(Pa) The SI unit of pressure.
Definition: 1 Pascal is equal to 1 N/m² = 1 J/m³ = 1 kg x m^-1x s^-2
1 kPa = 0.145 lbf/in².
Air pressure is measured in hectoPascal (hPa), with 1 hPa = 1 millibar.
The unit is named for Blaise Pascal (1623-1662), French philosopher and mathematician.

A peak is a maximum of activity.

A perfusion scintigraphy records the organ blood circulation usually directly or during the first two minutes after the injection of a radioactive tracer.
Different types of radiopharmaceuticals are used, depending on the target organ.

Typical perfusion scans include:
See also First Pass Scintigraphy, Myocardial Scintigraphy, Heart Scintigraphy, Whole Body Scintigraphy, and Flare Phenomenon.

A phantom is an artificial object of known size and composition that is imaged to test, adjust or monitor the linearity, sensitivity, homogeneity, imaging performance and geometric aspects of CT scanners, gamma cameras or other radiographic systems. A phantom can be a fluid-filled container or bottle including structures of various materials, sizes and shapes.

See also Daily Quality Assurance and Acceptance Checking.

Different stages of testing drugs in humans, from first application in humans through limited and broad clinical tests, to postmarketing studies. Preclinical trials are the testing in animals.