Faster, better resolution in new CT scanning provides improved medical imaging

CT or Computed Tomography (Greek tomos (slice) and graphein (to write)) scanning often referred to as CAT scanning uses special x-ray equipment to produce multiple images or pictures of the inside of the body. It is non - invasive and painless. The "slices" taken are combined to form a full 3-D and very detailed image of internal organs, bone, soft tissue and blood vessels.

The technique was originally developed by by Sir Godfrey Newbold Hounsfield at EMI (now a rapidly shrinking music company) for which with he was, with Allan McLeod Cormack of Tufts University, Massachusetts, USA awarded the Nobel Prize for medecine.

The original 1971 prototype took 160 parallel readings through 180 angles, each 1° apart, with each scan taking a little over five minutes. The images from these scans took 2.5 hours to be processed by algebraic reconstruction techniques on a Data General computer.

It is claimed that EMI could cover the immense research costs with the proceeds of the Beatles records - The first commercial EMI-Scanner was installed in Atkinson Morley's Hospital in Wimbledon, England, and the first patient brain-scan was made with it in 1972.

Since then there has been accelerating progress in developing new equipment, with the aim of reducing scanning time, and therefore radiation exposure and improved image handling to give more detail and an image that can be readily manipulated.

Today there are 4 major competing systems ;

Toshiba America Medical Systems has its AquilionONE 320-slice scanner

Before the AquilionONE, 64-slice volumetric imaging entailed imaging of separate pieces or sub-volumes. Sub-volumes were stitched together after the scan, a process that produces artifacts, particularly when imaging a moving organ such as in coronary CT angiography.As they have cut scan time to 0.5 second more slices can be undertaken for the equivalent radiation dose of other, slower eqipment.

Philips Healthcare’s offers the Brilliance iCT 256-slice scanner

This new system produces superior cardiac images as its speed and coverage freezes the motion of the heart and produces a clear snapshot of the coronary arteries.

reduces the amount of radiation a patient is exposed to by as much as 80 per cent and generates images in a fraction of the time of other scanners.

Dr Keith Prowse, chairman of the British Lung Foundation, said the Brilliance iCT machine enables clinicians to see much smaller things in both the lungs and the airways and the scanner is a quantum shift from the first CT scanners as it gives a lot more detail. Head scan on this system above, more here.

Siemens Medical Solutions has developed the SOMATOM Definition Adaptive Scanner (AS)

This is an “adaptive” scanner available in 40-, 64- and 128-count configurations. This relies on using lower numbers of scans but with fast high resolution - the system fits in an 18m2 space, allowing hospitals short on real estate to shoehorn the system into spaces previously too small to house a CT suite. At the same time, the table and gantry accommodate patients weighing up to 650 pounds !!!

GE Healthcare has developed what they describe as High-Definition CT (HDCT) technology.

HDCT is claimed to enable dual-energy imaging and improved registration in conjunction with iterative reconstruction.This is claimed to both suppress image noise and allow reduced radiation dose for the patient. A modified garnet gemstone scintillator improves x-ray conversion speed. As a result it produces very sharp images of the coronary arteries and abdominal visceral arteries.

GE claim that the Projection-based, dual-energy data processing reduces beam hardening artifacts. Also it allows t and should enhance diagnostic capabilities. Other potential clinical applications include iodine separation, accurate auto-bone removal in 3D assessments and material decomposition. They await FDA approval of the system this year.

Naturally they are all expensive bits of kit to buy, install, maintain and operate and require special operator training and image evaluation for the guys in white coats and with stethoscopes hung round their necks.