Bone densitometry measures the strength and density of bones. Changes in trabecular bone mineral density (BMD) is an early indicator of change in metabolic function. Bone densitometry measures the amount of calcium in regions of the bones. A bone densitometer is used to determine the risk of developing osteoporosis and can also be used to estimate a patient's risk of fracture.
Bone densitometry methods involve:
Dual energy x-rays (DEXA) or CT scans (Osteo CT or QCT) compare the numerical density of the bone (calculated from the image), with empirical data bases of bone density. DEXA is widely available and has an accuracy between those of QCT and ultrasound.

(Radioactive Seed Implantation Therapy) Brachytherapy is a type of radiation therapy in which a sealed source (encapsulated radionuclide) is placed inside the patient as close as possible to the area being treated. The brachytherapy source delivers usually gamma or beta radiation at a distance up to a few centimeters either by surface, intracavitary or interstitial application.

See also Low Dose Rate, Cryotherapy, RF Thermal Ablation and Prostate Ultrasound.

(DQA) This procedure is used by system operators to verify an x-ray system, gamma camera, or CT scanner operation based on relevant image quality parameters like e.g., geometric distortion, x-ray yield, signal to noise ratio. The quality assurance should carry out according to instructions of the manufacturer.

See also Acceptance Checking, Calibration and Calibration Factor.

The deep dose equivalent is related to the dose in tissue at a depth of one centimeter due to external radiation. Also called personnel dose equivalent at a depth of 1 cm. The unit for deep dose equivalent is J/kg or sievert (Sv).

Densitometry is a method to image the density of for example, the bones to measure the mineral content or lung tissue to quantify emphysema.
Densitometry is also used to control the optical density of x-ray films by shining light on the film and measuring the transmission with a densitometer.

See also Bone Densitometry and Osteo CT.