney D Rowland
- Albert Salomon
- Robert Steiner
- Juan M Taveras
- William L Thompson
- Ian Young
- Nobel Prize winners in radiology
- history of modalities
- plain radiography
- fluoroscopy
- nuclear medicine
- SPECT
- PET
- ultrasound
- CT
- MRI
- interventional radiology
- historical imaging techniques
- bronchography
- conventional tomography
- pneumoencephalography
- translumbar aortography
- history of radiology journals
- American Journal of Neuroradiology (AJNR)
- American Journal of Roentgenology (AJR)
- American X-Ray Journal
- Archives of Clinical Skiagraphy
- British Journal of Radiology (BJR)
- Clinical Radiology
- Emergency Radiology
- European Radiology
- Journal de Radiologie
- Journal of the American College of Radiology (JACR)
- Journal of Medical Imaging and Radiation Oncology (JMIRO)
- RadioGraphics
- Radiology
- Seminars in Roentgenology
- history of radiology meetings
- history of radiology organizations
- Australia
- United Kingdom
- United States
- international
- Asian Oceanian Society of Radiology (AOSR)
- Colegio Interamericano de Radiologia (CIR)
- European Society of Radiology (ESR)
- Fleischner Society
- International Society for Magnetic Resonance in Medicine (ISMRM)
- International Society of Radiographers and Radiological Technologists (ISRRT)
- International Society of Radiology (ISR)
- RAD-AID
- pioneering radiology books
- Atlas of Normal Roentgen Variants That May Simulate Disease
- Reeder and Felson's Gamuts in Radiology
- Radiographic Atlas of Skeletal Development of the Hand and Wrist
- Roentgenology - The Borderlands of the Normal and Early Pathological in the Skiagram
- The Roentgen Rays in Medicine and Surgery as an Aid in Diagnosis and as a Therapeutic Agent
- Textbook of X-ray Diagnosis by British Authors