A logarithmic measure of sound loudness closely related to the decibel. The unit decibel is used for objective measurements that mean, 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 decibels, 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.

A bone scan or bone scintigraphy is used to in evaluate diseases of the skeletal system. Scintigraphic whole body bone imaging is a highly sensitive method to show changes in bone metabolism. Increased metabolic activity is seen as a hot spot.
The study requires the injection of a 99mTc-labeled radiopharmaceutical (most commonly methylene diphosphonate (MDP), hydroxymethylene diphosphonate (HMDP) or hydroxyethylene diphosphonate (HDP)). The activity administered for bone scanning is around 500 MBq (300-1100 MBq, 8-30 mCi), depending on age and weight of the patient. After 2-5 hours, the emitted gamma rays are detected by gamma cameras. The produced planar images include anterior and posterior views of the skeleton.
Multiphase bone scintigraphy is used to differentiate a bone process from tissue pathology. In some cases additional SPECT imaging is helpful to better characterize the presence, location and extent of disease.

Amersham Health, now GE Healthcare was the imaging diagnostics and therapy business of Amersham plc. The imaging business produced contrast agents that are injected into the body to improve pictures obtained through medical imaging scans.

In June 2006 Bayer AG has bought the majority of shares of Schering AG. As a result of this take-over Schering AG has been renamed in December 2006 in Bayer Schering Pharma AG. The Bayer Schering Pharma AG is part of the Bayer HealthCare AG, which represents the pharmaceutical part of the Bayer Group.
Berlex Laboratories (USA) and Berlex Canada Inc., former affiliates of Schering AG, have been integrated into Bayer HealthCare and operate as a specialty pharmaceuticals business that also sells MRI contrast agents, under the name Bayer HealthCare Pharmaceuticals, which is a subsidiary of Bayer Schering Pharma AG.

The Germany-based pharmaceutical company is the result of the take-over of Schering AG by Bayer AG in 2006. The Bayer Schering Pharma AG is part of the Bayer HealthCare AG, which represents the pharmaceutical part of the Bayer Group. Activities of the Bayer Schering Pharma AG are Diagnostic Imaging, Hematology & Cardiology, Oncology, Primary Care, Specialized Therapeutics and Women's Healthcare. The diagnostic imaging part's contrast agents for MRI, x-ray and CT are 'world-market leaders'.
See also Bayer HealthCare Pharmaceuticals.