A phased array probe applies voltage pulses to all elements as a group but with small time differences (phasing). The time difference is changed each time so that the sound pulses will be sent out in different directions.

In 1918, Philips started with their first medical X-ray tube. Philips Medical Systems now is a global leader in diagnostic imaging systems, healthcare information technology solutions, and patient monitoring and cardiac devices. Philips also provides customer services such as financing, consultancy and maintenance & repair.
Philips lacked in the field of ultrasound till 1998. By buying ATL (Bothell, Washington) in this year Philips establishing itself as an important player in ultrasound. In 2001 Philips also acquired Agilent (formerly Hewlett-Packard; Andover, Massachusetts), a market leader in the cardiology and vascular ultrasound systems (HP2000 to HP5500, now Sonos 2000 to Sonos 5500).

Philips Medical System is the diagnostics business of Royal Philips Electronics of the Netherlands, one of the world's biggest electronics companies and Europe's largest. Philips is quoted on the NYSE (symbol: PHG), London, Frankfurt, Amsterdam and other stock exchanges. On October 19, 2001, Philips Medical Systems completed a 3-year acquisition strategy through its purchase of Marconi Medical Systems. Marconi Medical Systems offered leading multislice CT, MRI, and Nuclear Gamma Camera systems to medical institutions around the world. As well as new 3.0T developments, Philips is also in collaboration with researchers at the University of Nottingham, with the intention of developing an ultrahigh field strength clinical 7.0T whole body MR system.

Ultrasound Systems:

A logarithmic measure of sound loudness closely related to the decibel. The unit decibel is used for objective measurements, that means, they measure the actual pressure of the sound waves as recorded using a microphone. The unit phon is used for subjective measurements, which means, measurements made using the ears of a human listener.
A sound has the loudness 'p' phon if it seems to the listener to be equal in loudness to the sound of a pure tone of the frequency 1 kilohertz and strength 'p' decibel. A measurement in phons will be similar to a measurement in decibel, but not identical, since the perceived loudness of a sound depends on the distribution of frequencies in the sound as well as the pressure of the sound waves. In the U.S., sound loudness is frequently measured in sones rather than phons: a sound of loudness x sones has loudness 10 log2 x + 40 phons.

See also Acoustic Noise.

Phospholipids are a major component of all biological membranes. When placed in water, phospholipids form a bilayer, where the hydrophobic tails line up against each other. This forms a membrane with hydrophilic heads on both sides. This membrane is partially permeable and very flexible.
Phospholipid containing microbubbles are in use as diagnostic ultrasound contrast agents. Phospholipids can be targeted to atheroma and other pathologic components to enhance atherosclerosis imaging. The majority of these echogenic liposomes range in diameter from 0.25 to 5.0 μm.

(PACS) A system used to communicate and archive medical imaging data, mostly images and associated textural data generated in a radiology department, and disseminated throughout the hospital. A PACS is usually based on the DICOM (Digital Imaging and Communications in Medicine) standard.

The main components in the PACS are: acquisition devices where the images are acquired;
Acquisition devices, which acquire their data in direct digital format, like a MRI system, are most easily integrated into a PACS.
Short term archives need to have rapid access, such as provided by a RAID (redundant array of independent disks), whereas long term archives need not have such rapid access and can be consigned, e.g. to optical disks or a magnetic.
High speed networks are necessary for rapid transmission of imaging data from the short term archive to the diagnostic workstations. Optical fibre, ATM (asynchronous transfer mode), fast or switched Ethernet, are examples of high speed transmission networks, whereas demographic textural data may be transmitted along conventional Ethernet.
Sophisticated software is a major element in any hospital-wide PACS. The software concepts include: preloading or prefetching of historical images pertinent to current examinations, worklists and folders to subdivide the vast mass of data acquired in a PACS in a form, which is easy and practical to access, default display protocols whereby images are automatically displayed on workstation monitors in a prearranged clinically logical order and format, and protocols radiologists can rapidly report worklists of undictated examinations, using a minimum of computer manipulation.