Quantitative computed tomography

Quantitative computed tomography (QCT) is a medical technique that measures bone mineral density (BMD) using a standard X-ray Computed Tomography (CT) scanner with a calibration standard to convert Hounsfield Units (HU) of the CT image to bone mineral density values. Quantitative CT scans are primarily used to evaluate bone mineral density at the lumbar spine and hip.

In general, solid phantoms placed in a pad under the patient during CT image acquisition are used for calibration. These phantoms contain materials that represent a number of different equivalent bone mineral densities. Usually either calcium hydroxyapatite (CaHAP) or potassium phosphate (K₂HPO₄) are used as the reference standard.

History

QCT was invented at University of California San Francisco (UCSF) during the 1970s. Douglas Boyd, PhD and Harry Genant, MD used a CT head scanner to do some of the seminal work on QCT. At the same time, CT imaging technology progressed rapidly and Genant and Boyd worked with one of EMI’s first whole body CT systems in the late 1970s and early 1980s to apply the quantitative CT method to the spine, coining the term "QCT." Genant later published several articles on spinal QCT in the early 1980s with Christopher E. Cann, PhD. Today, QCT is being used in hundreds of medical imaging centers around the world, both clinically and as a powerful research tool.

QCT (Quanta Cloud Technology)

QCT (Quanta Cloud Technology) is a manufacturer of data center hardware and a provider of cloud solutions that are used by hyperscale data center operators, such as Facebook and Rackspace.

In conjunction with its parent company, Quanta Computer, QCT sells approximately one out of every seven servers manufactured in the world.

QCT is an early contributor to the Open Compute Project, a non-profit organization launched by Facebook engineers to open source the designs of data center products. QCT manufactured the Facebook servers that were among the first designs under the project.

In addition to its headquarters in Taoyuan, Taiwan, QCT has offices in San José, Seattle, Beijing, Hangzhou and Tokyo.

History

QCT is a subsidiary of Quanta Computer Inc., a Fortune Global 500 technology engineering and manufacturing company. Quanta Computer, an original design manufacturer founded in 1988. In May 2012, Quanta Computer launched QCT to offer data center products and services under its own brands.