In physics, attenuation (in some contexts also called extinction) is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, X-rays are attenuated by lead, and light and sound are attenuated by water.n engineering, attenuation is usually measured in units of decibels per unit length of medium (dB/cm, dB/km, etc.) and is represented by the attenuation coefficient of the medium in question.
PET Scan (Skull to Mid-Thigh) Cost and Procedure Information. Positron Emission Tomography, also called a PET scan, is a diagnostic examination that involves the acquisition of physiologic images based on the detection of radiation from the emission of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient.
Inferior to the fifth lumbar vertebra (L5) are the sacrum and coccyx bones. The large, triangular-shaped sacrum (os sacrum) is composed of five vertebrae (S1 - S5) that fuse during early adulthood (18 - 30 years). The smaller coccyx (os coccygis) articulates with S5 and is also known as the tailbone. It consists of three to five vertebrae (C1 - C5) that are also usually fused.